Academic Appointments

Administrative Appointments

  • Research Assistant Professor of Pharmacology, University of Illinios at Chicago (1992 - 1995)
  • Assistant Professor of Anatomy and Cell Biology, University of Illinois at Chicago (1996 - 2000)
  • Associate Professor, Anesthesia (2000 - Present)
  • Director of Pain Research, Anesthesia (2000 - Present)
  • Executive Committee, Neuroscience Institute at Stanford (2002 - 2005)
  • Vice Chair, Animal Care and Use Committee (2002 - 2005)

Honors & Awards

  • National Grant Review Committee, NIH IRG - ZRG1 IFCN - 7 (2005)
  • National Grant Review Committee, NSF IBN - ad hoc (2005)
  • National Grant Review Committee, Veterans Administration (2005)
  • Pfizer Professor of Pain Medicine, Pfizer Foundation (2002-2003)
  • Lundbeck Visting Professor Of Neurosurgery, Aarhus University (2014)

Professional Education

  • AB, Dartmouth College, Psychology (1979)
  • PhD, University of Florida, Neuroscience (1989)


  • Lawrence R. Toll, David C. Yeomans, Martin S. Angst, Daniel I. Jacobs. "United States Patent 8,551,949 Methods for treatment of pain", Nocicepta, LLC, Jul 27, 2010
  • David C. Yeomans, Martin S. Angst, H. Frey II William, Daniel I. Jacobs. "United States Patent 8,198,240 Methods for treatment of headaches by administration of oxytocin", leland Stanford Junior University, Aug 26, 2005
  • David Yeomans. "United States Patent 8,202,838 Methods for treatment of headaches by administration of oxytocin", David C. Yeomans, Martin S. Angst, H. Frey II William, Daniel I. Jacobs, Aug 26, 2005
  • David C. Yeomans, H. Frey II William, Daniel I. Jacobs, Martin S. Angst. "United States Patent 8,258,096 Therapy procedure for drug delivery for trigeminal pain", Leland Stanford Junior University, Aug 26, 2005
  • David C. Yeomans, Martin S. Angst, H. Frey II William, Daniel I. Jacobs. "United States Patent 8,501,691 Methods for treatment of headaches by administration of oxytocin", Leland Stanford Junior University, Aug 26, 2005
  • David C. Yeomans, Martin S. Angst, H. Frey II William, Daniel I. Jacobs. "United States Patent 8252745 Methods for treatment of headaches by administration of oxytocin", leland Stanford Junior University, Aug 26, 2005
  • Daria Mochly-Rosen, Sarah M. Sweitzer, Joan J. Kendig, David C. Yeomans. "United States Patent 7459424 Peptide inhibitors of protein kinase C gamma for pain management", Leland Stanford Junior University, Apr 22, 2003

Research & Scholarship

Current Research and Scholarly Interests

My laboratory’s research is centered on achieving a better understanding of and improving the management of pain. This work can be roughly divided into two distinct parts: pain physiology and diagnosis and pain therapy. In terms of pain diagnosis, my laboratory is focused on identifying biomolecular and physiological markers that are indicative of different pain pathologies and can be directive in choosing therapies for that pain state. Thus, we are examining changes in pain nerve (nociceptor) gene expression in skin and nerve tissue. For example, we have recently investigated changes in expression of voltage gated sodium channels under inflammatory and post-incisional conditions. We have also studied the release of neuropeptide, cytokine, and trophic biomarkers into skin and into the spinal epidural space during different pain and inflammatory states in rodents and humans and the effects of treatments on this release. This biomarker methodology is very useful in the process of analgesic and anti-inflammatory therapy development.
Pain Physiology
Pain is primarily subtended by two distinct nociceptor types. When activated, the thinly myelinated A-delta pain fibers create the sensation of sharp, pricking pain, whereas activation of unmyelinated C fibers produces a burning or aching sensation. One or the other type of nociceptor is thought to be dominant in different human pain states. Several years ago, we developed simple methods for differentiating pain or responses evoked by the activation of A-delta or C fiber nociceptors in humans and animals. Using a laser-based stimulation system, we are performing experiments examining both electrophysiological and biochemical responses to these two pain types. Some of this work is done in rodents, wherein we perform both single unit nociceptor recordings, as well as recordings from nociceptive neurons in the spinal cord. We are also using a combination of cortical evoked potential responses to laser pulsed pain stimuli as well as functional magnetic resonance imaging (fMRI) of the brain of volunteers (and eventually patients) to determine the cortical representation of these A-delta and C fiber mediated pain. The hope is that after defining these brain maps for the two pain physiologies, we will be better able to determine the physiology of clinical pain of unknown nociceptor dominance.
Gene Therapy for Pain
Over the last 10 years, we have developed herpes simplex I-based vectors to carry analgesic genes, antisense, or siRNAs into nociceptors. For example, we have developed a recombinant vector which, when placed on or in tissue of rodents or monkeys, is picked up by the nociceptors innervating that tissue and transported along the peripheral nerve back to the cell bodies of these nerve fibers. The inserted transgene is then expressed. For example, nociceptors exposed to vectors encoding human enkephalins begin to make this endorphin-like peptide. These enkephalins selectively inhibit the nociceptors exposed to these viruses for at least 20 weeks (in monkeys). Thus, this method may provide a means of long-term treatment of chronic, localized pain conditions. To this end, we are developing the bases for clinical trials wherein our vector is applied to painful metastatic sites of cancer patients.
In summary, we perform laboratory and clinical research in the area of pain and analgesia. Some of this work centers on improving our understanding of the mechanisms underlying clinical pain states, hopefully leading to more accurate diagnosis and treatment. It also centers on the development of a completely new way to treat chronic pain, namely gene therapy. The environment in which these studies are performed, that of the Department of Anesthesia and the Pain Working Group of the Neuroscience Institute at Stanford, is an ideal one in which to do this work.


Stanford Advisees


All Publications

  • Ex Vivo Whole Nerve Electrophysiology Setup, Action Potential Recording, and Data Analyses in a Rodent Model. Current protocols in neuroscience Sun, S., Delgado, J., Behzadian, N., Yeomans, D., Anderson, T. A. 2020; 93 (1): e99


    Ex vivo rodent whole nerves provide a model for assessing the effects of interventions on nerve impulse transmission and consequent sensory and/or motor function. Nerve impulse transmission can be measured through sciatic nerve compound action potential (CAP) recordings. However, de novo development and implementation of an ex vivo whole nerve resection protocol and an electrophysiology setup that retains nerve viability, that produces low noise CAP signals, and that allows for data analysis is challenging. Additionally, some of the existing literature lacks detail and accuracy and may be out of date. This article describes detailedprotocols for rodent ex vivo sciatic nerve dissection and handling; importance of an optimal physiologic solution; computer-aided designs for 3D printing of readily adaptable ex vivo rodent whole nerve electrophysiology chambers; construction of low-cost, effective suction electrodes; setup and use of nerve stimulators and amplifiers; acquisition of low noise, small voltage CAP data and digital conversion; use of software for data analyses of CAP components; and tips for troubleshooting. © 2020 Wiley Periodicals LLC. Basic Protocol 1: Electrophysiology wiring and hardware setup Support Protocol 1: 3D printing an electrophysiology chamber Support Protocol 2: Building suction electrodes Basic Protocol 2: Sciatic nerve dissection and compound action potential recording Basic Protocol 3: Data export and analysis Support Protocol 3: Preparation of HEPES-buffered physiologic solution.

    View details for DOI 10.1002/cpns.99

    View details for PubMedID 32663369

  • Migraine Attack Probability Is Modulated by Oxytocin Receptor Activity on Trigeminal Neurons Yeomans, D. C., Kori, S. H. WILEY. 2020: 21
  • The Chemokine Receptor CXCR2 Supports Nociceptive Sensitization after Traumatic Brain Injury. Molecular pain Liang, D. Y., Shi, X., Liu, P., Sun, Y., Sahbaie, P., Li, W. W., Yeomans, D. C., Clark, J. D. ; 13: 1744806917730212


    Chronic pain after traumatic brain injury (TBI) is very common, but the mechanisms linking TBI to pain and the pain-related interactions of TBI with peripheral injuries are poorly understood. Chemokine receptors play an important role in both pain and brain injury. In the current work, we pursued the hypothesis that the epigenetically regulated CXC chemokine receptor 2 (CXCR2) is a crucial modulator of nociceptive sensitization induced by TBI. For these studies, we used the rat lateral fluid percussion model of TBI. Histone actyltransferase activity was blocked using anacardic acid beginning immediately following injury, or delayed for seven days prior to administration. The selective CXCR2 antagonist SCH527123 administered systemically or intrathecally was used to probe the role of chemokine signaling on mechanical hindpaw sensitization after TBI. The expression of the CXCR2 receptor was accomplished using real-time PCR, immunohistochemistry, and Western blotting, while epigenetic regulation was assessed using chromatin immunoprecipitation assay. The spinal levels of several pain-related mediators including CXCL1, an endogenous ligand for CXCR2, as well as brain-derived neurotrophic factor and prodynorphin were measured by enzyme-linked immunosorbent assay. We observed that anacardic acid potently blocked and reversed mechanical hindpaw sensitization after TBI. The same drug was able to prevent the upregulation of CXCR2 after TBI, but did not affect the spinal expression of other pain mediators. On the other hand, both systemically and intrathecally administered SCH527123 reversed hindpaw allodynia after TBI. Most of the spinal CXCR2 appeared to be expressed by spinal cord neurons. Chromatin immunoprecipitation experiments demonstrated TBI-enhanced association of the CXCR2 promoter with acetylated-H3K9 histone protein that was also reversible using anacardic acid. Taken together, our findings suggested that TBI causes the upregulation of spinal CXCR2 through an epigenetic mechanism ultimately supporting nociceptive sensitization. The use of CXCR2 antagonists may, therefore, be useful in pain resulting from TBI.

    View details for PubMedID 28845733

  • Association between Anterior Cingulate Neurochemical Concentration and Individual Differences in Hypnotizability. Cerebral cortex (New York, N.Y. : 1991) DeSouza, D. D., Stimpson, K. H., Baltusis, L., Sacchet, M. D., Gu, M., Hurd, R., Wu, H., Yeomans, D. C., Willliams, N., Spiegel, D. 2020


    Hypnosis is the oldest form of Western psychotherapy and a powerful evidence-based treatment for numerous disorders. Hypnotizability is variable between individuals; however, it is a stable trait throughout adulthood, suggesting that neurophysiological factors may underlie hypnotic responsiveness. One brain region of particular interest in functional neuroimaging studies of hypnotizability is the anterior cingulate cortex (ACC). Here, we examined the relationships between the neurochemicals, GABA, and glutamate, in the ACC and hypnotizability in healthy individuals. Participants underwent a magnetic resonance imaging (MRI) session, whereby T1-weighted anatomical and MEGA-PRESS spectroscopy scans were acquired. Voxel placement over the ACC was guided by a quantitative meta-analysis of functional neuroimaging studies of hypnosis. Hypnotizability was assessed using the Hypnotic Induction Profile (HIP), and self-report questionnaires to assess absorption (TAS), dissociation (DES), and negative affect were completed. ACC GABA concentration was positively associated with HIP scores such that the higher the GABA concentration, the more hypnotizable an individual. An exploratory analysis of questionnaire subscales revealed a negative relationship between glutamate and the absorption and imaginative involvement subscale of the DES. These results provide a putative neurobiological basis for individual differences in hypnotizability and can inform our understanding of treatment response to this growing psychotherapeutic tool.

    View details for DOI 10.1093/cercor/bhz332

    View details for PubMedID 32108220

  • Intrathecal administration of AYX2 DNA-decoy produces a long-term pain treatment in rat models of chronic pain by inhibiting the KLF6, KLF9 and KLF15 transcription factors. Molecular pain Mamet, J., Klukinov, M., Harris, S., Manning, D. C., Xie, S., Pascual, C., Taylor, B. K., Donahue, R. R., Yeomans, D. C. ; 13: 1744806917727917


    Nociception is maintained by genome-wide regulation of transcription in the dorsal root ganglia?spinal cord network. Hence, transcription factors constitute a promising class of targets for breakthrough pharmacological interventions to treat chronic pain. DNA decoys are oligonucleotides and specific inhibitors of transcription factor activities. A methodological series of in vivo?in vitro screening cycles was performed with decoy/transcription factor couples to identify targets capable of producing a robust and long-lasting inhibition of established chronic pain. Decoys were injected intrathecally and their efficacy was tested in the spared nerve injury and chronic constriction injury models of chronic pain in rats using repetitive von Frey testing.Results demonstrated that a one-time administration of decoys binding to the Kruppel-like transcription factors (KLFs) 6, 9, and 15 produces a significant and weeks?month long reduction in mechanical hypersensitivity compared to controls. In the spared nerve injury model, decoy efficacy was correlated to its capacity to bind KLF15 and KLF9 at a specific ratio, while in the chronic constriction injury model, efficacy was correlated to the combined binding capacity to KLF6 and KLF9. AYX2, an 18-bp DNA decoy binding KLF6, KLF9, and KLF15, was optimized for clinical development, and it demonstrated significant efficacy in these models.These data highlight KLF6, KLF9, and KLF15 as transcription factors required for the maintenance of chronic pain and illustrate the potential therapeutic benefits of AYX2 for the treatment of chronic pain.

