Emmanuel Mignot

Abstract

Narcolepsy is a neurological disorder characterized by excessive daytime sleepiness, cataplexy, hypnagonic hallucinations, sleep paralysis, and disturbed nocturnal sleep patterns. Narcolepsy is caused by the loss of hypocretin (orexin)-producing neurons in the lateral hypothalamus. Evidence, such as a strong association with HLA DQB1*06:02, strongly suggests an autoimmune basis targeting hypocretin neurons. Genome-wide association studies have strengthened the association between narcolepsy and immune system gene polymorphisms, including the identification of polymorphisms in the T cell receptor alpha locus, TNFSF4 (also called OX40L), Cathepsin H (CTSH) the purinergic receptor P2RY11, and the DNA methyltransferase DNMT1. Recently, attention has been raised regarding a spike in cases of childhood narcolepsy in 2010 following the 2009 H1N1 pandemic (pH1N1) in China and vaccination with Pandemrix, an adjuvanted H1N1 vaccine that was used in Europe. How the immune system may be involved in disease initiation and/or progression remains a challenge to researchers. Potential immunological pathways that could lead to the specific elimination of hypocretin producing neurons include molecular mimicry or bystander activation, and are likely a combination of genetic and environmental factors, such as upper airway infections.

View details for DOI 10.1016/j.conb.2013.04.013

View details for PubMedID 23725858

Abstract

In recent years, a growing number of potential autoimmune disorders affecting neurons in the central nervous system have been identified, including narcolepsy. Narcolepsy is a lifelong sleep disorder characterized by excessive daytime sleepiness with irresistible sleep attacks, cataplexy (sudden bilateral loss of muscle tone), hypnagogic hallucinations, and abnormalities of Rapid Eye Movement sleep. Narcolepsy is generally a sporadic disorder and is caused by the loss of hypocretin (orexin)-producing neurons in the hypothalamus region of the brain. Studies have established that more than 90% of patients have a genetic association with HLA DQB1*06:02. Genome-wide association analysis shows a strong association between narcolepsy and polymorphisms in the TCR? locus and weaker associations within TNFSF4 (also called OX40L), Cathepsin H and the P2RY11-DNMT1 (purinergic receptor subtype P2Y11 to DNMT1, a DNA methytransferase) loci, suggesting an autoimmune basis. Mutations in DNMT1 have also been reported to cause narcolepsy in association with a complex neurological syndrome, suggesting the importance of DNA methylation in the pathology. More recently, narcolepsy was identified in association with seasonal streptococcus, H1N1 infections and following AS03-adjuvanted pH1N1 influenza vaccination in Northern Europe. Potential immunological pathways responsible for the loss of hypocretin producing neurons in these cases may be molecular mimicry or bystander activation. Specific autoantibodies or T cells cross-reactive with hypocretin neurons have not yet been identified, however, thus narcolepsy does not meet Witebsky's criteria for an autoimmune disease. As the brain is not an easily accessible organ, mechanisms of disease initiation and progression remain a challenge to researchers.

View details for DOI 10.1016/j.jaut.2013.02.003

View details for PubMedID 23497937

View details for DOI 10.1126/science.1237998

View details for PubMedID 23559238

Abstract

We analyzed the potential predictive factors for precocious puberty, observed in some cases of childhood narcolepsy with cataplexy (NC) and for obesity, a much more common feature of NC, through a systematic assessment of pubertal staging, body mass index (BMI), and metabolic/endocrine biochemical analyses.Cross-sectional on consecutive recruitment.Hospital sleep center and pediatric unit.Forty-three children and adolescents with NC versus 52 age-matched obese children as controls.N/A.Patients underwent clinical interview, polysomnographic recordings, cerebrospinal fluid hypocretin-1 measurement, and human leukocyte antigen typing. Height, weight, arterial blood pressure, and Tanner pubertal stage were evaluated. Plasma lipid and glucose profiles were analyzed. When an altered pubertal development was clinically suspected, plasma concentrations of hypothalamic-pituitary-gonadal axis hormones were determined. Children with NC showed a high prevalence of overweight/obesity (74%) and a higher occurrence of precocious puberty (17%) than obese controls (1.9%). Isolated signs of accelerated pubertal development (thelarche, pubic hair, advanced bone age) were also present (41%). Precocious puberty was significantly predicted by a younger age at first NC symptom onset but not by overweight/obesity or other factors. In addition, overweight/obesity was predicted by younger age at diagnosis; additional predictors were found for overweight/obesity (short disease duration, younger age at weight gain and lower high-density lipoprotein cholesterol), which did not include precocious puberty. NC symptoms, pubertal signs appearance, and body weight gain developed in close temporal sequence.NC occurring during prepubertal age is frequently accompanied by precocious puberty and overweight/obesity, suggesting an extended hypothalamic dysfunction. The severity of these comorbidities and the potential related risks require a multidiagnostic approach and a tailored therapeutic management.

View details for DOI 10.5665/sleep.2366

View details for Web of Science ID 000314393700006

View details for PubMedID 23372264

Abstract

In the diagnostic work-up of hypersomnias of central origin, the complaint of excessive daytime sleepiness should be objectively confirmed by MSLT findings. Indeed, the features and diagnostic utility of spontaneous daytime sleep at 24?h continuous polysomnography (PSG) have never been investigated. We compared daytime PSG features to MSLT data in 98 consecutive patients presenting with excessive daytime sleepiness and with a final diagnosis of narcolepsy with cataplexy/hypocretin deficiency (n?=?39), narcolepsy without cataplexy (n?=?7), idiopathic hypersomnia without long sleep time (n?=?19), and 'hypersomnia' with normal sleep latency at MSLT (n?=?33). Daytime sleep time was significantly higher in narcolepsy-cataplexy but similar in the other groups. Receiver operating characteristics (ROC) curves showed that the number of naps during daytime PSG predicted a mean sleep latency ?8?min at MSLT with an area under the curve of 0.67?±?0.05 (P?=?0.005). The number of daytime sleep-onset REM periods (SOREMPs) in spontaneous naps strikingly predicted the scheduled occurrence of two or more SOREMPs at MSLT, with an area under the ROC curve of 0.93?±?0.03 (P?

View details for DOI 10.1111/j.1365-2869.2012.01032.x

View details for Web of Science ID 000313732000005

View details for PubMedID 22716477

Abstract

Essential hypersomnia (EHS), a sleep disorder characterized by excessive daytime sleepiness, can be divided into two broad classes based on the presence or absence of the HLA-DQB1*06:02 allele. HLA-DQB1*06:02-positive EHS and narcolepsy with cataplexy are associated with the same susceptibility genes. In contrast, there are fewer studies of HLA-DQB1*06:02 negative EHS which, we hypothesized, involves a different pathophysiological pathway than does narcolepsy with cataplexy. In order to identify susceptibility genes associated with HLA-DQB1*06:02 negative EHS, we conducted a genome-wide association study (GWAS) of 125 unrelated Japanese EHS patients lacking the HLA-DQB1*06:02 allele and 562 Japanese healthy controls. A comparative study was also performed on 268 HLA-DQB1*06:02 negative Caucasian hypersomnia patients and 1761 HLA-DQB1*06:02 negative Caucasian healthy controls. We identified three SNPs that each represented a unique locus- rs16826005 (P = 1.02E-07; NCKAP5), rs11854769 (P = 6.69E-07; SPRED1), and rs10988217 (P = 3.43E-06; CRAT) that were associated with an increased risk of EHS in this Japanese population. Interestingly, rs10988217 showed a similar tendency in its association with both HLA-DQB1*06:02 negative EHS and narcolepsy with cataplexy in both Japanese and Caucasian populations. This is the first GWAS of HLA-DQB1*06:02 negative EHS, and the identification of these three new susceptibility loci should provide additional insights to the pathophysiological pathway of this condition.

View details for DOI 10.7717/peerj.66

View details for PubMedID 23646285

Abstract

We report on two sisters, 17 and 12 years of age, with clinical features suggesting narcolepsy with cataplexy (NC): daytime sleepiness, spontaneous and emotionally triggered sudden falls to the ground, and overweight/obesity. MSLT showed borderline sleep latency, with 1 and 0 sleep onset REM periods. HLA typing disclosed the DQB1*0602 allele. Video-polygraphy of the spells ruled out NC diagnosis by demonstrating their easy elicitation by suggestion, with wake EEG, electromyo-graphic persistence of muscle tone, and stable presence of tendon reflexes (i.e., pseudo-cataplexy), together with normal cerebrospinal hypocretin-1 levels. Our cases emphasize the need of a clear depiction of cataplexy pattern at the different ages, the usefulness of examining ictal neurophysiology, and collecting all available disease markers in ambiguous cases.Pizza F; Vandi S; Poli F; Moghadam KK; Fran-ceschini C; Bellucci C; Cipolli C; Ingravallo F; Natalini G; Mignot E; Plazzi G. Narcolepsy with cataplexy mimicry: the strange case of two sisters. J Clin Sleep Med 2013;9(6):611-612.

View details for DOI 10.5664/jcsm.2764

View details for PubMedID 23772196

Abstract

The aim of the study was to determine whether apolipoprotein E epsilon 4 genotype (APOE4) modifies the association of sleep disordered breathing (SDB) with cognitive function in a middle-aged population.Cross-sectional analysis of a community-dwelling cohort.Sleep laboratory at the Clinical Research Unit of the University of Wisconsin Hospitals and Clinics.There were 755 adults from the Wisconsin Sleep Cohort who provided a total of 1,843 polysomnography and cognitive evaluations (most participants were assessed multiple times at approximately 4-y intervals); 56% males, average age 53.9 years (range 30-81 years).None.In-laboratory overnight polysomnography was used to assess SDB. Cognition was evaluated by a battery of six neurocognitive tests assessing memory and learning, attention, executive function, and psychomotor efficiency. The APOE4 genotype (?3/?4 or ?4/ ?4) was identified in 200 participants. Data were analyzed using linear mixed-effects models, accounting for multiple observations per participant. Cognitive test scores were regressed on SDB categories (AHI < 5, 5 ? AHI < 15, AHI ? 15); APOE4 and their interaction; and age, education, sex, and body mass index. There was no statistically significant association between SDB and cognitive performance among APOE4-negative individuals. However, in APOE4-positive individuals, those with AHI ? 15 had significantly worse performance on the Auditory Verbal Learning Test and the Controlled Oral Word Association Test.In APOE4-positive individuals, moderate to severe sleep disordered breathing (AHI ? 15) was associated with poorer performance on cognitive tests that require both memory and executive function engagement.

View details for DOI 10.5665/sleep.2714

View details for PubMedID 23729930

Abstract

Kleine-Levin syndrome is a rare sleep disorder that mainly affects adolescents and is characterised by relapsing-remitting episodes of severe hypersomnia, cognitive impairment, apathy, derealisation, and psychiatric and behavioural disturbances. Boys are more frequently affected than girls. Just over half of patients have hyperphagia, are hypersexual (mainly boys), or have depressed mood (mainly girls), and 30% become anxious, delusional, and have hallucinations. Although some symptoms are similar to those in patients with encephalopathy, imaging and laboratory findings are unremarkable. The first episode of hypersomnia is often triggered by an infection, with relapses occurring every 1-12 months for a median of 14 years; disease duration can be much longer with childhood or adult onset than in patients with adolescent onset. Between episodes, patients generally have normal sleep patterns, cognition, mood, and eating habits. During episodes, electroencephalography might show diffuse or local slow activity. Functional imaging studies have revealed hypoactivity in thalamic and hypothalamic regions, and in the frontal and temporal lobes. Stimulants and mood stabilisers can be beneficial in the treatment of severe cases.

View details for Web of Science ID 000309634300016

View details for PubMedID 22995695

Abstract

Narcolepsy and other syndromes associated with excessive daytime sleepiness can be challenging to treat. New classifications now distinguish narcolepsy/hypocretin deficiency (also called type 1 narcolepsy), a lifelong disorder with well-established diagnostic procedures and etiology, from other syndromes with hypersomnolence of unknown causes. Klein-Levin Syndrome, a periodic hypersomnia associated with cognitive and behavioral abnormalities, is also considered a separate entity with separate therapeutic protocols. Non hypocretin-related hypersomnia syndromes are diagnoses of exclusion. These diagnoses are only made after eliminating sleep deprivation, sleep apnea, disturbed nocturnal sleep, and psychiatric comorbidities as the primary cause of daytime sleepiness. The treatment of narcolepsy/hypocretin deficiency is well-codified, and involves pharmacotherapies using sodium oxybate, stimulants, and/or antidepressants, plus behavioral modifications. These therapies are almost always needed, and the risk-to-benefit ratio is clear, notably in children. Detailed knowledge of the pharmacological profile of each compound is needed to optimize use. Treatment for other syndromes with hypersomnolence is more challenging and less codified. Preferably, therapy should be conservative (such as modafinil, atomoxetine, behavioral modifications), but it may have to be more aggressive (high-dose stimulants, sodium oxybate, etc.) on a case-by-case, empirical trial basis. As cause and evolution are unknown in these conditions, it is important to challenge diagnosis and therapy over time, keeping in mind the possibility of tolerance and the development of stimulant addiction. Kleine-Levin Syndrome is usually best left untreated, although lithium can be considered in severe cases with frequent episodes. Guidelines are provided based on the literature and personal experience of the author.

View details for DOI 10.1007/s13311-012-0150-9

View details for Web of Science ID 000310325000007

View details for PubMedID 23065655

View details for DOI 10.1007/s13311-012-0153-6

View details for Web of Science ID 000310325000001

View details for PubMedID 23070732

View details for DOI 10.1212/WNL.0b013e31825dce03

View details for Web of Science ID 000306176000021

View details for PubMedID 22722630

Abstract

Central nervous system (CNS) histamine is low in individuals with narcolepsy, a disease characterized by severe fragmentation of both sleep and wake. We have developed a primate model, the squirrel monkey, with which we can examine the role of the CNS in the wake-consolidation process, as these primates are day-active, have consolidated wake and sleep and have cerebrospinal fluid (CSF) that is readily accessible. Using this model and three distinct protocols, we report herein on the role of CNS histamine in the wake consolidation process. CSF histamine has a robust daily rhythm, with a mean of 24.9?±?3.29?pg?mL(-1) , amplitude of 31.7?±?6.46?pg?mL(-1) and a peak at 17:49?± 70.3?min (lights on 07:00-19:00?hours). These levels are not significantly affected by increases (up to 161?±?40.4% of baseline) or decreases (up to 17.2?±?2.50% of baseline) in locomotion. In direct contrast to the effects of sleep deprivation in non-wake-consolidating mammals, in whom CSF histamine increases, pharmacologically induced sleep (?-hydroxybutyrate) and wake (modafinil) have no direct effects on CSF histamine concentrations. These data indicate that the time-course of histamine in CSF in the wake-consolidated squirrel monkey is robust against variation in activity and sleep and wake-promoting pharmacological compounds, and may indicate that histamine physiology plays a role in wake-consolidation such as is present in the squirrel monkey and humans.

View details for DOI 10.1111/j.1365-2869.2011.00957.x

View details for Web of Science ID 000301931500010

View details for PubMedID 21910776

Abstract

The association of narcolepsy-cataplexy, a sleep disorder caused by the loss of hypocretin/orexin neurons in the hypothalamus, with DQA1*01:02-DQB1*06:02 is one of the tightest known single-allele human leukocyte antigen (HLA) associations. In this study, we explored genome-wide expression in peripheral white blood cells of 50 narcolepsy versus 47 controls (half of whom were DQB1*06:02 positive) and observed the largest differences between the groups in the signal from HLA probes. Further studies of HLA-DQ expression (mRNA and protein in a subset) in 125 controls and 147 narcolepsy cases did not reveal any difference, a result we explain by the lack of proper control of allelic diversity in Affymetrix HLA probes. Rather, a clear effect of DQB1*06:02 allelic dosage on DQB1*06:02 mRNA levels (1.65-fold) and protein (1.59-fold) could be demonstrated independent of disease status. These results indicate that allelic dosage is transmitted into changes in heterodimer availability, a phenomenon that may explain the increased risk for narcolepsy in DQB1*06:02 homozygotes versus heterozygotes.

View details for DOI 10.1016/j.humimm.2012.01.004

View details for Web of Science ID 000302986200014

View details for PubMedID 22326585

Abstract

Polymorphisms in the TCRA and P2RY11, two immune related genes, are associated with narcolepsy in Caucasians and Asians. In contrast, CPT1B/CHKB polymorphisms have only been shown to be associated with narcolepsy in Japanese, with replication in a small group of Koreans. Our aim was to study whether these polymorphisms are associated with narcolepsy and its clinical characteristics in Chinese patients with narcolepsy.We collected clinical data on 510 Chinese patients presenting with narcolepsy/hypocretin deficiency. Patients were included either when hypocretin deficiency was documented (CSF hypocretin-1?110 pg/ml, n=91) or on the basis of the presence of clear cataplexy and HLA-DQB1?0602 positivity (n=419). Genetic data was compared to typing obtained in 452 controls matched for geographic origin within China. Clinical evaluations included demographics, the Stanford Sleep Inventory (presence and age of onset of each symptom), and Multiple Sleep Latency Test (MSLT) data.Chinese narcolepsy was strongly and dose dependently associated with TCRA (rs1154155C) and P2RY11 (rs2305795A) but not CPT1B/CHKB (rs5770917C) polymorphisms. CPT1B/CHKB polymorphisms were not associated with any specific clinical characteristics. TCRA rs1154155A homozygotes (58 subjects) had a later disease onset, but this was not significant when corrected for multiple comparisons, thus replication is needed. CPT1B/CHKB or P2RY11 polymorphisms were not associated with any specific clinical characteristics.The study extends on the observation of a strong multiethnic association of polymorphisms in the TCRA and P2RY11 with narcolepsy, but does not confirm the association of CPT1B/CHKB (rs5770917) in the Chinese population.

View details for DOI 10.1016/j.sleep.2011.06.020

View details for Web of Science ID 000301695600008

View details for PubMedID 22177342

Abstract

Hypocretin (orexin) is a unique neuropeptide involved in the consolidation of wakefulness and sleep. Although hypocretin-1 levels in the cerebrospinal fluid (CSF) are stable after infancy, how levels change in preterm and term human infants is unknown.Hypocretin-1 levels were measured in CSF samples, obtained from 284 preterm (25-37 gestational weeks) and full-term infants in the first 4 months of life and 35 older children (ages 0.5-13 years), in a tertiary hospital.Detailed clinical and laboratory data were collected for each of the 319 participants. Based on that data, 108 neurologically intact children were selected (95 infants [43 preterm and 52 term] and 13 older children). CSF hypocretin-1 was measured by direct radioimmunoassay. Hypocretin-1 levels at the first weeks of the 3rd embryonic trimester (gestational age [GA] 28-34 weeks) were 314 ± 65 pg/mL (n = 17). The levels linearly increased during the third trimester and early infancy (r = 0.6), peaking in infants of 2-4 months ages (476 ± 72 pg/mL; n = 16) and decreasing thereafter; hypocretin levels in 2- to 4-month-old infants were significantly higher than those in children 0.5-13 years old (353 ± 78 pg/mL, n = 13; P = 0.0001).The present findings indicate that in human infants, CSF hypocretin-1 increases during the third embryonic trimester and is highest at 4 months of life. Thereafter, and consistent with previously published results, hypocretin levels are lower and stable until the geriatric age. This pattern may reflect the role of hypocretin in the dramatic process of sleep and wakefulness consolidation that occurs during early infancy.

View details for DOI 10.5665/sleep.1618

View details for Web of Science ID 000299779800005

View details for PubMedID 22294808

Abstract

Narcolepsy with cataplexy is characterized by daytime sleepiness, cataplexy (sudden loss of bilateral muscle tone triggered by emotions), sleep paralysis, hypnagogic hallucinations and disturbed nocturnal sleep. Narcolepsy with cataplexy is most often associated with human leucocyte antigen-DQB1*0602 and is caused by the loss of hypocretin-producing neurons in the hypothalamus of likely autoimmune aetiology. Noting that children with narcolepsy often display complex abnormal motor behaviours close to disease onset that do not meet the classical definition of cataplexy, we systematically analysed motor features in 39 children with narcolepsy with cataplexy in comparison with 25 age- and sex-matched healthy controls. We found that patients with narcolepsy with cataplexy displayed a complex array of 'negative' (hypotonia) and 'active' (ranging from perioral movements to dyskinetic-dystonic movements or stereotypies) motor disturbances. 'Active' and 'negative' motor scores correlated positively with the presence of hypotonic features at neurological examination and negatively with disease duration, whereas 'negative' motor scores also correlated negatively with age at disease onset. These observations suggest that paediatric narcolepsy with cataplexy often co-occurs with a complex movement disorder at disease onset, a phenomenon that may vanish later in the course of the disease. Further studies are warranted to assess clinical course and whether the associated movement disorder is also caused by hypocretin deficiency or by additional neurochemical abnormalities.

View details for DOI 10.1093/brain/awr244

View details for PubMedID 21930661

Abstract

The loss of hypothalamic hypocretin/orexin (hcrt) producing neurons causes narcolepsy with cataplexy. An autoimmune basis for the disease has long been suspected and recent results have greatly strengthened this hypothesis. Narcolepsy with hcrt deficiency is now known to be associated with a Human Leukocyte Antigen (HLA) and T-cell receptor (TCR) polymorphisms, suggesting that an autoimmune process targets a single peptide unique to hcrt-cells via specific HLA-peptide-TCR interactions. Recent data have shown a robust seasonality of disease onset in children and associations with Streptococcus Pyogenes, and influenza A H1N1-infection and H1N1-vaccination, pointing towards processes such as molecular mimicry or bystander activation as crucial for disease development. We speculate that upper airway infections may be common precipitants of a whole host of CNS autoimmune complications including narcolepsy.

View details for DOI 10.1016/j.conb.2011.09.003

View details for Web of Science ID 000299972600011

View details for PubMedID 21963829

View details for DOI 10.1093/brain/awr244

View details for Web of Science ID 000298189800007

Abstract

To assess the prevalence of sleep related-eating disorder (SRED) and nocturnal smoking (NS) in patients with narcolepsy with cataplexy (NC).Case-control study.University hospital.65 consecutive adult NC patients (33 men; mean age 43.9 ± 19.2 years) and 65 age-, sex-, and geographical origin-matched controls.Validated questionnaires were used to investigate SRED, NS, restless legs syndrome (RLS), and psychopathological traits (using Eating Disorder Inventory-2 [EDI-2]; Maudsley Obsessive-Compulsive Inventory [MOCI]; and Beck Depression Inventory [BDI]).NC patients showed a higher prevalence of SRED (32% vs 3%, P=0.00001), NS (21% vs 0%, P=0.00006), and RLS (18% vs 5%, P=0.013) than controls. Moreover, NC patients presented more frequently with an eating-related pathological profile on the EDI-2 (80% vs 46%, P=0.00006) and had a higher prevalence of depressed mood on the BDI (41% vs 18%, P=0.004). In comparison to patients without SRED, NC patients with SRED were more frequently women (71% vs 39%, P=0.013), had higher "bulimic" (29% vs 2%, P=0.004) and "social insecurity" (48% vs 18%, P=0.013) traits on the EDI-2, had higher obsessive-compulsiveness on the MOCI (29% vs 4%, P = 0.009), and were more depressed on the BDI (67% vs 29%, P=0.005). NC patients with NS showed more frequent pathological profiles on the EDI-2 (100% vs 75%, P=0.035), including the "bulimic" (29% vs 6%, P=0.015), "perfectionism" (43% vs 14%, P=0.016), and "social insecurity" (50% vs 22, P=0.035) profiles.Our study shows a strong association of the compulsive nocturnal behaviors SRED and NS with adult NC.

View details for DOI 10.5665/SLEEP.1280

View details for Web of Science ID 000295624800013

View details for PubMedID 21966068

Abstract

Streptococcal infections are known to trigger autoimmune disorders, affecting millions worldwide. Recently, we found an association between post-streptococcal autoantibodies against Protein Disulphide Isomerase (PDI), an enzyme involved in insulin degradation and insulin resistance. This led us to evaluate associations between post-streptococcal antibodies and metabolic syndrome, as defined by the updated National Cholesterol Education Program definition, 2005.Metabolic data (HDL, triglycerides, fasting glucose, blood pressure, waist circumference, BMI, smoking), post-streptococcal antibodies (anti-Streptolysin O (ASO) and anti-PDI), and C-reactive protein (CRP, as a general inflammatory marker), were assessed in 1156 participants of the Wisconsin Sleep Cohort Study. Anti-PDI antibodies were found in 308 participants (26.6%), ASO?100 in 258 (22.3%), and 482 (41.7%) met diagnostic criteria for metabolic syndrome. Anti-PDI antibodies but not ASO were significantly associated with metabolic syndrome [n?=?1156, OR 1.463 (95% CI 1.114, 1.920), p?=?0.0062; adjusted for age, gender, education, smoking]. Importantly, the anti-PDI-metabolic syndrome association remained significant after adjusting for CRP and fasting insulin.Post-streptococcal anti-PDI antibodies are associated with metabolic syndrome regardless of fasting insulin and CRP levels. Whereas these data are in line with a growing body of evidence linking infections, immunity and metabolism, additional studies are necessary to establish the post-streptococcal-metabolic syndrome association.

View details for DOI 10.1371/journal.pone.0025017

View details for Web of Science ID 000295260400036

View details for PubMedID 21949836

Abstract

Restless legs syndrome (RLS) is a sensorimotor disorder with an age-dependent prevalence of up to 10% in the general population above 65 years of age. Affected individuals suffer from uncomfortable sensations and an urge to move in the lower limbs that occurs mainly in resting situations during the evening or at night. Moving the legs or walking leads to an improvement of symptoms. Concomitantly, patients report sleep disturbances with consequences such as reduced daytime functioning. We conducted a genome-wide association study (GWA) for RLS in 922 cases and 1,526 controls (using 301,406 SNPs) followed by a replication of 76 candidate SNPs in 3,935 cases and 5,754 controls, all of European ancestry. Herein, we identified six RLS susceptibility loci of genome-wide significance, two of them novel: an intergenic region on chromosome 2p14 (rs6747972, P?=?9.03 × 10(-11), OR?=?1.23) and a locus on 16q12.1 (rs3104767, P?=?9.4 × 10(-19), OR?=?1.35) in a linkage disequilibrium block of 140 kb containing the 5'-end of TOX3 and the adjacent non-coding RNA BC034767.

View details for DOI 10.1371/journal.pgen.1002171

View details for Web of Science ID 000293338600020

View details for PubMedID 21779176

Abstract

To retrospectively describe childhood presentations of primary hypersomnia with an emphasis on narcolepsy-cataplexy in a Chinese population.A total of 417 children (< 18 years old) successively presenting with complaints of hypersomnia without anatomic cause or sleep apnea risk were evaluated using the Stanford Sleep Inventory, human leukocyte antigen (HLA) DQB1*0602 typing, and MSLT recordings. CSF hypocretin-1 was measured in 47 cases to document hypocretin deficiency. A subgroup ("narcolepsy/hypocretin deficiency") with likely hypocretin deficiency (low hypocretin-1 or HLA positive with clear-cut cataplexy) was further examined for presentations prior to, around, or after puberty.Narcolepsy with (n = 361) or without (n = 17) cataplexy presented at an earlier age and with increased male predominance when compared to idiopathic hypersomnia (n = 39, P < 0.01). Nearly 70% of those with narcolepsy/hypocretin deficiency (n = 271) had disease onset before age 10 y, and 15% had onset before age 6, an unusually young age distribution. Onset was prior to puberty in 78% of cases. Clinical features were similar in presentations across puberty groups except for sleep paralysis, which increased in frequency with age/puberty. Mean sleep latency (MSL) decreased and the number of sleep onset REM periods (SOREMPs) increased with age/puberty, but MSLT diagnosis criteria (MSL ? 8 min, ? 2 SOREMPs) were similarly positive across groups. Familial clustering was present in only 1.7% of probands.In children presenting with a complaint of primary hypersomnia to a sleep clinic in China, 86% (361/417) meet criteria for narcolepsy with cataplexy. Puberty did not affect positivity on the MSLT as a diagnostic feature. Sleep paralysis was the only symptom that increased with increasing age. In addition, narcolepsy with cataplexy in our clinic population appeared to begin at a younger age than usually reported in other studies.

View details for Web of Science ID 000291145800013

View details for PubMedID 21532956

Abstract

Nondipping nocturnal blood pressure (BP) is associated with target organ damage and cardiovascular disease. We hypothesized that ?1- and ?2-AR-associated single nucleotide polymorphisms (SNPs) would associate with nondipping BP patterns. Participants (n = 497, age range 30-74 years, 40% female) of the Wisconsin Sleep Cohort Study with at least one ambulatory BP monitoring test were included. Nondipping was defined as less than a 10% dip in sleep BP compared with wake BP. Dipping ratios were calculated as sleep/wake BP. Single nucleotide polymorphisms in the ?1-AR (rs7076938, tagging for Gly389Arg) and ?2-AR (rs17778257 and rs2400707, tagging for Arg16Gly and Gln27Glu) were selected. ?2-AR SNP rs2400707 A-positive subjects (tagging for Glu27) had higher systolic and diastolic dipping ratios in a dose-response fashion. Systolic dipping ratios were: GG = 0.846; AG = 0.854; AA = 0.861 (P = .015). Diastolic dip ratios were: GG = 0.807; AG = 0.815; AA = 0.824 (P = .026). The ?2-AR rs17778257/rs2400707 A/A haplotype was associated with dipping ratios and systolic nondipping status (nondipping odds radio 2.0 [1.0-3.8] for A/A versus A/G). Results were similar when models included participants on antihypertensive medications. Higher dipping ratios indicating a lack of nocturnal BP dipping are associated with ?2-AR polymorphisms. Nocturnal dipping patterns may be modulated by ?2-AR polymorphisms.

View details for DOI 10.1016/j.jash.2011.01.005

View details for Web of Science ID 000289136500007

View details for PubMedID 21414566

Abstract

The hypocretin (also known as orexin) neuropeptide system coordinates the regulation of various physiological processes. A reduction in Nr6a1 expression was observed in hypocretin neuron-ablated transgenic mice. To show that prepro-hypocretin transcription is functionally modulated by NR6A1, we performed chromatin immunoprecipitation (ChIP) analysis, double-immunostaining, a luciferase reporter assay, and an in utero electroporation study. ChIP analysis showed that endogenous NR6A1 binds to a putative NR6A1-binding site. Double-immunostaining indicated almost all hypocretin neurons were positive for NR6A1 immunoreactivity. NR6A1 overexpression in SH-SY5Y cells modulated hypocretin promoter activity, an effect that was countered by lacking a putative NR6A1-binding site. Electroporation with Nr6a1 in the foetal hypothalamus promoted hypocretin transcription as compared to GFP-electroporation. These experiments confirmed that NR6A1 works as a regulator for hypocretin transcription.

View details for DOI 10.1016/j.bbrc.2010.11.001

View details for Web of Science ID 000285534500004

View details for PubMedID 21056546

Abstract

to report on symptoms and therapies used in childhood narcolepsy-cataplexy.retrospective series of 51 children who completed the Stanford Sleep Inventory. HLA-DQB1*0602 typing (all tested, and 100% positive), polysomnography or Multiple Sleep Latency Test (76%), and cerebrospinal fluid hypocretin-1 measurements (26%, all with low levels) were also conducted. Prospective data on medication response was collected in 78% using a specially designed questionnaire.patients were separated into children with onset of narcolepsy prior to (53%), around (29%), and after (18%) puberty. None of the children had secondary narcolepsy. Clinical features were similar across puberty groups, except for sleep paralysis, which increased in frequency with age. Common features included excessive weight gain (84% ? 4 kg within 6 months of onset of narcolepsy) and earlier puberty (when compared with family members), notably in subjects who gained the most weight. Streptococcus-positive throat infections were reported in 20% of cases within 6 months of onset of narcolepsy. Polysomnographic features were similar across groups, but 3 prepubertal children did not meet Multiple Sleep Latency Test diagnostic criteria. Regarding treatment, the most used and continued medications were modafinil (84% continued), sodium oxybate (79%), and venlafaxine (68%). Drugs such as methylphenidate, tricyclic antidepressants, or selective serotonin reuptake inhibitors were often tried but rarely continued. Modafinil was reported to be effective for treating sleepiness, venlafaxine for cataplexy, and sodium oxybate for all symptoms, across all puberty groups. At the conclusion of the study, half of children with prepubertal onset of narcolepsy were treated "off label" with sodium oxybate alone or with the addition of one other compound. In older children, however, most patients needed more than 2 drugs.this study reports on the clinical features of childhood narcolepsy and documents the safe use of treatments commonly used in adults in young children.

View details for Web of Science ID 000285212600009

View details for PubMedID 21102987

View details for Web of Science ID 000285212600003

View details for PubMedID 21102981

Abstract

The human leukocyte antigen (HLA) DQB1*0602 allele is closely associated with narcolepsy, a neurologic disorder characterized by excessive daytime sleepiness, fragmented sleep, and shortened REM sleep latency. We evaluated whether DQB1*0602 was a novel marker of interindividual differences by determining its relationship to sleep homeostatic, sleepiness, and cognitive responses to baseline and chronic partial sleep deprivation (PSD) conditions.Ninety-two DQB1*0602-negative and 37 DQB1*0602-positive healthy adults participated in a protocol of 2 baseline 10 hours time in bed (TIB) nights followed by 5 consecutive 4 hours TIB nights. DQB1*0602 allelic frequencies did not differ significantly between Caucasians and African Americans.During baseline, although DQB1*0602-positive subjects were subjectively sleepier and more fatigued, they showed greater sleep fragmentation, and decreased sleep homeostatic pressure and differentially sharper declines during the night (measured by non-REM EEG slow-wave energy [SWE]). During PSD, DQB1*0602-positive subjects were sleepier and showed more fragmented sleep, despite SWE elevation comparable to negative subjects. Moreover, they showed differentially greater REM sleep latency reductions and smaller stage 2 reductions, along with differentially greater increases in fatigue. Both groups demonstrated comparable cumulative decreases in cognitive performance.DQB1*0602 positivity in a healthy population may represent a continuum of some sleep-wake features of narcolepsy. DQB1*0602 was associated with interindividual differences in sleep homeostasis, physiologic sleep, sleepiness, and fatigue-but not in cognitive measures-during baseline and chronic PSD. Thus, DQB1*0602 may represent a genetic biomarker for predicting such individual differences in basal and sleep loss conditions.

View details for Web of Science ID 000283819600006

View details for PubMedID 20975052

Abstract

Neurons exhibit rhythmic activity that ultimately affects behavior such as sleep. In living zebrafish larvae, we used time-lapse two-photon imaging of the presynaptic marker synaptophysin in hypocretin/orexin (HCRT) neurons to determine the dynamics of synaptic modifications during the day and night. We observed circadian rhythmicity in synapse number in HCRT axons. This rhythm is regulated primarily by the circadian clock but is also affected by sleep deprivation. Furthermore, NPTX2, a protein implicated in AMPA receptor clustering, modulates circadian synaptic changes. In zebrafish, nptx2b is a rhythmic gene that is mostly expressed in hypothalamic and pineal gland cells. Arrhythmic transgenic nptx2b overexpression (hcrt:NPTX2b) increases synapse number and abolishes rhythmicity in HCRT axons. Finally, hcrt:NPTX2b fish are resistant to the sleep-promoting effects of melatonin. This behavioral effect is consistent with NPTX2b-mediated increased activity of HCRT circuitry. These data provide real-time in vivo evidence of circadian and homeostatic regulation of structural synaptic plasticity.

View details for DOI 10.1016/j.neuron.2010.09.006

View details for Web of Science ID 000283704200010

View details for PubMedID 20920793

View details for Web of Science ID 000282517000008

View details for PubMedID 20921547

Abstract

Sleep influences the cardiovascular, endocrine, and thermoregulatory systems. Each of these systems may be affected by the activity of hypocretin (orexin)-producing neurons, which are involved in the etiology of narcolepsy. We examined sleep in male rats, either hypocretin neuron-ablated orexin/ataxin-3 transgenic (narcoleptic) rats or their wild-type littermates. We simultaneously monitored electroencephalographic and electromyographic activity, core body temperature, tail temperature, blood pressure, electrocardiographic activity, and locomotion. We analyzed the daily patterns of these variables, parsing sleep and circadian components and changes between states of sleep. We also analyzed the baroreceptor reflex. Our results show that while core temperature and heart rate are affected by both sleep and time of day, blood pressure is mostly affected by sleep. As expected, we found that both blood pressure and heart rate were acutely affected by sleep state transitions in both genotypes. Interestingly, hypocretin neuron-ablated rats have significantly lower systolic and diastolic blood pressure during all sleep stages (non-rapid eye movement, rapid eye movement) and while awake (quiet, active). Thus, while hypocretins are critical for the normal temporal structure of sleep and wakefulness, they also appear to be important in regulating baseline blood pressure and possibly in modulating the effects of sleep on blood pressure.

View details for DOI 10.1152/japplphysiol.00516.2010

View details for Web of Science ID 000285344900016

View details for PubMedID 20705949

Abstract

Post-streptococcal autoimmunity affects millions worldwide, targeting multiple organs including the heart, brain, and kidneys. To explore the post-streptococcal autoimmunity spectrum, we used western blot analyses, to screen 310 sera from healthy subjects with (33%) and without (67%) markers of recent streptococcal infections [anti-Streptolysin O (ASLO) or anti-DNAse B (ADB)]. A 58 KDa protein, reacting strongly with post-streptococcal sera, was identified as Protein Disulfide Isomerase (PDI), an abundant protein with pleiotropic metabolic, immunologic, and thrombotic effects. Anti-PDI autoantibodies, purified from human sera, targeted similar epitopes in Streptolysin O (SLO, P51-61) and PDI (P328-338). The correlation between post-streptococcal status and anti-human PDI auto-immunity was further confirmed in a total of 2987 samples (13.6% in 530 ASLO positive versus 5.6% in 2457 ASLO negative samples, p<0.0001). Finally, anti-PDI auto-antibodies inhibited PDI-mediated insulin degradation in vitro (n?=?90, p<0.001), and correlated with higher serum insulin (14.1 iu/ml vs. 12.2 iu/ml, n?=?1215, p?=?0.039) and insulin resistance (Homeostatic Model Assessment (HOMA) 4.1 vs. 3.1, n?=?1215, p?=?0.004), in a population-based cohort. These results identify PDI as a major target of post-streptococcal autoimmunity, and establish a new link between infection, autoimmunity, and metabolic disturbances.

View details for DOI 10.1371/journal.pone.0012875

View details for Web of Science ID 000282091100004

View details for PubMedID 20886095

Abstract

Recent studies have found increased autoantibodies against Tribbles homolog 2 (anti-TRIB2) and anti-streptolysin O (ASO) in narcolepsy. In this study, we replicated this finding with a primary focus on recent onset cases.Participants included (1) 90 cases with cataplexy, (2) 57 cases without cataplexy, and (3) 156 age-sex matched controls, including 73 human leukocyte antigen (HLA)-DQB1*0602 allele carriers. A radioligand binding assay was used to detect anti-TRIB2 antibodies.Anti-TRIB2 antibodies were prevalent in HLA-DQB1*0602 positive cases with cataplexy (25.0% of 76) and rare in cases without cataplexy (3.5% of 57, OR = 9.2, 95% CI = 2.5 - 33.5, P = 6.0 x 10(-4)) or controls (4.5% of 156, OR = 7.1, 95% CI = 3.1 - 16.2, P = 9.3 x 10(-6)). Anti-TRIB2 positivity in controls was not associated with DQB1*0602. In DQB1*0602 narcolepsy-cataplexy cases, the presence of anti-TRIB2 was associated with short disease duration (2.3 years from cataplexy onset), with 41.0% positive in this group (OR = 7.4 versus cases with onset > 2.3 years, 95% CI = 1.9- 28.5, P = 9.0 x 10(-4)). Anti-TRIB2 positivity in 39 DQB1*0602 positive recent onset cases was associated with increased ASO antibody (> 200 IU) (OR = 6.2, 95% CI = 1.6 - 24.6, P = 0.01), but did not correlate with age, gender, or body mass index.Anti-TRIB2 autoantibodies are strongly associated with narcolepsy close to cataplexy onset (< or = 2.3 years). Anti-TRIB2 was rarely found in cases without cataplexy or with distant onset.

View details for Web of Science ID 000279365600006

View details for PubMedID 20614846

View details for DOI 10.1002/mds.23008

View details for Web of Science ID 000277311500023

View details for PubMedID 20131387

Abstract

To investigate the behavioural and neurophysiological pattern of cataplexy.Seven narcolepsy with cataplexy patients underwent daytime videopolygraphy using humorous movies or/and jokes to trigger cataplectic attacks.During segmental cataplectic attacks, EMG showed brief and irregular periods of silencing focally involving facial, neck, axial or limb muscles, sometimes coinciding with bursts of rapid eye movements. All patients enacted intentional movements in response to these segmental postural lapses. During global cataplectic attacks, EMG showed suppression of activity alternated with patterned enhancement, enhanced EMG activity in neck muscles preceding that of other cranial, axial and lower limb muscles. This waxing and waning EMG pattern ended with a complete body collapse and persistent muscle atonia. Breathing irregularities, heart rate (HR) instability and EEG desynchronization were observed during global cataplectic attacks without any appreciable blood pressure changes, but with HR deceleration and silencing of sympathetic skin response while in complete atonia. Patients subjectively perceived the involuntary postural lapses as startling and alarming.Cataplexy in our patients showed many of the features of tonic REM sleep.Cataplexy can be construed as a "freezing-like" perturbation of the orienting response with transient impairment of posture and movements resulting in a "patchwork-compromise-behaviour".

View details for DOI 10.1016/j.clinph.2009.10.012

View details for Web of Science ID 000274557700007

View details for PubMedID 19955018

View details for DOI 10.1016/j.sleep.2009.08.003

View details for Web of Science ID 000274321000022

View details for PubMedID 19846338

Abstract

In mammals, hypocretin/orexin (HCRT) neuropeptides are important sleep-wake regulators and HCRT deficiency causes narcolepsy. In addition to fragmented wakefulness, narcoleptic mammals also display sleep fragmentation, a less understood phenotype recapitulated in the zebrafish HCRT receptor mutant (hcrtr-/-). We therefore used zebrafish to study the potential mediators of HCRT-mediated sleep consolidation. Similar to mammals, zebrafish HCRT neurons express vesicular glutamate transporters indicating conservation of the excitatory phenotype. Visualization of the entire HCRT circuit in zebrafish stably expressing hcrt:EGFP revealed parallels with established mammalian HCRT neuroanatomy, including projections to the pineal gland, where hcrtr mRNA is expressed. As pineal-produced melatonin is a major sleep-inducing hormone in zebrafish, we further studied how the HCRT and melatonin systems interact functionally. mRNA level of arylalkylamine-N-acetyltransferase (AANAT2), a key enzyme of melatonin synthesis, is reduced in hcrtr-/- pineal gland during the night. Moreover, HCRT perfusion of cultured zebrafish pineal glands induces melatonin release. Together these data indicate that HCRT can modulate melatonin production at night. Furthermore, hcrtr-/- fish are hypersensitive to melatonin, but not other hypnotic compounds. Subthreshold doses of melatonin increased the amount of sleep and consolidated sleep in hcrtr-/- fish, but not in the wild-type siblings. These results demonstrate the existence of a functional HCRT neurons-pineal gland circuit able to modulate melatonin production and sleep consolidation.

View details for DOI 10.1073/pnas.906637106

View details for Web of Science ID 000272994200086

View details for PubMedID 19966231

Abstract

Melanin-concentrating hormone (MCH) regulates feeding and complex behaviors in mammals and pigmentation in fish. The relationship between fish and mammalian MCH systems is not well understood. Here, we identify and characterize two MCH genes in zebrafish, Pmch1 and Pmch2. Whereas Pmch1 and its corresponding MCH1 peptide resemble MCH found in other fish, the zebrafish Pmch2 gene and MCH2 peptide share genomic structure, synteny, and high peptide sequence homology with mammalian MCH. Zebrafish Pmch genes are expressed in closely associated but non-overlapping neurons within the hypothalamus, and MCH2 neurons send numerous projections to multiple MCH receptor-rich targets with presumed roles in sensory perception, learning and memory, arousal, and homeostatic regulation. Preliminary functional analysis showed that whereas changes in zebrafish Pmch1 expression correlate with pigmentation changes, the number of MCH2-expressing neurons increases in response to chronic food deprivation. These findings demonstrate that zebrafish MCH2 is the putative structural and functional ortholog of mammalian MCH and help elucidate the nature of MCH evolution among vertebrates.

View details for DOI 10.1002/cne.22171

View details for Web of Science ID 000271112000011

View details for PubMedID 19827161

Abstract

Using microarray analysis, in situ hybridization and immunocytochemistry, we found that the transcription factor TBX3 is produced in three discrete neuronal populations of the adult mouse brain, the arcuate nucleus (including in NPY but not dopaminergic neurons), the histaminergic tuberomammillary nucleus and in cholinergic neurons of the solitary tract nucleus. The immunoreactive protein had a nuclear location in these neurons, consistent with its function as a transcription factor. Although the function of tbx3 in these neurons is unknown, a review of the literature strongly suggests that these neuronal populations may be abnormal in Ulnar-Mammary syndrome patients with tbx3 mutations, explaining previously overlooked phenotypes in this syndrome, such as obesity, sexual dysfunction and possibly sleep abnormalities.

View details for DOI 10.1016/j.brainres.2009.08.101

View details for Web of Science ID 000272071600024

View details for PubMedID 19765559

Abstract

To contribute to the anthropometric and metabolic phenotyping of orexin-A-deficient narcoleptic patients, and to explore a possible risk of their developing a metabolic syndrome.We performed a cross-sectional study comparing metabolic alterations in patients with narcolepsy with cataplexy (NC) and patients with idiopathic hypersomnia without long sleep time.University hospital.Fourteen patients with narcolepsy with cataplexy and 14 sex and age-matched patients with idiopathic hypersomnia without long sleep time. Interventions: N/A.Metabolic parameters were evaluated by measuring body mass index (BMI), waist circumference (also with abdominal computed tomography), blood pressure, and daily calorie intake (3-day diary). Chronotypes were assessed through the morningness-eveningness questionnaire. Lumbar puncture for cerebrospinal fluid orexin-A determination and HLA typing were performed. Patients with narcolepsy with cataplexy (all HLA DQB1*0602 positive and with cerebrospinal fluid orexin-A levels < 110 pg/mL) had a higher BMI and BMI-independent metabolic alterations, namely waist circumference, high-density lipoprotein cholesterol, and glucose/insulin ratio (an insulin resistance index), with respect to patients with idiopathic hypersomnia without long sleep time (cerebrospinal fluid orexin-A levels > 300 pg/mL). Despite lower daily food intake, patients with narcolepsy with cataplexy displayed significant alterations in metabolic parameters resulting in a diagnosis of metabolic syndrome in more than half the cases.BMI-independent metabolic alterations and the relative hypophagia of patients with narcolepsy with cataplexy, as compared with patients with idiopathic hypersomnia without long sleep time, suggest that orexin-A influences the etiology of this phenotype. Moreover, considering that these dysmetabolic alterations are present from a young age, a careful metabolic follow-up of patients diagnosed with narcolepsy with cataplexy is mandatory.

View details for Web of Science ID 000271693700012

View details for PubMedID 19928388

Abstract

Hypocretin-1 is a hypothalamic neuropeptide that is important in the regulation of wake and the lack of which results in the sleep disorder narcolepsy. Using a monkey that has consolidated wake akin to humans, we examined pharmacological manipulation of sleep and wake and its effects on hypocretin physiology. Monkeys were given the sleep-inducing ?-hydroxybutyrate (GHB) and the wake-inducing modafinil both in the morning and in the evening. Cerebrospinal fluid hypocretin-1 concentrations changed significantly in response to the drugs only when accompanied by a behavioral change (GHB-induced sleep in the morning or modafinil-induced wake in the evening). We also found that there was a large (180-fold) interindividual variation in GHB pharmacokinetics that explains variability in sleep induction in response to the drug. Our data indicate that the neurochemical concomitants of sleep and wake are capable of changing the physiological output of hypocretin neurons. Sleep independent of circadian timing is capable of decreasing cerebrospinal fluid hypocretin-1 concentrations. Furthermore, hypocretin neurons do not seem to respond to an 'effort' to remain awake, but rather keep track of time spent awake as a wake-promoting counterbalance to extended wakefulness.

View details for DOI 10.1097/FBP.0b013e328331b9db

View details for Web of Science ID 000270483300010

View details for PubMedID 19752724

Abstract

Narcolepsy with cataplexy is characterised by excessive daytime sleepiness, sudden drops of muscle tone triggered by emotions, termed cataplexy, disrupted nocturnal sleep and other dissociated rapid eye movement (REM) sleep phenomena. Narcolepsy has been linked to a loss of hypothalamic neurons producing hypocretins, neuropeptides implicated in the regulation of the arousal system. Neuroimaging and neurometabolic studies have shown the pathophysiological involvement of other brain structures such as cerebral cortex and thalamus, but, overall with inconsistent results. We investigated, by using an advanced quantitative MR technique, proton MR spectroscopy ((1)H-MRS), the distribution of brain neurochemical abnormalities in narcolepsy with cataplexy patients. Single voxel (1)H-MRS study was performed in the thalamus, hypothalamus, and parietal-occipital cortex of hypocretin deficient, narcolepsy with cataplexy patients, HLA-DQB1*0602-positive, drug free. No significant changes were detected in the thalamus and parietal-occipital cortex of the patients. On the other hand, the neuronal marker N-acetyl-aspartate was reduced in the hypothalamus of narcolepsy with cataplexy patients compared to controls. These (1)H-MRS findings further support that in narcolepsy with cataplexy patients, the hypothalamus is the primary site of neural lesions. The absence of (1)H-MRS neurodegenerative changes in the thalamus and cerebral cortex suggests that the abnormalities detected in these brain regions by other neuroimaging techniques are likely of functional nature.

View details for DOI 10.1016/j.brainresbull.2009.05.010

View details for Web of Science ID 000270259300009

View details for PubMedID 19463917

Abstract

In this issue of Neuron, Vyazovskiy et al. reports on progressive changes in cortical unit activity within extended wakefulness and within extended sleep paralleling changes in EEG slow-wave sleep activity. Sleep debt may be integrated at the level of individual cortical neurons, providing support for the synaptic homeostasis theory.

View details for DOI 10.1016/j.neuron.2009.09.008

View details for Web of Science ID 000270569700004

View details for PubMedID 19778500

Abstract

The cause of hypocretin cell loss in human narcolepsy-cataplexy is unknown but has been suggested to be neurodegenerative in nature. To test this hypothesis, we evaluated the remaining hypocretin cells in human narcolepsy brains for the presence of aggregated protein inclusions, gliosis, and inflammation.Brains were examined by routine histologic methods for potential comorbid neurodegenerative diseases and through immunohistochemical screening for protein inclusions in the hypothalamus. Hypothalamic sections of 4 subjects with narcolepsy and 5 nonneurologic controls were examined immunohistochemically with antibodies against ubiquitin (a marker of aggregated protein), allograft inflammatory factor 1 (AIF1, a microglial activation marker), glial fibrillary acidic protein (GFAP, a reactive astrocytic marker), and hypocretin. Hypothalami of subjects with narcolepsy were additionally examined for the presence of known components of protein aggregates (tau, alpha-synuclein, amyloid beta, and TDP-43).Hypocretin cells were markedly decreased in all 4 subjects with narcolepsy. Ubiquitinated inclusions were not observed in the total of 96 remaining hypocretin cells in these subjects. Further, we noted that even in patients with dementia neuropathology, the lateral hypothalamic hypocretin area was spared from ubiquitinated inclusions. AIF1 and GFAP staining in the perifornical area was unremarkable.Our findings suggest that hypocretin cell loss does not involve ubiquitinated inclusions, the hallmark of most neurodegenerative diseases. The lack of increased markers of inflammation also argues against a progressive and continuous neurodegenerative process.

View details for DOI 10.1212/WNL.0b013e3181b2a6af

View details for Web of Science ID 000269038300005

View details for PubMedID 19687452

Abstract

Narcolepsy-cataplexy has long been thought to have an autoimmune origin. Although susceptibility to narcolepsy, like many autoimmune conditions, is largely genetically determined, environmental factors are involved based on the high discordance rate (approximately 75%) of monozygotic twins. This study evaluated whether Streptococcus pyogenes and Helicobacter pylori infections are triggers for narcolepsy.Retrospective, case-control.Sleep centers of general hospitals.200 patients with narcolepsy/hypocretin deficiency, with a primary focus on recent onset cases and 200 age-matched healthy controls. All patients were DQB1*0602 positive with low CSF hypocretin-1 or had clear-cut cataplexy.Participants were tested for markers of immune response to beta hemolytic streptococcus (anti-streptolysin O [ASO]; anti DNAse B [ADB]) and Helicobacter pylori [Anti Hp IgG], two bacterial infections known to trigger autoimmunity. A general inflammatory marker, C-reactive protein (CRP), was also studied. When compared to controls, ASO and ADB titers were highest close to narcolepsy onset, and decreased with disease duration. For example, ASO > or = 200 IU (ADB > or = 480 IU) were found in 51% (45%) of 67 patients within 3 years of onset, compared to 19% (17%) of 67 age matched controls (OR = 4.3 [OR = 4.1], P < 0.0005) or 20% (15%) of 69 patients with long-standing disease (OR = 4.0 [OR = 4.8], P < 0.0005]. CRP (mean values) and Anti Hp IgG (% positive) did not differ from controls.Streptococcal infections are probably a significant environmental trigger for narcolepsy.

View details for Web of Science ID 000268557600004

View details for PubMedID 19725248

Abstract

To examine whether cerebrospinal fluid (CSF) histamine contents are altered in human narcolepsy and whether these alterations are specific to hypocretin deficiency, as defined by low CSF hypocretin-1.Patients meeting the ICSD-2 criteria for narcolepsy with and without cataplexy and who had CSF hypocretin-1 results available were selected from the Stanford Narcolepsy Database on the basis of CSF availability and adequate age and sex matching across 3 groups: narcolepsy with low CSF hypocretin-1 (n=34, 100% with cataplexy), narcolepsy without low CSF hypocretin-1 (n=24, 75% with cataplexy), and normal controls (n=23). Low CSF hypocretin-1 was defined as CSF < or =110 pg/mL (1/3 of mean control values). Six of 34 patients with low CSF hypocretin-1, six of 24 subjects with normal CSF hypocretin-1, and all controls were unmedicated at the time of CSF collection. CSF histamine was measured in all samples using a fluorometric HPLC system.Mean CSF histamine levels were: 133.2 +/- 20.1 pg/mL in narcoleptic subjects with low CSF hypocretin-1, 233.3 +/- 46.5 pg/mL in patients with normal CSF hypocretin-1 (204.9 +/- 89.7 pg/mL if only patients without cataplexy are included), and 300.5 +/- 49.7 pg/mL in controls, reaching statistically significant differences between the 3 groups.CSF histamine levels are reduced in human narcolepsy. The reduction of CSF histamine levels was more evident in the cases with low CSF hypocretin-1, and levels were intermediate in other narcolepsy cases. As histamine is a wake-promoting amine known to decrease during sleep, decreased histamine could either passively reflect or partially mediate daytime sleepiness in these pathologies.

View details for Web of Science ID 000262890300008

View details for PubMedID 19238804

Abstract

Autonomic nervous system activity changes have been described during cataplexy as playing a role in triggering it. To confirm these previous findings, we investigated the time course of sympathetic and cardiovascular activities during cataplexy. We made for the first time microneurographic recordings of 10 cataplectic episodes in three patients with hypocretin-deficient narcolepsy. During microneurography, muscle sympathetic nerve activity (MSNA) was recorded simultaneously with heart rate (HR), respiratory movements, arterial finger blood pressure (BP), electroencephalography, electro-oculogram and superficial electromyogram. Results showed no significant autonomic changes before the onset of the cataplectic episodes. Cataplexy was associated with a significant increase in MSNA and BP compared with baseline, whereas HR was markedly decreased. An irregular breathing pattern mainly characterized by apnea typically occurred during the attacks. In conclusion, our findings did not show significant changes in autonomic activity prior to cataplexy onset, ruling out a triggering role of the autonomic system. However, cataplexy was associated with co-activation of sympathetic and parasympathetic autonomic systems, a pattern reminiscent of that reported during the vigilance reaction in animals.

View details for DOI 10.1111/j.1365-2869.2008.00672.x

View details for Web of Science ID 000261263300014

Abstract

Narcolepsy (hypocretin deficiency), a sleep disorder characterized by sleepiness, cataplexy and rapid eye movement (REM) sleep abnormalities, is tightly associated with HLA-DRB1*1501 (M17378) and HLA-DQB1*0602 (M20432). Susceptibility genes other than those in the HLA region are also likely involved. We conducted a genome-wide association study using 500K SNP microarrays in 222 Japanese individuals with narcolepsy and 389 Japanese controls, with replication of top hits in 159 Japanese individuals with narcolepsy and 190 Japanese controls, followed by the testing of 424 Koreans, 785 individuals of European descent and 184 African Americans. rs5770917, a SNP located between CPT1B and CHKB, was associated with narcolepsy in Japanese (rs5770917[C], odds ratio (OR) = 1.79, combined P = 4.4 x 10(-7)) and other ancestry groups (OR = 1.40, P = 0.02). Real-time quantitative PCR assays in white blood cells indicated decreased CPT1B and CHKB expression in subjects with the C allele, suggesting that a genetic variant regulating CPT1B or CHKB expression is associated with narcolepsy. Either of these genes is a plausible candidate, as CPT1B regulates beta-oxidation, a pathway involved in regulating theta frequency during REM sleep, and CHKB is an enzyme involved in the metabolism of choline, a precursor of the REM- and wake-regulating neurotransmitter acetylcholine.