    View details for PubMedID 28814144

    View details for PubMedCentralID PMC5582654

  • Analgesic Effect of Intranasal Oxytocin in a Rat Model of Trigeminal Neuralgia Klukinov, M., Yeomans, D. C. WILEY. 2019: 156?57
  • Effect of Nasal Oxytocin on Pain Following Traumatic Brain Injury in Rats Yeomans, D. C., Meidahl, A., Eisenried, A., Klukinov, M., Tzabazis, A. WILEY. 2018: 1336
  • Evaluation of Selective Na(V)1.7 Inhibitors for the Treatment of Ocular Pain Delwig, A., Pajouhesh, H., Yeomans, D., Du Bois, J., Miljanich, G., Mulcahy, J. ASSOC RESEARCH VISION OPHTHALMOLOGY INC. 2018
  • Intranasal Oxytocin Attenuates Reactive and Ongoing, Chronic Pain in a Model of Mild Traumatic Brain Injury. Headache Meidahl, A. C., Eisenried, A., Klukinov, M., Cao, L., Tzabazis, A. Z., Yeomans, D. C. 2018; 58 (4): 545?58


    BACKGROUND: Approximately 1.7 million Americans sustain a traumatic brain injury (TBI) each year and chronic pain is a common complication.OBJECTIVE: We studied the effects of intranasally administered oxytocin as a potential treatment for chronic pain in an animal model of mild TBI.METHODS: The lateral fluid percussion model of mild TBI was chosen for this purpose and after exposure to mild TBI the rats (n=12) developed hind paw and facial allodynia compared to sham animals (n=6). Oxytocin or a vehicle was afterwards administered intranasally and reactive pain was assessed by hind paw and facial von Frey testing. Some animals received the oxytocin receptor antagonist, atosiban, in addition to oxytocin/vehicle treatment (n=12). The effect of oxytocin on ongoing and spontaneous pain was examined through conditioned place preference testing. To determine whether the effects of intranasal oxytocin could be attributed to delivery via the peripheral blood stream, some TBI animals received an intravenous injection of the same oxytocin dose that was given intranasally. ELISA immunoassays were carried out (n=6) to measure concentrations of oxytocin in the trigeminal ganglia, pons, spinal cord, and olfactory bulb after intranasal administration and evaluate the most likely route of entry.RESULTS: These studies confirmed that the fluid percussion model can be used to study post-TBI facial allodynia. Oxytocin attenuated both reactive and spontaneous, ongoing non-reactive pain following mild TBI for at least 3-4 hours after intranasal administration by binding to OT or VA1-receptors most likely by a peri-trigeminal nerve mediated uptake.CONCLUSIONS: Intranasal oxytocin attenuates measures of reactive and non-reactive pain in a model of mild TBI and may represent a novel treatment for chronic pain in TBI patients.

    View details for PubMedID 29266199

  • Wavelet analysis of heart rate variability: Impact of wavelet selection BIOMEDICAL SIGNAL PROCESSING AND CONTROL Tzabazis, A., Eisenried, A., Yeomans, D. C., Moore, H. 2018; 40: 220?25
  • Correlation of changes in hemodynamic response as measured by cerebral optical spectrometry with subjective pain ratings in volunteers and patients: a prospective cohort study JOURNAL OF PAIN RESEARCH Eisenried, A., Austin, N., Cobb, B., Akhbardeh, A., Carvalho, B., Yeomans, D. C., Tzabazis, A. Z. 2018; 11: 1991?98
  • Correlation of changes in hemodynamic response as measured by cerebral optical spectrometry with subjective pain ratings in volunteers and patients: a prospective cohort study. Journal of pain research Eisenried, A., Austin, N., Cobb, B., Akhbardeh, A., Carvalho, B., Yeomans, D. C., Tzabazis, A. Z. 2018; 11: 1991?98


    Noninvasive cerebral optical spectrometry is a promising candidate technology for the objective assessment physiological changes during pain perception. This study's primary objective was to test if there was a significant correlation between the changes in physiological parameters as measured by a cerebral optical spectrometry-based algorithm (real-time objective pain assessment [ROPA]) and subjective pain ratings obtained from volunteers and laboring women. Secondary aims were performance assessment using linear regression and receiver operating curve (ROC) analysis.Prospective cohort study performed in Human Pain Laboratory and Labor and Delivery Unit. After institutional review board approval, we evaluated ROPA in volunteers undergoing the cold pressor test and in laboring women before and after epidural or combined spinal epidural placement. Linear regression was performed to measure correlations. ROCs and corresponding areas under the ROCs (AUC), as well as Youden's indices, as a measure of diagnostic effectiveness, were calculated.Correlations between numeric rating scale or visual analog scale and ROPA were significant for both volunteers and laboring women. AUCs for both volunteers and laboring women with numeric rating scale and visual analog scale subjective pain ratings as ground truth revealed at least good (AUC: 70%-79%) to excellent (AUC >90%) distinction between clinically meaningful pain severity differentiations (no/mild-moderate-severe).Cerebral Optical Spectrometry-based ROPA significantly correlated with subjectively reported pain in volunteers and laboring women, and could be a useful monitor for clinical circumstances where direct assessment is not available, or to complement patient-reported pain scores.

    View details for PubMedID 30288094

  • Nervous system delivery of antilysophosphatidic acid antibody by nasal application attenuates mechanical allodynia after traumatic brain injury in rats PAIN Eisenried, A., Meidahl, A. N., Klukinov, M., Tzabazis, A. Z., Sabbadini, R. A., Clark, J., Yeomans, D. C. 2017; 158 (11): 2181?88


    Lysophosphatidic acid (LPA) is a bioactive lipid that impacts neurological outcomes after neurotrauma by inhibiting neuroregeneration, promoting inflammation, and contributing to behavioral deficits. Blocking LPA signaling with a novel anti-LPA monoclonal antibody (mAb) is neuroprotective after traumatic brain injury (TBI) if given to injured animals whose blood-brain barrier (BBB) has been compromised. It is hypothesized that the anti-LPA mAb could improve chronic pain initiated by TBI. However, poor brain penetration after systemic application of the antibody makes access to the central nervous system (CNS) problematic in situations where the BBB is intact. Our experiments investigated whether intranasal delivery of the anti-LPA mAb could bypass the BBB, allowing for direct entry of the antibody to certain areas of the CNS. When the humanized anti-LPA mAb, LT3114, was intranasally applied to injured rats within 30 minutes after mild TBI using the central lateral percussion model, enzyme-linked immunospecific assay and immunohistochemistry demonstrated antibody uptake to several areas in the CNS, including the area of cortical injury, the corpus callosum, cerebellum, and the subventricular region. Compared with control rats that received LT3114 but no TBI, TBI rats demonstrated significantly higher concentrations of intranasally administered LT3114 antibody in some tissues. In behavioral studies, a significant attenuation of mechanical allodynia after TBI was observed in the anti-LPA treatment group (P = 0.0079), when compared with vehicle controls within 14 days after TBI. These results suggest that intranasal application of the anti-LPA antibody directly accesses CNS sites involved in TBI-related pain and that this access attenuates pain sequelae to the neurotrauma.

    View details for PubMedID 29028747

  • Modulation of the Neural Circuitry Underlying Trait Hypnotizability With Spaced Continuous Theta-Burst Stimulation Williams, N., Sudheimer, K., Stimpson, K., Duvio, D., Chung, C., DeSouza, D., Jo, B., Williams, L., Yeomans, D., Spiegel, D. NATURE PUBLISHING GROUP. 2017: S508?S509
  • Formulation and Toxicology Evaluation of the Intrathecal AYX1 DNA-Decoy in Sprague Dawley Rats TOXICOLOGICAL SCIENCES Mamet, J., Yeomans, D. C., Yaksh, T. L., Manning, D. C., Harris, S. 2017; 159 (1): 76?85


    The longevity of pain after surgery is debilitating and limits the recovery of patients. AYX1 is a double-stranded, unprotected, 23 base-pair oligonucleotide designed to reduce acute post-surgical pain and prevent its chronification with a single intrathecal perioperative dose. AYX1 mimics the DNA sequence normally bound by EGR1 on chromosomes, a transcription factor transiently induced in the dorsal root ganglia-spinal cord network following a noxious input. AYX1 binds to EGR1 and prevents it from launching waves of gene regulation that are necessary to maintain pain over time. A formulation suitable for an intrathecal injection of AYX1 was developed, including a specific ratio of AYX1 and calcium so the ionic homeostasis of the cerebrospinal fluid is maintained and no impact on neuromuscular control is produced upon injection. A GLP toxicology study in naïve Sprague Dawley rats was conducted using 3 dose levels up to the maximum feasible dose. Clinical observations, neurobehavioral observations, clinical pathology and histopathology of the nervous system and peripheral tissues were conducted. An additional nonGLP study was conducted in the spared nerve injury model of chronic neuropathic pain in which EGR1 is induced in the dorsal root ganglia and spinal cord. Similar testing was performed, including a modified Irwin test to assess a potential impact of AYX1 on autonomic nervous system responses, locomotion, activity, arousal, sensorimotor, and neuromuscular function. No AYX1-related adverse events were observed in any of the studies and the no-observed-adverse-effect-level was judged to be the maximum feasible dose.

    View details for PubMedID 28903493

  • Opioid-induced hyperalgesia in clinical anesthesia practice: what has remained from theoretical concepts and experimental studies? Current opinion in anaesthesiology Weber, L., Yeomans, D. C., Tzabazis, A. 2017


    This article reviews the phenomenon of opioid-induced hyperalgesia (OIH) and its implications for clinical anesthesia. The goal of this review is to give an update on perioperative prevention and treatment strategies, based on findings in preclinical and clinical research.Several systems have been suggested to be involved in the pathophysiology of OIH with a focus on the glutaminergic system. Very recently preclinical data revealed that peripheral ?-opioid receptors (MORs) are key players in the development of OIH and acute opioid tolerance (AOT). Peripheral MOR antagonists could, thus, become a new prevention/treatment option of OIH in the perioperative setting. Although the impact of OIH on postoperative pain seems to be moderate, recent evidence suggests that increased hyperalgesia following opioid treatment correlates with the risk of developing persistent pain after surgery. In clinical practice, distinction among OIH, AOT and acute opioid withdrawal remains difficult, especially because a specific quantitative sensory test to diagnose OIH has not been validated yet.Since the immediate postoperative period is not ideal to initiate long-term treatment for OIH, the best strategy is to prevent its occurrence. A multimodal approach, including choice of opioid, dose limitations and addition of nonopioid analgesics, is recommended.

    View details for DOI 10.1097/ACO.0000000000000485

    View details for PubMedID 28590258

  • Antihyperalgesic effect by herpes vector-mediated knockdown of NaV1.7 sodium channels after skin incision. Neuroreport Eisenried, A., Klukinov, M., Yeomans, D. C., Tzabazis, A. Z. 2017


    Postincisional hyperalgesia and allodynia play an important role in perioperative medicine. NaV1.7 sodium channel has proven to be a key player in several pain states, including acute, inflammatory, and neuropathic pain. This study investigated the effects of silencing NaV1.7 through Herpes-based gene therapy with an antisense transcript on pain states after incision of the skin in rodents. Seventy-six Balb/C mice were subdivided into six groups and were treated with no virus, control virus, or NaV1.7 antisense vector before lateral hindpaw skin incision or sham procedure. All mice were tested for mechanical allodynia, cold allodynia, and thermal hyperalgesia. For time series analysis, a two-way analysis of variance with post-hoc Bonferroni testing was used. After incision mice developed significant hypersensitivity to mechanical, cold, and heat stimuli. The NaV1.7 antisense vector blocked the hypersensitivity to mechanical, cold, and heat stimuli that was normally observed 24 and 48?h after incision. We demonstrated that a gene therapy-based NaV1.7 knockdown affects postincisional hyperalgesia and allodynia. The data provide evidence that the incision model leads to periwound hypersensitivity after incision and that application of the NaV1.7 antisense virus prevents this sensitization. This then, in turn, provides presumptive support to the hypothesis that overexpression of the NaV1.7 channel is an important mechanism underlying hyperalgesia and allodynia following skin incision.

    View details for DOI 10.1097/WNR.0000000000000814

    View details for PubMedID 28562485

  • Oxytocin and Migraine Headache HEADACHE Tzabazis, A., Kori, S., Mechanic, J., Miller, J., Pascual, C., Manering, N., Carson, D., Klukinov, M., Spierings, E., Jacobs, D., Cuellar, J., Frey, W. H., Hanson, L., Angst, M., Yeomans, D. C. 2017; 57: 64-75


    This article reviews material presented at the 2016 Scottsdale Headache Symposium. This presentation provided scientific results and rationale for the use of intranasal oxytocin for the treatment of migraine headache. Results from preclinical experiments are reviewed, including in vitro experiments demonstrating that trigeminal ganglia neurons possess oxytocin receptors and are inhibited by oxytocin. Furthermore, most of these same neurons contain CGRP, the release of which is inhibited by oxytocin. Results are also presented which demonstrate that nasal oxytocin inhibits responses of trigeminal nucleus caudalis neurons to noxious stimulation using either noxious facial shock or nitroglycerin infusion. These studies led to testing the analgesic effect of intranasal oxytocin in episodic migraineurs-studies which did not meet their primary endpoint of pain relief at 2 h, but which were highly informative and led to additional rat studies wherein inflammation was found to dramatically upregulate the number of oxytocin receptors available on trigeminal neurons. This importance of inflammation was supported by a series of in vivo rat behavioral studies, which demonstrated a clear craniofacial analgesic effect when a pre-existing inflammatory injury was present. The significance of inflammation was further solidified by a small single-dose clinical study, which showed analgesic efficacy that was substantially stronger in chronic migraine patients that had not taken an anti-inflammatory drug within 24 h of oxytocin dosing. A follow-on open label study examining effects of one month of intranasal oxytocin dosing did show a reduction in pain, but a more impressive decrease in the frequency of headaches in both chronic and high frequency episodic migraineurs. This study led to a multicountry double blind, placebo controlled study studying whether, over 2 months of dosing, "as needed" dosing of intranasal oxytocin by chronic and high frequency migraineurs would reduce the frequency of their headaches compared to a 1-month baseline period. This study failed to meet its primary endpoint, due to an extraordinarily high placebo rate in the country of most of the patients (Chile), but was also highly informative, showing strong results in other countries and strong post hoc indications of efficacy. The results provide a strong argument for further development of intranasal oxytocin for migraine prophylaxis.