View details for DOI 10.1038/ng.231

View details for Web of Science ID 000260501500025

View details for PubMedID 18820697

Abstract

We report on the outcome of intravenous high-dose immunoglobulin (IVIg) treatment in four children with narcolepsy and cataplexy, in whom the early diagnosis and the extreme disease severity were indications for this potentially efficacious therapy. One of four patients showed an objective and persistent improvement in clinical features during and after IVIg treatment. Our data partially support the recent report of the efficacy of IVIg treatment in early diagnosed narcolepsy with cataplexy and support the need for a controlled multicenter clinical trial on IVIg in narcolepsy.

View details for DOI 10.1007/s00415-008-0983-7

View details for Web of Science ID 000260877600016

View details for PubMedID 18769859

Abstract

To determine whether hypocretin receptor gene (hcrtR1 and hcrtR2) expression is affected after long-term hypocretin ligand loss in humans and animal models of narcolepsy.Animal and human study. We measured hcrtR1 and hcrtR2 expression in the frontal cortex and pons using the RT-PCR method in murine models (8-week-old and 27-week-old orexin/ataxin-3 transgenic (TG) hypocretin cell ablated mice and wild-type mice from the same litter, 10 mice for each group), in canine models (8 genetically narcoleptic Dobermans with null mutations in the hcrtR2, 9 control Dobermans, 3 sporadic ligand-deficient narcoleptics, and 4 small breed controls), and in humans (5 narcolepsy-cataplexy patients with hypocretin deficiency (average age 77.0 years) and 5 control subjects (72.6 years).27-week-old (but not 8-week-old) TG mice showed significant decreases in hcrtR1 expression, suggesting the influence of the long-term ligand loss on the receptor expression. Both sporadic narcoleptic dogs and human narcolepsy-cataplexy subjects showed a significant decrease in hcrtR1 expression, while declines in hcrtR2 expression were not significant in these cases. HcrtR2-mutated narcoleptic Dobermans (with normal ligand production) showed no alteration in hcrtR1 expression.Moderate declines in hcrtR expressions, possibly due to long-term postnatal loss of ligand production, were observed in hypocretin-ligand deficient narcoleptic subjects. These declines are not likely to be progressive and complete. The relative preservation of hcrtR2 expression also suggests that hypocretin based therapies are likely to be a viable therapeutic options in human narcolepsy-cataplexy.

View details for Web of Science ID 000258111000009

View details for PubMedID 18714784

Abstract

Concentrations of CSF hypocretin-1 (formerly orexin A) have been measured in many patients with sleep or neurological conditions. Low CSF hypocretin-1 is most predictive of narcolepsy in patients positive for HLA allele DQB1*0602, most of whom have cataplexy. By contrast, the diagnostic significance of low CSF hypocretin-1 is unclear in the presence of acute CNS inflammation or trauma. The clinical usefulness of CSF testing in hypersomnia that is symptomatic of a neurological disorder remains to be evaluated. Determination of CSF hypocretin-1 concentration to diagnose narcolepsy might be most useful in ambulatory patients with cataplexy but with a normal multiple sleep latency test (MSLT) result, or if MSLT is not interpretable, conclusive, or feasible. Because 98% of patients with hypocretin-1 deficiency are positive for HLA DQB1*0602, we suggest that HLA typing is a useful screen before lumbar puncture. Although hypocretin-1 deficiency in narcolepsy might have therapeutic relevance, additional research is needed in this area.

View details for Web of Science ID 000257213600021

View details for PubMedID 18565458

Abstract

Cataplexy is observed in a subset of patients with narcolepsy and affects approximately 1 in 2,000 persons. Cataplexy is most often triggered by strong emotions such as laughter, which can result in transient, yet debilitating, muscle atonia. The objective of this study was to examine the neural systems underlying humor processing in individuals with cataplexy.While undergoing functional Magnetic Resonance Imaging (fMRI), we showed ten narcolepsy-cataplexy patients and ten healthy controls humorous cartoons. In addition, we examined the brain activity of one subject while in a full-blown cataplectic attack. Behavioral results showed that participants with cataplexy rated significantly fewer humorous cartoons as funny compared to controls. Concurrent fMRI showed that patients, when compared to controls and in the absence of overt cataplexy symptoms, showed pronounced activity in the emotional network including the ventral striatum and hypothalamus while viewing humorous versus non-humorous cartoons. Increased activity was also observed in the right inferior frontal gyri--a core component of the inhibitory circuitry. In comparison, the one subject who experienced a cataplectic attack showed dramatic reductions in hypothalamic activity.These findings suggest an overdrive of the emotional circuitry and possible compensatory suppression by cortical inhibitory regions in cataplexy. Moreover, during cataplectic attacks, the hypothalamus is characterized by a marked decrease in activity similar to that observed during sleep. One possible explanation for these findings is an initial overdrive and compensatory shutdown of the hypothalamus resulting in full cataplectic symptoms.

View details for DOI 10.1371/journal.pone.0002225

View details for Web of Science ID 000262258700033

View details for PubMedID 18493621

Abstract

Down syndrome is characterized by a host of behavioral abnormalities including sleep disturbances. Sleep and EEG was studied at the age of 3 months in two mouse models of the condition, Ts65Dn and Ts1Cje, carrying one extra copy of partially overlapping segments of the mmu chromosome 16 (equivalent to the human chromosome 21). We found that the Ts65Dn mice showed increased waking amounts at the expense of non-REM sleep, increased theta power during sleep and a delayed sleep rebound after sleep deprivation. In contrast, Ts1Cje had limited sleep and EEG abnormalities, showing only a delayed sleep rebound after sleep deprivation and no difference in theta power. We previously found that mice over-expressing the human APPwt transgene, a gene triplicated in Ts65Dn but not Ts1Cje, also show increased wake and theta power during sleep. These results demonstrate abnormalities in sleep and EEG in Ts65Dn mice and underscore a possible correlation between App overexpression and hippocampal theta oscillations.

View details for DOI 10.1016/j.nbd.2007.07.014

View details for Web of Science ID 000254665100001

View details for PubMedID 18282758

View details for DOI 10.1016/j.smrv.2007.12.006

View details for Web of Science ID 000254992900001

View details for PubMedID 18342260

Abstract

Peripherin, a type III neuronal intermediate filament, is widely expressed in neurons of the peripheral nervous system and in selected central nervous system hindbrain areas with projections towards peripheral structures, such as cranial nerves and spinal cord neurons. Peripherin appears to play a role in neurite elongation during development and axonal regeneration, but its exact function is not known. We noticed high peripherin expression in the posterior hypothalamus of mice, and decided to investigate further the exact location of expression and function of peripherin in the mouse posterior hypothalamus.In situ hybridization indicated expression of peripherin in neurons with a distribution reminiscent of the histaminergic neurons, with little signal in any other part of the forebrain. Immunocytochemical staining for histidine decarboxylase and peripherin revealed extensive colocalization, showing that peripherin is produced by histaminergic neurons in all parts of the tuberomammillary nucleus. We next used histamine immunostaining in peripherin knockout, overexpressing and wild type mice to study if altered peripherin expression affects these neurons, but could not detect any visible difference in the appearance of these neurons or their axons. Peripherin knockout mice and heterozygotic littermates were used for measurement of locomotor activity, feeding, drinking, and energy expenditure. Both genotypes displayed diurnal rhythms with all the parameters higher during the dark period. The respiratory quotient, an indicator of the type of substrate being utilized, also exhibited a significant diurnal rhythm in both genotypes. The diurnal patterns and the average values of all the recorded parameters for 24 h, daytime and night time were not significantly different between the genotypes, however.In conclusion, we have shown that peripherin is expressed in the tuberomammillary neurons of the mouse hypothalamus. Monitoring of locomotor activity, feeding, drinking, and energy expenditure in mice either lacking or overexpressing peripherin did not reveal any difference, so the significance of peripherin in these neurons remains to be determined. The complete overlap between histidine decarboxylase and peripherin, both the protein and its mRNA, renders peripherin a useful new marker for histaminergic neurons in the hypothalamus.

View details for DOI 10.1186/1471-2202-9-26

View details for Web of Science ID 000253966200001

View details for PubMedID 18294400

Abstract

Patients with myotonic dystrophy type 1 (DM1) frequently have symptoms of excessive daytime sleepiness (EDS). Some patients with DM1 show sleep-onset REM, similar to that observed in narcolepsy. Narcolepsy is characterized by impaired hypocretin (Hcrt) neurotransmission.To test for dysregulation of Hcrt neurotransmission in a prospective cohort of patients with DM1.Hcrt levels in CSF were measured by radioimmunoassay. Sleep physiology was assessed by overnight polysomnography (PSG) and a multiple sleep latency test (MSLT). Splicing of Hcrt receptor 1 and 2 (HcrtR1 and HcrtR2) mRNA was examined in postmortem samples of temporal cortex.Seventeen of 38 patients with DM1 reported symptoms of EDS. Among patients with DM1 with EDS who underwent PSG/MSLT, 7 of 13 showed reduced sleep latency, sleep-onset REM, or both. However, CSF Hcrt levels in DM1 (mean 277 pg/mL, n = 38) were not different from controls (mean 277 pg/mL, n = 33). Also, splicing of HcrtR1 and HcrtR2 mRNA in patients with DM1 was similar to controls.Excessive daytime sleepiness and dysregulation of REM sleep occur frequently in patients with myotonic dystrophy type 1 (DM1). However, the pathophysiologic basis is distinct from narcolepsy, as patients with DM1 do not have a consistent defect of Hcrt release or receptor splicing.

View details for Web of Science ID 000252505000012

View details for PubMedID 18195268

Abstract

More than one in three adult patients suffering from narcolepsy-cataplexy experience rapid eye movement (REM) behavior disorder (RBD), while RBD in childhood is extremely rare. We present the cases of two girls (aged 9 and 7 years old) with narcolepsy-cataplexy, in whom RBD was one of the first symptoms of the disease. The coincidence of RBD was seen by nocturnal video-polysomnography (v-PSG), and narcolepsy was diagnosed from short sleep latency and multiple sleep onset REMs (SOREMs) during a multiple sleep latency test (MSLT). Both girls were human leukocyte antigen (HLA)-DQB1 *0602 positive, and their cerebrospinal fluid (CSF) hypocretin level (Hcrt-1) was extremely low.

View details for DOI 10.1016/j.sleep.2006.11.018

View details for Web of Science ID 000250794300015

View details for PubMedID 17569582

Abstract

The hypocretin/orexin (HCRT/ORX) excitatory neuropeptides are expressed in a small population of lateral hypothalamic cells in mammals and fish. In humans, loss of these cells causes the sleep disorder narcolepsy. Identification of genes expressed in HCRT-producing cells may be revealing as to the regulation of sleep and the pathophysiology of narcolepsy. In this study, in situ hybridization analyses were performed to characterize the expression pattern of receptors and enzyme, which regulate ATP-mediated transmission in hypocretin cells of zebrafish larvae. The zebrafish cDNA encoding the ecto-nucleoside triphosphate diphosphohydrolase 3 (ENTPD3/NTPDase3) was isolated. This transcript was found to be expressed in zebrafish HCRT cells as previously reported in mammals. It was also expressed in the cranial nerves (gV, gVII, gIV and gX) and in primary sensory neurons (i.e., Rohon-Beard neurons) in the spinal cord. The expression of known zebrafish p2rx purinergic receptor family members was next studied and found to overlap with the entpd3 expression pattern. Specifically, p2rx2, p2rx3.1, p2rx3.2 and p2rx8 were expressed in the trigeminal ganglia and subsets of Rohon-Beard neurons. In contrast to mammals, p2rx2 was not expressed in HCRT cells; rather, p2rx8 was expressed with entpd3 in this hypothalamic region. The conservation of expression of these genes in HCRT cells and sensory neurons across vertebrates suggests an important role for ATP mediated transmission in the regulation of sleep and the processing of sensory inputs.

View details for DOI 10.1016/j.brainres.2007.06.103

View details for Web of Science ID 000250612200008

View details for PubMedID 17868657

Abstract

The neuropeptides hypocretins (orexins), the loss of which results in the sleep disorder narcolepsy, are hypothesized to be involved in the consolidation of wakefulness and have been proposed to be part of the circadian-driven alertness signal. To elucidate the role of hypocretins in the consolidation of human wakefulness we examined the effect of wake extension on hypocretin-1 in squirrel monkeys, primates that consolidate wakefulness during the daytime as do humans. Wake was extended up to 7 h with hypocretin-1, cortisol, ghrelin, leptin, locomotion, and feeding, all being assayed. Hypocretin-1 (P < 0.01), cortisol (P < 0.001), and locomotion (P < 0.005) all increased with sleep deprivation, while ghrelin (P = 0.79) and leptin (P = 1.00) did not change with sleep deprivation. Using cross-correlation and multivariate modeling of these potential covariates along with homeostatic pressure (a measure of time awake/asleep), we found that time of day and homeostatic pressure together explained 44% of the variance in the hypocretin-1 data (P < 0.001), while cortisol did not significantly contribute to the overall hypocretin-1 variance. Locomotion during the daytime, but not during the nighttime, helped explain < 5% of the hypocretin-1 variance (P < 0.05). These data are consistent with earlier evidence indicating that in the squirrel monkey hypocretin-1 is mainly regulated by circadian inputs and homeostatic sleep pressure. Concomitants of wakefulness that affect hypocretin-1 in polyphasic species, such as locomotion, food intake, and food deprivation, likely have a more minor role in monophasic species, such as humans.

View details for DOI 10.1152/ajpregu.00460.2007

View details for Web of Science ID 000250088000033

View details for PubMedID 17686881

Abstract

Sleep is a fundamental biological process conserved across the animal kingdom. The study of how sleep regulatory networks are conserved is needed to better understand sleep across evolution. We present a detailed description of a sleep state in adult zebrafish characterized by reversible periods of immobility, increased arousal threshold, and place preference. Rest deprivation using gentle electrical stimulation is followed by a sleep rebound, indicating homeostatic regulation. In contrast to mammals and similarly to birds, light suppresses sleep in zebrafish, with no evidence for a sleep rebound. We also identify a null mutation in the sole receptor for the wake-promoting neuropeptide hypocretin (orexin) in zebrafish. Fish lacking this receptor demonstrate short and fragmented sleep in the dark, in striking contrast to the excessive sleepiness and cataplexy of narcolepsy in mammals. Consistent with this observation, we find that the hypocretin receptor does not colocalize with known major wake-promoting monoaminergic and cholinergic cell groups in the zebrafish. Instead, it colocalizes with large populations of GABAergic neurons, including a subpopulation of Adra2a-positive GABAergic cells in the anterior hypothalamic area, neurons that could assume a sleep modulatory role. Our study validates the use of zebrafish for the study of sleep and indicates molecular diversity in sleep regulatory networks across vertebrates.

View details for DOI 10.1371/journal.pbio.0050277

View details for Web of Science ID 000251072700025

View details for PubMedID 17941721

Abstract

Sleep disturbances are important correlates of depression, with epidemiologic research heretofore focused on insomnia and sleepiness. This epidemiologic study's aim was to investigate, in a community sample, depression's relationships to other sleep disturbances: sleep paralysis (SP), hypnagogic/hypnopompic hallucinations (HH), cataplexy - considered rapid eye movement-related disturbances - and automatic behavior (AB). Although typical of narcolepsy, these disturbances are prevalent, albeit under-studied, in the population. Cross-sectional analyses (1998-2002), based on Wisconsin Sleep Cohort Study population-based data from 866 participants (mean age 54, 53% male), examined: depression (Zung Self-Rating Depression Scale), trait anxiety (Spielberger State-Trait Anxiety Inventory, STAI-T >or= 75th percentile), and self-reported sleep disturbances. Descriptive sleep data were obtained by overnight polysomnography. Adjusted logistic regression models estimated depression's associations with each (>few times ever) outcome - SP, HH, AB, and cataplexy. Depression's associations with self-reported SP and cataplexy were not explained by anxiety. After anxiety adjustment, severe depression (Zung >or=55), vis-à-vis Zung <50, increased SP odds approximately 500% (P = 0.0008). Depression (Zung >or=50), after stratification by anxiety given an interaction (P = 0.02), increased self-reported cataplexy odds in non-anxious (OR 8.9, P = 0.0008) but not anxious (OR 1.1, P = 0.82) participants. Insomnia and sleepiness seemed only partial mediators or confounders for depression's associations with self-reported cataplexy and SP. Anxiety (OR 1.9, P = 0.04) partially explained depression's (Zung >or=55) association with HH (OR 2.2, P = 0.08). Anxiety (OR 1.6, P = 0.02) was also more related than depression to AB. Recognizing depression's relationships to oft-neglected sleep disturbances, most notably SP, might assist in better characterizing depression and the full range of its associated sleep problems in the population. Longitudinal studies are warranted to elucidate mediators and causality.

View details for Web of Science ID 000249329000009

View details for PubMedID 17716279

Abstract

Narcolepsy is linked to a widespread loss of neurons containing the neuropeptide hypocretin (HCRT), also named orexin. A transgenic (TG) rat model has been developed to mimic the neuronal loss found in narcoleptic humans. In these rats, HCRT neurons gradually die as a result of the expression of a poly-glutamine repeat under the control of the HCRT promoter. To better characterize the changes in HCRT-1 levels in response to the gradual HCRT neuronal loss cerebrospinal fluid (CSF) HCRT-1 levels were measured in various age groups (2-82 weeks) of wild-type (WT) and TG Sprague-Dawley rats. TG rats showed a sharp decline in CSF HCRT-1 level at week 4 with levels remaining consistently low (26%+/-9%, mean+/-S.D.) thereafter compared with WT rats. In TG rats, HCRT-1 levels were dramatically lower in target regions such as the cortex and brainstem (100-fold), indicating decreased HCRT-1 levels at terminals. In TG rats, CSF HCRT-1 levels significantly increased in response to 6 h of prolonged waking, indicating that the remaining HCRT neurons can be stimulated to release more neuropeptide. Rapid eye movement (REM) sleep in TG rats (n=5) was consistent with a HCRT deficiency. In TG rats HCRT immunoreactive (HCRT-ir) neurons were present in the lateral hypothalamus (LH), even in old rats (24 months) but some HCRT-ir somata were in various stages of disintegration. The low output of these neurons is consistent with a widespread dysfunction of these neurons, and establishes this model as a tool to investigate the consequences of partial hypocretin deficiency.

View details for DOI 10.1016/j.neuroscience.2007.05.029

View details for Web of Science ID 000249157900004

View details for PubMedID 17618058

Abstract

Increasing evidence suggests that alterations in sleep duration are associated with cardiovascular disease (CVD) and mortality. Additionally, sleep disordered breathing (SDB), which is associated with disturbed nighttime sleep and hypoxemia, may be an independent risk factor for CVD. The inflammatory marker, C-reactive protein (CRP), is an important predictor of CVD. We investigated potential associations between circulating CRP, sleep duration, and SDB.Cross-sectional Study.Participants were 907 adults from the Wisconsin Sleep Cohort Study (WSCS).CRP was measured after overnight polysomnography. The relationships between CRP and sleep parameters were evaluated using multiple linear regression with and without controlling for age, sex, and body mass index (BMI) and other potential confounders. CRP was found to be higher for women and had a strong positive correlation with age and BMI. CRP showed a significant positive association with current smoking, waist-hip ratio (WHR), LDL-cholesterol, triglycerides, leptin, and insulin, independent of age, sex, and BMI. Significant independent negative associations for CRP were observed with HDL-cholesterol (HDL), insulin sensitivity (quantitative insulin sensitivity check index [QUICKI]), and hours of exercise. There was a significant positive association between CRP levels and the apnea-hypopnea index (AHI, the measure of SDB), but these relationships were not significant after adjustment for age, sex, and BMI. No significant association between CRP levels and measures of sleep duration (polysomnographic and self-reported) were found.There was no significant association between CRP levels and sleep duration. The lack of an independent association between CRP levels and SDB suggests that the reported relationship between these 2 variables may be primarily driven by their association with obesity.

View details for Web of Science ID 000248515800007

View details for PubMedID 17702268

View details for Web of Science ID 000248446900005

View details for PubMedID 17660808

Abstract

Recent population studies have identified important interrelationships between sleep duration and body weight regulation. The hypothalamic hypocretin/orexin neuropeptide system is able to influence each of these. Disruption of the hypocretin system, such as occurs in narcolepsy, leads to a disruption of sleep and is often associated with increased body mass index. We examined the potential interrelationship between the hypocretin system, metabolism and sleep by measuring locomotion, feeding, drinking, body temperature, sleep/wake and energy metabolism in a mouse model of narcolepsy (ataxin-ablation of hypocretin-expressing neurons). We found that locomotion, feeding, drinking and energy expenditure were significantly reduced in the narcoleptic mice. These mice also exhibited severe sleep/wake fragmentation. Upon awakening, transgenic and control mice displayed a similar rate of increase in locomotion and food/water intake with time. A lack of long wake episodes partially or entirely explains observed differences in overall locomotion, feeding and drinking in these transgenic mice. Like other parameters, energy expenditure also rose and fell depending on the sleep/wake status. Unlike other parameters, however, energy expenditure in control mice increased upon awakening at a greater rate than in the narcoleptic mice. We conclude that the profound sleep/wake fragmentation is a leading cause of the reduced locomotion, feeding, drinking and energy expenditure in the narcoleptic mice under unperturbed conditions. We also identify an intrinsic role of the hypocretin system in energy expenditure that may not be dependent on sleep/wake regulation, locomotion, or food intake. This investigation illustrates the need for coordinated study of multiple phenotypes in mouse models with altered sleep/wake patterns.

View details for DOI 10.1113/jphysiol.2007.129510

View details for Web of Science ID 000246756000022

View details for PubMedID 17379635

Abstract

Narcolepsy causes dramatic behavioral alterations in both humans and dogs, with excessive sleepiness and cataplexy triggered by emotional stimuli. Deficiencies in the hypocretin system are well established as the origin of the condition; both from studies in humans who lack the hypocretin ligand (HCRT) and in dogs with a mutation in hypocretin receptor 2 (HCRTR2). However, little is known about molecular alterations downstream of the hypocretin signals.By using microarray technology we have screened the expression of 29760 genes in the brains of Doberman dogs with a heritable form of narcolepsy (homozygous for the canarc-1 [HCRTR-2-2] mutation), and their unaffected heterozygous siblings. We identified two neuropeptide precursor molecules, Tachykinin precursor 1 (TAC1) and Proenkephalin (PENK), that together with Suppressor of cytokine signaling 2 (SOCS2), showed reduced expression in narcoleptic brains. The difference was particularly pronounced in the amygdala, where mRNA levels of PENK were 6.2 fold lower in narcoleptic dogs than in heterozygous siblings, and TAC1 and SOCS2 showed 4.4 fold and 2.8 fold decrease in expression, respectively. The results obtained from microarray experiments were confirmed by real-time RT-PCR. Interestingly, it was previously shown that a single dose of amphetamine-like stimulants able to increase wakefulness in the dogs, also produce an increase in the expression of both TAC1 and PENK in mice.These results suggest that TAC1, PENK and SOCS2 might be intimately connected with the excessive daytime sleepiness not only in dogs, but also in other species, possibly including humans.

View details for DOI 10.1186/1471-2202-8-34

View details for Web of Science ID 000247020700001

View details for PubMedID 17521418

Abstract

To publish the first English translations, with commentary, of the original reports describing narcolepsy and cataplexy by Westphal in German (1877) and by Gélineau in French (1880).A professional translation service translated the 2 reports from either German or French to English, with each translation then being slightly edited by one of the authors. All authors then provided commentary.Both Westphal and Gélineau correctly identified and described the new clinical entities of cataplexy and narcolepsy, with recurrent, self-limited sleep attacks and/or cataplectic attacks affecting 2 otherwise healthy people. Narcolepsy was named by Gélineau (and cataplexy was named by Henneberg in 1916). The evidence in both cases is sufficiently convincing to conclude that they were likely each HLA-DQB1*0602 positive and hypocretin deficient.The original descriptions of narcolepsy and cataplexy are now available in English, allowing for extensive clinical and historical commentary.

View details for PubMedID 17561602

Abstract

The hypothalamic neuropeptide hypocretin (orexin) modulates sleep-wake, feeding and endocrine functions. Cerebrospinal fluid (CSF) hypocretin-1 (Hcrt-1) concentrations are low in patients with narcolepsy-cataplexy, a sleep disorder characterized by hypersomnolence and rapid eye movement (REM) sleep abnormalities.We determined CSF Hcrt-1 concentrations of patients with the fibromyalgia syndrome (FMS), a condition characterized by fatigue, insomnia and in some cases daytime hypersomnolence.Basal CSF levels of Hcrt-1 in FMS did not differ from those in healthy normal controls.These findings suggest that abnormally low Hcrt-1 is not a likely cause of fatigue in FMS.

View details for DOI 10.1016/j.sleep.2006.08.015

View details for Web of Science ID 000246343100010

View details for PubMedID 17369087

Abstract

The zebrafish is an ideally suited vertebrate animal model for large-scale genetic screens and is emerging as a model organism in pharmacological and behavioral research. We investigated the effects of sedative hypnotics commonly used in humans on zebrafish locomotor activity and identified the corresponding genomic and receptor binding targets.We studied radioreceptor binding and behavioral responses to compounds with known sedative hypnotic properties representing multiple pharmacological classes. These included GABAergic hypnotics such as benzodiazepines, barbiturates, and baclofen; alpha-2 adrenergic agonists; and histaminergic H1 antagonists. An automated system was used to quantify behavioral effects. Zebrafish homologs of histamine receptor H1, gamma-amino-n-butyric acid type A (alpha-subunit), and gamma-amino-n-butyric acid type B (1 and 2) receptor genes were identified through translating queries of the zebrafish Zv4 database with human receptor protein sequences. A pilot screen of 154 N-ethyl-N-nitroso-urea-mutagenized F2 families was conducted with pentobarbital, flurazepam and mepyramine.Radioreceptor binding studies revealed high affinity binding sites for known gamma-amino-n-butyric acid type A, gamma-amino-n-butyric acid type B, and histaminergic ligands. Drug immersion of 5-7-day-old larvae reduced mobility and, in some cases, produced a complete state of unresponsive immobility similar to anesthesia. These effects were dose-dependent and rapidly reversible in water. As established in mammals, (R)-baclofen was more active behaviorally and had higher affinity in binding studies when compared with (S)-baclofen. In this model, (S)-baclofen only partially reduced activity at high dose and blocked (R)-baclofen behavioral hypnotic effects. Genomic sequences with high similarity to the corresponding pharmacological targets were identified, but no mutants were found in the pilot screen.These results demonstrate conservation of gene, protein and function for many established sedative hypnotic pathways. The results indicate feasibility of conducting large-scale pharmacogenomic screens to isolate novel proteins modulating susceptibility to hypnotic compounds in a vertebrate system.

View details for Web of Science ID 000245374200002

View details for PubMedID 17496723

Abstract

Human leucocyte antigen (HLA)-DRB1*15 is associated with predisposition to multiple sclerosis (MS), although conjecture surrounds the possible involvement of an alternate risk locus in the class I region of the HLA complex. We have shown previously that an alternate MS risk allele(s) may be encompassed by the telomerically extended DRB1*15 haplotype, and here, we have attempted to map the putative variant. Thirteen microsatellite markers encompassing a 6.79-megabase (D6S2236-G51152) region, and the DRB1 and DQB1 genes, were genotyped in 166 MS simplex families and 104 control families from the Australian State of Tasmania and 153 narcolepsy simplex families (trios) from the USA. Complementary approaches were used to investigate residual predisposing effects of microsatellite alleles comprising the extended DRB1*15 haplotype taking into account the strong predisposing effect of DRB1*15: (1) Disease association of the extended DRB1*15 haplotype was compared for MS and narcolepsy families--predisposing effects were observed for extended class I microsatellite marker alleles in MS families, but not narcolepsy families; (2) disease association of the extended DRB1*15 haplotype was investigated after conditioning MS and control haplotypes on the absence of DRB1*15--a significant predisposing effect was observed for a 627-kb haplotype (D6S258 allele 8-MOGCA allele 4; MOG, myelin oligodendrocyte glycoprotein) spanning the extended class I region. MOGCA allele 4 displayed the strongest predisposing effect in DRB1*15-conditioned haplotypes (p = 0.0006; OR 2.83 [1.54-5.19]). Together, these data confirm that an alternate MS risk locus exists in the extended class I region in Tasmanian MS patients independent of DRB1*15.