    View details for DOI 10.1111/head.13082

    View details for PubMedID 28485846

  • Pharmacology, pharmacokinetics, and metabolism of the DNA-decoy AYX1 for the prevention of acute and chronic post-surgical pain MOLECULAR PAIN Mamet, J., Harris, S., Klukinov, M., Yeomans, D. C., Donahue, R. R., Taylor, B. K., Eddinger, K., Yaksh, T., Manning, D. C. 2017; 13


    Background AYX1 is an unmodified DNA-decoy designed to reduce acute post-surgical pain and its chronification with a single intrathecal dose at the time of surgery. AYX1 inhibits the transcription factor early growth response protein 1, which is transiently induced at the time of injury and triggers gene regulation in the dorsal root ganglia and spinal cord that leads to long-term sensitization and pain. This work characterizes the AYX1 dose-response profile in rats and the link to AYX1 pharmacokinetics and metabolism in the cerebrospinal fluid, dorsal root ganglia, and spinal cord. Results The effects of ascending dose-levels of AYX1 on mechanical hypersensitivity were measured in the spared nerve injury model of chronic pain and in a plantar incision model of acute post-surgical pain. AYX1 dose-response profile shows that efficacy rapidly increases from a minimum effective dose of ? 0.5?mg to a peak maximum effective dose of ? 1?mg. With further dose escalation, the efficacy paradoxically appears to decrease by ? 30% and then returns to full efficacy at the maximum feasible dose of ? 4?mg. The reduction of efficacy is associated to doses triggering a near-saturation of AYX1 metabolism by nucleases in the cerebrospinal fluid and a paradoxical reduction of AYX1 exposure during the period of early growth response protein 1 induction. This effect is overcome at higher doses that compensate for the effect of metabolism. Discussion AYX1 is a competitive antagonist of early growth response protein 1, which is consistent with the overall increased efficacy observed as dose-levels initially escalate. Chemically, AYX1 is unprotected against degradation by nucleases. The sensitivity to nucleases is reflected in a paradoxical reduction of efficacy in the dose-response curve. Conclusions These findings point to the importance of the nuclease environment of the cerebrospinal fluid to the research and development of AYX1 and other intrathecal nucleotide-based therapeutics.

    View details for DOI 10.1177/1744806917703112

    View details for Web of Science ID 000399904200001

    View details for PubMedID 28394696

  • Analgesic Microneedle Patch for Neuropathic Pain Therapy ACS NANO Xie, X., Pascual, C., Lieu, C., Oh, S., Wang, J., Zou, B., Xie, J., Li, Z., Xie, J., Yeomans, D. C., Wu, M. X., Xie, X. S. 2017; 11 (1): 395-406


    Neuropathic pain caused by nerve injury is debilitating and difficult to treat. Current systemic pharmacological therapeutics for neuropathic pain produce limited pain relief and have undesirable side effects, while current local anesthetics tend to nonspecifically block both sensory and motor functions. Calcitonin gene related peptide (CGRP), a neuropeptide released from sensory nerve endings, appears to play a significant role in chronic neuropathic pain. In this study, an analgesic microneedle (AMN) patch was developed using dissolvable microneedles to transdermally deliver selective CGRP antagonist peptide in a painless manner for the treatment of localized neuropathic pain. Local analgesic effects were evaluated in rats by testing behavioral pain sensitivity in response to thermal and mechanical stimuli using neuropathic pain models such as spared-nerve injury and diabetic neuropathy pain, as well as neurogenic inflammatory pain model induced by ultraviolet B (UVB) radiation. Unlike several conventional therapies, the AMN patches produced effective analgesia on neuropathic pain without disturbing the normal nociception and motor function of the rat, resulting from the high specificity of the delivered peptide against CGRP receptors. The AMN patches did not cause skin irritation or systemic side effects. These results demonstrate that dissolvable microneedle patches delivering CGRP antagonist peptide provide an effective, safe, and simple approach to mitigate neuropathic pain with significant advantages over current treatments.

    View details for DOI 10.1021/acsnano.6b06104

    View details for Web of Science ID 000392886500040

    View details for PubMedID 28001346

  • Visualizing Nerve Injury in a Neuropathic Pain Model with [(18)F]FTC-146 PET/MRI. Theranostics Shen, B., Behera, D., James, M. L., Reyes, S. T., Andrews, L., Cipriano, P. W., Klukinov, M., Lutz, A. B., Mavlyutov, T., Rosenberg, J., Ruoho, A. E., McCurdy, C. R., Gambhir, S. S., Yeomans, D. C., Biswal, S., Chin, F. T. 2017; 7 (11): 2794?2805


    The ability to locate nerve injury and ensuing neuroinflammation would have tremendous clinical value for improving both the diagnosis and subsequent management of patients suffering from pain, weakness, and other neurologic phenomena associated with peripheral nerve injury. Although several non-invasive techniques exist for assessing the clinical manifestations and morphological aspects of nerve injury, they often fail to provide accurate diagnoses due to limited specificity and/or sensitivity. Herein, we describe a new imaging strategy for visualizing a molecular biomarker of nerve injury/neuroinflammation, i.e., the sigma-1 receptor (S1R), in a rat model of nerve injury and neuropathic pain. The two-fold higher increase of S1Rs was shown in the injured compared to the uninjured nerve by Western blotting analyses. With our novel S1R-selective radioligand, [(18)F]FTC-146 (6-(3-[(18)F]fluoropropyl)-3-(2-(azepan-1-yl)ethyl)benzo[d]thiazol-2(3H)-one), and positron emission tomography-magnetic resonance imaging (PET/MRI), we could accurately locate the site of nerve injury created in the rat model. We verified the accuracy of this technique by ex vivo autoradiography and immunostaining, which demonstrated a strong correlation between accumulation of [(18)F]FTC-146 and S1R staining. Finally, pain relief could also be achieved by blocking S1Rs in the neuroma with local administration of non-radioactive [(19)F]FTC-146. In summary, [(18)F]FTC-146 S1R PET/MR imaging has the potential to impact how we diagnose, manage and treat patients with nerve injury, and thus warrants further investigation.

    View details for PubMedID 28824716

  • Oxytocin alleviates orofacial mechanical hypersensitivity associated with infraorbital nerve injury through vasopressin-1A receptors of the rat trigeminal ganglia. Pain Kubo, A., Shinoda, M., Katagiri, A., Takeda, M., Suzuki, T., Asaka, J., Yeomans, D. C., Iwata, K. 2017; 158 (4): 649?59


    Oxytocin (OXT) is a neuropeptide hormone synthesized and secreted by hypothalamic neurons and has been reported to play a significant role in pain modulation. However, the mechanisms underlying OXT's antinociceptive effect on neuropathic pain are not fully understood. In this study, we examined the peripheral effect of OXT on mechanical hypersensitivity induced by partial ligation of the infraorbital nerve (PNL) in rats. Mechanical hypersensitivity in the whisker pad skin after PNL was attenuated by the direct administration of OXT into the trigeminal ganglion (TG). The proportion of vasopressin-1A receptor (V1A-R)-immunoreactive, but not OXT-receptor-immunoreactive, neurons significantly increased among TG neurons innervating the whisker pad skin after PNL. In a patch-clamp recording from TG neurons isolated from PNL rats, the resting membrane potential of OXT-treated neurons was significantly decreased, and the current thresholds of OXT-treated neurons for spike generation (rheobases) were significantly greater than those of vehicle-treated neurons. In addition, OXT increased voltage-gated K channel currents in PNL animals. Furthermore, intra-TG administration of a selective V1A-R antagonist reversed the OXT-induced alleviation of mechanical hypersensitivity, and coapplication of the antagonist opposed OXT's effects on the resting membrane potential, rheobase, and K current. These findings suggest that OXT is effective at suppressing TG neuronal hyperexcitability after nerve injury, likely by modulation of voltage-gated K channels through V1A-R. This signaling mechanism represents a potential therapeutic target for the treatment of orofacial neuropathic pain.

    View details for PubMedID 28072605

  • Nasal application of HSV encoding human preproenkephalin blocks craniofacial pain in a rat model of traumatic brain injury. Gene therapy Meidahl, A. C., Klukinov, M., Tzabazis, A. Z., Sorensen, J. C., Yeomans, D. C. 2017; 24 (8): 482?86


    According to Centers for Disease Control and Prevention, each year, an estimated 1.7 million Americans sustain a traumatic brain injury (TBI), which frequently leads to chronic craniofacial pain. In this study we examine a gene therapy approach to the treatment of post-TBI craniofacial neuropathic pain using nasal application of a herpes simplex virus (HSV)-based vector expressing human proenkephalin (SHPE) to target the trigeminal ganglia. Mild TBI was induced in rats by the use of a modified fluid percussion model. Two days after mild TBI, following the development of facial mechanical allodynia, animals received either an intranasal application of vehicle or recombinant HSV encoding human preproenkephalin or lacZ reporter gene encoding control vector (SHZ.1). Compared with baseline response thresholds, mild TBI in SHZ.1 or vehicle-treated animals induced a robust craniofacial allodynia lasting at least 45 days. On the other hand, nasal SHPE application 2 days post-TBI attenuated facial allodynia, reaching significance by day 4-7 and maintaining this effect throughout the duration of the experiment. Immunohistochemical examination revealed strong expression of human proenkephalin in trigeminal ganglia of SHPE, but not SHZ.1-treated rats. This study demonstrates that intranasal administration of HSV-based gene vectors may be a viable, non-invasive means of treating chronic craniofacial pain, including post-TBI pain.

    View details for PubMedID 28682314

  • TBI-induced nociceptive sensitization is regulated by histone acetylation. IBRO reports Liang, D. Y., Sahbaie, P., Sun, Y., Irvine, K. A., Shi, X., Meidahl, A., Liu, P., Guo, T. Z., Yeomans, D. C., Clark, J. D. 2017; 2: 14?23


    Chronic pain after traumatic brain injury (TBI) is very common, but the mechanisms linking TBI to pain and the pain-related interactions of TBI with peripheral injuries are poorly understood. In these studies we pursued the hypothesis that TBI pain sensitization is associated with histone acetylation in the rat lateral fluid percussion model. Some animals received hindpaw incisions in addition to TBI to mimic polytrauma. Neuropathological analysis of brain tissue from sham and TBI animals revealed evidence of bleeding, breakdown of the blood brain barrier, in the cortex, hippocampus, thalamus and other structures related to pain signal processing. Mechanical allodynia was measured in these animals for up to eight weeks post-injury. Inhibitors of histone acetyltransferase (HAT) and histone deacetylase (HDAC) were used to probe the role of histone acetylation in such pain processing. We followed serum markers including glial fibrillary acidic protein (GFAP), neuron-specific enolase 2 (NSE) myelin basic protein (MBP) and S100? to gauge TBI injury severity. Our results showed that TBI caused mechanical allodynia in the hindpaws of the rats lasting several weeks. Hindpaws contralateral to TBI showed more rapid and profound sensitization than ipsilateral hindpaws. The inhibition of HAT using curcumin 50 mg/kg s.c reduced mechanical sensitization while the HDAC inhibitor suberoylanilide hydroxamic acid 50 mg/kg i.p. prolonged sensitization in the TBI rats. Immunohistochemical analyses of spinal cord tissue localized changes in the level of acetylation of the H3K9 histone mark to dorsal horn neurons. Taken together, these findings demonstrate that TBI induces sustained nociceptive sensitization, and changes in spinal neuronal histone proteins may play an important role.

    View details for PubMedID 30135929

  • Oxytocin receptor: Expression in the trigeminal nociceptive system and potential role in the treatment of headache disorders. Cephalalgia Tzabazis, A., Mechanic, J., Miller, J., Klukinov, M., Pascual, C., Manering, N., Carson, D. S., Jacobs, A., Qiao, Y., Cuellar, J., Frey, W. H., Jacobs, D., Angst, M., Yeomans, D. C. 2016; 36 (10): 943-950


    Our studies investigated the location of oxytocin receptors in the peripheral trigeminal sensory system and determined their role in trigeminal pain.Oxytocin receptor expression and co-localization with calcitonin gene-related peptide was investigated in rat trigeminal ganglion using immunohistochemistry. Enzyme-linked immunosorbent assay was used to determine the effects of facial electrocutaneous stimulation and adjuvant-induced inflammation of the temporomandibular joint on oxytocin receptor expression in the trigeminal ganglion. Finally, the effects of oxytocin on capsaicin-induced calcitonin gene-related peptide release from dural nociceptors were investigated using isolated rat dura mater.Oxytocin receptor immunoreactivity was present in rat trigeminal neurons. The vast majority of oxytocin receptor immunoreactive neurons co-expressed calcitonin gene-related peptide. Both electrocutaneous stimulation and adjuvant-induced inflammation led to a rapid upregulation of oxytocin receptor protein expression in trigeminal ganglion neurons. Oxytocin significantly and dose-dependently decreased capsaicin-induced calcitonin gene-related peptide release from dural nociceptors.Oxytocin receptor expression in calcitonin gene-related peptide containing trigeminal ganglion neurons, and the blockade of calcitonin gene-related peptide release from trigeminal dural afferents suggests that activation of these receptors may provide therapeutic benefit in patients with migraine and other primary headache disorders.