View details for DOI 10.1007/s00251-006-0183-5

View details for Web of Science ID 000244066300001

View details for PubMedID 17256150

Abstract

Narcolepsy with cataplexy is a disabling sleep disorder affecting 0.02% of adults worldwide. It is characterised by severe, irresistible daytime sleepiness and sudden loss of muscle tone (cataplexy), and can be associated with sleep-onset or sleep-offset paralysis and hallucinations, frequent movement and awakening during sleep, and weight gain. Sleep monitoring during night and day shows rapid sleep onset and abnormal, shortened rapid-eye-movement sleep latencies. The onset of narcolepsy with cataplexy is usually during teenage and young adulthood and persists throughout the lifetime. Pathophysiological studies have shown that the disease is caused by the early loss of neurons in the hypothalamus that produce hypocretin, a wakefulness-associated neurotransmitter present in cerebrospinal fluid. The cause of neural loss could be autoimmune since most patients have the HLA DQB1*0602 allele that predisposes individuals to the disorder. Treatment is with stimulant drugs to suppress daytime sleepiness, antidepressants for cataplexy, and gamma hydroxybutyrate for both symptoms. Because narcolepsy is an under-recognised disease, it is important that general practitioners and other primary health-care workers identify abnormal daytime sleepiness early.

View details for Web of Science ID 000244188300033

View details for PubMedID 17292770

Abstract

Circadian rhythms are established by transcription of clock genes and autoregulatory transcriptional feedback loops. In this issue, Xu et al. (2007) characterize mice expressing a human Per2 mutation identified in patients with familial advanced sleep phase syndrome. Their results reveal that PER2 phosphorylation, by CK1delta and other kinases, is surprisingly complex and has opposite effects on PER2 levels and period length.

View details for DOI 10.1016/j.cell.2006.12.024

View details for Web of Science ID 000244420400009

View details for PubMedID 17218251

Abstract

The association of narcolepsy with HLA-DQB1*0602 is established in Japanese, African-Americans, European, and North American Caucasians. We examined DRB1, DRB3, DRB4, DRB5, DQA1, and DQB1 in 163 patients with centrally mediated daytime sleepiness (100 with narcolepsy) and 211 Korean controls. In this population, the DQB1*0602 association was always evident in the context of the DRB1*1501-DQA1*0102-DQB1*0602 haplotype. The DQB1*0602 association was highest in cases with hypocretin deficiency (100% vs 13% in controls), most of which had narcolepsy-cataplexy (81%). A weaker DQB1*0602 (45%) association was present in cases without cataplexy. No human leukocyte antigen (HLA) association was present in idiopathic hypersomnia or in cases with normal cerebrospinal fluid (CSF) hypocretin-1. As in other populations, DQB1*0602 homozygosity increased risk in cases with cataplexy and/or hypocretin deficiency (odds ratio = 2.0 vs heterozygotes). Non-DQB1*0602 allelic effects were also observed but could not be interpreted in the context of DQB1*0602 overabundance and linkage disequilibrium. We therefore next analyzed compound heterozygote effects in 77 subjects with either hypocretin deficiency or cataplexy and one copy of DRB1*1501-DQA1*0102-DQB1*0602, a sample constructed to maximize etiologic homogeneity. In this analysis, we found additional predisposing effects of DQB1*0301 and protective effects for DQA1*0103-DQB1*0601. Unexpectedly, the predisposing effects of DQB1*0301 were present in the context of various DQA1-bearing haplotypes. A predisposing effect of DQA1*0303 was also suggested. These results indicate a remarkable consistency in the complex HLA association present in narcolepsy across multiple ethnic groups.

View details for DOI 10.1016/j.humimm.2006.10.006

View details for Web of Science ID 000243570200007

View details for PubMedID 17207713

Abstract

To analyze periodic leg movements (PLM) during sleep in patients with narcolepsy and compare the results with those obtained in normal controls and subjects with restless legs syndrome (RLS).We recruited 40 HLA DQB1*0602-positive patients with narcolepsy/cataplexy, 22 with RLS, and 22 controls. The time structure of their polysomnographically recorded LMs was analyzed by means of an approach particularly able to consider their periodicity.Nineteen patients with narcolepsy had a PLM index greater than 15. The distribution of inter-LM intervals was clearly bimodal in RLS and narcoleptics, with 1 peak at 2 to 4 seconds and another at around 22 to 26 seconds; in the range 22 to 40 seconds, patients with RLS had values significantly higher than patients with narcolepsy. All periodicity parameters were significantly lower in the narcolepsy group. Finally, the distribution of the number of PLM per hour of sleep was bell shaped in normal controls and patients with narcolepsy, whereas patients with RLS showed a progressive decrease throughout the night.Most narcoleptic patients show a high number of LMs that are significantly less periodic than those of patients with RLS. PLM are in functional interrelationship with the cyclic alternating pattern, which is reduced in patients with narcolepsy; decreased arousal fluctuations during sleep may be one of the factors influencing the reduction in periodicity of LMs during sleep in narcolepsy.

View details for Web of Science ID 000243067900008

View details for PubMedID 17252889

Abstract

To study DQB1*0602 status and hypocretin-1 levels in the cerebrospinal fluid (CSF) in a cohort of patients with hypersomnolence and to test International Classification of Sleep Disorders-2 (ICSD-2) criteria for hypersomnia of central origin.Retrospective case series.One hundred sixty-three consecutive patients with unexplained sleepiness and 282 controls recruited at St. Vincent's Hospital, Korea. The gold standard for diagnosis was ICSD-2 criteria. Patients and controls completed the Stanford Sleep Inventory, and agreed to HLA typing. Polysomnography (87%), Multiple Sleep Latency Test (MSLT) (96%), and CSF hypocretin-1 measurements (53%) were conducted in patients.Most patients (80%) could be classified using the ICSD-2. The 33 patients who could not be classified were without cataplexy (4 with low CSF hypocretin-1). These could not be included because of sleep apnea (apnea-hypopnea index > or = 5/h, 84%) and/or because sleep prior to MSLT was less than 6 hours (27%). Narcolepsy with cataplexy cases were 92% HLA positive with low hypocretin-1. Cataplexy at interview was predicted by validated Stanford Sleep Inventory questions regarding cataplexy triggers. In contrast, cataplexy-like events were frequently reported in all groups, including controls. Cases with narcolepsy without cataplexy were frequently men (73%) and heterogeneous biologically (36% HLA positive, 40% with low CSF hypocretin-1). None of the controls had low CSF hypocretin-1, whereas 13% were HLA positive.The ICSD-2 was easily applicable in cases with typical cataplexy. In these cases, the MSLT and further evaluations were almost always positive and may thus not always be needed. Many patients without cataplexy were difficult to classify because of difficulties in interpreting the MSLT in the presence of sleep apnea or reduced sleep.

View details for Web of Science ID 000242181700015

View details for PubMedID 17162989

Abstract

Hypocretins/orexins are neuropeptides involved in the regulation of sleep and energy balance in mammals. Conservation of gene sequence, hypothalamic localization of cell bodies, and projection patterns in adult zebrafish suggest that the architecture and function of the hypocretin system are conserved in fish. We report on the complete genomic structure of the zebrafish and Tetraodon hypocretin genes and the complete predicted hypocretin protein sequences from five teleosts. Using whole mount in situ hybridization, we have traced the development of hypocretin cells in zebrafish from onset of expression at 22 h post-fertilization through the first week of development. Promoter elements of similar size from zebrafish and Tetraodon were capable of driving efficient and specific expression of enhanced green fluorescent protein in developing zebrafish embryos, thus defining a minimal promoter region able to accurately mimic the native hypocretin pattern. This enhanced green fluorescent protein expression also revealed a complex pattern of projections within the hypothalamus, to the midbrain, and to the spinal cord. To further analyze the promoter, a series of deletion and substitution constructs were injected into embryos, and resulting promoter activity was monitored in the first week of development. A critical region of 250 base pairs was identified containing a core 13-base pair element essential for hypocretin expression.

View details for DOI 10.1074/jbc.M605811200

View details for Web of Science ID 000240896300037

View details for PubMedID 16867991

Abstract

To determine if hypocretin deficiency is associated with abnormally low serum leptin levels, a putative cause of increased body mass index in narcoleptics.Cross-sectional controlled study.Three hundred seventy subjects, including 111 healthy controls, 93 narcoleptic subjects with hypocretin deficiency (cerebrospinal fluid [CSF] hypocretin-1 levels < 110 pg/mL), 72 narcoleptic subjects with normal hypocretin levels, and 89 subjects with other sleep disordersAfter completing the Stanford Sleepiness Inventory, participants underwent spinal taps and blood sampling for measurement of CSF leptin and hypocretin-1 levels, HLA DQB1*0602 phenotyping, and serum leptin and C-reactive protein levels.Serum leptin levels were similar in narcoleptic subjects, whether hypocretin-deficient (13.2 +/- 1.7 ng/mL, mean +/- SEM) or not (13.0 +/- 1.8 ng/mL), controls (10.1 +/- 1.1 ng/mL) and subjects with other sleep disorders (11.5 +/- 1.6 ng/mL). Similarly, the CSF leptin levels and the CSF: serum leptin ratios (an indicator of brain leptin uptake) were not different between groups. Serum and CSF leptin levels were higher in women and in subjects with higher body mass indexes. Leptin brain uptake decreased in women, in the aged, and in more-obese subjects. In contrast with a presumed inhibitory effect of leptin on hypocretin-containing cells, CSF leptin levels tended to correlate positively with CSF hypocretin-1 levels. C-reactive protein was higher (4.2 +/- 0.9 mg/L) in narcoleptic subjects with hypocretin deficiency than in controls (1.4 +/- 0.3 mg/L, p = .0055), a difference still significant after adjustment on confounding factors.Our data do not support a role for leptin in mediating increased body mass index in narcolepsy. A moderate but selective increase in C-reactive protein in hypocretin-1 deficient subjects should prompt research on inflammation in narcolepsy.

View details for Web of Science ID 000240046400004

View details for PubMedID 16944669

Abstract

Narcolepsy is characterized by excessive daytime sleepiness, cataplexy and other manifestations of dissociated rapid eye movement sleep. Narcolepsy is typically treated with amphetamine-like stimulants (sleepiness) and antidepressants (cataplexy). Newer compounds, such as modafinil (non-amphetamine wake-promoting compound for excessive daytime sleepiness) and sodium oxybate (short-acting sedative for fragmented nighttime sleep, cataplexy, excessive daytime sleepiness), are increasingly used. Recent discoveries indicate that the major pathophysiology of human narcolepsy is the loss of lateral hypothalamic neurons that produce the neuropeptide hypocretin (orexin). Approximately 90% of people diagnosed as having narcolepsy with cataplexy are hypocretin ligand deficient. This has led to the development of new diagnostic tests (cerebrospinal fluid hypocretin-1 measurements). Hypocretin receptor agonists are likely to be ideal therapeutic options for hypocretin-deficient narcolepsy but such compounds are still not available in humans.

View details for DOI 10.1016/j.tips.2006.05.006

View details for Web of Science ID 000239368900005

View details for PubMedID 16766052

Abstract

In children, narcolepsy may be the symptom of a brain lesion or genetic disease. The authors report two cases with severe narcolepsy-cataplexy emerging in childhood in close temporal association with obesity and precocious puberty.

View details for Web of Science ID 000237706900027

View details for PubMedID 16717224

View details for Web of Science ID 000233734700021

View details for PubMedID 16408421

Abstract

Kleine-Levin syndrome (KLS) is a rare disorder with symptoms that include periodic hypersomnia, cognitive and behavioural disturbances. Large series of patients are lacking. In order to report on various KLS symptoms, identify risk factors and analyse treatment response, we performed a systematic review of 195 articles, written in English and non-English languages, which are available on Medline dating from 1962 to 2004. Doubtful or duplicate cases, case series without individual details and reviews (n = 56 articles) were excluded. In addition, the details of 186 patients from 139 articles were compiled. Primary KLS cases (n = 168) were found mostly in men (68%) and occurred sporadically worldwide. The median age of onset was 15 years (range 4-82 years, 81% during the second decade) and the syndrome lasted 8 years, with seven episodes of 10 days, recurring every 3.5 months (median values) with the disease lasting longer in women and in patients with less frequent episodes during the first year. It was precipitated most frequently by infections (38.2%), head trauma (9%), or alcohol consumption (5.4%). Common symptoms were hypersomnia (100%), cognitive changes (96%, including a specific feeling of derealization), eating disturbances (80%), hypersexuality (43%), compulsions (29%), and depressed mood (48%). In 75 treated patients (213 trials), somnolence decreased using stimulants (mainly amphetamines) in 40% of cases, while neuroleptics and antidepressants were of poor benefit. Only lithium (but not carbamazepine or other antiepileptics) had a higher reported response rate (41%) for stopping relapses when compared to medical abstention (19%). Secondary KLS (n = 18) patients were older and had more frequent and longer episodes, but had clinical symptoms and treatment responses similar to primary cases. In conclusion, KLS is a unique disease which may be more severe in female and secondary cases.

View details for DOI 10.1093/brain/awh620

View details for Web of Science ID 000233667500004

View details for PubMedID 16230322

Abstract

Narcolepsy with cataplexy is associated with a loss of orexin/hypocretin. It is speculated that an autoimmune process kills the orexin-producing neurons, but these cells may survive yet fail to produce orexin.To examine whether other markers of the orexin neurons are lost in narcolepsy with cataplexy.We used immunohistochemistry and in situ hybridization to examine the expression of orexin, neuronal activity-regulated pentraxin (NARP), and prodynorphin in hypothalami from five control and two narcoleptic individuals.In the control hypothalami, at least 80% of the orexin-producing neurons also contained prodynorphin mRNA and NARP. In the patients with narcolepsy, the number of cells producing these markers was reduced to about 5 to 10% of normal.Narcolepsy with cataplexy is likely caused by a loss of the orexin-producing neurons. In addition, loss of dynorphin and neuronal activity-regulated pentraxin may contribute to the symptoms of narcolepsy.

View details for Web of Science ID 000232813600010

View details for PubMedID 16247044

View details for Web of Science ID 000232461200004

View details for PubMedID 16295203

View details for DOI 10.1002/ana.20603

View details for Web of Science ID 000231679200025

View details for PubMedID 16130098

Abstract

Hypocretin-1 is involved in the regulation of the sleep-wake cycle. The authors prospectively assessed CSF hypocretin-1 levels in 44 consecutive patients with acute traumatic brain injury (TBI). Compared with controls, hypocretin-1 levels were abnormally lower in 95% of patients with moderate to severe TBI and in 97% of patients with posttraumatic brain CT changes. Hypocretin-1 deficiency after TBI may reflect hypothalamic damage and be linked with the frequent development of posttraumatic sleep-wake disorders.

View details for Web of Science ID 000230427200032

View details for PubMedID 16009905

Abstract

Pinschers and other dogs with coat color dilution show a characteristic pigmentation phenotype. The fur colors are a lighter shade, e.g. silvery grey (blue) instead of black and a sandy color (Isabella fawn) instead of red or brown. In some dogs the coat color dilution is sometimes accompanied by hair loss and recurrent skin inflammation, the so called color dilution alopecia (CDA) or black hair follicular dysplasia (BHFD). In humans and mice a comparable pigmentation phenotype without any documented hair loss is caused by mutations within the melanophilin gene (MLPH).We sequenced the canine MLPH gene and performed a mutation analysis of the MLPH exons in 6 Doberman Pinschers and 5 German Pinschers. A total of 48 sequence variations was identified within and between the breeds. Three families of dogs showed co-segregation for at least one polymorphism in an MLPH exon and the dilute phenotype. No single polymorphism was identified in the coding sequences or at splice sites that is likely to be causative for the dilute phenotype of all dogs examined. In 18 German Pinschers a mutation in exon 7 (R199H) was consistently associated with the dilute phenotype. However, as this mutation was present in homozygous state in four dogs of other breeds with wildtype pigmentation, it seems unlikely that this mutation is truly causative for coat color dilution. In Doberman Pinschers as well as in Large Munsterlanders with BHFD, a set of single nucleotide polymorphisms (SNPs) around exon 2 was identified that show a highly significant association to the dilute phenotype.This study provides evidence that coat color dilution is caused by one or more mutations within or near the MLPH gene in several dog breeds. The data on polymorphisms that are strongly associated with the dilute phenotype will allow the genetic testing of Pinschers to facilitate the breeding of dogs with defined coat colors and to select against Large Munsterlanders carrying BHFD.

View details for DOI 10.1186/1471-2156-6-34

View details for Web of Science ID 000231069500001

View details for PubMedID 15960853

Abstract

In the past, narcolepsy was primarily treated using amphetamine-like stimulants and tricyclic antidepressants. Newer and novel agents, such as the wake-promoting compound modafinil and more selective reuptake inhibitors targeting the adrenergic, dopaminergic, and/or serotoninergic reuptake sites (ie, venlafaxine, atomoxetine) are better-tolerated available alternatives. The development of these agents, together with sodium oxybate (a slow-wave sleep-enhancing agent that consolidates nocturnal sleep, reduces cataplexy, and improves sleepiness), has led to improved functioning and quality of life for many patients with the disorder. However, these treatments are all symptomatically based and do not target hypocretin, a major neurotransmitter involved in the pathophysiology of narcolepsy. In this review, we discuss emerging therapies in the area of narcolepsy. These include novel antidepressant or anticataplectic, wake-promoting, and hypnotic compounds. We also report on novel strategies designed to compensate for hypocretin deficiency and on the use of immunosupression at the time of narcolepsy onset.

View details for Web of Science ID 000229900500014

View details for PubMedID 16477963

Abstract

Sleep Medicine has only recently been recognized as a specialty of medicine. Its development is based on an increasing amount of knowledge concerning the physiology of sleep, circadian biology and the pathophysiology of sleep disorders. This review chronicles the major advances in sleep science over the past 70 years and the development of the primary organizations responsible for the emergence of Sleep Medicine as a specialty, sleep disorders as a public health concern and sleep science as an important area of research.

View details for PubMedID 17561617

Abstract

Four patients with clinically and genetically confirmed Prader-Willi syndrome (PWS) underwent nocturnal polysomnograpy (PSG), multiple sleep latency test (MSLT), human leukocyte antigens (HLA) typing and estimation of cerebrospinal fluid (CSF) hypocretin-1 (Hcrt-1) level to investigate if a role of hypothalamic dysfunction and sleep disturbance might be functionally connected through the hypocretin (orexin) system. In all four patients physical examination confirmed extreme obesity (increasing with age) with dysmorphogenetic features. Excessive daytime sleepiness (EDS) was manifested in only two subjects without any imperative feature. None of the patients under study suffered from cataplexy. Nocturnal PSG revealed fragmented sleep with low efficiency, the hypopnea and apnea indexes increasing from borderline up to very high values in direct proportion to the patients' age. MSLT latency was shortened in two patients with clinically expressed EDS, only one sleep onset rapid eye movements (REM) period (SOREM) was found. HLA typing showed DQB1*0602 positivity in two patients; the further two were negative. Mean value of CSF Hcrt-1 in the patients group was down to 164 +/- 46.8 pg/ml (in comparison with 265.8 +/- 48.8 pg/ml in 10 young healthy subjects, P=0.02). The deficiency of CSF Hcrt-1 level correlated in PWS patients with their EDS severity.

View details for Web of Science ID 000225955700012

View details for PubMedID 15613151

Abstract

The angiotensin-converting enzyme (ACE) gene insertion/deletion polymorphism influences ACE activity, cardiovascular risk, blood pressure, and possibly the risk of developing Alzheimer's dementia. We explored the association of the insertion/deletion polymorphism with sleep-disordered breathing (SDB) and hypertension in 1,100 subjects of the Wisconsin Sleep Cohort. The polymorphism did not influence body mass index or the occurrence of SDB, but was dose-dependently associated with blood pressure. Interestingly, SDB and the insertion/deletion polymorphism interacted significantly to modulate blood pressure independently of age, sex, ethnicity, and body mass index. Most specifically, the association of the deletion allele with hypertension was most pronounced in subjects with mild to moderate degrees of sleep apnea (5 < or = apnea-hypopnea index < or = 30). We hypothesize that in the absence of SDB the effect of the deletion allele alone may not be sufficient to increase blood pressure. At severe levels of SDB, the effect of sleep apnea on blood pressure overwhelms any association of the deletion allele with hypertension and occurs independent of any ACE gene genotype.

View details for DOI 10.1164/rccm.200405-6160C

View details for Web of Science ID 000225780800014

View details for PubMedID 15447944

View details for Web of Science ID 000225093100003

View details for PubMedID 15586777

Abstract

Obstructive sleep apnea/hypopnea (OSAH) has a strong heritable component, although its genetic basis remains largely unknown. One epidemiologic study found a significant association between the APOE epsilon4 allele and OSAH in middle-aged adults, a finding that was not replicated in a cohort of elderly adults. The objective of this study was to further examine the association of the APOE epsilon4 allele with OSAH in a community-dwelling cohort, exploring age dependency of the association.A genetic association study was performed, nested within a prospective cohort study of the cardiovascular consequences of OSAH. Unattended, in-home nocturnal polysomnography was used to measure apnea-hypopnea index (AHI) in 1,775 participants age 40 to 100 years. OSAH was defined as an AHI > or = 15. The relation of APOE genotype to prevalent OSAH was analyzed using generalized estimating equations to account for non-independent observations of individuals from the same sibship.At least one APOE epsilon4 allele was present in 25% of subjects, with 1.3% epsilon4/epsilon4 homozygotes. The prevalence of OSAH was 19%. After adjustment for age, sex, and BMI, the presence of any APOE epsilon4 allele was associated with increased odds of OSAH (OR 1.41, 95% CI 1.06 to 1.87, p = 0.02). The effect was approximately twice as great in subjects <75 (OR 1.61, CI 1.02 to 2.54) as in those > or =75 years old (OR 1.32, CI 0.91 to 1.90). Exploratory analyses revealed that the strongest effect of APOE epsilon4 was in subjects age <65 (OR 3.08, CI 1.43 to 6.64), and was stronger in those with hypertension or cardiovascular disease than in those without.The APOE epsilon4 allele is associated with increased risk of OSAH, particularly in individuals under age 65. The mechanisms underlying this association are uncertain. Age-dependency of the APOE-OSAH association may explain previous conflicting results.

View details for Web of Science ID 000223493800013

View details for PubMedID 15326239

Abstract

Hypocretins (HCRT-1 and HCRT-2), also known as orexins, are neuropeptides localized in neurons surrounding the perifornical region of the posterior hypothalamus. These neurons project to major arousal centers in the brain and are implicated in regulating wakefulness. In young rats and monkeys, levels of HCRT-1 are highest at the end of the wake-active period and lowest toward the end of the sleep period. However, the effects of age on the diurnal rhythm of HCRT-1 are not known.To provide such data, cerebrospinal fluid (CSF) was collected from the cisterna magna of young (2-month-old, n = 9), middle-aged (12 months, n = 10), and old (24 months, n = 10) F344 rats at 4-hour intervals, (beginning at zeitgeber [ZT]0, lights on). CSF was collected once from each rat every 4 days at 1 ZT point. After collecting the CSF at all of the time points, the rats were kept awake by gentle handling for 8 hours (ZT 0-ZT8), and the CSF was collected again at the end of the sleep-deprivation procedure. HCRT-1 levels in the CSF were determined by radioimmunoassayBasic neuroscience research lab.Old rats had significantly less HCRT-1 in the CSF versus young and middle-aged rats (P < .002) during the lights-on and lights-off periods and over the 24-hour period. In old rats, significantly low levels of HCRT-1 were evident at the end of the lights-off period (predominantly wake-active period). The old rats continued to have less HCRT-1 even after 8 hours of prolonged waking. Northern blot analysis did not show a difference in pre-proHCRT mRNA between age groups.In old rats there is a 10% decline in CSF HCRT-1 over the 24-hour period. Functionally, if there is less HCRT-1, which our findings indicated, and there is also a decline in HCRT receptor mRNA, as has been previously found, then the overall consequence would be diminished action of HCRT at target sites. This would diminish the waking drive, which in the elderly could contribute to the increased tendency to fall asleep during the normal wake period.

View details for Web of Science ID 000223451400006

View details for PubMedID 15453542

View details for Web of Science ID 000222901400025

View details for PubMedID 15320603

Abstract

Hypocretins (orexins) are involved in the sleep disorder narcolepsy. While hypocretin-1 has a daily oscillation, little is known regarding the relative contribution of circadian and homeostatic components on hypocretin release. The effect of lesions of the suprachiasmatic nucleus (SCN) on hypocretin-1 in the cerebrospinal fluid (CSF) was examined.SCN-ablated (SCNx) and sham-operated control rats were implanted with activity-temperature transmitters. Animals were housed individually under 1 of 3 lighting conditions: 12-hour:12-hour light:dark cycle (LD), constant light (LL), and constant darkness (DD). Lesions were verified histologically and shown not to affect hypocretin-containing cells. Hypocretin-1 concentrations in the CSF were determined every 4 hours using radioimmunoassays.Control animals displayed robust circadian (LL, DD) and diurnal (LD) fluctuations in CSF hypocretin-1, locomotor activity, and temperature. Peak CSF hypocretin-1 was at the end of the active period. Activity, temperature, and CSF hypocretin-1 were arrhythmic in SCNx animals in LL and DD. In LD, a weak but significant fluctuation in activity and temperature but not CSF hypocretin-1 was observed in SCNx animals. We also explored correlations between CSF hypocretin-1, CSF corticosterone, and locomotor activity occurring prior to CSF sampling in arrhythmic SCNx rats under constant conditions. Significant correlations between hypocretin-1 and activity were observed both across and within animals, suggesting that interindividual and time-of-the-day differences in activity have significant effects on hypocretin release in arrhythmic animals. No correlation was found between CSF hypocretin-1 and corticosterone.Hypocretin-1 release is under SCN control. Locomotor activity influences the activity of the hypocretin neurons.

View details for Web of Science ID 000223169300007

View details for PubMedID 15282996

Abstract

The hypocretin system is involved in the integration of hypothalamic functions with sleep and wake. Hypocretin-1 release peaks at the end of the active period in both diurnal and nocturnal species. A role for hypocretin-1 in the generation of locomotor activity has been suggested by electrophysiological and neurochemical studies in rodents, dogs and cats. These species, however, do not consolidate wake into a single, daily bout and manipulations of locomotion elicit changes in wakefulness, making it difficult to parse the relative contribution of these two factors. We have examined the relationship between locomotion and hypocretin-1 in a wake-consolidating animal, the squirrel monkey (Saimiri sciureus). Strikingly, we found that restricting locomotion to 17% of usual activity had no significant effect on the normal diurnal rise in cerebrospinal fluid (CSF) hypocretin-1, despite an associated increase in CSF cortisol. Increasing locomotion to greater than baseline activity did not significantly increase CSF hypocretin-1 concentrations, but did appear to have a positive modulatory effect on CSF hypocretin-1. In this wake-consolidating animal, locomotion is not necessary for CSF hypocretin-1 to increase throughout the daytime, but high levels of locomotion are likely to provide a small positive feedback onto the hypocretin system.

View details for DOI 10.1113/jphysiol.2004.061606

View details for Web of Science ID 000222403700029

View details for PubMedID 15107479

Abstract

Narcolepsy is a disabling neurologic condition affecting 1 in 2000 individuals, characterized by sleepiness, cataplexy, and transitions from wakefulness into rapid-eye-movement sleep. Current treatments include amphetamine-like stimulants and antidepressants. Human narcolepsy is HLA-associated, multigenic, and environmentally influenced. Positional cloning was used to isolate narcolepsy genes in canine families with autosomal recessive narcolepsy transmission. Three mutations in the G-protein-coupled hypocretin (orexin) receptor-2 (Hcrtr-2) gene were identified. In humans, most cases of narcolepsy are not linked to hypocretin (Hcrt) ligand or receptor mutations but are associated with undetectable cerebrospinal fluid Hcrt-1 levels. A single Hcrt gene/narcolepsy mutation was identified in narcoleptic patients. Hcrt-1 is wake-promoting in vivo, and studies in sporadic human narcolepsy indicate a loss of brain Hcrt-1 and Hcrt-2 and a disappearance of Hcrt-1-containing cells in the hypothalamus. Narcolepsy with cataplexy may therefore be due to Hcrt deficiency. The HLA association in humans suggests possible autoimmune activity against hypothalamic Hcrt-containing cells. Hypocretins may also have roles in regulating normal sleep, appetite, neuroendocrine function and energy metabolism, uniquely positioning them as a link between multiple important behaviors. Abnormal Hcrt transmission is also found in neurologic disorders featuring excessive daytime sleepiness and/or hypothalamic abnormalities. Pharmacologic manipulations of Hcrts may have multiple therapeutic applications.

View details for DOI 10.1016/j.sleep.2004.04.000

View details for Web of Science ID 000222352700002

View details for PubMedID 15301991

Abstract

Cataplexy, an emotion-triggered sudden loss of muscle tone specific to narcolepsy, is tightly associated with hypocretin deficiency. Using hypocretin receptor 2 gene (hcrtr 2)-mutated narcoleptic Dobermans, we have previously demonstrated that altered dopamine (DA) D(2/3) receptor mechanisms in mesencephalic DA nuclei are important for the induction of cataplexy. In the current study, we also found that the administration of D(2/3) agonists into diencephalic dopaminergic cell groups, including the area dorsal to the ventral tegmental area (DRVTA) and the periventricular gray (PVG) matter of the caudal thalamus (corresponding to area A11), significantly aggravated cataplexy in hcrtr 2-mutated narcoleptic Dobermans. A D(1) agonist and antagonist and a DA uptake inhibitor perfused into the DRVTA had no effect on cataplexy, suggesting an involvement of D(2/3) receptors located on DA cell bodies (i.e., autoreceptors) for the regulation of cataplexy. Because the A11 cell group projects to the spinal ventral horn, the A11 D(2/3) receptive mechanisms may directly modulate the activity of spinal motoneurons and modulate cataplexy.