    View details for DOI 10.1177/0333102415618615

    View details for PubMedID 26590611

  • Postoperative Analgesia Due to Sustained-Release Buprenorphine, Sustained-Release Meloxicam, and Carprofen Gel in a Model of Incisional Pain in Rats (Rattus norvegicus) JOURNAL OF THE AMERICAN ASSOCIATION FOR LABORATORY ANIMAL SCIENCE Seymour, T. L., Adams, S. C., Felt, S. A., Jampachaisri, K., Yeomans, D. C., Pacharinsak, C. 2016; 55 (3): 300-305


    Postoperative analgesia in laboratory rats is complicated by the frequent handling associated with common analgesic dosing requirements. Here, we evaluated sustained-release buprenorphine (Bup-SR), sustained-release meloxicam (Melox-SR), and carprofen gel (CG) as refinements for postoperative analgesia. The aim of this study was to investigate whether postoperative administration of Bup-SR, Melox-SR, or CG effectively controls behavioral mechanical and thermal hypersensitivity in a rat model of incisional pain. Rats were randomly assigned to 1 of 5 treatment groups: saline, 1 mL/kg SC BID; buprenorphine HCl (Bup HCl), 0.05 mg/kg SC BID; Bup-SR, 1.2 mg/kg SC once; Melox-SR, 4 mg/kg SC once; and CG, 2 oz PO daily. Mechanical and thermal hypersensitivity were tested daily from day-1 through 4. Bup HCl and Bup-SR attenuated mechanical and thermal hypersensitivity on days 1 through 4. Melox-SR and CG attenuated mechanical hypersensitivity-but not thermal hypersensitivity-on days 1 through 4. Plasma concentrations, measured by using UPLC with mass spectrometry, were consistent between both buprenorphine formulations. Gross pathologic examination revealed no signs of toxicity in any group. These findings suggest that postoperative administration of Bup HCl and Bup-SR-but not Melox-SR or CG-effectively attenuates mechanical and thermal hypersensitivity in a rat model of incisional pain.

    View details for Web of Science ID 000375510400008

    View details for PubMedID 27177563

  • Nociceptive sensitization and BDNF up-regulation in a rat model of traumatic brain injury NEUROSCIENCE LETTERS Feliciano, D. P., Sahbaie, P., Shi, X., Klukinov, M., Clark, J. D., Yeomans, D. C. 2014; 583: 55-59


    Chronic pain after traumatic brain injury (TBI) is very common, but the mechanisms linking TBI to pain experienced in the periphery have not been described. In this set of studies we examined nociceptive sensitization and changes in spinal cord gene expression using the rat lateral fluid percussion model of mild TBI. We did not identify changes in thermal nociceptive thresholds in rats with mild TBI. However, mechanical allodynia in hind paws contralateral to TBI was significant and sustained. We also found that spinal cord levels of brain derived neurotrophic factor (BDNF) but not several other pain-related genes were up-regulated one week after injury. Our findings suggest that TBI-induced up-regulation of spinal BDNF levels might contribute to chronic TBI-related pain, and that the lateral fluid percussion model might be useful for exploring this relationship.

    View details for DOI 10.1016/j.neulet.2014.09.030

    View details for Web of Science ID 000345604300011

  • Nociceptive sensitization and BDNF up-regulation in a rat model of traumatic brain injury. Neuroscience letters Feliciano, D. P., Sahbaie, P., Shi, X., Klukinov, M., Clark, J. D., Yeomans, D. C. 2014; 583: 55-59


    Chronic pain after traumatic brain injury (TBI) is very common, but the mechanisms linking TBI to pain experienced in the periphery have not been described. In this set of studies we examined nociceptive sensitization and changes in spinal cord gene expression using the rat lateral fluid percussion model of mild TBI. We did not identify changes in thermal nociceptive thresholds in rats with mild TBI. However, mechanical allodynia in hind paws contralateral to TBI was significant and sustained. We also found that spinal cord levels of brain derived neurotrophic factor (BDNF) but not several other pain-related genes were up-regulated one week after injury. Our findings suggest that TBI-induced up-regulation of spinal BDNF levels might contribute to chronic TBI-related pain, and that the lateral fluid percussion model might be useful for exploring this relationship.

    View details for DOI 10.1016/j.neulet.2014.09.030

    View details for PubMedID 25246352

  • Opioid induced hyperalgesia in anesthetic settings. Korean journal of anesthesiology Lee, H. J., Yeomans, D. C. 2014; 67 (5): 299-304


    Pain is difficult to investigate and difficult to treat, in part, because of problems in quantification and assessment. The use of opioids, combined with classic anesthetics to maintain hemodynamic stability by controlling responses to intraoperative painful events has gained significant popularity in the anesthetic field. However, several side effects profiles concerning perioperative use of opioid have been published. Over the past two decades, many concerns have arisen with respect to opioid-induced hyperalgesia (OIH), which is the paradoxical effect wherein opioid usage may decrease pain thresholds and increase atypical pain unrelated to the original, preexisting pain. This brief review focuses on the evidence, mechanisms, and modulatory and pharmacologic management of OIH in order to elaborate on the clinical implication of OIH.

    View details for DOI 10.4097/kjae.2014.67.5.299

    View details for PubMedID 25473457

  • Visualizing Dermal Permeation of Sodium Channel Modulators by Mass Spectrometric Imaging JOURNAL OF THE AMERICAN CHEMICAL SOCIETY Eberlin, L. S., Mulcahy, J. V., Tzabazis, A., Zhang, J., Liu, H., Logan, M. M., Roberts, H. J., Lee, G. K., Yeomans, D. C., Du Bois, J., Zare, R. N. 2014; 136 (17): 6401-6405


    Determining permeability of a given compound through human skin is a principal challenge owing to the highly complex nature of dermal tissue. We describe the application of an ambient mass spectrometry imaging method for visualizing skin penetration of sodium channel modulators, including novel synthetic analogs of natural neurotoxic alkaloids, topically applied ex vivo to human skin. Our simple and label-free approach enables successful mapping of the transverse and lateral diffusion of small molecules having different physicochemical properties without the need for extensive sample preparation.

    View details for DOI 10.1021/ja501635u

    View details for Web of Science ID 000335369200044

    View details for PubMedID 24708172

    View details for PubMedCentralID PMC4017602

  • Gene therapy for trigeminal pain in mice. Gene therapy Tzabazis, A. Z., Klukinov, M., Feliciano, D. P., Wilson, S. P., Yeomans, D. C. 2014; 21 (4): 422-426


    The aim of this study was to test the efficacy of a single direct injection of viral vector encoding for encephalin to induce a widespread expression of the transgene and potential analgesic effect in trigeminal behavioral pain models in mice. After direct injection of herpes simplex virus type 1 based vectors encoding for human preproenkephalin (SHPE) or the lacZ reporter gene (SHZ.1, control virus) into the trigeminal ganglia in mice, we performed an orofacial formalin test and assessed the cumulative nociceptive behavior at different time points after injection of the viral vectors. We observed an analgesic effect on nociceptive behavior that lasted up to 8 weeks after a single injection of SHPE into the trigeminal ganglia. Control virus-injected animals showed nociceptive behavior similar to naive mice. The analgesic effect of SHPE injection was reversed/attenuated by subcutaneous naloxone injections, a ?-opioid receptor antagonist. SHPE-injected mice also showed normalization in withdrawal latencies upon thermal noxious stimulation of inflamed ears after subdermal complete Freund's adjuvant injection, indicating widespread expression of the transgene. Quantitative immunohistochemistry of trigeminal ganglia showed expression of human preproenkephalin after SHPE injection. Direct injection of viral vectors proved to be useful for exploring the distinct pathophysiology of the trigeminal system and could also be an interesting addition to the pain therapists' armamentarium.

    View details for DOI 10.1038/gt.2014.14

    View details for PubMedID 24572785

    View details for PubMedCentralID PMC3975690

  • Single intrathecal administration of the transcription factor decoy AYX1 prevents acute and chronic pain after incisional, inflammatory, or neuropathic injury PAIN Mamet, J., Klukinov, M., Yaksh, T. L., Malkmus, S. A., Williams, S., Harris, S., Manning, D. C., Taylor, B. K., Donahue, R. R., Porreca, F., Xie, J. Y., Oyarzo, J., Brennan, T. J., Subieta, A., Schmidt, W. K., Yeomans, D. C. 2014; 155 (2): 322-333


    The persistence of pain after surgery increases the recovery interval from surgery to a normal quality of life. AYX1 is a DNA-decoy drug candidate designed to prevent post-surgical pain following a single intrathecal injection. Tissue injury causes a transient activation of the transcription factor EGR1 in the dorsal root ganglia-dorsal horn network, which then triggers changes in gene expression that induce neuronal hypersensitivity. AYX1 is a potent, specific inhibitor of EGR1 activity that mimics the genomic EGR1-binding sequence. Administered in the peri-operative period, AYX1 dose dependently prevents mechanical hypersensitivity in models of acute incisional (plantar), inflammatory (CFA), and chronic neuropathic pain (SNI) in rats. Furthermore, in a knee surgery model evaluating functional measures of postoperative pain, AYX1 improved weight-bearing incapacitance and spontaneous rearing compared to control. These data illustrate the potential clinical therapeutic benefits of AYX1 for preventing the transition of acute to chronic post-surgical pain.

    View details for DOI 10.1016/j.pain.2013.10.015

    View details for Web of Science ID 000329984200015

    View details for PubMedID 24145208

  • Antinociceptive Effects of Sustained-Release Buprenorphine in a Model of Incisional Pain in Rats (Rattus norvegicus). Journal of the American Association for Laboratory Animal Science Chum, H. H., Jampachairsri, K., McKeon, G. P., Yeomans, D. C., Pacharinsak, C., Felt, S. A. 2014; 53 (2): 193-197


    Effective management of postoperative pain is an essential component of the care and welfare of laboratory animals. A sustained-release formulation of buprenorphine (Bup-SR) has recently been introduced to the veterinary market and has been reported to provide analgesia for as long as 72 h. Using evoked mechanical and thermal hypersensitivity tests, we here evaluated the antinociceptive effects of Bup-SR in a model of incisional pain in rats. Paw withdrawal responses were obtained before and 1 through 4 d after surgery. Rats are assigned to receive Bup-SR (0.3, 1.2, or 4.5 mg/kg SC once) or buprenorphine HCl (Bup HCl, 0.05 mg/kg SC twice daily for 3 d). Responses to mechanical and thermal stimuli in the 1.2 and 4.5 Bup-SR groups did not differ from those of rats in the Bup HCl group. Thermal latency on day 3 in rats that received 0.3 mg/kg Bup-SR was significantly different from baseline, indicating that this dose effectively decreased thermal hypersensitivity for at least 48 h. Marked sedation occurred in rats in the 4.5 Bup-SR group. Our findings indicate that Bup-SR at 0.3 or 1.2 mg/kg SC is effective in minimizing hypersensitivity with minimal sedation for at least 48 h (thermal hypersensitivity) and 72 h, respectively, in the incisional pain model in rats.

    View details for PubMedID 24602547

  • A (18)F-Labeled Saxitoxin Derivative for in Vivo PET-MR Imaging of Voltage-Gated Sodium Channel Expression Following Nerve Injury. Journal of the American Chemical Society Hoehne, A., Behera, D., Parsons, W. H., James, M. L., Shen, B., Borgohain, P., Bodapati, D., Prabhakar, A., Gambhir, S. S., Yeomans, D. C., Biswal, S., Chin, F. T., Bois, J. D. 2013; 135 (48): 18012-18015


    Both chronic and neuropathic pain conditions are associated with increased expression of certain voltage-gated sodium ion channel (NaV) isoforms in peripheral sensory neurons. A method for noninvasive imaging of these channels could represent a powerful tool for investigating aberrant expression of NaV and its role in pain pathogenesis. Herein, we describe the synthesis and evaluation of a positron emission tomography (PET) radiotracer targeting NaVs, the design of which is based on the potent, NaV-selective inhibitor saxitoxin. Both autoradiography analysis of sciatic nerves excised from injured rats as well as whole animal PET-MR imaging demonstrate that a systemically administered [(18)F]-labeled saxitoxin derivative concentrates at the site of nerve injury, consistent with upregulated sodium channel expression following axotomy. This type of PET agent has potential use for serial monitoring of channel expression levels at injured nerves throughout wound healing and/or following drug treatment. Such information may be correlated with pain behavioral analyses to help shed light on the complex molecular processes that underlie pain sensation.

    View details for DOI 10.1021/ja408300e

    View details for PubMedID 24261833

  • A F-18-Labeled Saxitoxin Derivative for in Vivo PET-MR Imaging of Voltage-Gated Sodium Channel Expression Following Nerve Injury JOURNAL OF THE AMERICAN CHEMICAL SOCIETY Hoehne, A., Behera, D., Parsons, W. H., James, M. L., Shen, B., Borgohain, P., Bodapati, D., Prabhakar, A., Gambhir, S. S., Yeomans, D. C., Biswal, S., Chin, F. T., Du Bois, J. 2013; 135 (48): 18012-18015


    Both chronic and neuropathic pain conditions are associated with increased expression of certain voltage-gated sodium ion channel (NaV) isoforms in peripheral sensory neurons. A method for noninvasive imaging of these channels could represent a powerful tool for investigating aberrant expression of NaV and its role in pain pathogenesis. Herein, we describe the synthesis and evaluation of a positron emission tomography (PET) radiotracer targeting NaVs, the design of which is based on the potent, NaV-selective inhibitor saxitoxin. Both autoradiography analysis of sciatic nerves excised from injured rats as well as whole animal PET-MR imaging demonstrate that a systemically administered [(18)F]-labeled saxitoxin derivative concentrates at the site of nerve injury, consistent with upregulated sodium channel expression following axotomy. This type of PET agent has potential use for serial monitoring of channel expression levels at injured nerves throughout wound healing and/or following drug treatment. Such information may be correlated with pain behavioral analyses to help shed light on the complex molecular processes that underlie pain sensation.

    View details for DOI 10.1021/ja408300e

    View details for Web of Science ID 000328100000002

    View details for PubMedID 24261833

  • Shaped magnetic field pulses by multi-coil repetitive transcranial magnetic stimulation (rTMS) differentially modulate anterior cingulate cortex responses and pain in volunteers and fibromyalgia patients MOLECULAR PAIN Tzabazis, A., Aparici, C. M., Rowbotham, M. C., Schneider, M. B., Etkin, A., Yeomans, D. C. 2013; 9
  • Effect of High-Frequency Alternating Current on Spinal Afferent Nociceptive Transmission NEUROMODULATION Cuellar, J. M., Alataris, K., Walker, A., Yeomans, D. C., Antognini, J. F. 2013; 16 (4): 318-327


    OBJECTIVE: The study was performed to test the hypothesis that high-frequency alternating current (HFAC) ranging from 2 to 100?kHz delivered to the spinal dorsal roots reduces activity of spinal wide dynamic range (WDR) dorsal horn neurons (DHNs) during noxious peripheral stimulation. MATERIALS AND METHODS: This hypothesis was tested in both small and large animal in vivo preparations. Single-unit extracellular spinal DHN recordings were performed in seven adult rats and four adult goats while testing various parameters of HFAC delivered to the nerve roots or dorsal root entry zone using various electrode types. Frequencies tested ranged from 2 to 100?kHz but focused on the 3 to 50?kHz range. This study investigated the ability of HFAC to inhibit WDR neuronal activity evoked by noxious mechanical (pinch), and electrical stimuli was tested but was primarily focused on electrical stimulation. RESULTS: Rat Study: Effects of HFAC were successfully tested on 11 WDR neurons. Suppression or complete blockade of evoked activity was observed in all 11 of these neurons. Complete data sets for neurons systematically tested with 15 baseline and post-HFAC stimulus sweeps were obtained in five neurons, the nociceptive activity of which was suppressed by an average of 69 ± 9.7% (p < 0.0001). Goat Study: HFAC was successfully tested on 15 WDR neurons. Conclusive suppression or complete nociceptive blockade was observed for 12/15 and complete data sets with at least 20 baseline and post-HFAC stimulus sweeps were obtained from eight DHNs. For these neurons the mean activity suppression was 70 ± 10% (p < 0.005). CONCLUSIONS: Delivery of HFAC to the region of epidural nerve root or nerve root entry inhibited afferent nociceptive input and therefore may have potential to serve as an alternative to traditional spinal cord stimulation without sensory paresthesia as neuronal activation cannot occur at frequencies in this range.

    View details for DOI 10.1111/ner.12015

    View details for Web of Science ID 000325925100007

    View details for PubMedID 23252766

  • High-dose remifentanil prevents development of thermal hyperalgesia in a neuropathic pain model BRITISH JOURNAL OF ANAESTHESIA Manering, N. A., Reuter, T., Ihmsen, H., Yeomans, D. C., Tzabazis, A. 2013; 110 (2): 287-292


    Intraoperative nerve lesions can lead to chronic postoperative pain. There are conflicting data as to whether or not anaesthetics administered intraoperatively are beneficial. We investigated if remifentanil administered at the time of nerve injury was able to attenuate neuropathic hypersensitivity.Rats were anaesthetized with isoflurane, endotracheally intubated, and a tail vein catheter was inserted. Rats received an i.v. infusion of either saline or low- or high-dose remifentanil (2 or 20 ?g kg(-1) min(-1), respectively) for 20 min. During this time, rats received a spinal nerve L5 transection to induce neuropathic pain or a sham procedure. Behavioural tests to assess mechanical and cold allodynia and heat hyperalgesia were performed on postoperative days 1, 3, 7, 14, 21, and 28.Sham-operated animals exhibited no hypersensitivity regardless of the intraoperative remifentanil dose. In rats which received spinal nerve L5 transection, mechanical and cold allodynia developed with no significant differences between treatment groups. However, thermal hyperalgesia was reduced in rats given high-dose remifentanil: mean (standard deviation) area under the curve 426 (53) compared with 363 (34) and 342 (24) in saline or low-dose remifentanil treated rats, respectively (P<0.05).High-dose remifentanil administered at the time of transection of the spinal nerve at L5 prevents subsequent thermal hyperalgesia.

    View details for DOI 10.1093/bja/aes360

    View details for Web of Science ID 000313826500018

    View details for PubMedID 23045364

  • Cytokine Expression in the Epidural Space A Model of Noncompressive Disc Herniation-Induced Inflammation SPINE Cuellar, J. M., Borges, P. M., Cuellar, V. G., Yoo, A., Scuderi, G. J., Yeomans, D. C. 2013; 38 (1): 17-23


    Animal study.Development of an animal model for the study of biochemical changes that occur in the epidural space after intervertebral disc herniation.Although strong evidence for an inflammatory component exists, the biochemical processes underlying pain after disc herniation remain unknown.Epidural lavage was performed in 48 rats after L5 dorsal root ganglion exposure at baseline and 3, 6, or 24 hours after placement of autologous nucleus pulposus (NP) (N = 15), saline (N = 15), or NP + an interferon-? antibody (anti-IFN-?; N = 18) directly onto the dorsal root ganglion. Multiplex assays quantifying interleukin (IL)-1?, IL-1?, IL-2, IL-4, IL-6, IL-10, tumor necrosis factor ? (TNF-?), IFN-?, and granulocyte-macrophage colony-stimulating factor (GM-CSF) were performed. NP (N = 7) was also analyzed for these cytokines by placing NP into saline and measuring the relative concentration.Cytokines measured low at baseline (0-100 pg/mL) in all groups. Compared with saline, NP application caused IL-6 elevation, peaking at T = 3 hours, that was prevented by anti-IFN-?. NP induced elevation of TNF-?, peaking at T = 24 hours and was prevented by anti-IFN-?. IFN-? was elevated after NP at T = 3 hours and T = 24 hours. IL-1? was similar after saline versus NP. The concentrations of IL-1? and IL-10 were elevated at T = 3 hours, 6 hours, and 24 hours in all groups without between-groups difference. The level of IL-4 peaked at T = 3 hours in the NP group and was different than saline and NP + anti-IFN-? groups, but the time effect was insignificant. There was no change for GM-CSF. The concentration of cytokines measured in normal NP was less than 2 pg/mL for all cytokines except TNF-?.In this model of acute noncompressive disc herniation, NP caused the elevation of epidural IL-6, TNF-?, and IFN-?--all attenuated by IFN-? blockade. IL-1? and IL-10 were both significantly elevated by saline alone and their response was not prevented by IFN-? blockade. This model may prove useful for the study of the biochemical processes by which NP induces inflammation-induced nerve root irritation and radiculopathic pain.

    View details for DOI 10.1097/BRS.0b013e3182604baa

    View details for Web of Science ID 000312946800014

    View details for PubMedID 22648034

  • Shaped magnetic field pulses by multi-coil repetitive transcranial magnetic stimulation (rTMS) differentially modulate anterior cingulate cortex responses and pain in volunteers and fibromyalgia patients. Molecular pain Tzabazis, A., Aparici, C. M., Rowbotham, M. C., Schneider, M. B., Etkin, A., Yeomans, D. C. 2013; 9 (1): 33


    Repetitive transcranial magnetic stimulation (rTMS) has shown promise in the alleviation of acute and chronic pain by altering the activity of cortical areas involved in pain sensation. However, current single-coil rTMS technology only allows for effects in surface cortical structures. The ability to affect activity in certain deep brain structures may however, allow for a better efficacy, safety, and tolerability. This study used PET imaging to determine whether a novel multi-coil rTMS would allow for preferential targeting of the dorsal anterior cingulate cortex (dACC), an area always activated with pain, and to provide preliminary evidence as to whether this targeted approach would allow for efficacious, safe, and tolerable analgesia both in a volunteer/acute pain model as well as in fibromyalgia chronic pain patients.Part 1: Different coil configurations were tested in a placebo-controlled crossover design in volunteers (N = 16). Tonic pain was induced using a capsaicin/thermal pain model and functional brain imaging was performed by means of H215O positron emission tomography -- computed tomography (PET/CT) scans. Differences in NRS pain ratings between TMS and sham treatment (NRSTMS-NRSplacebo) which were recorded each minute during the 10 minute PET scans. Part 2: 16 fibromyalgia patients were subjected to 20 multi-coil rTMS treatments over 4 weeks and effects on standard pain scales (Brief Pain Inventory, item 5, i.e. average pain NRS over the last 24 hours) were recorded.A single 30 minute session using one of 3 tested rTMS coil configurations operated at 1 Hz consistently produced robust reduction (mean 70% on NRS scale) in evoked pain in volunteers. In fibromyalgia patients, the 20 rTMS sessions also produced a significant pain inhibition (43% reduction in NRS pain over last 24 hours), but only when operated at 10 Hz. This degree of pain control was maintained for at least 4 weeks after the final session.Multi-coil rTMS may be a safe and effective treatment option for acute as well as for chronic pain, such as that accompanying fibromyalgia. Further studies are necessary to optimize configurations and settings as well as to elucidate the mechanisms that lead to the long-lasting pain control produced by these treatments.

    View details for DOI 10.1186/1744-8069-9-33

    View details for PubMedID 23819466

  • Preprotachykinin-A Gene Disruption Attenuates Nociceptive Sensitivity After Opioid Administration and Incision by Peripheral and Spinal Mechanisms in Mice JOURNAL OF PAIN Sahbaie, P., Shi, X., Li, X., Liang, D., Guo, T., Qiao, Y., Yeomans, D. C., Kingery, W. S., Clark, J. D. 2012; 13 (10): 997-1007


    The preprotachykinin A gene (ppt-A) codes for Substance P (SP), supports nociceptive sensitization, and modulates inflammatory responses after incision. Repeated opioid use produces paradoxical pain sensitization-termed opioid-induced hyperalgesia (OIH) -which can exacerbate pain after incision. Here the contribution of SP to peri-incisional nociceptive sensitization and nociceptive mediator production after opioid treatment was examined utilizing ppt-A knockout (-/-) mice and the neurokinin (NK1) receptor antagonist LY303870. Less mechanical allodynia was observed in ppt-A(-/-) mice compared to wild types (wt) after morphine treatment both before and after incision. Moreover, LY303870 administered with morphine reduced incisional hyperalgesia in wt mice. Incision after saline or escalating morphine treatment upregulated skin IL-1?, IL-6, G-CSF and MIP-1? levels in ppt-A(-/-) and wt mice similarly. However, chronic morphine treatment greatly exacerbated increases in skin nerve growth factor levels after incision, an effect entirely dependent upon intact SP signaling. Additionally, SP dependent upregulation of prodynorphin, NMDA1 and NK1 receptor expression in spinal cord was seen after morphine treatment and incision. A similar pattern was seen for 5-HT3 receptor expression in tissue from dorsal root ganglia. Therefore, SP may work at both central and peripheral sites to enhance nociceptive sensitization after morphine treatment and incision.These studies show that SP signaling modulates enhanced nerve growth factor production and changes in neuronal gene expression seen after incision in mice previously exposed to morphine.

    View details for DOI 10.1016/j.jpain.2012.07.009

    View details for Web of Science ID 000310042600011

    View details for PubMedID 23031399

    View details for PubMedCentralID PMC3491068

  • Collecting And Measuring Wound Exudate Biochemical Mediators In Surgical Wounds JOVE-JOURNAL OF VISUALIZED EXPERIMENTS Carvalho, B., Clark, D. J., Yeomans, D., Angst, M. S. 2012


    We describe a methodology by which we are able to collect and measure biochemical inflammatory and nociceptive mediators at the surgical wound site. Collecting site-specific biochemical markers is important to understand the relationship between levels in serum and surgical wound, determine any associations between mediator release, pain, analgesic use and other outcomes of interest, and evaluate the effect of systemic and peripheral drug administration on surgical wound biochemistry. This methodology has been applied to healthy women undergoing elective cesarean delivery with spinal anesthesia. We have measured wound exudate and serum mediators at the same time intervals as patient's pain scores and analgesics consumption for up to 48 hours post-cesarean delivery. Using this methodology we have been able to detect various biochemical mediators including nerve growth factor (NGF), prostaglandin E2 (PG-E2) substance P, IL-1?, IL-2, IL-4, IL-6, IL-7, IL-8, IL-10, IL-12, IL-13, IL-17, TNF?, INF?, G-CSF, GM-CSF, MCP-1 and MIP-1?. Studies applying this human surgical wound bioassay have found no correlations between wound and serum cytokine concentrations or their time-release profile (J Pain. 2008; 9(7):650-7).(1) We also documented the utility of the technique to identify drug-mediated changes in wound cytokine content.

    View details for DOI 10.3791/50133

    View details for Web of Science ID 000209225700056

  • Analgesic Effects of Sustained Release Buprenorphine in an Incisional Model of Hyperalgesia in Rats (Rattus norvegicus) Chum, H., McKeon, G., Yeomans, D. C., Jampachaisri, K., Pacharinsak, C., Felt, S. AMER ASSOC LABORATORY ANIMAL SCIENCE. 2012: 692?92
  • Oral manganese as an MRI contrast agent for the detection of nociceptive activity NMR IN BIOMEDICINE Jacobs, K. E., Behera, D., Rosenberg, J., Gold, G., Moseley, M., Yeomans, D., Biswal, S. 2012; 25 (4): 563-569


    The ability of divalent manganese to enter neurons via calcium channels makes manganese an excellent MRI contrast agent for the imaging of nociception, the afferent neuronal encoding of pain perception. There is growing evidence that nociceptive neurons possess increased expression and activity of calcium channels, which would allow for the selective accumulation of manganese at these sites. In this study, we show that oral manganese chloride leads to increased enhancement of peripheral nerves involved in nociception on T(1)-weighted MRI. Oral rather than intravenous administration was chosen for its potentially better safety profile, making it a better candidate for clinical translation with important applications, such as pain diagnosis, therapy and research. The spared nerve injury (SNI) model of neuropathic pain was used for the purposes of this study. SNI rats were given, sequentially, increasing amounts of manganese chloride (lowest, 2.29 mg/100 g weight; highest, 20.6 mg/100 g weight) with alanine and vitamin D(3) by oral gavage. Compared with controls, SNI rats demonstrated increased signal-to-background ratios on T(1)-weighted fast spin echo MRI, which was confirmed by and correlated strongly with spectrometry measurements of nerve manganese concentration. We also found the difference between SNI and control rats to be greater at 48 h than at 24 h after dosing, indicating increased manganese retention in addition to increased manganese uptake in nociceptive nerves. This study demonstrates that oral manganese is a viable method for the imaging of nerves associated with increased nociceptive activity.