View details for DOI 10.1016/j.nbd.2004.02.008

View details for Web of Science ID 000221365300029

View details for PubMedID 15207284

View details for Web of Science ID 000221603900059

View details for PubMedID 15159515

Abstract

Idiopathic narcolepsy is associated with deficient hypocretin transmission. Narcoleptic symptoms have recently been described in paraneoplastic encephalitis with anti-Ma2 antibodies. The authors measured CSF hypocretin-1 levels in six patients with anti-Ma2 encephalitis, and screened for anti-Ma antibodies in patients with idiopathic narcolepsy. Anti-Ma autoantibodies were not detected in patients with idiopathic narcolepsy. Four patients with anti-Ma2 encephalitis had excessive daytime sleepiness; hypocretin-1 was not detectable in their cerebrospinal fluid, suggesting an immune-mediated hypocretin dysfunction.

View details for Web of Science ID 000188010100037

View details for PubMedID 14718718

Abstract

Rat cisternal (CSF) hypocretin-1 in cerebrospinal fluid was measured after 6 or 96 h of REM sleep deprivation and following 24 h of REM sleep rebound. REM deprivation was found to increase CSF hypocretin-1 collected at zeitgeber time (ZT) 8 but not ZT0. Decreased CSF hypocretin levels were also observed at ZT8 after 24 h of REM sleep rebound. These results suggest that REM sleep deprivation activates and REM sleep rebound inhibits the hypocretin system. Increased hypocretin tone during REM deprivation may be important in mediating some of the effects of REM sleep deprivation such as antidepressant effects, hyperphagia and increased sympathetic activity.

View details for DOI 10.1016/j.brainres.2003.09.032

View details for Web of Science ID 000187747400001

View details for PubMedID 14644464

Abstract

Excessive daytime sleepiness, hallucinations and REM sleep behavior disorder are symptoms reported in both dementia with Lewy bodies (DLB) and narcolepsy. Considering the demonstration of low hypocretin-1/orexin A levels in the cerebrospinal fluid (CSF) of most patients with narcolepsy, we hypothesized the presence of a deficient hypocretinergic transmission in DLB. Hypocretin-1 was tested in the CSF of 10 DLB patients. Levels were found to be in the normal range (mean 521 pg/ml, range 382-667) when compared to controls (n = 20, mean 497 pg/ml, range 350-603) and Alzheimer's disease patients (n = 7, mean 474 pg/ml, range 333-564). In DLB, excessive daytime sleepiness, hallucinations and REM sleep behavior may occur in the absence of a detectable hypocretin deficiency.

View details for DOI 10.1159/000079749

View details for Web of Science ID 000224988600002

View details for PubMedID 15256827

Abstract

An underlying complex genetic susceptibility exists in multiple sclerosis (MS), and an association with the HLA-DRB1*1501-DQB1*0602 haplotype has been repeatedly demonstrated in high-risk (northern European) populations. It is unknown whether the effect is explained by the HLA-DRB1 or the HLA-DQB1 gene within the susceptibility haplotype, which are in strong linkage disequilibrium (LD). African populations are characterized by greater haplotypic diversity and distinct patterns of LD compared with northern Europeans. To better localize the HLA gene responsible for MS susceptibility, case-control and family-based association studies were performed for DRB1 and DQB1 loci in a large and well-characterized African American data set. A selective association with HLA-DRB1*15 was revealed, indicating a primary role for the DRB1 locus in MS independent of DQB1*0602. This finding is unlikely to be solely explained by admixture, since a substantial proportion of the susceptibility chromosomes from African American patients with MS displayed haplotypes consistent with an African origin.

View details for Web of Science ID 000187723500015

View details for PubMedID 14669136

Abstract

Using two different canine models of narcolepsy, we evaluated the therapeutic effects of hypocretin-1 on cataplexy and sleep.Intracerebroventricular administration of hypocretin-1 (10 and 30 nmol per dog) but not intravenous administration (up to 6 microg/kg) induced significant wakefulness in control dogs. However, hypocretin-1 had no effect on cataplexy or wakefulness in hypocretin receptor-2 gene (Hcrtr2) mutated narcoleptic Dobermans. Only very high intravenously doses of hypocretin-1 (96-384 microg/kg) penetrated the brain, to produce a short-lasting anticataplectic effect in a hypocretin-ligand-deficient animal.Hypocretin-1 administration, by central and systemic routes, does not improve narcoleptic symptoms in Hcrtr2 mutated Dobermans. Systemic hypocretin-1 hardly crosses the blood-brain barrier to produce therapeutic effects. The development of more centrally penetrable and longer lasting hypocretin analogs will be needed to further explore this therapeutic pathway in humans.

View details for Web of Science ID 000188205200008

View details for PubMedID 14746374

View details for Web of Science ID 000188205200029

View details for PubMedID 14746394

Abstract

The sleep disorder narcolepsy may now be considered a neurodegenerative disease, as there is a massive reduction in the number of neurons containing the neuropeptide, hypocretin (HCRT). Most narcoleptic patients have low to negligible levels of HCRT in the cerebrospinal fluid (CSF), and such measurements serve as an important diagnostic tool. However, the relationship between HCRT neurons and HCRT levels in CSF in human narcoleptics is not known and cannot be directly assessed. To identify this relationship in the present study, the neurotoxin, hypocretin-2-saporin (HCRT2-SAP), was administered to the lateral hypothalamus (LH) to lesion HCRT neurons. CSF was extracted at circadian times (ZT) 0 (time of lights-on) or ZT8 at various intervals (2, 4, 6, 12, 21, 36, 60 days) after neurotoxin administration. Compared to animals given saline in the LH, rats with an average loss of 73% of HCRT neurons had a 50% decline in CSF HCRT levels on day 60. The decline in HCRT levels was evident by day 6 and there was no recovery or further decrease. The decline in HCRT was correlated with increased REM sleep. Lesioned rats that were kept awake for 6 h were not able to release HCRT to match the output of saline rats. As most human narcoleptics have more than 80% reduction of CSF HCRT, the results from this study lead us to conclude that in these patients, virtually all of the HCRT neurons might be lost. In those narcoleptics where CSF levels are within the normal range, it is possible that not all of the HCRT neurons are lost and that the surviving HCRT neurons might be increasing output of CSF HCRT.

View details for DOI 10.1016/S0014-4886(03)00388-1

View details for Web of Science ID 000187634400049

View details for PubMedID 14769395

Abstract

CSF hypocretin-1 levels at 6 PM did not significantly differ between patients with restless legs syndrome (RLS) and control subjects as measured by direct radioimmunoassay and after acid extraction. The authors did not observe significant differences between early onset and late onset RLS. Hypocretin-1 levels did not correlate with RLS severity or polysomnographic measures. These results contrast with previous findings reporting significantly increased CSF hypocretin-1 in the late evening and mostly in early onset RLS.

View details for Web of Science ID 000186767800025

View details for PubMedID 14638970

Abstract

To explore whether acute destruction of hypocretin cells in a patient with narcolepsy could be detected and if the course of the disease could be reversed or altered by the use of prednisone for immunosuppression.Case report.A sleep-clinic population in a tertiary-care hospital.An 8-year-old boy with a very acute recent (< 2 month) onset of sleepiness.Sleep studies; fluid-attenuated inversion recovery and gadolinium magnetic resonance imaging studies with a focus on the hypothalamus; examinations of cerebrospinal fluid for cytology, protein, and hypocretin-1 levels; and HLA typing were performed.A 3-week regimen of 1 mg x kg(-1) x day(-1) of prednisone was administered in an attempt to modify the course of the disease.Sleep evaluations were consistent with a diagnosis of narcolepsy. Hypocretin-1 was absent in the cerebrospinal fluid, and HLA-DQB1*0602 was present. All other results were within normal limits, and prednisone did not have any noticeable effects. Clinical manifestation of narcolepsy might occur when the hypocretin cell damage is too advanced to be reversible.

View details for Web of Science ID 000186745800007

View details for PubMedID 14655912

Abstract

CSF hypocretin-1 was measured in 28 Guillain-Barré syndrome (GBS), 12 Miller-Fisher syndrome, 12 chronic inflammatory demyelinating polyneuropathy (CIDP), and 48 control subjects. Seven GBS subjects had undetectably low hypocretin-1 levels (<100 pg/mL). Hypocretin-1 levels were moderately reduced in an additional 11 GBS, 5 Miller-Fisher syndrome, and 1 CIDP subject. Low levels in GBS occurred early in the disease and were associated with upper CNS level abnormalities.

View details for Web of Science ID 000185460600020

View details for PubMedID 14504329

View details for Web of Science ID 000185472200002

View details for PubMedID 14572113

Abstract

Hypocretins, excitatory neuropeptides at monoaminergic synapses, appear to regulate human sleep-wake cycles. Undetectable cerebrospinal fluid hypocretin-1 levels are seen in narcolepsy, which is frequently associated with secondary depression. Shortened rapid eye movement latency is observed in both narcolepsy and depression. Cerebrospinal fluid hypocretin-1 levels have not been reported in mood disorders.We examined hypocretin-1 levels in 14 control and 15 depressed subjects. Cerebrospinal fluid was drawn continuously in supine subjects for 24 hours with an indwelling intrathecal catheter under entrained light-dark conditions. Depressed subjects were studied before and after 5 weeks of sertraline (n=10, three nonresponders) or bupropion (n=5, two nonresponders).Hypocretin-1 levels varied slightly (amplitude 10%) but significantly across the diurnal cycle in control subjects, with amplitude significantly reduced in depression (3%). Levels were lowest at midday, surprising for a hypothetically wake-promoting peptide. Mean hypocretin levels trended higher in depressive than in control subjects. Hypocretin-1 levels decreased modestly but significantly after sertraline (-14%) but not bupropion.Our results are consistent with previous physiologic findings in depression indicating dampened diurnal variations in hypocretin-1. The finding that sertraline but not bupropion slightly decreased cerebrospinal fluid hypocretin-1 indicates a serotoninergic influence on hypocretin tone.

View details for DOI 10.1016/S0006-3223(03)01740-7

View details for Web of Science ID 000184213800002

View details for PubMedID 12873798

Abstract

Subjects with Niemann-Pick disease, type C have been reported to display narcolepsylike symptoms, including cataplexy. In this study, 5 patients with juvenile Niemann-Pick disease were evaluted for sleep abnormalities using nocturnal polysomnography, clinical evaluation, and the Multiple Sleep Latency Test. HLA typing and cerebrospinal fluid hypocretin levels were also evaluated in 4 patients. Niemann-Pick disease diagnosis was confirmed in all cases biochemically and by the presence of foam cells in the bone marrow.Deterioration of intellectual function; the presence of pyramidal, dystonic and cerebellar features; and splenomegaly were observed in all cases. Cataplexy was reported in 1 patient. Nocturnal polysomnography revealed disrupted sleep in all patients. Total sleep time, sleep efficiency, rapid eye movement sleep, and delta sleep amounts were decreased when compared to age-matched controls. Altered sleep patterns included sudden increases in muscle tone during delta sleep, electroencephalographic sigma activity connected with rapid eye movements and muscle atonia, atypical K-complexes and spindle activity, and the presence of alpha-delta sleep. All Niemann-Pick disease cases exhibited fragmentary myoclonus. Shortened mean sleep latencies were observed in 3 patients during the Multiple Sleep Latency Test, but sleep-onset rapid eye movement periods were observed only in the case with cataplexy. This patient was HLA DQB1*0602 positive, while the other subjects were HLA negative. Cerebrospinal fluid hypocretin-1 levels were reduced in 2 patients (1 with cataplexy) while in the 2 other patients, the levels were at the lower range of the normal values. Hypocretin levels in the Niemann-Pick disease group (204.8 +/- 39.3 pg/mL) were significantly reduced when compared to controls (265.8 +/- 48.8 pg/mL).The findings suggest that lysozomal storage abnormalities in Niemann-Pick disease patients may impact the hypothalamus and, more specifically, hypocretin-containing cells. These changes might be partially responsible for sleep abnormalities and cataplexy in patients with Niemann-Pick disease.

View details for Web of Science ID 000183452600006

View details for PubMedID 12841368

Abstract

In humans, consolidation of wakefulness into a single episode can be modeled as the interaction of two processes, a homeostatic "hour-glass" wake signal that declines throughout the daytime and a circadian wake-promoting signal that peaks in the evening. Hypocretins, novel hypothalamic neuropeptides that are dysfunctional in the sleep disorder narcolepsy, may be involved in the expression of the circadian wake-promoting signal. Hypocretins (orexins) are wake-promoting peptides, but their role in normal human sleep physiology has yet to be determined. We examined the daily temporal pattern of hypocretin-1 in the cisternal CSF of the squirrel monkey, a New World primate with a pattern of wake similar to that of humans. Hypocretin-1 levels peaked in the latter third of the day, consistent with the premise that hypocretin-1 is involved in wake regulation. When we lengthened the wake period by 4 hr, hypocretin-1 concentrations remained elevated, indicating a circadian-independent component to hypocretin-1 regulation. Changes in the stress hormone cortisol were not correlated with hypocretin-1 changes. Although hypocretin-1 is at least partially activated by a reactive homeostatic mechanism, it is likely also regulated by the circadian pacemaker. In the squirrel monkey, hypocretin-1 works in opposition to the accumulating sleep drive during the day to maintain a constant level of wake.

View details for Web of Science ID 000182475200052

View details for PubMedID 12716965

Abstract

Recent studies suggest that narcolepsy is caused by degeneration of hypocretin (orexin) producing neurons. To find evidence for this hypothesis, we aimed to detect structural changes in the hypothalamus and/or hypocretin projection areas of patients with narcolepsy.We used voxel-based morphometry (VBM), an unbiased MRI morphometric method with a high sensitivity for subtle changes in gray and white matter volumes.Image acquisition was carried out in the department of Radiology at Leiden University Medical Center; image post-processing was performed in the Wellcome Department of Cognitive Neurology, London.Fifteen narcoleptic patients were studied, all having cataplexy and typical findings on Multiple Sleep Latency Testing. All patients were HLA-DQB1*0602 positive and hypocretin-1 deficient. The control group consisted of 15 age and sex matched healthy subjects.We found no differences in global gray or white matter volumes between patients and controls. Furthermore, regional gray or white matter volumes in the hypothalamus and hypocretin projection areas did not differ between patients and controls.VBM failed to show structural changes in the brains of patients with narcolepsy. This suggests that narcolepsy either is associated with microscopic changes undetectable by VBM or that functional abnormalities of hypocretin neurons are not associated with structural correlates.

View details for Web of Science ID 000181724800010

View details for PubMedID 12627731

Abstract

Delineating the basic mechanisms that regulate sleep will likely result in the development of better treatments for sleep disorders. The hypothalamus is now recognized as a key center for sleep regulation, with hypothalamic neurotransmitter systems providing the framework for therapeutic advances. An increased awareness of the close interaction between sleep and homeostatic systems is also emerging. Progress has occurred in the understanding of narcolepsy--molecular techniques have identified the lateral hypothalamic hypocretin (orexin) neuropeptide system as key to the disorder. Other sleep disorders are now being tackled in the same way and are likely to yield to efforts combining basic and clinical research. Here we highlight the role of the hypothalamus in sleep physiology and discuss neurotransmitter systems, such as adenosine, dopamine, GABA, histamine and hypocretin, that may have therapeutic applications for sleep disorders.

View details for DOI 10.1038/nn944

View details for Web of Science ID 000179041300017

View details for PubMedID 12403989

Abstract

Hypocretin-1 levels were increased in evening CSF samples from subjects with restless legs syndrome, indicating altered hypocretin transmission in this sleep disorder. Increases in CSF hypocretin-1 levels were most striking in patients with early-onset restless legs syndrome.

View details for Web of Science ID 000177613500035

View details for PubMedID 12196669

Abstract

Very few studies have evaluated narcolepsy in Asian countries, outside of Japan. Our goal was to study narcolepsy at the genetic, clinical and pathophysiological level in Korea.Prospective study of consecutive patients and age matched controls. Clinical data ascertained from the Stanford Sleep Inventory, Polysomnography and MSLT data, as well as clinical notes. High resolution DRB1 and DQB1 typing in all subjects and studies of CSF hypocretin-1 was also evaluated in a subset of patients.20 patients diagnosed at St. Vincent and Korea University Hospitals (Seoul, Korea). 21 Korean control subjects.N/A.For narcoleptic subjects, mean age was 28.2 years old and 45% were female. Mean BMI was 23.9+/-3.4 kg/m2, a significantly higher value than that expected in an age- and sex-matched sample (p<0.01). All patients had sleepiness and cataplexy while the prevalence of other symptoms ranged from 60-75%. All but 2 subjects were HLA-DR15 (DR2), DQB1*0602 positive (90%). This high DQB1*0602 percentage compared with 24% DQB1*0602 positivity in 21 control Koreans. Protective effects were observed for the DQB1*0601 and DRB1*0406 alleles, Hypocretin (orexin) CSF studies were also performed in 6 cataplectic subjects, all of which had undetectable CSF hypocretin levels. Two of these subjects had started narcolepsy less than 1 year before analysis yet had undetectable hypocretin levels.These results illustrate the similarity of narcolepsy-cataplexy in Korea in comparisons with other more studied populations. We also identified a new potential HLA protective subtype, HLA-DRB1*0406.

View details for Web of Science ID 000176089100011

View details for PubMedID 12071546

Abstract

In vitro functional analyses of hypocretin/orexin receptor systems were performed using [(125)I]hypocretin radioreceptor and hypocretin-stimulated [(35)S]GTP gamma S binding assay in cell lines expressing human or canine (wild-type and narcoleptic-mutation) hypocretin receptor 2 (Hcrtr 2). Hypocretin-2 stimulated [(35)S]GTP gamma S binding in human and canine Hcrtr 2 expressing cell lines, while cell lines expressing the mutated canine Hcrtr 2 did not exhibit specific binding for [(125)I]hypocretin or hypocretin-stimulated [(35)S]GTP gamma S. In rat brain homogenates, regional specific hypocretin-stimulated [(35)S]GTP gamma S binding was also observed. Hypocretin-stimulated [(35)S]GTP gamma S binding, may thus be a useful functional assay for hypocretin receptors in both cell lines and brain tissue homogenates.

View details for Web of Science ID 000176364700017

View details for PubMedID 12056812

Abstract

Hypocretins/orexins are newly identified peptides of hypothalamic origin. Hypocretin deficiency is involved in the sleep disorder narcolepsy, suggesting the importance of hypocretin neurotransmission for the regulation of sleep. Hypocretin is known to excite midbrain dopaminergic neurons and to induce hyperactivity and stereotypy in animals. Altered hypocretin neurotransmission might therefore be involved in schizophrenia, since an involvement of dopaminergic mechanisms and an association with sleep disturbance are well demonstrated in patients with schizophrenia. Hypocretin is also known to affect the hypothalamic-pituitary-adrenal axis by stimulating the release of corticotropin releasing hormone (CRH). In the current study, we measured CSF hypocretin levels in 12 controls and 13 patients with chronic schizophrenia associated with moderate sleep disturbance, such as longer sleep onset latency, decreased total sleep time and decreased sleep efficacy. No difference in CSF hypocretin levels between schizophrenia and control subjects was found. CSF hypocretin levels were positively correlated with CSF CRH levels in the patient, control and combined subject populations, but the correlation did not reach statistical significance in any population. The hypocretin levels in schizophrenic patients were, however, positively and significantly correlated with sleep latency, one of the most consistent sleep abnormalities seen in schizophrenia. This correlation was not significant in controls, and no other significant correlation between CSF hypocretin levels and any measure of sleep architecture in either patients or controls was observed. Further studies of whether CNS hypocretin neurotransmission is involved in sleep and neuroendocrine abnormalities seen in patients with schizophrenia and other psychiatric conditions are warranted.

View details for Web of Science ID 000176095700001

View details for PubMedID 12007588

Abstract

The objectives of this study were to compare severity and clinical presentation for narcolepsy-cataplexy across various ethnic groups. A large sample of narcoleptic patients was also used to further describe symptomatology and natural history for this sleep disorder.Retrospective review of clinical data ascertained from the Stanford Sleep Inventory, polysomnography and MSLT data, as well as clinical notes. Ethnicity was narrowly defined as African (Black) Americans, Caucasians, Asians, and Latinos when both parents and the subject identified with a given ethnic group.N/A.We compared the severity and clinical presentation of narcolepsy in 64 African Americans, 353 Caucasians, 32 Asians, 26 Latinos, and 9 subjects of mixed ethnicity. Subjects were recruited through the Stanford center for narcolepsy research.N/A.A striking similarity in symptomatology, age of onset, and disease severity was found across ethnic groups. Mean age of onset for sleepiness, hypnagogic hallucinations, sleep paralysis and cataplexy were 19.20, 19.50, 20.11 and 23.02 years old. We also found that narcoleptic patients have slightly but significantly elevated body mass index relative to normative data (106.6% of matched controls, p<0.005) and are born slightly more frequently during the month of March. A tight correlation between our previously validated cataplexy scale and DQB1*0602 positivity was observed. Two thirds of patients reported having cataplexy with laughing, 92% of those being DQB1*0602 positive independent of ethnicity.These results confirm the similarities in clinical presentation and natural history of narcolepsy-cataplexy in a large number of patients of various ethnic groups and cultural backgrounds.

View details for Web of Science ID 000173415100006

View details for PubMedID 11833858

Abstract

The hypocretins (orexins) are two novel neuropeptides (Hcrt-1 and Hcrt-2), derived from the same precursor gene, that are synthesized by neurons located exclusively in the lateral, posterior, and perifornical hypothalamus. Hypocretin-containing neurons have widespread projections throughout the CNS with particularly dense excitatory projections to monoaminergic centers such as the noradrenergic locus coeruleus, histaminergic tuberomammillary nucleus, serotoninergic raphe nucleus, and dopaminergic ventral tegmental area. The hypocretins were originally believed to be primarily important in the regulation of appetite; however, a major function emerging from research on these neuropeptides is the regulation of sleep and wakefulness. Deficiency in hypocretin neurotransmission results in the sleep disorder narcolepsy in mice, dogs, and humans. The hypocretins are also uniquely positioned to link sleep, appetite, and neuroendocrine control. The aim of this review is to describe and discuss the current knowledge regarding the hypocretin neurotransmitter system in narcolepsy and normal sleep.

View details for DOI 10.1146/annurev.neuro.25.112701.142826

View details for Web of Science ID 000177354800009

View details for PubMedID 12052911

Abstract

To examine the specificity of low CSF hypocretin-1 levels in narcolepsy and explore the potential role of hypocretins in other neurologic disorders.A method to measure hypocretin-1 in 100 microL of crude CSF sample was established and validated. CSF hypocretin-1 was measured in 42 narcolepsy patients (ages 16-70 years), 48 healthy controls (ages 22-77 years,) and 235 patients with various other neurologic conditions (ages 0-85 years).As previously reported, CSF hypocretin-1 levels were undetectably low (<100 pg/mL) in 37 of 42 narcolepsy subjects. Hypocretin-1 levels were detectable in all controls (224-653 pg/mL) and all neurologic patients (117-720 pg/mL), with the exception of three patients with Guillain-Barré syndrome (GBS). Hypocretin-1 was within the control range in most neurologic patients tested, including patients with AD, PD, and MS. Low but detectable levels (100-194 pg/mL) were found in a subset of patients with acute lymphocytic leukemia, intracranial tumors, craniocerebral trauma, CNS infections, and GBS.Undetectable CSF hypocretin-1 levels are highly specific to narcolepsy and rare cases of GBS. Measuring hypocretin-1 levels in the CSF of patients suspected of narcolepsy is a useful diagnostic procedure. Low hypocretin levels are also observed in a large range of neurologic conditions, most strikingly in subjects with head trauma. These alterations may reflect focal lesions in the hypothalamus, destruction of the blood brain barrier, or transient or chronic hypofunction of the hypothalamus. Future research in this area is needed to establish functional significance.

View details for Web of Science ID 000172891500018

View details for PubMedID 11756606

Abstract

Human narcolepsy/cataplexy is associated with reduced hypocretin (orexin) transmission. A common preprophypocretin (HCRT) polymorphism (-909C/T) was identified and tested in 502 subjects (105 trio families, 80 Caucasian narcolepsy cases, and 107 Caucasian control subjects). This polymorphism was not associated with the disease. The promoter and 5' untranslated (5'URT) regions of the HCRT gene (-320 to +21 from ATG) were also sequenced in 281 subjects. None of the subjects carried -22T, a rare 5'UTR polymorphism previously reported to be associated with narcolepsy. The HCRT locus is not a major narcolepsy susceptibility locus.

View details for Web of Science ID 000172334700029

View details for PubMedID 11723284

Abstract

A growing amount of evidence suggests that a deficiency in hypocretin/orexin neurotransmission is critically involved in animal and human forms of narcolepsy. Since hypocretin-containing neurons innervate and excite histaminergic tuberomammillary neurons, altered histaminergic neurotransmission may also be involved in narcolepsy. We found a significant decrease in histamine content in the cortex and thalamus, two structures important for histamine-mediated cortical arousal, in Hcrtr-2 mutated narcoleptic Dobermans. In contrast, dopamine and norepinephrine contents in these structures were elevated in narcoleptic animals, a finding consistent with our hypothesis of altered catecholaminergic transmission in these animals. Considering the fact that histamine promotes wakefulness, decreases in histaminergic neurotransmission may also account for the sleep abnormalities in hypocretin-deficient narcolepsy.

View details for Web of Science ID 000172056000004

View details for PubMedID 11682143

Abstract

Hypocretins/orexins are rapidly emerging as functionally important neurotransmitters. Two related neuropeptides (Hcrt-1/OXA, Hcrt-2/OXB) encoded by the same precursor gene and two G-protein coupled receptors (Hcrtr1/OXR1, Hcrtr2/OXR2) are currently known. Hypocretin-containing cells are discretely localized within the perifornical hypothalamus but have widespread projections, with generally excitatory postsynaptic effects. Dense excitatory projections to all monoaminergic cell groups have been reported. A major emerging function for this system is likely to be the regulation of sleep. Alterations in hypocretin neurotransmission causes the sleep disorder narcolepsy in mice, dogs and humans. Effects on appetite, neuroendocrine and energy metabolism regulation are also suggested by other studies. Hypocretins are uniquely positioned to link sleep, appetite and neuroendocrine control, three behaviors of major importance in psychiatry. The potential role of this system in regulating the sleep cycle, modulating wakefulness at selected circadian times and in mediating the deleterious effects of sleep deprivation is discussed.

View details for Web of Science ID 000172066000003

View details for PubMedID 11682267

Abstract

Hypocretins/orexins are neuropeptides implicated in sleep regulation and the sleep disorder narcolepsy. In order to examine how hypocretin activity fluctuates across 24 h with respect to the sleep-wake cycle, we measured changes in extracellular hypocretin-1 levels in the lateral hypothalamus and medial thalamus of freely moving rats with simultaneous sleep recordings. Hypocretin levels exhibited a robust diurnal fluctuation; levels slowly increased during the dark period (active phase), and decreased during the light period (rest phase). Levels were not correlated with the amount of wake or sleep in each period. Although an acute 4-h light-shift did not alter hypocretin levels, 6-h sleep deprivation significantly increased hypocretin release during the forced-wake period. Hypocretin activity is, thus, likely to build up during wakefulness and decline with the occurrence of sleep. These findings, together with the fact that a difficulty in maintaining wakefulness during the daytime is one of the primary symptoms of hypocretin-deficient narcolepsy, suggest that hypocretin activity may be critical in opposing sleep propensity during periods of prolonged wakefulness.

View details for Web of Science ID 000171795700004

View details for PubMedID 11683899

Abstract

Narcolepsy was first shown to be tightly associated with HLA-DR2 and DQ1 in 1983, suggesting a possible autoimmune mechanism. Early investigations failed to demonstrate this hypothesis, postulating that HLA-DR2 was only a linkage marker for another, unknown narcolepsy-causing gene. The autoimmune hypothesis is now being re-evaluated under the light of recent results. Like many other autoimmune disorders, narcolepsy usually starts during adolescence, is human leukocyte antigen (HLA)-associated, multigenic and environmentally influenced. Furthermore, HLA-association studies indicated a primary HLA-DQ effect with complex HLA class II allele interactions and a partial contribution of HLA to overall genetic susceptibility. Finally, recent result suggests that human narcolepsy is associated with the destruction of a small number of hypothalamic neurons containing the peptide hypocretins (orexins). This data is consistent with an immune destruction of hypocretin-containing cells as the most common etiology for human narcolepsy.