    View details for DOI 10.1002/nbm.1773

    View details for Web of Science ID 000302015500011

    View details for PubMedID 22447731

  • A rodent model of trigeminal neuralgia. Methods in molecular biology (Clifton, N.J.) Yeomans, D. C., Klukinov, M. 2012; 851: 121-131


    Trigeminal Neuralgia (Tic Douloureux) is a neuropathic pain syndrome caused by compression of the trigeminal nerve root and is characterized by severe paroxysms of pain in the face commonly triggered by light mechanical stimulation to the peri-oral area. Trigeminal neuralgia is very difficult to treat in part due to the lack of an suitable animal model for testing novel therapeutic approaches. This chapter describes a model of trigeminal neuralgia in which crystals of a superabsorbent polymer are placed next to the trigeminal nerve root of rats, producing ongoing mechanical compression of the nerve root. The chapter then describes means of behaviorally assessing the robust mechanical hypersensitivity consequent to the compression that can be used to determine the efficacy of potential therapies for this devastating condition.

    View details for DOI 10.1007/978-1-61779-561-9_8

    View details for PubMedID 22351086

  • Opioid Modulation of Nociceptive Afferents in vivo Encyclopedic Reference of Pain Tzabazis, A. Z., Yeomans, D. C. 2012; 2
  • Collecting and measuring wound exudate biochemical mediators in surgical wounds. Journal of visualized experiments : JoVE Carvalho, B., Clark, D. J., Yeomans, D., Angst, M. S. 2012


    We describe a methodology by which we are able to collect and measure biochemical inflammatory and nociceptive mediators at the surgical wound site. Collecting site-specific biochemical markers is important to understand the relationship between levels in serum and surgical wound, determine any associations between mediator release, pain, analgesic use and other outcomes of interest, and evaluate the effect of systemic and peripheral drug administration on surgical wound biochemistry. This methodology has been applied to healthy women undergoing elective cesarean delivery with spinal anesthesia. We have measured wound exudate and serum mediators at the same time intervals as patient's pain scores and analgesics consumption for up to 48 hours post-cesarean delivery. Using this methodology we have been able to detect various biochemical mediators including nerve growth factor (NGF), prostaglandin E2 (PG-E2) substance P, IL-1?, IL-2, IL-4, IL-6, IL-7, IL-8, IL-10, IL-12, IL-13, IL-17, TNF?, INF?, G-CSF, GM-CSF, MCP-1 and MIP-1?. Studies applying this human surgical wound bioassay have found no correlations between wound and serum cytokine concentrations or their time-release profile (J Pain. 2008; 9(7):650-7).(1) We also documented the utility of the technique to identify drug-mediated changes in wound cytokine content.

    View details for DOI 10.3791/50133

    View details for PubMedID 23117346

  • A rodent model of Trigeminal Neuralgia Pain Research: Methods and Protocols Yeomans, D. C., Klukinov, M., Levinson, S. R. 2012; 2
  • The Orofacial Formalin Test in Mice Revisited-Effects of Formalin Concentration, Age, Morphine and Analysis Method JOURNAL OF PAIN Bornhof, M., Ihmsen, H., Schwilden, H., Yeomans, D. C., Tzabazis, A. 2011; 12 (6): 633-639


    The orofacial formalin test is established in rats and was recently transferred to mice. The aim of this study was to determine the ideal formalin concentration for testing analgesic drugs, to examine alternatives for the assessment of nociceptive and non-nociceptive behavior as well as the effects of morphine and age on formalin-induced nociception. Formalin (.5, 1, 2.5, 5, 7.5, 10, and 15%) was injected into the vibrissa of mice. The cumulative nociceptive behavior was measured as well as nociceptive and non-nociceptive behavior based on a score that was recorded over a 5-second observation period once per minute. We also examined the effects of morphine on the nociceptive response induced by 2.5% formalin. Age-dependent differences were tested in the third part of the experiment. NONMEM was used to model the pharmacodynamic effects of formalin and morphine. Injection of formalin lead to a concentration-dependent increase in cumulative nociceptive behavior ratings as well as the specific nociceptive behavior 3 of scratching injection site with hindpaw (score 3). The formalin concentrations that lead to 50% of the maximum effect were 2.6 and 3.3%, respectively, for the continuous rating method and the scoring method. Morphine dose dependently suppressed the nociceptive behavior and the number of score 3 ratings of the nociceptive behavior. Age differences in behavior could not be detected by either analytic method.To improve the existing behavioral nociceptive assay for pain processed by the trigeminal system, we determined an ideal formalin concentration for the orofacial formalin test in mice, evaluated alternative timesaving analysis approaches, and investigated effects of morphine and age on formalin-induced nociception.

    View details for DOI 10.1016/j.jpain.2010.11.009

    View details for Web of Science ID 000291959100003

    View details for PubMedID 21481645

  • Selective nociceptor activation in volunteers by infrared diode laser MOLECULAR PAIN Tzabazis, A. Z., Klukinov, M., Crottaz-Herbette, S., Nemenov, M. I., Angst, M. S., Yeomans, D. C. 2011; 7


    Two main classes of peripheral sensory neurons contribute to thermal pain sensitivity: the unmyelinated C fibers and thinly myelinated A? fibers. These two fiber types may differentially underlie different clinical pain states and distinctions in the efficacy of analgesic treatments. Methods of differentially testing C and A? thermal pain are widely used in animal experimentation, but these methods are not optimal for human volunteer and patient use. Thus, this project aimed to provide psychophysical and electrophysiological evidence that whether different protocols of infrared diode laser stimulation, which allows for direct activation of nociceptive terminals deep in the skin, could differentially activate A? or C fiber thermonociceptors in volunteers.Short (60 ms), high intensity laser pulses (SP) evoked monomodal "pricking" pain which was not enhanced by topical capsaicin, whereas longer, lower power pulses (LP) evoked monomodal "burning" pain which was enhanced by topical capsaicin. SP also produced cortical evoked EEG potentials consistent with A? mediation, the amplitude of which was directly correlated with pain intensity but was not affected by topical capsaicin. LP also produced a distinct evoked potential pattern the amplitude of which was also correlated with pain intensity, which was enhanced by topical capsaicin, and the latency of which could be used to estimate the conduction velocity of the mediating nociceptive fibers.Psychophysical and electrophysiological data were consistent with the ability of short high intensity infrared laser pulses to selectively produce A? mediated pain and of longer pulses to selectively produce C fiber mediated thermal pain. Thus, the use of these or similar protocols may be useful in developing and testing novel therapeutics based on the differential molecular mechanisms underlying activation of the two fiber types (e.g., TRPV1, TRPV2, etc). In addition, these protocol may be useful in determining the fiber mediation of different clinical pain types which may, in turn be useful in treatment choice.

    View details for DOI 10.1186/1744-8069-7-18

    View details for Web of Science ID 000289115700001

    View details for PubMedID 21426575

    View details for PubMedCentralID PMC3070669

  • Analgesic Effects of Tramadol, Tramadol-Gabapentin, and Buprenorphine in an Incisional Model of Pain in Rats (Rattus norvegicus) JOURNAL OF THE AMERICAN ASSOCIATION FOR LABORATORY ANIMAL SCIENCE McKeon, G. P., Pacharinsak, C., Long, C. T., Howard, A. M., Jampachaisri, K., Yeomans, D. C., Felt, S. A. 2011; 50 (2): 192-197


    Postoperative pain management in laboratory animals relies heavily on a limited number of drug classes, such as opioids and nonsteroidal antiinflammatory drugs. Here we evaluated the effects of saline, tramadol, tramadol with gabapentin, and buprenorphine (n = 6 per group) in a rat model of incisional pain by examining thermal hyperalgesia and weight-bearing daily for 6 d after surgery. All drugs were administered preemptively and continued for 2 consecutive days after surgery. Rats treated with saline or with tramadol only showed thermal hyperalgesia on days 1 through 4 and 1 through 3 after surgery, respectively. In contrast, buprenorphine-treated rats showed no thermal hyperalgesia on days 1 and 2 after surgery, and rats given tramadol with gabapentin showed reduced thermal hyperalgesia on days 2 and 4. For tests of weight-bearing, rats treated with saline or with tramadol only showed significantly less ipsilateral weight-bearing on day 1 after surgery, whereas rats given either buprenorphine or tramadol with gabapentin showed no significant change in ipsilateral weight-bearing after surgery. These data suggest that tramadol alone provides insufficient analgesia in this model of incisional pain; buprenorphine and, to a lesser extent, tramadol with gabapentin provide relief of thermal hyperalgesia and normalize weight-bearing.

    View details for Web of Science ID 000288643600006

    View details for PubMedID 21439212

  • Continuous Subcutaneous Instillation of Bupivacaine Compared to Saline Reduces Interleukin 10 and Increases Substance P in Surgical Wounds After Cesarean Delivery ANESTHESIA AND ANALGESIA Carvalho, B., Clark, D. J., Yeomans, D. C., Angst, M. S. 2010; 111 (6): 1452-1459


    Recent evidence suggests that locally delivered local anesthetics may exert tissue-damaging effects such as chondrolysis after intraarticular injection. Alteration of the inflammatory response is a potential mechanism for local anesthetic-induced tissue toxicity. In this study, we tested the effects of continuous local anesthetic infiltration on the release of inflammatory and nociceptive mediators in skin wounds after cesarean delivery.Thirty-eight healthy women undergoing cesarean delivery with spinal anesthesia were enrolled in this study, and were randomized to receive subcutaneous surgical wound infiltration with bupivacaine 5 mg/mL or saline at 2 mL/h for 24 hours after cesarean delivery. Wound exudate was sampled at 1, 3, 5, 7, and 24 hours after cesarean delivery using a subcutaneous wound drain technique. Cytokines, chemokines, substance P, prostaglandin E(2), and nerve growth factor were assayed using multiplex Bio-Plex® (Bio-Rad, Hercules, CA) and enzyme-linked immunosorbent assays.Bupivacaine wound infusion resulted in a significant decrease of interleukin 10 and increase of substance P in wounds compared with saline infusion (area under the 24-hour concentration-time curve; P < 0.001). No statistically significant differences were detected for other cytokines, nerve growth factor, and prostaglandin E(2).This study demonstrates that the continuous administration of clinically used doses of bupivacaine into wounds affects the local composition of wound mediators. Observed changes in interleukin 10 are compatible with a disruption of antiinflammatory mechanisms. Whether such modulation combined with the release of the proinflammatory mediator substance P results in an overall proinflammatory wound response will require future studies of wound healing.

    View details for DOI 10.1213/ANE.0b013e3181f579de

    View details for PubMedID 20861424

  • The Role of Interleukin-1 in Wound Biology. Part II: In Vivo and Human Translational Studies ANESTHESIA AND ANALGESIA Hu, Y., Liang, D., Li, X., Liu, H., Zhang, X., Zheng, M., Dill, D., Shi, X., Qiao, Y., Yeomans, D., Carvalho, B., Angst, M. S., Clark, J. D., Peltz, G. 2010; 111 (6): 1534-1542


    In the accompanying paper, we demonstrate that genetic variation within Nalp1 could contribute to interstrain differences in wound chemokine production through altering the amount of interleukin (IL)-1 produced. We further investigate the role of IL-1 in incisional wound biology and its effect on wound chemokine production in vivo and whether this mechanism could be active in human subjects.A well-characterized murine model of incisional wounding was used to assess the in vivo role of IL-1 in wound biology. The amount of 7 different cytokines/chemokines produced within an experimentally induced skin incision on a mouse paw and the nociceptive response was analyzed in mice treated with an IL-1 inhibitor. We also investigated whether human IL-1? or IL-1? stimulated the production of chemokines by primary human keratinocytes in vitro, and whether there was a correlation between IL-1? and chemokine levels in 2 experimental human wound paradigms.Administration of an IL-1 receptor antagonist to mice decreased the nociceptive response to an incisional wound, and reduced the production of multiple inflammatory mediators, including keratinocyte-derived chemokine (KC) and macrophage inhibitory protein (MIP)-1?, within the wounds. IL-1? and IL-1? stimulated IL-8 and GRO-? (human homologues of murine keratinocyte-derived chemokine) production by primary human keratinocytes in vitro. IL-1? levels were highly correlated with IL-8 in human surgical wounds, and at cutaneous sites of human ultraviolet B-induced sunburn injury.IL-1 plays a major role in regulating inflammatory mediator production in wounds through a novel mechanism; by stimulating the production of multiple cytokines and chemokines, it impacts clinically important aspects of wound biology. These data suggest that administration of an IL-1 receptor antagonist within the perioperative period could decrease postsurgical wound pain.