View details for Web of Science ID 000170168100002

View details for PubMedID 11431000

Abstract

Idiopathic narcolepsy usually results from a loss of the hypothalamic neuropeptide orexin (hypocretin), but the cause of secondary narcolepsy resulting from focal brain lesions is unknown. The authors describe a young man who developed narcolepsy after a large hypothalamic stroke. His lesion included much of the hypothalamic region in which orexin is produced, and his CSF concentration of orexin was low. The authors hypothesize that a loss of orexin neurons or their relevant targets may be the specific neuropathology causing this and many other cases of secondary narcolepsy.

View details for Web of Science ID 000169424200026

View details for PubMedID 11425947

Abstract

Apolipoprotein E epsilon4(ApoE epsilon4) is a well-known risk factor for Alzheimer disease and cardiovascular disease. Sleep-disordered breathing occurs in Alzheimer disease patients and increases risks for cardiovascular disease. Complex interactions among sleep, brain pathology, and cardiovascular disease may occur in ApoE epsilon4 carriers.To study whether genetic variation at the level of ApoE is associated with sleep-disordered breathing or sleep abnormalities in the general population.Ongoing longitudinal cohort study of sleep disorders at a US university beginning in 1989, providing a population-based probability sample of 791 middle-aged adults (mean [SD] age, 49 [8] years; range, 32-68 years).Nocturnal polysomnography to evaluate apnea-hypopnea index.The probability of moderate-to-severe sleep-disordered breathing (apnea-hypopnea index >/=15%) was significantly higher in participants with epsilon4, independent of age, sex, body mass index, and ethnicity (12.0% vs 7.0%; P =.003). Mean (SEM) apnea-hypopnea index was also significantly higher in participants with ApoE epsilon4 (6.5 [0.6] vs 4.8 [0.3]; P =.01). These effects increased with the number of ApoE epsilon4 alleles carried.A significant portion of sleep-disordered breathing is associated with ApoE epsilon4 in the general population.

View details for Web of Science ID 000169156300028

View details for PubMedID 11401610

Abstract

Familial and sporadic forms of narcolepsy exist in both humans and canines. Mutations in the hypocretin receptor 2 gene (Hcrtr 2) cause canine familial narcolepsy. In humans, mutations in hypocretin-related genes are rare, but cerebrospinal fluid (CSF) hypocretin-1 is undetectable in most sporadic cases. Using the canine model, we investigated ( 1 ) whether hypocretin deficiency is involved in sporadic cases and ( 2 ) whether alterations in hypocretin neurons or ligand levels also contribute to the phenotype in Hcrtr 2 mutants. We found that hypocretins were undetectable in the brains of three of three and the CSF of two of two sporadic narcoleptic dogs tested. In contrast, hypocretin levels were not altered in brains and CSF of genetically narcoleptic Dobermans, and hypocretin-containing neurons were of normal appearance. Therefore, multiple hypocretin-related etiologies are likely to be involved in canine narcolepsy. The presence of hypocretin peptides in Hcrtr 2-mutated animals suggests that neurotransmission through Hcrtr 1 may be intact, arguing for a preferential importance of Hcrtr 2-mediated function in narcolepsy.

View details for Web of Science ID 000169459000014

View details for PubMedID 11442359

Abstract

The discovery that hypocretins are involved in narcolepsy, a disorder associated with excessive daytime sleepiness, cataplexy and unusually rapid transitions to rapid-eye-movement sleep, opens a new field of investigation in the area of sleep control physiology. Hypocretin-1 and -2 (also called orexin-A and -B) are newly discovered neuropeptides processed from a common precursor, preprohypocretin. Hypocretin-containing cells are located exclusively in the lateral hypothalamus, with widespread projections to the entire neuroaxis. Two known receptors, Hcrtr1 and Hcrtr2, have been reported. The functional significance of the hypocretin system is rapidly emerging in both animals and humans. Hypocretin abnormalities cause narcolepsy in dogs, human and mice. The role of the hypocretin system in normal sleep regulation is more uncertain. We believe hypocretin cells drive cholinergic and monoaminergic activity across the sleep cycle. Input from the suprachiasmatic nucleus to hypocretin-containing neurons may explain the occurrence of clock-dependent alertness. Other functions are suggested by pharmacological and neurochemical experiments. These include regulation of food intake, neuroendocrine function, autonomic nervous system activity and energy balance.

View details for Web of Science ID 000168435600005

View details for PubMedID 11340621

Abstract

The positional cloning of the hypocretin receptor 2, the gene for autosomal recessive canine narcolepsy, has led to the development of a physical map spanning a large portion of canine chromosome 12 (CFA12), in a region corresponding to human chromosome 6p12-q13. More than 40 expressed sequence tags (ESTs) were used in homology search experiments, together with chromosome walking, to build both physical and radiation hybrid maps of the CFA12 13-21 region. The resulting map of bacterial artificial chromosome ends, ESTs, and microsatellite markers represents the longest continuous high-density map of the dog genome reported to date. These data further establish the dog as a system for studying disease genes of interest to human populations and highlight feasible approaches for positional cloning of disease genes in organisms where genomic resources are limited.

View details for Web of Science ID 000168774400007

View details for PubMedID 11350122

Abstract

Hypocretin-1 is consistently detectable in the CSF of healthy human subjects, but is absent in narcoleptics. However, functional roles of CSF hypocretin are largely unknown. We examined fluctuation of CSF hypocretin-1 across 24 h and in response to food restriction in rats. Hypocretin-1 levels were high during the dark period when animals were active, but decreased by 40% toward the end of the light (rest) period. After 72 h food deprivation hypocretin-1 levels during the rest phase increased to concentrations similar to those seen during the baseline active phase; however, no increase in response to food deprivation was observed during the active phase. These results indicate an important link between circadian control of sleep and energy homeostasis via the hypocretin system.

View details for Web of Science ID 000167905600027

View details for PubMedID 11303775

View details for Web of Science ID 000168093800004

View details for PubMedID 11330202

Abstract

Narcolepsy is a sleep disorder affecting animals and humans. Exon skipping mutations of the Hypocretin/Orexin-receptor-2 (Hcrtr2) gene were identified as the cause of narcolepsy in Dobermans and Labradors. Preprohypocretin (Hcrt) knockout mice have symptoms similar to human and canine narcolepsy. In this study, 11 sporadic cases of canine narcolepsy and two additional multiplex families were investigated for possible Hcrt and Hcrtr2 mutations. Sporadic cases have been shown to have more variable disease onset, increased disease severity, and undetectable Hypocretin-1 levels in cerebrospinal fluid. The canine Hcrt locus was isolated and characterized for this project. Only one novel mutation was identified in these two loci. This alteration results in a single amino acid substitution (E54K) in the N-terminal region of the Hcrtr2 receptor and autosomal recessive transmission in a Dachshund family. Functional analysis of previously-described exon-skipping mutations and of the E54K substitution were also performed using HEK-293 cell lines transfected with wild-type and mutated constructs. Results indicate a truncated Hcrtr2 protein, an absence of proper membrane localization, and undetectable binding and signal transduction for exon-skipping mutated constructs. In contrast, the E54K abnormality was associated with proper membrane localization, loss of ligand binding, and dramatically diminished calcium mobilization on activation of the receptor. These results are consistent with a loss of function for all three mutations. The absence of mutation in sporadic cases also indicates genetic heterogeneity in canine narcolepsy, as reported previously in humans.

View details for Web of Science ID 000167885400004

View details for PubMedID 11282968

Abstract

Narcolepsy is characterized by excessive daytime sleepiness and abnormal manifestations of rapid eye movement sleep such as cataplexy. The authors review the clinical features of narcolepsy, including epidemiology, symptoms, diagnosis, and treatment, in detail. Recent findings show that a loss of hypocretin-producing neurons lies at the root of the signs and symptoms of narcolepsy. The authors review the current state of knowledge on hypocretin anatomy, physiology, and function with special emphasis on the research regarding the hypocretin deficiency in narcolepsy, which may also explain associated features of the disorder, such as obesity. Lastly, they discuss some future perspectives for research into the pathophysiology of sleep/wake disorders, and the potential impact of the established hypocretin deficiency on the diagnosis and treatment of narcolepsy.

View details for Web of Science ID 000169315700002

View details for PubMedID 11435802

Abstract

The role of dopamine in sleep regulation and in mediating the effects of wake-promoting therapeutics is controversial. In this study, polygraphic recordings and caudate microdialysate dopamine measurements in narcoleptic dogs revealed that the wake-promoting antinarcoleptic compounds modafinil and amphetamine increase extracellular dopamine in a hypocretin receptor 2-independent manner. In mice, deletion of the dopamine transporter (DAT) gene reduced non-rapid eye movement sleep time and increased wakefulness consolidation independently from locomotor effects. DAT knock-out mice were also unresponsive to the normally robust wake-promoting action of modafinil, methamphetamine, and the selective DAT blocker GBR12909 but were hypersensitive to the wake-promoting effects of caffeine. Thus, dopamine transporters play an important role in sleep regulation and are necessary for the specific wake-promoting action of amphetamines and modafinil.

View details for Web of Science ID 000167129700040

View details for PubMedID 11222668

View details for Web of Science ID 000174224300035

Abstract

Narcolepsy is a chronic sleep disorder marked by excessive daytime sleepiness, cataplexy, sleep paralysis, and hypnagogic hallucinations. Since the discovery of sleep onset REM periods (SOREMPs) in narcoleptic patients, narcolepsy has often been regarded as a disorder of REM sleep generation: REM sleep intrudes in active wake or at sleep onset, resulting in cataplexy, sleep paralysis, or hypnagogic hallucinations. However, this hypothesis has not been experimentally verified. In the current study, we characterized the sleep abnormalities of genetically narcoleptic-cataplectic Dobermans, a naturally occurring animal model of narcolepsy, in order to verify this concept. Multiple sleep latency tests during the daytime revealed that narcoleptic Dobermans exhibit a shorter sleep latency and a higher frequency of SOREMPs, compared to control Dobermans. The total amount of time spent in wake and sleep during the daytime is not altered in narcoleptic dogs, but their wake and sleep patterns are fragmented, and state transitions into and from wake and other sleep stages are altered. A clear 30 min REM sleep cyclicity exists in both narcoleptic and control dogs, suggesting that generation of the ultradian rhythm of REM sleep is not altered in narcoleptics. In contrast, cataplexy displays no cyclicity and can be elicited in narcoleptic animals anytime with emotional stimulation and displays no cyclicity. Stimulation of a cholinoceptive site in the basal forebrain induces a long-lasting attack of cataplexy in narcoleptic dogs; however, bursts of rapid eye movements during this state still occur with a 30 min cyclicity. Sites and mechanisms for triggering cataplexy may therefore be different from those for REM sleep. Cataplexy and a dysfunction in the maintenance of vigilance states, but not abnormal REM sleep generation, may therefore be central to narcolepsy.

View details for Web of Science ID 000166120200013

View details for PubMedID 11164570

Abstract

Cataplexy, an abnormal manifestation of REM sleep atonia, is currently treated with antidepressants. These medications also reduce physiological REM sleep and induce nocturnal sleep disturbances. Because a recent work on canine narcolepsy suggests that the mechanisms for triggering cataplexy are different from those for REM sleep, we hypothesized that compounds which act specifically on cataplexy, but not on REM sleep, could be developed. Canine studies also suggest that the dopamine D2/D3 receptor mechanism is specifically involved in the regulation of cataplexy, but little evidence suggests that this mechanism is important for REM sleep regulation. We therefore assessed the effects of sulpiride, a commonly used D2/D3 antagonist, on cataplexy and sleep in narcoleptic canines to explore the possible clinical application of D2/D3 antagonists for the treatment of human narcolepsy. Both acute and chronic oral administration of sulpiride (300 mg/dog, 600 mg/dog) significantly reduced cataplexy without noticeable side effects. Interestingly, the anticataplectic dose of sulpiride did not significantly reduce the amount of REM sleep. Sulpiride (and other D2/D3 antagonists) may therefore be an attractive new therapeutic indication in human narcolepsy.

View details for Web of Science ID 000089867500005

View details for PubMedID 11027918

Abstract

The effects on cataplexy and daytime sleep of acute and chronic oral administration of CG-3703, a potent TRH analog were assessed in canine narcolepsy. CG-3703 was found to be orally active and to reduce cataplexy (0.25 to 16 mg/kg) and sleep (8 and 16 mg/kg) in a dose-dependent manner. Two-week oral administration of CG-3703 (16 mg/kg) significantly reduced cataplexy and daytime sleep. The anticataplectic effects of CG-3703 were not associated with changes in general behavior, heart rate, blood pressure, rectal temperature, blood chemistry and thyroid function. Although drug tolerance for the effects on cataplexy and sleep were observed during the second week of chronic drug administration, therapeutic efficacy on cataplexy was improved with individual dose adjustment (final dose range: 16 to 28 mg/kg, p.o.). These results suggest that TRH analogs could be a promising new form of treatment for human narcolepsy.

View details for Web of Science ID 000087772700004

View details for PubMedID 10869884

View details for Web of Science ID 000208300300005

View details for Web of Science ID 000086058200006

Abstract

Alterations in the hypocretin receptor 2 and preprohypocretin genes produce narcolepsy in animal models. Hypocretin was undetectable in seven out of nine people with narcolepsy, indicating abnormal hypocretin transmission.

View details for Web of Science ID 000085049200016

View details for PubMedID 10615891

View details for PubMedID 10767648

Abstract

A mutation in the HCRT locus was proved in 18-yrs old male suffering from narcolepsy-cataplexy. He has demonstrated cataplectic attacks (brief spells of head dropping provoked by laughter) as well as imperative sleep in spells of several minutes up to one hour since the age of six months. He has suffered from severe bulimia since five years; later hypnagogic hallucinations, sleep paralysis and unquiet nocturnal sleep accompanied by periodic limb movements appeared. Symptoms are partially controlled with methylphenidate and either imipramine, clomipramine or fluoxetine. Periodic leg movements poorly responded to L-DOPA and clonazepam treatment. He is HLA-DQB1*0602 negative. Repeated MSLT (over 16 years followed-up period) showed extremely short latency with predominant SOREMPs and also nocturnal PSG recordings revealed fragmented sleep with SOREMPs. This case report demonstrates that hypocretin (orexin) mutations in human can produce the full narcolepsy phenotype and validates data recently reported in dog and mouse models suggesting a role for hypocretin (orexin) in the pathophysiology of narcolepsy and the regulation of REM sleep.

View details for PubMedID 11702580

Abstract

Using a canine model of narcolepsy and selective DA and NE uptake inhibitors, we have recently shown that DA uptake inhibition promotes wakefulness, while NE uptake inhibition inhibits rapid eye movement sleep and cataplexy. In order to further delineate the respective roles of the dopaminergic and noradrenergic systems in the pharmacological control of symptoms of narcolepsy, we compared the potency of amphetamine isomers (D- and L-amphetamines) and a derivative (L-methamphetamine) on wakefulness and cataplexy. Their respective effects on these narcolepsy symptoms were then compared with their in vivo effects on extracellular DA levels in the caudate and NE levels in the frontal cortex during local drug perfusion in narcoleptic dogs. Polygraphic recordings demonstrated that D-amphetamine was about twice as potent as L-amphetamine, and was six times more potent than L-methamphetamine in increasing wakefulness and reducing slow-wave sleep. D-Amphetamine and L-amphetamine were equipotent in reducing rapid eye movement sleep and cataplexy, and L-methamphetamine was about half as potent as L- and D-amphetamines. D-Amphetamine was found to be more potent in increasing DA efflux than L-amphetamine, and L-methamphetamine was found to have little effect on DA efflux; there was no significant difference in the potencies of the three derivatives on NE efflux. The potencies of these amphetamines on wakefulness correlated well with DA, but not NE, efflux in the brain of narcoleptic dogs during local drug perfusion. Our current results further exemplify the importance of the DA system for the pharmacological control of electroencephalogram arousal and suggest that increased DA transmission mediates the wake-promoting effects of amphetamine-like stimulants.

View details for Web of Science ID 000089250800007

View details for PubMedID 10974428

Abstract

Narcolepsy is a disabling sleep disorder characterized by excessive daytime somnolence (EDS), cataplexy and REM sleep-related abnormalities. It is a frequently-occurring but under-diagnosed condition that affects 0.02 to 0.18% of the general population in various countries. Although most cases occur sporadically, familial clustering may be observed; the risk of a first-degree relative of a narcoleptic developing narcolepsy is 10-40 times higher than in the general population. The disorder is tightly associated with the specific human leukocyte antigen (HLA) allele, DQB1*0602 [most often in combination with HLA-DR2 (DRB1*15)]. Genetic transmission is, however, likely to be polygenic in most cases, and genetic factors other than HLA-DQ are also likely to be implicated. In addition, environmental factors are involved in disease predisposition; most monozygotic twins pairs reported in the literature are discordant for narcolepsy. Narcolepsy was reported to exist in canines in the early 1970s. Both sporadic and familial cases are also observed in this animal species. A highly-penetrant single autosomal recessive gene, canarc-1, is involved in the transmission of narcolepsy in Doberman pinschers and Labrador retrievers. Positional cloning of this gene is in progress, and a human homologue of this gene, or a gene with a functional relationship to canarc-1, might be involved in some human cases. Human narcolepsy is currently treated with central nervous system (CNS) stimulants for EDS and antidepressants for cataplexy and abnormal REM sleep. These treatments are purely symptomatic and induce numerous side effects. These compounds disturb nocturnal sleep in many patients, and tolerance may develop as a result of continuous treatment. The canine model is an invaluable resource for studying the pharmacological and physiological control of EDS and cataplexy. Experiments using canine narcolepsy have demonstrated that increased cholinergic and decreased monoaminergic transmission are likely to be at the basis of the pathophysiology of the disorder. Pharmacological studies have shown that blockade of norepinephrine uptake mediates the anticataplectic effect of currently prescribed antidepressants, while blockade of dopamine uptake and/or stimulation of dopamine release mediates the awake-promoting effect of CNS stimulants. Studies in canine narcolepsy also suggest that mechanisms and brain sites for triggering cataplexy are not identical to those regulating REM sleep. It may thus be possible to develop new pharmacological compounds that specifically target abnormal symptoms in narcolepsy, but do not disturb physiological sleep/wake cycles. (See also postscript remarks).

View details for PubMedID 12531161

Abstract

The effect of a single nucleotide polymorphism, a glutamine to arginine amino acid substitution in the human Timeless gene (Q831R, A2634G), on diurnal preferences was studied in a random sample of normal volunteers enrolled in a population-based epidemiology study of the natural history of sleep disorders. We genotyped 528 subjects for this single nucleotide polymorphism and determined morningness-eveningness tendencies using the Horne-Ostberg questionnaire. Our results indicate that Q831R Timeless has no influence on morningness- eveningness tendencies in humans.

View details for PubMedID 11382904

Abstract

We have recently demonstrated that local perfusion of dopaminergic D2/D3 agonists into the ventral tegmental area (VTA) significantly aggravates cataplexy and increases sleep in narcoleptic Dobermans. We further assessed the roles of the mesostriatal dopaminergic system and found that local perfusion of quinpirole and 7-OH-DPAT into the substantia nigra (SN) significantly aggravated cataplexy, while perfusion of a D2/D3 antagonist significantly reduced cataplexy. Neither a D1 agonist nor a D1 antagonist modified cataplexy. SN perfusion of quinpirole did not significantly modify sleep, while VTA perfusion significantly increased the drowsy state. Although autoregulation of the VTA and SN dopaminergic neurons are involved in the regulation of cataplexy, both structures have distinct roles for the regulation of sleep.

View details for Web of Science ID 000083934000001

View details for PubMedID 10619672

Abstract

We have recently demonstrated that local perfusion of dopaminergic D2/D3 agonists into the ventral tegmental area (VTA) significantly aggravates cataplexy and increases sleep in narcoleptic Dobermans. We further assessed the roles of the mesostriatal dopaminergic system and found that local perfusion of quinpirole and 7-OH-DPAT into the substantia nigra (SN) significantly aggravated cataplexy, while perfusion of a D2/D3 antagonist significantly reduced cataplexy. Neither a D1 agonist nor a D1 antagonist modified cataplexy. SN perfusion of quinpirole did not significantly modify sleep, while VTA perfusion significantly increased the drowsy state. Although autoregulation of the VTA and SN dopaminergic neurons are involved in the regulation of cataplexy, both structures have distinct roles for the regulation of sleep.

View details for Web of Science ID 000082865500046

View details for PubMedID 10549832

Abstract

Mammalian circadian rhythmicity has recently been shown to be regulated at the genetic level by transcription--translation feed-back loops. Key molecular components such as Clock, Bmal-1, Timeless and three Period proteins have been isolated in mammals. In this study, we hypothesized that polymorphisms at the level of one of these genes--HPER1--could be associated with differential morningness-eveningness tendencies. The sample comprised 463 middle-aged participants enrolled in the Wisconsin Sleep Cohort Study. Diurnal preferences were evaluated using the Horne-Ostberg questionnaire. An A to G synonymous substitution at position 2548 was identified in HPER1 c-DNA sequence by comparing available sequence data. This polymorphism was verified by sequencing and typed using established oligotyping techniques in all subjects, yielding allele frequencies of 0.85 and 0.15 for HPER1 2548G and HPER1 2548A, respectively. Morningness-eveningness scores were then compared between genotype groups. In contrast to data previously published using a Clock polymorphism, scores did not differ significantly across HPER1 groups. These results suggest that polymorphism at the level of HPER1 does not significantly modulate morningness-eveningness tendencies in the general population.

View details for Web of Science ID 000081591900010

View details for PubMedID 10412192

Abstract

A large insert canine genomic bacterial artificial chromosome (BAC) library was built from a Doberman pinscher. Approximately 166,000 clones were gridded on nine high-density hybridization filters. Insert analysis of randomly selected clones indicated a mean insert size of 155 kb and predicted 8.1 coverage of the canine genome. Two percent of the clones were nonrecombinant. Chromosomal fluorescence in situ hybridization studies of 60 BAC clones indicated no chimerism. The library was hybridized with dog PCR products representing eight genes (ADA, TNFA, GCA, MYB, HOXA, GUSB, THY1, and TOP1). The resulting positive clones were characterized and shown to be compatible with an eightfold redundant library.

View details for Web of Science ID 000080706600002

View details for PubMedID 10331940

Abstract

Narcolepsy, a neurological disorder characterized by excessive daytime sleepiness and abnormal REM sleep, is known to be tightly associated with the Human Leukocyte Antigen (HLA) DQ allele DQB1*0602. In this study, we have explored the possibility that normal subjects carrying this HLA allele (25% of the general population) could display subclinical REM sleep abnormalities and increased daytime sleepiness. Data from 525 middle-aged adults enrolled in the Wisconsin Sleep Cohort study were used for this analysis. Nocturnal polysomnography, sleep latency during the multiple sleep latency test (MSLT), and questionnaire items pertaining to excessive daytime sleepiness were compared between DQB1*0602 positive (n = 132) and negative (n = 393) participants. Results indicate shorter REM latency whether or not the latency was adjusted for wake after sleep onset (p = 0.003) and p = 0.02 respectively), increased sleep efficiency (p = 0.06) and decreased percent time spent in stage I sleep (p = 0.02) during nocturnal polysomnography in DQB1*0602 subjects. Data gathered using the Multiple Sleep Latency Test or the Epworth and Stanford sleepiness scales did not differentiate between DQB1*0602 positive and negative subjects. These results support the hypothesis that polymorphisms at the level of HLA DQ modulates sleep tendencies in humans.

View details for Web of Science ID 000082053300008

View details for PubMedID 10341385

Abstract

Narcolepsy is a disabling sleep disorder characterized by excessive daytime sleepiness and abnormal manifestations of rapid eye movement (REM) sleep including cataplexy, sleep paralysis, and hypnagogic hallucinations. It is known to be a complex disorder, with both genetic predisposition and environmental factors playing a role. In humans, susceptibility to narcolepsy is tightly associated with a specific HLA allele, DQB1*0602. In humans and canines, most cases are sporadic. In Doberman pinschers and Labrador retrievers, however, the disease is transmitted as an autosomal recessive gene canarc-1 with full penetrance. This gene is not linked with the dog leukocyte antigen complex, but is tightly linked with a marker with high homology to the human mu-switch immunoglobulin gene. We have isolated several genomic clones encompassing the canarc-1 marker and the variable heavy chain immunoglobulin region in canines. These have been partially sequenced and have been mapped onto specific dog chromosomes by fluorescence in situ hybridization (FISH). Our results indicate that the mu-switch-like marker is not part of the canine immunoglobulin machinery. We are continuing to extend the genomic contig using a newly developed canine BAC library and attempting to identify the corresponding human region of conserved synteny.

View details for Web of Science ID 000078225400026

View details for PubMedID 9987919

Abstract

Cholinergic stimulation in the basal forebrain (BF) triggers cataplexy in canine narcolepsy. Extracellular single unit recordings in the BF were carried out in freely moving narcoleptic dogs to study the neuronal mechanisms mediating cataplexy induction in the BF. Among the 64 recorded neurons, 12 were wake-active, three were slow wave sleep (SWS)-active, 17 were wake-/REM-active, 11 were REM sleep-active, three were cataplexy-active, and the other 18 were state-independent. Systemic administration of physostigmine, a cholinesterase inhibitor, induces status cataplecticus, decreases SWS and increases acetylcholine levels in the BF. Firing of most of the state-dependent neurons in the BF was significantly modified by physostigmine. Some of these neurons may thus mediate sleep stage changes or the effect on cataplexy observed after cholinergic stimulation in the BF.

View details for Web of Science ID 000077493400021

View details for PubMedID 9858375

Abstract

A single nucleotide polymorphism located in the 3' flanking region of the human CLOCK gene was investigated as a predictor of diurnal preference in a population-based random sample of 410 normal adults. Morningness-eveningness preferences were determined using the 19-item Home-Ostberg questionnaire. Subjects carrying one of the two CLOCK alleles, 3111C, had a significantly lower mean Horne-Ostberg score. The distribution of scores was clearly shifted toward eveningness for these subjects. The score difference was independent of age, sex and ethnic heritage, thus making population stratification effects unlikely to explain this difference. These subjects had a substantial 10- to 44-minute delay in preferred timing for activity or sleep episodes. We suggest that the identified polymorphism or another tightly linked polymorphism within the CLOCK gene or its regulatory elements may be responsible for the finding.

View details for Web of Science ID 000076046000003

View details for PubMedID 9779516

Abstract

Forty-two genetically narcoleptic Doberman puppies [20 pure narcoleptic (N) puppies (from four narcoleptic x narcoleptic crosses) and 22 backcross narcoleptic (BN) puppies (from six narcoleptic x heterozygous crosses)] were systematically observed during the developmental period (4-24 weeks) to assess the age at onset and severity of cataplexy, a pathological manifestation of REM sleep atonia seen in narcolepsy. The mean age of onset of cataplexy was 9.69 +/- 1.15 weeks, with a median age of 7 weeks. The severity of cataplexy increased with age and reached a plateau at around 16-24 weeks. The effects of cross type (N vs BN) and sex on the development of cataplexy were analyzed. There was no difference in severity between N and BN puppies (P = 0.51). However, females had more severe cataplexy than males (P = 0.01), and this trend was preserved in five of the six litters that had both male and female puppies. These results suggest that the pathophysiological process in genetic canine narcolepsy emerges during the early developmental period and that it may involve a differential development in males and females. Furthermore, our results revealed that cataplexy onset corresponds to the emergence of adult-like REM sleep and to previously reported neuroanatomical and neurochemical abnormalities in canine narcolepsy.

View details for Web of Science ID 000075698200014

View details for PubMedID 9710528

Abstract

Sequencing studies were performed in three previously described microsatellite and minisatellite markers located within the HLA-DQ region, DQCAR, DQCARII and G51152. Multiple nucleotide substitutions that did not change size polymorphisms were observed in all three markers. In all loci, the number of core repeats did not correlate with neighboring DQ allele sequence motifs while single nucleotide changes within or flanking the microsatellite sequence did. This result indicates higher mutation rates for microsatellite expansions/contractions than for nucleotide substitutions in these loci. Further analysis indicated an almost complete phylogenetic correspondence between DQCAR single nucleotide polymorphisms (SNPs) and DQB1 sequences on one side (1.0-1.5 kb apart) and a complete relationship between DQCARII and DQA1 sequences on the other (4.5 kb apart). In contrast, G51152 sequences did not correspond perfectly with DQB1 allelic sequences, thus suggesting the existence of several ancestral crossovers between this marker and DQB1 (20-25 kb). Sequencing microsatellites might be useful in disease mapping studies by increasing marker informativeness and by helping in the interpretation of association study results. It is also proposed that SNPs within the flanking region of CA repeats could be used to develop biallelic markers from already available mapped microsatellite markers.