    View details for DOI 10.1213/ANE.0b013e3181f691eb

    View details for PubMedID 20889944

  • The Role of Interleukin-1 in Wound Biology. Part I: Murine In Silico and In Vitro Experimental Analysis ANESTHESIA AND ANALGESIA Hu, Y., Liang, D., Li, X., Liu, H., Zhang, X., Zheng, M., Dill, D., Shi, X., Qiao, Y., Yeomans, D., Carvalho, B., Angst, M. S., Clark, J. D., Peltz, G. 2010; 111 (6): 1525-1533


    Wound healing is a multistep, complex process that involves the coordinated action of multiple cell types. Conflicting results have been obtained when conventional methods have been used to study wound biology. Therefore, we analyzed the wound response in a mouse genetic model.We analyzed inflammatory mediators produced within incisional wounds induced in 16 inbred mouse strains. Computational haplotype-based genetic analysis of inter-strain differences in the level of production of 2 chemokines in wounds was performed. An in vitro experimental analysis system was developed to investigate whether interleukin (IL)-1 could affect chemokine production by 2 different types of cells that are present within wounds.The level of 2 chemokines, keratinocyte-derived chemokine (KC) and macrophage inflammatory protein 1?, exhibited very large (75- and 463-fold, respectively) interstrain differences within wound tissue across this inbred strain panel. Genetic variation within Nalp1, an inflammasome component that regulates IL-1 production, correlated with the interstrain differences in KC and macrophage inhibitory protein 1? production. Consistent with the genetic correlation, IL-1? was shown to stimulate KC production by murine keratinocyte and fibroblast cell lines in vitro.Genetic variation within Nalp1 could contribute to interstrain differences in wound chemokine production by altering the amount of IL-1 produced.

    View details for DOI 10.1213/ANE.0b013e3181f5ef5a

    View details for PubMedID 20889942

  • Caspase-1 Modulates Incisional Sensitization and Inflammation ANESTHESIOLOGY Liang, D., Li, X., Li, W., Fiorino, D., Qiao, Y., Sahbaie, P., Yeomans, D. C., Clark, J. D. 2010; 113 (4): 945-956


    Surgical injury induces production and release of inflammatory mediators in the vicinity of the wound. They in turn trigger nociceptive signaling to produce hyperalgesia and pain. Interleukin-1? plays a crucial role in this process. The mechanism regulating production of this cytokine after incision is, however, unknown. Caspase-1 is a key enzyme that cleaves prointerleukin-1? to its active form. We hypothesized that caspase-1 is a crucial regulator of incisional interleukin-1? levels, nociceptive sensitization, and inflammation.These studies employed a mouse hind paw incisional model. Caspase-1 was blocked using the selective inhibitors Ac-YVAD-CMK and VRTXSD727. Nociceptive sensitization, edema, and hind paw warmth were followed in intact animals whereas caspase-1 activity, cytokine, and prostaglandin E2 levels were assessed in homogenized skin. Confocal microscopy was used to detect the expression of caspase-1 near the wounds.Analysis of enzyme activity demonstrated that caspase-1 activity was significantly increased in periincisional skin. Pretreatment with Ac-YVAD-CMK significantly reduced mechanical allodynia and thermal hyperalgesia. Repeated administration of this inhibitor produced robust analgesia, especially to mechanical stimulation. Administration of VRTXSD727 provided qualitatively similar results. Caspase-1 inhibition also reduced edema and the normally observed increase in paw warmth around the wound site. Correspondingly, caspase-1 inhibition significantly reduced interleukin-1? as well as macrophage-inflammatory protein 1?, granulocyte colony-stimulating factor, and prostaglandin E2 levels near the wound. The expression of caspase-1 was primarily observed in keratinocytes in the epidermal layer and in neutrophils deeper in the wounds.The current study demonstrates that the inhibition of caspase-1 reduces postsurgical sensitization and inflammation, likely through a caspase-1/interleukin-1?-dependent mechanism.

    View details for DOI 10.1097/ALN.0b013e3181ee2f17

    View details for Web of Science ID 000282139700022

    View details for PubMedID 20823759

  • Cytokine Profiling in Acute Anterior Cruciate Ligament Injury ARTHROSCOPY-THE JOURNAL OF ARTHROSCOPIC AND RELATED SURGERY Cuellar, V. G., Cuellar, J. M., Golish, S. R., Yeomans, D. C., Scuderi, G. J. 2010; 26 (10): 1296-1301


    To evaluate the presence and relative concentrations of cytokines, known to be involved in the inflammatory cascade, in acute anterior cruciate ligament (ACL) injury.We evaluated an extensive cytokine profile in synovial fluid from 12 patients with acute ACL injury undergoing arthroscopy compared with 15 control subjects using a BioPlex assay (Bio-Rad Laboratories, Hercules, CA) to measure the concentration of 17 inflammatory cytokines.In patients with acute ACL injury compared with asymptomatic control subjects, the following cytokines were identified at significantly increased concentrations (P < .001, Mann-Whitney U test) compared with control samples: interleukin 6 (105 ± 72 v 0 ± 0 pg/ml), interferon ? (1,544 ± 608 v 9 ± 7.5 pg/ml), macrophage inflammatory protein 1? (16 ± 3.8 v 0.3 ± 0.2 pg/ml), and monocyte chemotactic protein 1 (35 ± 13 v 0.5 ± 0.4 pg/ml). There was no case of a cytokine exhibiting increased levels in asymptomatic compared with symptomatic knee samples.This investigation identified 4 specific cytokines (interleukin 6, interferon ?, monocyte chemotactic protein 1, and macrophage inflammatory protein 1?) out of a panel of 17 inflammatory molecules for which the levels were consistently elevated in the context of ACL injury compared with non-painful, non-acutely injured knees in a volunteer population.Level IV, prognostic case series.

    View details for DOI 10.1016/j.arthro.2010.02.011

    View details for Web of Science ID 000282366300009

    View details for PubMedID 20887928

  • Thermal nociceptive properties of trigeminal afferent neurons in rats MOLECULAR PAIN Cuellar, J. M., Manering, N. A., Klukinov, M., Nemenov, M. I., Yeomans, D. C. 2010; 6


    Although nociceptive afferents innervating the body have been heavily studied form many years, much less attention has been paid to trigeminal afferent biology. In particular, very little is known concerning trigeminal nociceptor responses to heat, and almost nothing in the rat. This study uses a highly controlled and reproducible diode laser stimulator to investigate the activation of trigeminal afferents to noxious skin heating.The results of this experiment demonstrate that trigeminal thermonociceptors are distinct from themonociceptors innervating the limbs. Trigeminal nociceptors have considerably slower action potential conduction velocities and lower temperature thresholds than somatic afferent neurons. On the other hand, nociceptors innervating both tissue areas separate into those that respond to short pulse, high rate skin heating and those that respond to long pulse, low rate skin heating.This paper provides the first description in the literature of the in vivo properties of thermonociceptors in rats. These finding of two separate populations aligns with the separation between C and A-delta thermonociceptors innervating the paw, but have significant differences in terms of temperature threshold and average conduction velocities. An understanding of the temperature response properties of afferent neurons innervating the paw skin have been critical in many mechanistic discoveries, some leading to new pain therapies. A clear understanding of trigeminal nociceptors may be similarly useful in the investigation of trigeminal pain mechanisms and potential therapies.

    View details for DOI 10.1186/1744-8069-6-39

    View details for PubMedID 20609212

  • Trigeminal antihyperalgesic effect of intranasal carbon dioxide LIFE SCIENCES Tzabazis, A. Z., Niv, S. H., Manering, N. A., Klyukinov, M., Cuellar, J. M., Bhatnagar, A., Yeomans, D. C. 2010; 87 (1-2): 36-41


    Clinical studies demonstrate attenuation of trigeminal-related pain states such as migraine by intranasal CO(2) application. This study investigated the underlying mechanisms of this observation and its potential use to reverse trigeminal pain and hypersensitivity.We used a behavioral rat model of capsaicin-induced trigeminal thermal hyperalgesia, intranasal CO2 application and several pharmacologic agents such as carbonic anhydrase, acid-sensing ion channels (ASICs), and TRPV1 blocker as well as acidic buffer solutions to investigate and mimic the underlying mechanism.Intranasal CO(2) application produced a robust dose-dependent antihyperalgesic effect in rats that lasted at least one hour. Blockade of nasal carbonic anhydrase with a dorzolamide solution (Trusopt ophthalmic solution) showed only a non-significant decrease of the antihyperalgesic effect of intranasal CO(2) application. Pharmacologic blockade of ASICs or TRPV(1) receptor significantly attenuated the antihyperalgesic effect of CO(2) application. The effect of intranasal CO(2) application could be mimicked by application of pH 4, but not pH 5, buffer solution to the nasal mucosa. As with CO(2) application, the antihyperalgesic effect of intranasal pH 4 buffer was blocked by nasal application of antagonists to ASICs and TRPV(1) receptors.Our results indicate that intranasal CO(2) application results in a subsequent attenuation of trigeminal nociception, mediated by protonic activation of TRPV(1) and ASIC channels. A potential central mechanism for this attenuation is discussed. The antihyperalgesic effects of intranasal CO(2) application might be useful for the treatment of trigeminal pain states.

    View details for DOI 10.1016/j.lfs.2010.05.013

    View details for Web of Science ID 000279499000005

    View details for PubMedID 20561904

    View details for PubMedCentralID PMC2900516

  • Identification of a complex between fibronectin and aggrecan G3 domain in synovial fluid of patients with painful meniscal pathology CLINICAL BIOCHEMISTRY Scuderi, G. J., Woolf, N., Dent, K., Golish, S. R., Cuellar, J. M., Cuellar, V. G., Yeomans, D. C., Carragee, E. J., Angst, M. S., Bowser, R., Hanna, L. S. 2010; 43 (10-11): 808-814


    We previously described a panel of four cytokines biomarkers in knee synovial fluid for acute knee pain associated with meniscal pathology. The cytokine biomarkers included interferon gamma (IFN-gamma), interleukin 6 (IL-6), monocyte chemotactic protein 1 (MCP-1), and macrophage inflammatory protein-1 beta (MIP-1beta). Validation studies using other immunologic techniques confirmed the presence of IL-6, MCP-1 and MIP-1beta, but not IFN-gamma. Therefore we sought the identity of the IFN-gamma signal in synovial fluid.Knee synovial fluid was collected from patients with an acute, painful meniscal injury, as well as asymptomatic volunteers. A combination of high-pressure chromatography, mass spectrometry and immunological techniques were used to enrich and identify the protein components representing the IFN-gamma signal.A protein complex of fibronectin and the aggrecan G3 domain was identified in the synovial fluid of patients with a meniscal tear and pain that was absent in asymptomatic controls. This protein complex correlated to the IFN-gamma signal. A novel enzyme-linked immunosorbent assay (ELISA) was developed to specifically identify the complex in synovial fluid.We have identified a protein complex of fibronectin and aggrecan G3 domain that is a candidate biomarker for pain associated with meniscal injury.

    View details for DOI 10.1016/j.clinbiochem.2010.04.069

    View details for PubMedID 20460120

  • Cytokine evaluation in individuals with low back pain using discographic lavage SPINE JOURNAL Cuellar, J. M., Golish, S. R., Reuter, M. W., Cuellar, V. G., Angst, M. S., Carragee, E. J., Yeomans, D. C., Scuderi, G. J. 2010; 10 (3): 212-218


    The pathophysiology underlying degenerative disc disease and its implication in painful syndromes remain unclear. However, spine magnetic resonance imaging (MRI) can demonstrate changes in disc water content and the annulus; provocative discography purportedly identifies degenerate discs causing serious low back pain; and biochemical assays have identified local inflammatory markers. No study to date has correlated pain on disc injection during discography evaluation with relevant MRI findings and biochemical markers.The purpose of this study was to correlate concordant pain on during discography to biochemical markers obtained by disc lavage and MRI findings.This is a Phase 1 Diagnostic Test Assessment Cohort Study (Sackett and Haynes).The patient sample included 21 symptomatic patients with suspected discogenic pain and three Phase 1 control subjects.The outcome measures included discography pain scores, MRI degenerative grades, and immunoreactivity to various inflammatory cytokine concentrations present in disc lavage samples.Twenty-one symptomatic patients with lumbar degenerative disc disease and three control subjects underwent discography, MRI, and biochemical analysis of disc lavage fluid. Lumbar MRI was scored for Pfirrmann grading of the lumbar discs, and annular disruption was identified by nuclear disc lavage. Disc lavage samples were analyzed for biochemical markers by high-sensitivity immunoassay.Eighty-three discs from 24 patients were studied: 67 discs from 21 patients with axial back pain (suspected discogenic pain group) and 16 discs from 3 scoliosis patients without back pain (Phase 1 control subjects). Among the biochemical markers surveyed, interferon gamma (IFN-gamma) immunoreactivity was most consistently identified in patients with axial back pain. Discs with annular disruption and concordant pain reproduction at a visual analog scale of 7 to 10/10 had greater IFN-gamma immunoreactivity than those without this finding (p=.003); however, at least some IFN-gamma immunoreactivity was found in all but one disc in the symptomatic group.Among the potential inflammatory markers tested in this Phase 1 study, IFN-gamma immunoreactivity was most commonly elevated in discogram "positive" discs but absent in asymptomatic controls. However, this marker was also frequently elevated in degenerative but "negative" discography discs. From these findings, Phase 2 and Phase 3 validity studies are reasonable to pursue. Phase 4 utility studies may be performed concurrently to assess this method's predictive value in outcome studies.