View details for Web of Science ID 000074956100002

View details for PubMedID 9714469

Abstract

Sleep abnormalities have been consistently observed in patients with schizophrenia. Elevated levels of corticotropin releasing factor (CRF) and prostaglandins (PGs) in the cerebrospinal fluid (CSF) of patients with schizophrenia have been reported, and these neurochemical substances, known to modulate sleep in experimental animals, may play a role in these sleep abnormalities. In this study, we measured PGD2, PGE2, PGF2alpha and CRF levels in the CSF of 14 unmedicated schizophrenic patients and 14 age- and sex-matched control subjects. Polysomnographic recordings were also carried out for each subject. As expected, the sleep of the schizophrenic subjects significantly differed from that of the controls; schizophrenic subjects had a longer sleep onset latency, slept less, spent fewer minutes in stage 2 sleep and had a lower sleep efficiency. We could not, however, detect any differences in CSF CRF and PG levels between normal and schizophrenic subjects, nor could we find any correlation between CSF variables and sleep parameters in the schizophrenic subjects and the non-psychiatric controls. These results do not favor the hypothesis of a role for CRF or PGs in the pathophysiology of sleep disturbances in schizophrenia.

View details for Web of Science ID 000074238900003

View details for PubMedID 9657418

Abstract

Basal forebrain (BF) cholinergic regulation of cataplexy was investigated in narcoleptic canines. Specific cholinergic agonists and antagonists, and excitatory or inhibitory amino acid neurotransmitter receptor agonists, were perfused through microdialysis probes implanted bilaterally in the BF of narcoleptic canines. Cataplexy was monitored using the food-elicited cataplexy test (FECT) and recordings of electroencephalogram, electrooculogram, and electromyogram. In narcoleptic canines, carbachol and oxotremorine (10(-5)-10(-3) M), but not McN-A-343 or nicotine (10(-4)-10(-3) M), produced a dose-dependent increase in cataplexy. In addition, N-methyl-d-aspartate (10(-4)-10(-3) M) and kainic acid (10(-5)-10(-4) M) did not have any effects, while muscimol (10(-3) M) produced a weak (P < 0.10) increase in cataplexy. In control canines, carbachol (10(-5)-10(-3) M), but not oxotremorine (10(-4)-10(-3) M), produced muscle atonia after the highest concentration in one of three animals. Carbachol (10(-3) M)-induced cataplexy in narcoleptic canines was blocked by equimolar perfusion with the muscarinic antagonists atropine, gallamine, and 4-DAMP but not pirenzepine. These findings indicate that carbachol-stimulated cataplexy in the BF of narcoleptic canines is mediated by M2, and perhaps M3, muscarinic receptors. The release of acetylcholine in the BF was also examined during FECT and non-FECT behavioral stimulation in narcoleptic and control canines. A significant increase in acetylcholine release was found in both narcoleptic and control BF during FECT stimulation. In contrast, simple motor activity and feeding, approximating that which occurs during an FECT, did not affect acetylcholine release in the BF of narcoleptic canines. These findings indicate that BF acetylcholine release is enhanced during learned emotion/reward associated behaviors in canines.

View details for Web of Science ID 000073593600008

View details for PubMedID 9582257

View details for Web of Science ID 000072594700016

Abstract

Narcolepsy-cataplexy is a disabling sleep disorder characterized by excessive daytime sleepiness and abnormal REM sleep. The development of human narcolepsy involves environmental factors acting on a specific genetic background. The importance of environmental factors is evidenced by the reported 25 to 31% of monozygotic twins who are concordant for narcolepsy. One of the predisposing genetic factors is located in the MHC DQ region. More than 85% of all narcoleptic patients with definite cataplexy share a specific HLA allele, HLA DQB1*0602 (most often in combination with HLA DR2), compared with 12 to 38% of the general population, as evaluated in various ethnic groups. Genetic factors other than HLA are also likely to be involved. Even if genuine multiplex families are rare, 1 to 2% of the first-degree relatives of narcolepsy patients manifest the disorder, compared with 0.02 to 0.18% in the general population. Studies using a canine model of narcolepsy illustrate the importance of non-MHC genes in disease predisposition. In this model, narcolepsy is transmitted as a single autosomal recessive trait, canarc-1. In spite of an association with immune-related polymorphisms, narcolepsy does not appear to be a classic autoimmune disease. Other pathophysiologic models involving the microglia and the release of specific cytokines in the CNS may be involved and are being explored. This approach, together with positional cloning studies in humans and canines, should reveal the cause of narcolepsy and open new therapeutic avenues.

View details for Web of Science ID 000072168200004

View details for PubMedID 9484418

Abstract

Narcolepsy is a disabling sleep disorder of unknown aetiology. In humans, the disease is mostly sporadic, with a few familial cases having been reported. In 1973 a sporadic case of narcolepsy was reported in a poodle, and in 1975 familial cases of narcolepsy occurred in dobermanns. As with human narcoleptics, these narcoleptic dogs exhibited excessive daytime sleepiness and cataplexy. A colony of narcoleptic dogs was established at Stanford University in 1976 to study the pathophysiology of the disease. Between 1976 and 1995, a total of 669 animals of various breeds were born, of which 487 survived. Dobermanns accounted for 78 per cent of the total. The narcolepsy genotype in dobermanns had no significant influence on puppy mortality rate (numbers of stillborn and survival rate). The sex, maternal parity or the age of the sire or dam had no significant effect. The percentage of stillborn puppies increased from 6.1 per cent in outbred litters to 15.4 per cent in inbred litters (P = 0.10). Birth season also had a significant effect, and the highest survival rate (P = 0.02), and the lowest percentage of stillborn puppies (P = 0.09) occurred between April and June.

View details for Web of Science ID 000071662300006

View details for PubMedID 9481825

View details for Web of Science ID 000076658100010

Abstract

Narcolepsy is a neurological disorder known to be tightly associated with HLA-DQA1*0102 and DQB1*0602. In this study, we have examined if homozygosity for DQB1*0602 increases disease susceptibility and/or severity. Patients diagnosed at Stanford University (n=160) or enrolled in a multicenter clinical trial (n=509) were included in this analysis. In both African-Americans and Caucasian-Americans with or without cataplexy, a significantly higher than expected number of subjects were DQB1*0602 homozygotes. Relative risks were 2-4 times higher in DQB1*0602 homozygotes vs heterozygotes across all patient groups. In contrast, symptom severity did not differ between DQB1*0602 homozygous and heterozygous subjects. These results indicate that HLA-DQB1*0602 homozygosity increases susceptibility to narcolepsy but does not appear to influence disease severity.

View details for Web of Science ID 000071134000012

View details for PubMedID 9459509

Abstract

Polymorphism at the level of three microsatellite markers (DQCAR, DQCARII, G51152) located in the HLA-DQ region was characterized in 78 10th International Histocompatibility Workshop B-cell lines, 718 random Japanese Asians, 99 Norwegian Caucasians and 95 New Guinean Aborigines with established HLA-DRB1, -DQA1 and -DQB1 typing. DQCAR, DQCARII, and G51152 result in 13, 13, and 11 alleles respectively. All three markers were in tight linkage disequilibrium with HLA-DRB1, -DQA1 and -DQB1. DRB1, DQA1, DQCARII, DQCAR, DQB1, and G51152 haplotypes could be defined for all subjects. In fact, DQ microsatellite typing data could predict DQA1 and DQB1 genotypes with high accuracy and may be used as a simple first pass HLA-DQ typing method. The haplotype data was also used to determine recombination in the DRB1-DQA1 (about 80 kb), DQA1-DQCARII (about 4.5 kb), DQCARII-DQCAR (about 7.5 kb), DQCAR-DQB1 (about 1-1.5 kb) and DQB1-G51152 (about 20-25 kb) genomic segments and the relative rate of slippage microsatellite mutations for DQCAR, DQCARII, and G51152. This led us to conclude that recombination is more frequent in the DRB1-DQA1 and DQCAR-DQCARII segments, thus suggesting cross-overs within small genomic segments are not proportional to genetic distance. We also observed that DQCAR had a higher mutation rate than DQCARII or G51152 and that 1 or 2 CA slippage mutations were arising more frequently from large size microsatellite alleles.

View details for Web of Science ID A1997YC43900012

View details for PubMedID 9389326

Abstract

The therapeutic potential of thyrotropin-releasing hormone (TRH) and TRH analogs in narcolepsy, a sleep disorder characterized by abnormal rapid eye movement (REM) sleep and daytime sleepiness, was examined using the canine model. The effects of TRH and the biologically stable TRH analogs CG3703, CG3509, and TA0910 on daytime sleep and cataplexy, a symptom of abnormal REM sleep, were assessed using polysomnographic recordings and the food elicited cataplexy test (FECT), respectively. CG3703 (100 and 400 microg/kg, i.v.) and TA0910 (100 and 400 microg/kg, i.v.) significantly increased wakefulness and decreased sleep in narcoleptic canines, whereas TRH (400 and 1600 microg/kg, i.v.) had no significant effect. TRH (25-1600 microg/kg, i.v.) and all three TRH analogs, CG3703 (6. 25-400 microg/kg, i.v., and 0.25-16 mg/kg, p.o.), CG3509 (25-1600 microg/kg, i.v.), and TA0910 (25-1600 microg/kg, i.v.), significantly reduced cataplexy in canine narcolepsy. These compounds did not produce any significant side effects during behavioral assays, nor did they alter free T3 and T4 levels in serum even when used at doses that completely suppressed cataplexy. Although more work is needed to establish the mode of action of TRH analogs on alertness and REM sleep-related symptoms, our results suggest a possible therapeutic application for TRH analogs in human sleep disorders.

View details for Web of Science ID A1997XU78100037

View details for PubMedID 9236248

View details for Web of Science ID A1997XE29400005

View details for PubMedID 9199548

Abstract

Narcolepsy is considered a homogeneous clinical entity when excessive daytime sleepiness and cataplexy are present. Cataplexy is a polymorphic symptom that can be very mild and is thus subjectively defined. The Multiple Sleep Latency Test (MSLT) is widely used as a diagnostic test for narcolepsy. A short mean sleep latency and multiple sleep onset REM periods (SOREMPs) are typically observed in narcoleptic patients. The discovery of a tight association of narcolepsy with HLA class II antigens offers a unique opportunity to explore the respective value of the MSLT or of the presence of clear-cut cataplexy in defining an etiologically homogeneous group of narcoleptic patients. In this study, we carried out HLA typing for DR15(DR2) and DQB1*0602 in 188 narcoleptic patients with cataplexy in three ethnic groups (24 Asians, 61 Blacks, and 103 Caucasians). These results confirm the importance of DQB1*0602 typing rather than DR15 (DR2) typing in Black narcoleptic patients and demonstrate that the presence of clear-cut cataplexy is a better predictor for DQB1*0602 positivity than the presence of abnormal MSLT results.

View details for Web of Science ID A1997XE09100015

View details for PubMedID 9191765

Abstract

Narcolepsy is a sleep disorder that has been shown to be tightly associated with HLA DR15 (DR2). In this study, 58 non-DR15 patients with narcolepsy-cataplexy were typed at the HLA DRB1, DQA1 and DQB1 loci. Subjects included both sporadic cases and narcoleptic probands from multiplex families. Additional markers studied in the class II region were the promoters of the DQA1 and DQB1 genes, two CA repeat polymorphisms (DQCAR and DQCARII) located between the DQA1 and DQB1 genes, three CA repeat markers (G51152, T16CAR and G411624R) located between DQB1 and DQB3 and polymorphisms at the DQB2 locus. Twenty-one (36%) of these 58 non-DR15 narcoleptic patients were DQA1*0102 and DQB1*0602, a DQ1 subtype normally associated with DRB1*15 in DR2-positive narcoleptic subjects. Additional microsatellite and DQA1 promoter diversity was found in some of these non-DR15 but DQB1*0602-positive haplotypes but the known allele specific codons of DQA1*0102 and DQB1*0602 were maintained in all 21 cases. The 37 non-DQA1*0102/DQB1*0602 subjects did not share any particular HLA DR or DQ alleles. We conclude that HLA DQA1*0102 and DQB1*0602 are the most likely primary candidate susceptibility genes for narcolepsy in the HLA class II region.

View details for Web of Science ID A1997WV41100002

View details for PubMedID 9151385

Abstract

Canine narcolepsy is a unique experimental model of a human sleep disorder characterized by excessive daytime sleepiness and cataplexy. There is a consensus recognition of an imbalance between cholinergic and catecholaminergic systems in narcolepsy although the underlying mechanisms remain poorly understood. Possible substrates could be an abnormal organization, numbers and/or ratio of cholinergic to catecholaminergic cells in the brain of narcoleptic dogs. Therefore, we sought to characterize the corresponding neuronal populations in normal and narcoleptic dogs (Doberman Pinscher) by using choline acetyltransferase (ChAT), nicotinamide adenosine dinucleotide phosphate (NADPH)-diaphorase, tyrosine hydroxylase (TH), and dopamine beta-hydroxylase (DBH). Cholinergic cell groups were found in an area extending from the central to the gigantocellular tegmental field and the periventricular gray corresponding to the pedunculopontine tegmental nucleus (PPT), the laterodorsal tegmental nucleus (LDT), and the parabrachial nucleus. An almost perfect co-localization of ChAT and NADPH-diaphorase was also observed. Catecholaminergic cell groups detected included the ventral tegmental area, the substantia nigra, and the locus coeruleus nucleus (LC). The anatomical distribution of catecholaminergic neurons was unusual in the dog in two important aspects: i) TH- and/or DBH-immunoreactive neurons of the LC were found almost exclusively in the reticular formation and not within the periventricular gray, ii) very few, if any TH-positive neurons were found in the central gray and dorsal raphe. Quantitative analysis did not reveal any significant differences in the organization and the number of cells identified in the LDT, PPT, and LC of normal and narcoleptic dogs. Moreover, the cholinergic to catecholaminergic ratio was found identical in the two groups. In conclusion, the present results do not support the hypothesis that the neurochemical imbalance in narcolepsy could result from abnormal organization, numbers, or ratio of the corresponding neuronal populations.

View details for Web of Science ID A1997WL65800002

View details for PubMedID 9050784

View details for Web of Science ID 000071716700074

Abstract

A group of 153 probands with narcolepsy included 38 subjects (24.8%) with a familial incidence of excessive daytime sleepiness (EDS). In 15 cases (9.8%), at least one additional family member suffered from narcolepsy-cataplexy; only EDS was present in the remaining 23 cases (15.0%). One thousand eighty-two relatives were evaluated. The percentage of first degree relatives affected with narcolepsy-cataplexy was 2.28% (1.20% if only clinically confirmed cases were accounted); the adequate value for second degree relatives was 1.49%. The occurrence of EDS exceeded these values several times (4.28% in first degree relatives, 6.57% in second degree relatives). The vertical mode of transmission was found in most families. Human leukocyte antigen (HLA) typing was performed in six families with multiple-case incidence of narcolepsy. Forty-one blood samples were analyzed (12 patients with narcolepsy, 7 with only EDS, 2 with sleep apnea syndrome, and 20 healthy relatives). HLA DR2+ and DQB1*0602+ were found in only 8 out of 12 narcoleptic patients with cataplexy and in six out of seven patients with isolated attacks of sleepiness. These findings support the hypothesis that there is a common genetic basis for narcolepsy associated with cataplexy and "monosymptomatic" forms of narcolepsy and suggest the existence of non-major histocompatibility complex (MHC) susceptibility factors for narcolepsy.

View details for Web of Science ID 000071355600012

View details for PubMedID 9456468

Abstract

Narcolepsy is a sleep disorder associated with HLA DR15 (DR2) and DQB1*0602. We HLA typed 509 patients enrolled in a clinical trial for the drug modafinil and analyzed the results in relation to cataplexy, a symptom of narcolepsy characterized by muscle weakness triggered by emotions. The patients were either subjects with cataplexy who had a mean sleep latency (SL) of less than 8 minutes and two or more sleep onset rapid eye movement (REM) periods (SOREMPs) during a multiple sleep latency test, or narcoleptic patients without cataplexy but with a mean SL shorter than 5 minutes and two or more SOREMPs. The respective values of DRB1*15 (DR2) and DQB1*0602 as markers for narcolepsy were first compared in different ethnic groups and in patients with and without cataplexy. DQB1*0602 was found to be a more sensitive marker for narcolepsy than DRB1*15 across all ethnic groups. DQB1*0602 frequency was strikingly higher in patients with cataplexy versus patients without cataplexy (76.1% in 421 patients versus 40.9% in 88 patients). Positivity was highest in patients with severe cataplexy (94.8%) and progressively decreased to 54.2% in patients with the mildest cataplexy. A voluntary 50-item questionnaire focusing on cataplexy was also analyzed in 212 of the 509 HLA-typed patients. Subjects with definite cataplexy as observed by an experienced clinician were more frequently HLA DQB1*0602-positive than those with doubtful cataplexy, and the manifestations of cataplexy were clinically more typical in DQB1*0602-positive patients. These results show that the HLA association is as tight as previously reported (85-95%) when cataplexy is clinically typical or severe. We also found that patients with mild, atypical, or no cataplexy have a significantly increased DQB1*0602 frequency (40-60%) in comparison with ethnically matched controls (24%). These results could be explained by increased disease heterogeneity in the noncataplexy group or by a direct effect of the HLA DQB1*0602 genotype on the clinical expression of narcolepsy.

View details for Web of Science ID 000071355600011

View details for PubMedID 9456467

Abstract

The understanding of the mutational mechanism that generates high levels of variation at microsatellite loci lags far behind the application of these genetic markers. A phylogenetic approach was developed to study the pattern and rate of mutations at a dinucleotide microsatellite locus tightly linked to HLA-DQB1 (DQCAR). A random Japanese population (n = 129) and a collection of multiethnic samples (n = 941) were typed at the DQB1 and DQCAR loci. The phylogeny of DQB1 alleles was then reconstructed and DQCAR alleles were superimposed onto the phylogeny. This approach allowed us to group DQCAR alleles that share a common ancestor. The results indicated that the DQCAR mutation rate varies drastically among alleles within this single microsatellite locus. Some DQCAR alleles never mutated during a long period of evolutionary time. Sequencing of representative DQCAR alleles showed that these alleles lost their ability to mutate because of nucleotide substitutions that shorten the length of uninterrupted CA repeat arrays; in contrast, all mutating alleles had relatively longer perfect CA repeat sequences.

View details for Web of Science ID A1996WC20400055

View details for PubMedID 8986803

Abstract

Cataplexy in the narcoleptic canine may be modulated by systemic administration of monoaminergic compounds. In the present study, we have investigated the effects of monoaminergic drugs on cataplexy in narcoleptic canines when perfused locally via microdialysis probes in the amygdala, globus pallidus/putamen, basal forebrain, pontine reticular formation and ventral tegmental area of narcoleptic and control Doberman pinchers. Cataplexy was quantified using the Food-Elicited Cataplexy Test and analyzed by electroencephalogram, electroculogram and electromyogram. Local perfusion with the monoaminergic agonist quinpirole, 7-OH-DPAT and BHT-920, into the ventral tegmental area produced a dose-dependent increase in cataplexy without significantly reducing basal muscle tone. Perfusion with the antagonist raclopride in the same structure produced a moderate reduction in cataplexy. Local perfusion with quinpirole, 7-OH-DPAT and BHT-920 into the globus pallidus/putamen also produced an increase, while raclopride produced a decrease, in cataplexy in narcoleptic canines. In control animals, none of the above drugs produced cataplexy or muscle atonia when perfused into either the ventral tegmental area or the globus pallidus/putamen. Other monoaminergic drugs tested in these two brain areas; prazosin, yohimbine, amphetamine, SKF 38393 and SCH 23390 had no effects on cataplexy. Local perfusion with each of the above listed drugs had no effect on cataplexy in any of the other brain regions examined. These findings show that cataplexy may be regulated by D2/D3 dopaminergic receptors in the ventral tegmental area and perhaps the globus pallidus/ putamen. It is suggested that neurons in the mesolimbic dopamine system of narcoleptics are hypersensitive to dopaminergic autoreceptor agonists.

View details for Web of Science ID A1996VJ89400011

View details for PubMedID 8891251

Abstract

Thalidomide is a sedative hypnotic that was widely used in the 1950s but was withdrawn due to its teratogenic properties. The compound has recently been reintroduced as an immune modulating agent. Thalidomide significantly aggravates canine cataplexy, a pathological manifestation of rapid eye movement (RFM) sleep atonia seen in narcolepsy. This compound also increases REM sleep and slow wave sleep in these animals. In vitro receptor binding and enzyme assays demonstrate that thalidomide does not bind to or enzymatically modulate the neurotransmitter systems reported to be involved in the regulation of cataplexy. Thalidomide may therefore affect cataplexy through its immune modulation properties. Further studies on the mechanisms of action of thalidomide should increase our understanding of the pathophysiology of this disabling disorder.

View details for Web of Science ID A1996VP15900002

View details for PubMedID 8905685

Abstract

Human narcolepsy is a neurological disorder known to be closely associated with HLA-DR2 and DQB1*0602. Because most autoimmune diseases are HLA-associated, a similar mechanism has been proposed for narcolepsy. However, neither systemic nor CNS evidence of an autoimmune abnormality has ever been reported. In this study, major histocompatibility (MHC) class I and class II expression was studied in the CNS of human and canine narcoleptics using immunohistochemistry and Northern analysis. Results indicated that canine narcolepsy is associated with a significant increase of MHC class II expression by the microglia. Moreover, the highest values were found between 3 and 8 months of age, strikingly concomitant to the development of narcolepsy in the canine model. In humans, class II expression was not found significantly different between control and narcoleptic subjects. This result could be explained by the old age of the subjects (69.86 +/- 5.31 and 68.36 +/- 4.74 years in narcoleptics and controls, respectively), because class II expression is significantly correlated with age in both humans and dogs. For the first time, this study demonstrated that the expression of MHC class II molecules in the CNS is age-dependent and that a consistent increase of their expression by the microglia might be critically involved in the development of narcolepsy.

View details for Web of Science ID A1996UX95500006

View details for PubMedID 8764647

Abstract

Predisposition to narcolepsy involves genetic factors both in humans and in a canine model of the disorder. In humans, narcolepsy is strongly associated with HLA DR15 and DQB1*0602. In Dobermans and Labradors, narcolepsy is transmitted as a single autosomal recessive gene with full penetrance (canarc-1). Canine narcolepsy is not linked with DLA, the canine equivalent of HLA, but co-segregates with a DNA segment with high homology with the mu immunoglobulin heavy-chain (IgH) switch-like region (S mu). To determine if the IgH locus is involved in genetic predisposition to human narcolepsy, restriction fragment length polymorphisms specific for the IgM and IgG cluster within this locus were studied in sporadic cases of the disease, as well as in five families with two or more affected individuals. Comparisons were made between control populations and both familial and sporadic cases and for patients with and without HLA-DR15 and DQB1*0602. RFLP analysis at the S mu and gamma-1 loci, which cover over 200 kb of 14q32.3, indicates that there is no evidence for any association between the IgH region and human narcolepsy.

View details for Web of Science ID A1996VA01500004

View details for PubMedID 8840222

View details for Web of Science ID A1996UC74600005

View details for PubMedID 8855033

View details for Web of Science ID A1996VC57500007

Abstract

The effects of modafinil and amphetamine on daytime sleep (polysomnographic recordings) and cataplexy (the food-elicited cataplexy test) were compared using the narcoleptic canine model. Results indicate that both modafinil (5 and 10 mg/kg body weight i.v.) and amphetamine (100 and 200 micrograms/kg i.v.) increase wakefulness and reduce slow-wave sleep in control and narcoleptic dogs. In contrast, the results of cataplexy testing demonstrate that amphetamine (2.5-160 micrograms/kg i.v.), but not modafinil (0.125-8.0 mg/kg i.v.) significantly suppresses canine cataplexy. These results suggest that the pharmacological property of modafinil is distinct from amphetamine. Results of polysomnographic recordings also demonstrate that narcoleptic dogs slept significantly more during the daytime than control dogs and required very high doses (10 mg/kg i.v. modafinil; 200 micrograms/kg i.v. amphetamine) of stimulants to reduce their level of sleepiness to that of control dogs. This finding is consistent with the data collected in human narcolepsy and validates the use of this canine model for the screening of stimulant compounds.

View details for Web of Science ID A1995TQ23600001

View details for PubMedID 8746387

Abstract

DQCAR is a very polymorphic CA repeat microsatellite located between the HLA DQA1 and DQB1 gene. Previous studies have shown that specific DQCAR alleles are in tight linkage disequilibrium with known HLA DR-DQ haplotypes. Of special interest was the fact that haplotypes containing long CA repeat alleles (DQCAR > 111) were generally more polymorphic within and across ethnic groups. In these latter cases, several DQCAR alleles were found even in haplotypes containing the same flanking DQA1 and DQB1 alleles. In this work, three HLA class II associated diseases were studied using the DQCAR microsatellite. The aim of this study was to test if DQCAR typing could distinguish haplotypes with the same DRB1, DQA1 and DQB1 alleles in control and affected individuals. To do so, patients with selected HLA DR-DQ susceptibility haplotypes were compared with HLA DR and DQ matched controls. This included: Norwegian subjects with Celiac disease and the HLA DRB1*0301, DQA1*05011, DQB1*02 haplotype; Japanese subjects with Type 1 (insulin-dependent) Diabetes Mellitus and the HLA DRB1*0405, DQA1*0302, DQB1*0401 haplotype; and French patients with corticosensitive Idiopathic Nephrotic Syndrome and the HLA DRB1*0701, DQA1*0201, DQB1*0202 haplotype. These specific haplotypes were selected from our earlier work to include one haplotype bearing a short DQCAR allele (celiac disease and DR3,DQ2-DQCAR99) and two haplotypes bearing long DQCAR alleles (Diabetes Mellitus and DR4,DQ4-DQCAR 113 or 115 Idiopathic Nephrotic syndrome and DR7,DQ2-DQCAR 111-121). Additional DQCAR diversity was found in both control and patients bearing haplotypes with long CA repeat alleles. The results indicate that DQCAR typing did not improve specificity in combination with high resolution DNA HLA typing as a marker for these three disorders.

View details for PubMedID 8560448

Abstract

Narcolepsy is a sleep disorder characterized by excessive daytime sleepiness and rapid eye movement (REM) sleep-related symptoms, such as cataplexy. The exact pathophysiology underlying the disease is unknown but may involve central cholinergic systems. It is known that the brainstem cholinergic system is activated during REM sleep. Furthermore, REM sleep and REM sleep atonia similar to cataplexy can be triggered in normal and narcoleptic dogs by stimulating cholinergic receptors within the pontine brainstem. The pontine cholinergic system is, therefore, likely to play a role in triggering cataplexy and other REM-related abnormalities seen in narcolepsy. The other cholinergic system that could be involved in the pathophysiology of narcolepsy is located in the basal forebrain (BF). This system sends projections to the entire cerebral cortex. Since acetylcholine release in the cortex is increased both during REM and wake, the basocortical cholinergic system is believed to be involved in cortical desynchrony. In the current study, we analyzed the effect of cholinergic compounds injected into the forebrain structures of narcoleptic and control dogs. We found that carbachol (a cholinergic agonist) injected into the BF triggers cataplexy in narcoleptic dogs while it increases wakefulness in control dogs. Much higher doses of carbachol bilaterally injected in the BF were, however, shown to trigger muscle atonia even in control dogs. These results suggest that a cholinoceptive site in the BF is critically implicated in triggering muscle atonia and cataplexy. Together with similar results previously obtained in the pontine brainstem, it appears that a widespread hypersensitivity to cholinergic stimulation may be central to the pathophysiology of canine narcolepsy.(ABSTRACT TRUNCATED AT 250 WORDS)

View details for Web of Science ID A1995RJ66200008

View details for PubMedID 7623112

Abstract

A highly polymorphic (CA)n microsatellite marker (DQCAR), located between the DQA1 and the DQB1 genes, was characterized in four ethnic groups. Based on length polymorphism, 12 alleles could be defined. The marker is located 1- to 2-kb telomeric to the DQB1 gene and 10 kb centromeric to the DQA1 gene and was shown to be in tight linkage disequilibrium with HLA-DQ. Analysis of the linkage disequilibrium pattern revealed little additional diversity in DQ1-associated haplotypes. Almost all DQ1 subjects examined were DQCAR 103 or DQCAR 107 (13 and 15 CA repeats, respectively). In contrast, significant haplotypic diversity was observed for most DQ2-, DQ3-, and DQ4-associated haplotypes. These haplotypes often had longer allele sizes (DQCAR > 111, more than 17 CA repeats) and more DQCAR alleles per haplotype. These haplotypes also carried DQCAR alleles of different sizes, even though they bore the same DQA1 and DQB1 alleles, and sometimes the same DRB1 allele as well. These results indicate that DQCAR could be a useful marker to better define disease associations with HLA. Our results are also consistent with the hypothesis that CAR alleles with higher numbers of repeats have higher mutation rates and that recombination within the HLA-DR/DQ region is haplotype dependent.

View details for Web of Science ID A1995QL39300004

View details for PubMedID 7759308

Abstract

Pharmacological studies using a canine model of narcolepsy have demonstrated that adrenergic rather than serotonergic or dopaminergic uptake inhibition is the primary mode of action of antidepressants on cataplexy, a pathological manifestation of rapid eye movement (REM) sleep atonia that occurs in narcolepsy. This result is in line with the known involvement of adrenergic systems in the regulation of REM sleep. However, the lack of anticataplectic effects of selective serotonergic compounds was puzzling as serotonergic neurons of the dorsal raphe nuclei are known to decrease activity during the REM sleep in a manner similar to the adrenergic neurons of the locus coeruleus. To further explore the role of serotonergic systems, we tested the effect on canine cataplexy of six 5-HT1A agonists and five 5-HT1A antagonists. Results indicate that 5-HT1A agonists significantly suppress cataplexy in correlation with their in vitro affinities to the canine central 5-HT1A receptors. Anticataplectic effects were, however, accompanied by various behavioral changes, such as flattened body posture, increased panting and agitation. In contrast, the selective 5-HT1A antagonist did not aggravate cataplexy, although a 5-HT1A antagonist was able to block the anticataplectic effect of a 5-HT1A agonist. These results suggest that the anticataplectic effects of 5-HT1A agonists are truly mediated by 5-HT1A receptor stimulation. It is, however, likely that anticataplectic effects occur due to the behavioral side effects rather than the direct involvement of this receptor subtype in the regulation of cataplexy. Further studies are therefore necessary to address the question of whether these 5-HT1A agonists hold promise in the pharmacological treatment of human cataplexy.

View details for Web of Science ID A1995QL99500028

View details for PubMedID 7891329

View details for Web of Science ID A1995PV36000010

View details for PubMedID 7528725

Abstract

Narcolepsy is a neurological disorder known to be associated with human leukocyte antigen (HLA)-DQB1*0602 in humans. In a canine model, the disorder is also genetically linked to a gene of high homology with the human mu-switch-like immunoglobulin (Ig) gene (current LOD score 13.6 at 0% recombination). Since association with HLA or other immune function polymorphic genes (T cell receptor of Ig, mainly) is a hallmark of most autoimmune diseases, it is proposed that autoimmunity may also play a role in the development of narcolepsy. Arguments for and against this hypothesis are reviewed. It is shown that both on the basis of the most recent molecular studies, and because of some of its clinical features, narcolepsy may be an autoimmune disorder. However, neither systemic nor central nervous system (CNS) evidence of any autoimmune abnormality have ever been found. To reconcile this discrepancy, it is suggested that the pathological immune process involved in narcolepsy could be difficult to detect because it is restricted to a very small region of the brain or targets a low abundance neuroeffector. Alternatively, it is possible that a more fundamental relationship is involved between sleep generation and immune regulation. The pathophysiology of narcolepsy may then involve new CNS-immune mechanisms that may shed new light on the sleep process itself.

View details for Web of Science ID A1995QP30900004

View details for PubMedID 7795891

Abstract

Both rapid eye movement sleep and cataplexy in the narcoleptic canine have been shown to increase after both systemic and local administration of cholinergic agonists in the pontine reticular formation. Furthermore, binding studies indicate an increase in the number of M2 muscarinic receptors in the pontine reticular formation of narcoleptic canines. In the present study we have investigated the receptor subtypes involved in mediating the cholinergic stimulation of cataplexy, as defined by brief periods of hypotonia induced by emotions, within the pontine reticular formation of narcoleptic canines. Specific cholinergic and monoaminergic agonists and antagonists, and excitatory or inhibitory amino-acid neurotransmitter receptor agonists, were perfused through microdialysis probes implanted bilaterally in the pontine reticular formation of narcoleptic canines, and cataplexy was monitored using the Food-Elicited Cataplexy Test and recordings of electroencephalogram, electrooculogram and electromyogram. In narcoleptic canines, bilateral perfusion with oxotremorine (M2 muscarinic) (10(-5)-10(-3) M) in the pontine reticular formation produced a dose-dependent increase in cataplexy, which reached complete muscle atonia (status cataplecticus) during the highest concentration. In control canines bilateral perfusion with oxotremorine (10(-5)-10(-3) M) did not produce any cataplectic attacks, but did produce muscle atonia after the highest concentration. Bilateral perfusion with either McN-A-343 (M1 muscarinic) or nicotine (both 10(-5)-10(-3) M) did not have any effect on cataplexy in either narcoleptic or control canines. The increase in cataplexy in narcoleptic canines produced by local perfusion with carbachol (10(-4) M) followed by equimolar perfusion with a muscarinic antagonist was rapidly reversed by atropine (muscarinic) and gallamine (M2 muscarinic), partially reversed by 4-DAMP (M3/M1 muscarinic) and completely unaffected by pirenzepine (M1 muscarinic). Bilateral perfusion with excitatory, glutamatergic receptor agonists N-methyl-D-aspartate, AMPA (both at 10(-4)-10(-3) M) and kainic acid (10(-5)-10(-4) M) did not have any effect on cataplexy, whereas bilateral perfusion with the inhibitory GABAergic receptor agonist muscimol (10(-4)-10(-3) M) produced a moderate increase in cataplexy in the narcoleptic canines. Bilateral perfusion with numerous monoaminergic compounds, BHT-920 (alpha-2 agonist), yohimbine (alpha-2 antagonist), propranolol (beta antagonist) and prazosin (alpha-1 antagonist), did not have any effect on cataplexy. These findings demonstrate that cholinergic regulation of cataplexy in the narcoleptic canine at the level of the pontine reticular formation is mediated by M2, and possibly M3, muscarinic receptors. The effects of muscimol indicate that the stimulation of cataplexy might be elicited by local neuronal inhibition.

View details for Web of Science ID A1994PE28600005

View details for PubMedID 7991953

View details for Web of Science ID A1994PE28600006

View details for PubMedID 7991954

Abstract

Cataplexy in the narcoleptic canine has been shown to increase after systemic administration of cholinergic agonists. Furthermore, the number of cholinergic receptors in the pontine reticular formation of narcoleptic canines is significantly elevated. In the present study we have investigated the effects of cholinergic drugs administered directly into the pontine reticular formation on cataplexy, as defined by brief episodes of hypotonia induced by emotions, in narcoleptic canines. Carbachol and atropine were perfused through microdialysis probes implanted bilaterally in the pontine reticular formation of freely moving, narcoleptic and control Doberman pinschers. Cataplexy was quantified using the Food-Elicited Cataplexy Test, and analysed using recordings of electroencephalogram, electrooculogram and electromyogram. Cataplexy was characterized by a desynchronized electroencephalogram and a drop in electromyogram and electrooculogram activity. In narcoleptic canines, both unilateral and bilateral carbachol (10(-5) to 10(-3) M) produced a dose-dependent increase in cataplexy, which resulted in complete muscle tone suppression at the highest concentration. In control canines, neither bilateral nor unilateral carbachol (10(-5) to 10(-3) M) produced cataplexy, although bilateral carbachol, did produce muscle atonia at the highest dose (10(-3)). The increase in cataplexy after bilateral carbachol (10(-4) M) was rapidly reversed when the perfusion medium was switched to one containing atropine (10(-4) M). Bilateral atropine (10(-3) to 10(-2) M) alone did not produce any significant effects on cataplexy in narcoleptic canines; however, bilateral atropine (10(-2) M) did reduce the increase in cataplexy produced by systemic administration of physostigmine (0.05 mg/kg, i.v.). These findings demonstrate that cataplexy in narcoleptic canines can be stimulated by applying cholinergic agonists directly into the pontine reticular formation. The ability of atropine to inhibit locally and systemically stimulated cataplexy indicates that the pontine reticular formation is a critical component in cholinergic stimulation of cataplexy. Therefore, it is suggested that the pontine reticular formation plays a significant role in the cholinergic regulation of narcolepsy.

View details for Web of Science ID A1994NF79800003

View details for PubMedID 8008205

Abstract

Twenty-seven narcoleptic patients severely affected with cataplexy completed four symptom diaries over a 4-month period in order to clarify some of the controversies surrounding assessment of anticataplectic medications. The home diary method was found to be a viable model for the assessment of anticataplectic activity. Assessment of reliability in 1-, 2-, 3-, 4-, 5- and 10-day intervals indicated that reliability increases with the number of days included. A 10-day design was found to be optimal. Reliability decreased, however, with each successive diary over the 4-month period. Power analysis indicates that two groups of 30-40 subjects in a parallel design, or one group of 30-40 subjects in a crossover design, would be sufficient to demonstrate a significant therapeutic anticataplectic effect in most cases. A "first diary effect" was observed, suggesting that a training period prior to the actual trial might improve reliability. Whether the patient was treated or untreated with stimulant medications did not affect severity or fluctuation of cataplexy, suggesting that both groups of patients could be included in therapeutic trials. No time-of-day fluctuation was observed in the daily distribution of cataplexy attacks. Sudden increases in cataplexy were often, although not always, caused by unusual emotional events or sleepiness. The finding of a long-lasting "precataplectic" feeling or "aura" pointed to the need to carefully clarify the symptom prior to beginning a therapeutic trial.

View details for Web of Science ID A1994NQ80400010

View details for PubMedID 7939127

Abstract

Cataplexy in the narcoleptic canine has been shown to increase after local administration of carbachol into the pontine reticular formation. Rapid eye movement sleep has also been shown to increase after local administration of carbachol in the pontine reticular formation, and furthermore, acetylcholine release in the pontine tegmentum was found to increase during rapid eye movement sleep in rats. Therefore, in the present study we have investigated acetylcholine release in the pontine reticular formation during cataplexy in narcoleptic canines. Extracellular acetylcholine levels were measured in the pontine reticular formation of freely moving narcoleptic and control Doberman pinschers using in vivo microdialysis probes. Cataplexy was induced by the Food-Elicited Cataplexy Test and monitored using recordings of electroencephalogram, electrooculogram and electromyogram. Basal levels of acetylcholine in the microdialysis perfusates were approximately 0.5 pmol/10 min in both control and narcoleptic canines. Local perfusion with tetrodotoxin (10(-5) M) or artificial cerebrospinal fluid without Ca2+ produced a decrease, while intravenous injections of physostigmine (0.05 mg/kg) produced an increase in acetylcholine levels, indicating that the levels of acetylcholine levels measured are derived from neuronal release. During cataplexy induced by the Food-Elicited Cataplexy Test, acetylcholine levels increased by approximately 50% after four consecutive tests in narcoleptic canines, but did not change after four consecutive tests in control canines. Motor activity and feeding behavior, similar to that occurring during a Food-Elicited Cataplexy Test, had no effect on acetylcholine levels in the narcoleptic canines.(ABSTRACT TRUNCATED AT 250 WORDS)

View details for Web of Science ID A1994NF79800004

View details for PubMedID 8008206

Abstract

Our series of pharmacological studies on canine narcolepsy has suggested that the adrenergic systems are more critically involved in the regulation of cataplexy than the serotonergic and dopaminergic systems. This, however, is an apparent contradiction to data obtained in human patients, which show that chronic oral administration of serotonergic uptake inhibitors, such as clomipramine, zimelidine and fluoxetine, is effective in reducing cataplexy. To explore this discrepancy, we have assessed the anticataplectic effects of various serotonergic uptake inhibitors and their active desmethyl metabolites on canine cataplexy. We found that the anticataplectic effect of the desmethyl metabolites, which are usually more potent for in vitro adrenergic uptake inhibition, was more potent and developed more rapidly than the effect of the parent compounds. Furthermore, the anticataplectic potency was positively correlated to the adrenergic uptake inhibition and was negatively correlated with serotonergic uptake inhibition among the 10 compounds tested. These results are consistent with our hypothesis of a preferential involvement of the adrenergic system in the control of cataplexy. Our results also suggest that the anticataplectic effect of "selective" serotonergic uptake inhibitors in human narcolepsy might be mediated by their less selective active metabolites.

View details for Web of Science ID A1993MV96900004

View details for PubMedID 8165384

Abstract

We have demonstrated previously that central noradrenergic mechanisms, especially postsynaptic alpha-1 receptors, are critically involved in the regulation of cataplexy, a pathological manifestation of rapid eye movement sleep atonia in narcolepsy. However, it has been shown recently that alpha-1 receptors constitute a heterogeneous population of binding sites, which is encoded by several distinct genes. In light of these findings, we investigated the possibility that the effect of alpha-1 compounds on cataplexy found in our previous study is mediated more specifically by certain alpha-1 receptor subtypes than by other subtypes. We therefore examined the effects of eight selective alpha-1 antagonists and five agonists on canine cataplexy and compared these with the affinities of the same compounds for the canine central alpha-1a and alpha-1b subtypes. The affinities of the compounds for the alpha-1 receptor subtypes were assessed by using [3H]prazosin receptor binding in combination with a 5-methylurapidil (an alpha-1a selective ligand) mask. Six of the eight alpha-1 antagonists tested exacerbated canine cataplexy, whereas all five agonists tested suppressed cataplexy. Furthermore, the potency (ED50 values) of the compounds on cataplexy significantly correlated with the affinity of the compounds for the alpha-1b binding site. These results are consistent with our earlier implication of the alpha-1 receptor mechanisms in the control of cataplexy and further suggest a specific involvement of the alpha-1b receptor subtype in these mechanisms.

View details for Web of Science ID A1993KT84600009

View details for PubMedID 8095546

View details for Web of Science ID A1993BY66S00036

Abstract

Human narcolepsy is a genetically determined disorder of sleep strongly associated with the human leucocyte antigens (HLA) DR2 and DQw1. In black narcoleptic patients, susceptibility for narcolepsy is more closely related to a specific gene subtype of DQw1, DQB1-0602, than to DR2. About 30% of black narcoleptic patients are nonDR2, but all carry the HLA DQB1-0602 gene. In the present study, we have tested caucasian nonDR2 cataplectic patients (6 sporadic cases and 7 familial cases from 3 multiplex families) for the presence of the HLA DQB1-0602 and DQA1-0102 (DQw1) using a specific polymerase chain reaction (PCR)-oligotyping technique. None of the patients was DQB1-0602 or DQA1-0102 positive, thus proving that, in caucasians, DQB1-0602 and DQA1-0102 (DQw1) are not prerequisites for the diagnosis of narcolepsy. Further studies with more patients are warranted to exclude the possibility that a few caucasian patients carry rare haplotypes with DQB1-0602 independently of DR2.

View details for Web of Science ID A1992JT08400005

View details for PubMedID 1455124

Abstract

Canine narcolepsy, a model of the human disorder, is associated with altered catecholamine but not serotonin (5-HT) metabolism in some brain areas, particularly the amygdala. A possible explanation for these global changes could be the existence of specific defects in monoamine uptake processes. We have studied the uptake of [3H]norepinephrine (NE), [3H]dopamine (DA) and [3H]5-HT in synaptosomes prepared from cortex and amygdala of narcoleptic and control Doberman pinscher brains. Since narcoleptic canines are relatively few in number, we have used a specific brain freezing procedure that has been reported to allow restoration of metabolically functional tissue upon thawing. Preliminary studies comparing monoamine uptake in fresh and frozen brain samples of both groups of dogs were carried out and demonstrated that this procedure significantly altered serotoninergic but not noradrenergic and dopaminergic uptake. All further investigations were then done on synaptosomes prepared from frozen samples. Our results demonstrate that synaptosomal uptake of [3H]NE, [3H]DA and [3H]5-HT in cortex and amygdala are not altered in narcolepsy.

View details for Web of Science ID A1992JL38700014

View details for PubMedID 1393561

Abstract

Narcolepsy has been hypothesized to be a disease of rapid eye movement (REM) sleep. According to this hypothesis, cataplexy is a result of the triggering during waking of the mechanism that normally serves to suppress muscle tone in REM sleep. REM sleep control mechanisms have been localized to the pons. Narcoleptic dogs have increased numbers of cholinergic receptors in the medial pons. These findings suggest that neurons mediating the triggering of cataplexy might be located in medial pontine regions. In the present study, this hypothesis has been investigated by recording the discharge of units in the medial mesopontine region of the narcoleptic dog. Unit activity was examined in the nucleus reticularis pontis oralis, caudalis, and central gray, with each cell being recorded during both cataplexy and sleep states. Maximal discharge rates were observed, in all of these regions, during active waking states (mean rate, 45.3/sec) and REM sleep (16.0/sec), with minimal discharge rates in non-REM sleep (8.3/sec). Unit discharge was reduced in cataplexy relative to precataplexy periods. Cataplexy discharge rates were 8.3/sec, 52% of the mean REM sleep rate. Cataplexy discharge rates were also significantly lower than those at REM sleep onset. Cataplexy discharge rates were comparable to rates in quiet waking and non-REM sleep. While medial mesopontine neurons discharge at high rates in REM sleep, they have little or no activity in cataplexy. We interpret the lack of activation of medial mesopontine units in cataplexy as indicating that the characteristic phasic motor activation of REM sleep does not occur in this state.(ABSTRACT TRUNCATED AT 250 WORDS)

View details for Web of Science ID A1992HT83700007

View details for PubMedID 1578258

View details for Web of Science ID A1992BW57Z00015

Abstract

Narcolepsy is a sleep disorder characterized by abnormal manifestations of rapid-eye-movement (REM) sleep and excessive daytime sleepiness. Using a canine model of the disease, we found that central D2 antagonists suppressed cataplexy, a form of REM-sleep atonia occurring in narcolepsy, whereas this symptom was aggravated by D2 agonists. The effect on cataplexy was stereospecific for the S(-) enantiomer of sulpiride (a D2 antagonist) and the R(+) enantiomer of 3-PPP (a D2 agonist). There was also a significant correlation between the in vivo pharmacological potency and in vitro drug affinity for D2 receptors (but not for D1 and alpha 2 receptors) among the seven central D2 antagonists tested. Selective D1 compounds were also tested; however, the results were inconsistent because both antagonists and agonists generally suppressed cataplexy. Our current results demonstrate that central D2-type receptors are critically involved in the control of cataplexy and REM sleep. Furthermore, the finding that small doses of D2 antagonists suppressed cataplexy and induced behavioral excitation, while small doses of D2 agonists aggravated cataplexy and induced sedation, suggests that this effect is mediated presynaptically. However, considering the fact that selective dopamine reuptake inhibitors did not modify cataplexy and that our previous pharmacological results demonstrated a preferential involvement of the noradrenergic system in the control of cataplexy, we believe that the effect of D2 compounds on cataplexy is mediated secondarily via the noradrenergic systems.

View details for Web of Science ID A1991GE83100004

View details for PubMedID 1831837

Abstract

Narcolepsy is a neurological disorder characterized by sleepiness and episodes of cataplexy. Cataplexy is an abrupt loss of muscle tone, most often triggered by sudden, strong emotions. A subset of cells in the medial medulla of the narcoleptic dog discharged at high rates only in cataplexy and rapid eye movement (REM) sleep. These cells were noncholinergic and were localized to ventromedial and caudal portions of the nucleus magnocellularis. The localization and discharge pattern of these cells indicate that cataplexy results from a triggering in waking of the neurons responsible for the suppression of muscle tone in REM sleep. However, most medullary cells were inactive during cataplexy but were active during REM sleep. These data demonstrate that cataplexy is a distinct behavioral state, differing from other sleep and waking states in its pattern of brainstem neuronal activity.

View details for Web of Science ID A1991FN85700043

View details for PubMedID 1925546

Abstract

Identification of genes determining narcolepsy susceptibility is important not only for understanding that disorder but also for possible clues to general sleep-control mechanisms. Studies in humans reveal at least one such gene related to the major histocompatibility complex and in dog an as-yet-unmapped single, autosomal recessive gene canarc-1. Gene markers for canarc-1 were therefore sought by DNA restriction fragment length polymorphisms in our colony of narcoleptic dogs. A human mu-switch immunoglobulin probe and the enzyme Hae III identified a gene cosegregating with canarc-1 in backcrossed animals (logarithm of odds scores: m = 24, Z max = 7.2 at theta = 0%). canarc-1 was also shown not to be tightly linked with the dog major histocompatibility complex (m = 40, Z less than -2 at theta less than 4.8%). These results represent the mapping of a non-major histocompatibility complex narcolepsy gene and strongly suggest involvement of the immune system in the pathophysiology of that disease.

View details for Web of Science ID A1991FG91300106

View details for PubMedID 1673032

Abstract

The present study compares the characteristics of radioligand binding to adenosine receptors and adenosine uptake sites in 100- and 50-day-old normal and narcoleptic dogs. Binding to A1 receptors was quantified using a selective A1 agonist ([3H]N6-[(R)-1-methyl-2-phenylethyl] adenosine, [3H]R-PIA) and an antagonist ([3H]dipropyl-8-cyclopentyl-xanthine, [3H]CPX). Differences in the binding of [3H]R-PIA and that of [3H]5'-ethylcarboxamide adenosine ([3H]NECA), which binds to both A1 and A2 receptors with similar affinities, were used to quantify A2 receptors. Nucleoside transport sites were labeled with [3H]nitrobenzylthioinosine ([3H]NBTI), a potent inhibitor of nucleoside transport systems. The present study offered no evidence that either adenosine A1 receptors and adenosine uptake sites in the frontal cortex or adenosine A2 receptors in the putamen were altered in narcoleptic dogs. However, we found that adenosine A1 receptors in the dog exist in different affinity states and that the affinity state in which the receptor is found depends on the brain region examined. A characterization of these low- and high-affinity sites was performed and results indicated that these sites cannot be explained by a single interaction of the A1 receptor with a single G-protein population.

View details for Web of Science ID A1991EQ55300001

View details for PubMedID 1901994

Abstract

Recent experiments have demonstrated that pharmacological activation of central noradrenergic systems by monoaminergic stimulators or uptake blockers or through the stimulation of alpha-1 adrenergic receptors improved cataplexy, a major symptom of narcolepsy. In order to further the understanding of the control of cataplexy by noradrenergic mechanisms, the involvement of central alpha-2 adrenoceptors was examined in genetically narcoleptic Doberman pinschers using in vivo pharmacology. Yohimbine (1.5-96.0 micrograms/kg i.v.) and seven other selective and centrally acting alpha-2 adrenoceptor antagonists (rauwolscine: 1.5-96 micrograms/kg i.v.; atipemazole: 1.5-96 micrograms/kg i.v.; Wy-25309: 1.5-386 micrograms/kg i.v.; CGS-7525A: 1.5-386 micrograms/kg i.v.; idazoxan, 6-1536 micrograms/kg i.v.; piperoxan, 6-1536 micrograms/kg i.v.; and mianserin, 6-1536 micrograms/kg i.v.) significantly suppressed cataplexy. The alpha-2 mediation of this effect was demonstrated by a close correlation between drug affinities (Ki) toward the alpha-2 site (defined using [3H]yohimbine in canine cortex) and the ability of these drugs to reduce cataplexy [ED50 in nanomoles per kilogram i.v.) (r2 = 0.71, n = 8, P less than .01). The effects of six centrally acting alpha-2 agonists on canine cataplexy were also examined and two groups of compounds were distinguished on the basis of their pharmacological profile. Classical alpha-2 agonists such as clonidine (0.0625-4.0 micrograms/kg i.v.), p-aminoclonidine (0.0625-4.0 micrograms/kg i.v.) and guanfacine (0.0625-4.0 micrograms/kg i.v.) had no effect on cataplexy whereas BHT-920 (0.01875-3.0 micrograms/kg i.v.), BHT-933 (16.0-258 micrograms/kg i.v.) and xylazine (16.0-258 micrograms/kg i.v.) dramatically aggravated cataplexy.(ABSTRACT TRUNCATED AT 250 WORDS)

View details for Web of Science ID A1990DK70200035

View details for PubMedID 1972749

View details for Web of Science ID A1990BR70B00096

View details for Web of Science ID A1990BT19L00009

View details for Web of Science ID A1990BT19L00021

Abstract

Familial patterns of narcolepsy were investigated in a clinic population of 334 unrelated narcoleptic patients. 40% of probands had at least 1 family member with an isolated daytime sleepiness complaint and 6% had a positive family history of narcolepsy. Multicase families were rare; only two families were found with 3 or more affected relatives. Family members often shared the same HLA-DR2 haplotype as the proband but did not have narcolepsy. However, the risk of disease for first-degree relatives was six to eighteen times greater than that for unrelated individuals. Although most patients were HLA-DR2+, 2 new HLA-DR2- individuals were found. The data predict that as many as 9% of unrelated North-American white patients with narcolepsy will be DR2-. Analysis of these and other data indicates that although strongly associated with disease, the HLA-DR2 haplotype is neither sufficient nor necessary for the development of narcolepsy.

View details for Web of Science ID A1989CD35200012

View details for PubMedID 2574313

Abstract

Two classes of alpha 1 adrenoceptors were identified in canine brain and liver using conventional radioligand binding methods. Scatchard plots of specific [3H]prazosin binding to brain and liver membranes prepared from 100-150-day-old Doberman pinscher dogs were consistently curvilinear and best fit a two-site binding model (frontal cortex, Kd1 = 57.7 +/- 10.0 pM, Bmax1 = 64.6 +/- 17.1 fmol/mg protein, Kd2 = 1.5 +/- 0.5 nM, Bmax2 = 159 +/- 37.6 fmol/mg protein; liver, Kd1 = 82.6 +/- 36 pM, Bmax1 = 7.0 +/- 5.1 fmol/mg protein, Kd2 = 0.8 +/- 0.2 nM, Bmax2 = 62.1 +/- 8.7 fmol/mg protein). Kinetically derived affinity constants from association and dissociation experiments agreed with those obtained by Scatchard analyses of equilibrium binding data. Binding sites were saturable, heat labile, bound ligand reversibly, and appeared to be appropriately distributed in relation to endogenous catecholamine. [3H]Prazosin also bound with high affinity to two classes of binding site in porcine and bovine brain membrane but [3H]prazosin binding in monkey and rat brain was best described by a single-site binding model. Affinities obtained were in between values obtained for high and low affinity Kds in the other species. Competitions for [3H]prazosin binding sites in canine frontal cortex were conducted with the following antagonists: WB-4101, corynanthine, phentolamine, benoxathian, phenoxybenzamine, chlorethylclonidine, thymoxamine, prazosin, yohimbine and agonists: methoxamine, (-)-norepinephrine, and clonidine. All ligands but prazosin, norepinephrine and clonidine competed for specific [3H]prazosin binding in a statistically significant biphasic manner. Benoxathian and WB-4101 displayed the highest affinities (benoxathian: Ki1 = 0.26 nM, WB-4101: Ki1 = 0.20 nM) and selectivity (high affinity/low affinity: benoxathian = 1640, WB-4101 = 13204) for the high affinity [3H]prazosin binding site; chlorethylclonidine had highest affinity (Ki2 = 91 nM) and selectivity (low affinity/high affinity = 405) for the lower affinity [3H]prazosin binding site. As defined, the two sites were similar to the alpha 1a and alpha 1b recently described in the rat and rabbit. A noticeable difference was that the subtypes described in dog brain had a 30-fold difference in affinity for prazosin.

View details for Web of Science ID A1989U375200007

View details for PubMedID 2541871

Abstract

The effects of intravenous administration of prostaglandins (PGs) were investigated in genetically narcoleptic Doberman pinschers. The treatment of narcoleptic dogs with PGE2 and PGE2 methyl ester, but not PGD2 and PGD2 methyl ester, induced a dose-dependent reduction of canine cataplexy, a dissociated manifestation of rapid-eye-movement sleep. The effect was specific and not associated with any change in other behavior. Furthermore, the effect was long-lasting (up to 2 hr) and could not be explained by the acute cardiovascular changes seen after intravenous PG administration. PGE2 methyl ester, a lipophilic derivative of PGE2 with more central penetration than PGE2, was 4 times more potent than PGE2. These results indicate that PGE2 modifies cataplexy through a central effect and suggest that this prostaglandin may play a role in rapid-eye-movement sleep regulation.

View details for Web of Science ID A1989U042300075

View details for PubMedID 2928344

Abstract

The role of central alpha-1 adrenergic receptors in cataplexy was investigated in genetically narcoleptic Doberman pinschers. Treatment of narcoleptic dogs with 25-600 micrograms/kg prazosin, a selective alpha-1 adrenergic receptor blocker, exacerbated cataplexy, whereas treatment with the alpha-1 agonist, methoxamine, ameliorated it. Subsequent studies showed that the beneficial effects of classical treatments of human narcolepsy (amphetamines and tricyclic antidepressants) are antagonized by prazosin, suggesting that these drugs are active through an indirect alpha-1 stimulation (via an increase of norepinephrine in the synaptic cleft). Other studies confirmed that the observed effects were not due to peripheral alpha-1 cardiovascular involvement. Atropine, a central anticholinergic agent, but not methylatropine, a peripheral one, completely suppressed the prazosin effect, which suggests that adrenergic and cholinergic systems act sequentially and not independently to generate cataplexy. Little is known about the physiological role of central alpha-1 adrenoceptors. This series of experiments implicates these receptors in narcolepsy-cataplexy.

View details for Web of Science ID A1988Q160600022

View details for PubMedID 2843574