    View details for DOI 10.1016/j.spinee.2009.12.007

    View details for Web of Science ID 000208284600006

    View details for PubMedID 20207331

  • Diagnostic utility of cytokine biomarkers in the evaluation of acute knee pain. journal of bone and joint surgery. American volume Cuellar, J. M., Scuderi, G. J., Cuellar, V. G., Golish, S. R., Yeomans, D. C. 2009; 91 (10): 2313-2320


    The diagnosis of clinically important meniscal tears of the knee remains challenging, and it is unknown why only some injuries become painful. The role of inflammatory cytokines in generating pain following meniscal injury remains unclear. This study aimed to investigate the cytokine profile in patients with acute knee pain believed to be secondary to meniscal damage.This prospective cohort study included thirty-two patients without rheumatoid arthritis who had knee pain for less than six months, with either an acute or insidious onset, and elected to have arthroscopic treatment after nonoperative management had failed. Twenty-three of these patients elected to have the contralateral, nonoperatively treated knee lavaged at the time of arthroscopy. Fifteen asymptomatic control subjects also contributed samples of knee joint fluid, for a total of seventy samples from forty-seven subjects. Lavage of the operatively treated, contralateral, and control knees was performed with the patient under regional anesthesia prior to arthroscopy, if applicable, by the infusion of sterile saline solution into the knee followed by the immediate withdrawal into a syringe. The concentrations of seventeen inflammatory cytokines and chemokines were measured with use of a multiplexed immunoassay panel. Preoperative magnetic resonance imaging findings and cytokine assay results were compared with intraoperative findings.Multivariate analysis of variance detected significantly greater concentrations of interferon gamma (IFN-gamma); interleukins 2, 4, 6, 10, and 13 (IL-2, IL-4, IL-6, IL-10, and IL-13); monocyte chemotactic protein-1 (MCP-1); and macrophage inflammatory protein-1 beta (MIP-1beta) in fluid samples from painful knees than in samples from nonpainful knees. Correlation analysis demonstrated a significant positive correlation between patient-reported pain scores and concentrations of IL-6 (Spearman rho = 0.7), MCP-1 (rho = 0.8), MIP-1beta (rho = 0.6), and IFN-gamma (rho = 0.6). These four cytokines also demonstrated a positive correlation with each other (rho = 0.5 to 0.7). The presence of IFN-gamma, IL-6, MCP-1, or MIP-1beta performed as well as magnetic resonance imaging in the prediction of intraoperative findings.Intra-articular concentrations of four inflammatory cytokines IFN-gamma, IL-6, MCP-1, and MIP-1beta correlated to pain in patients with symptomatic meniscal tears in the knee but were markedly lower in asymptomatic normal knees and in asymptomatic knees with meniscal tears. These cytokines may be involved in the generation of pain following meniscal injury.

    View details for DOI 10.2106/JBJS.H.00835

    View details for PubMedID 19797564

  • Diagnostic Utility of Cytokine Biomarkers in the Evaluation of Acute Knee Pain JOURNAL OF BONE AND JOINT SURGERY-AMERICAN VOLUME Cuellar, J. M., Scuderi, G. J., Cuellar, V. G., Golish, S. R., Yeomans, D. C. 2009; 91A (10): 2313-2320
  • Role of substance P signaling in enhanced nociceptive sensitization and local cytokine production after incision PAIN Sahbaie, P., Shi, X., Guo, T., Qiao, Y., Yeomans, D. C., Kingery, W. S., Clark, J. D. 2009; 145 (3): 341-349


    Substance P (SP) signaling facilitates nociceptive sensitization in various inflammatory and chronic pain models and we postulated that SP signaling might also contribute to the development of post-incisional hyperalgesia. These studies used mice with a deletion of the pre-protachykinin A gene (ppt-A(-/-)) which codes for SP to determine the role of SP signaling in post-incisional pain and in the increased cytokine and nerve growth factor (NGF) expression observed in the incised skin. SP deficient ppt-A(-/-) mice displayed reduced mechanical allodynia and heat hyperalgesia compared to the wild-type (wt) mice at all post-incision time points, despite similar baseline values (p<0.001). Furthermore, the NK-1 receptor antagonist LY303870 attenuated mechanical allodynia produced by incision in the wt mice (p<0.001). Incision also up-regulated IL-6, TNF-alpha and KC levels but not IL-1beta after 2h in the wt mice skin. However, ppt-A(-/-) mice had more skin NGF levels 2h post-incision. Subcutaneous hind paw SP injection produced acute and transient elevations of IL-1beta, IL-6, and KC but modest elevations in TNF-alpha levels in the wt mice. Systemic LY303870 reversed the SP-induced elevations of these cytokines. Hind paw injection of IL-6 and NGF dose dependently produced less mechanical allodynia in the ppt-A(-/-) compared to wt mice. Additionally, SP produced mechanical allodynia in a dose-dependent fashion in wt mice. Therefore, SP supports nociceptive sensitization after hind paw incision and potentially participates directly in modulating the intensity of inflammatory response in peri-incisional tissue.

    View details for DOI 10.1016/j.pain.2009.06.037

    View details for PubMedID 19660865

  • Epidural Interferon Gamma-Immunoreactivity A Biomarker for Lumbar Nerve Root Irritation SPINE Scuderi, G. J., Cuellar, J. M., Cuellar, V. G., Yeomans, D. C., Carragee, E. J., Angst, M. S. 2009; 34 (21): 2311-2317


    Prospective observational cohort.Correlate epidural inflammatory cytokines with the clinical response to epidural steroid injection in patients with lumbar nerve root irritation.Some back pain syndromes are thought to be associated with activation of inflammatory pathways and others may be associated with primary mechanical derangements. Human studies providing detailed evidence for the primary inflammatory causation, which may be best treated with anti-inflammatory strategies, are lacking. There are currently no accurate diagnostic tests to predict the response to epidural steroid injection or surgical intervention in back pain and sciatica syndromes. METHODS.: Forty-seven consecutive patients with lumbar degenerative changes and low back and/or leg pain were prospectively enrolled. An epidural lavage was performed, followed by injection of marcaine/depo-medrol. Subjects scored their pain before and 3 months after the procedure. The immunoreactivity of an array of cytokines was measured in lavage samples and compared with clinical response to the therapeutic injection. Ten subjects underwent repeat epidural lavage sampling 3 months after the steroid injection.Interferon gamma (IFNgamma) was the most consistently detected cytokine. IFNgamma-immunoreactivity also highly correlated with reported reduction of pain 3-months after the epidural steroid injection. In subjects reporting significant pain relief (>50%) from the injection, mean [IFNgamma] was significantly greater compared with patients experiencing no significant relief. The IFNgamma-immunoreactivity in repeat lavage samples decreased to trace residual concentrations in patients who reported pain relief from the steroid injection.The presence of epidural IFNgamma-immunoreactivity corresponding to >10 pg/mL predicted significant pain relief after epidural steroid injection with >95% accuracy. These results suggest that IFNgamma may be part of a biochemical cascade triggering pain in sciatica; IFNgamma-immunoreactivity may aid as a biomarker for predicting the response to steroid therapy and/or surgical intervention, and may serve as a future therapeutic target.

    View details for DOI 10.1097/BRS.0b013e3181af06b6

    View details for Web of Science ID 000270382600011

    View details for PubMedID 19934811

  • Herpes virus-based recombinant herpes vectors: gene therapy for pain and molecular tool for pain science GENE THERAPY Yeomans, D. C., Wilson, S. P. 2009; 16 (4): 502-508


    This paper reviews work by Yeomans and Wilson in the area of herpes vector-mediated gene transfer to sensory neurons. Beginning in 1997, these researchers have published a number of papers describing and exploiting this technology in altering the phenotype of pain-sensing neurons (nociceptors). Their initial work, continuing to the present, inserted a transgene cassette encoding the human preproenkephalin gene into the thymidine kinase locus under control of a cytomegalovirus promoter. This vector induced enkephalin expression selectively in the nociceptors innervating the tissue onto which it was applied, producing a profound analgesic and antihyperalgesic in acute and chronic pain models in both rodents and non-human primates. An improved version of this vector is now in clinical trials. In addition to inducing the de novo expression of foreign transgenes, this group also investigated the utility of herpes vectors in altering the endogenous genome of nociceptors. Thus, they inserted antisense sequences for genes of interest in the physiology of these neurons and successfully and selectively knocked down expression of several proteins known or thought to be involved in various pain states, including calcitonin gene-related peptide and mu-opioid receptors. They also used similar techniques to investigate the involvement of acid-sensing ion channels and Nav1.7 sodium channel in different pain states. These experiments uniquely allowed for spatially and temporally selective investigations into the function of these proteins in pain, highly valuable information in target validation for therapy development.

    View details for DOI 10.1038/gt.2009.25

    View details for Web of Science ID 000265021400008

    View details for PubMedID 19225546

  • Cytokine profile in human skin in response to experimental inflammation, noxious stimulation, and administration of a COX-inhibitor: A microdialysis study PAIN Angst, M. S., Clark, J. D., Carvalho, B., Tingle, M., Schmelz, M., Yeomans, D. C. 2008; 139 (1): 15-27


    Animal studies have documented a critical role for cytokines in cell signaling events underlying inflammation and pain associated with tissue injury. While clinical reports indicate an important role of cytokines in inflammatory pain, methodological limitations have made systematic human studies difficult. This study examined the utility of a human in vivo bioassay combining microdialysis with multiplex immunoassay techniques for measuring cytokine arrays in tissue. The first experiment measured cytokines in interstitial fluid collected from non-inflamed and experimentally inflamed skin (UVB). The effects of noxious heat on cytokine release were also assessed. The second experiment examined whether anti-hyperalgesic effects of the COX-inhibitor ibuprofen were associated with decreased tissue levels of the pro-inflammatory cytokines IL-1 beta and IL-6. In the first experiment, inflammation significantly increased IL-1 beta, IL-6, IL-8, IL-10, G-CSF, and MIP-1 beta. Noxious heat but not experimental inflammation significantly increased IL-7 and IL-13. In the second experiment, an oral dose of 400 and 800 mg ibuprofen produced similar anti-hyperalgesic effects suggesting a ceiling effect. Tissue levels of IL-1 beta and IL-6 were not affected after the 400mg dose but decreased significantly (44+/-32% and 38+/-13%) after the 800 mg dose. These results support the utility of explored method for tracking cytokines in human tissue and suggest that anti-hyperalgesic and anti-inflammatory effects of ibuprofen are at least partially dissociated. The data further suggest that high clinical doses of ibuprofen exert anti-inflammatory effects by down-regulating tissue cytokine levels. Explored human bioassay is a promising tool for studying the pathology and pharmacology of inflammatory and chronic pain conditions.

    View details for DOI 10.1016/j.pain.2008.02.028

    View details for PubMedID 18396374

  • Effect of anti-NGF antibodies in a rat tibia fracture model of complex regional pain syndrome type I PAIN Sabsovich, I., Wei, T., Guo, T., Zhao, R., Shi, X., Li, X., Yeomans, D. C., Klyukinov, M., Kingery, W. S., Clark, J. D. 2008; 138 (1): 47-60


    Tibia fracture in rats evokes chronic hindpaw warmth, edema, allodynia, and regional osteopenia resembling the clinical characteristics of patients with complex regional pain syndrome type I (CRPS I). Nerve growth factor (NGF) has been shown to support nociceptive and other types of changes found in neuropathic pain models. We hypothesized that anti-NGF antibodies might reduce one or more of the CRPS I-like features of the rat fracture model. For our studies one distal tibia of each experimental rat was fractured and casted for 4 weeks. The rats were injected with anti-NGF or vehicle at days 17 and 24 post-fracture. Nociceptive testing as well as assessment of edema and hindpaw warmth were followed during this period. Molecular and biochemical techniques were used to follow cytokine, NGF and neuropeptide levels in hindpaw skin and sciatic nerves. Lumbar spinal cord Fos immunostaining was performed. Bone microarchitecture was measured using microcomputed tomography (microCT). We found that tibia fracture upregulated NGF expression in hindpaw skin and tibia bone along with sciatic nerve neuropeptide content. We also found nociceptive sensitization, enhanced spinal cord Fos expression, osteopenia and enhanced cytokine content of hindpaw skin on the side of the fracture. Anti-NGF treatment reduced neuropeptide levels in sciatic nerve and reduced nociceptive sensitization. There was less spinal cord Fos expression and bone loss in the anti-NGF treated animals. Conversely, anti-NGF did not decrease hindpaw edema, warmth or cytokine production. Collectively, anti-NGF reduced some but not all signs characteristic of CRPS illustrating the complexity of CRPS pathogenesis and NGF signaling.

    View details for DOI 10.1016/j.pain.2007.11.004

    View details for Web of Science ID 000258746100009

    View details for PubMedID 18083307

    View details for PubMedCentralID PMC2538487

  • Joint capsule treatment with enkephalin-encoding HSV-1 recombinant vector reduces inflammatory damage and behavioural sequelae in rat CFA monoarthritis EUROPEAN JOURNAL OF NEUROSCIENCE Lu, Y., McNearney, T. A., Wilson, S. P., Yeomans, D. C., Westlund, K. N. 2008; 27 (5): 1153-1165


    This study assessed enkephalin expression induced by intra-articular application of recombinant, enkephalin-encoding herpes virus (HSV-1) and the impact of expression on nociceptive behaviours and synovial lining inflammation in arthritic rats. Replication-conditional HSV-1 recombinant vectors with cDNA encoding preproenkephalin (HSV-ENK), or control transgene beta-galactosidase cDNA (HSV-beta-gal; control) were injected into knee joints with complete Freund's adjuvant (CFA). Joint temperatures, circumferences and nociceptive behaviours were monitored on days 0, 7, 14 and 21 post CFA and vector treatments. Lumbar (L4-6) dorsal root ganglia (DRG) and spinal cords were immunostained for met-enkephalin (met-ENK), beta-gal, HSV-1 proteins and Fos. Joint tissues were immunostained for met-ENK, HSV-1 proteins, and inflammatory mediators Regulated on Activation, Normal T-cell Expressed and Secreted (RANTES) and cyclo-oxygenase-2, or stained with haematoxylin and eosin for histopathology. Compared to exuberant synovial hypertrophy and inflammatory cell infiltration seen in arthritic rats treated with CFA only or CFA and HSV-beta-gal, the CFA- and HSV-ENK-treated arthritic rats had: (i) striking preservation of synovial membrane cytoarchitecture with minimal inflammatory cell infiltrates; (ii) significantly improved nociceptive behavioural responses to mechanical and thermal stimuli; (iii) normalized Fos staining in lumbar dorsal horn; and (iv) significantly increased met-ENK staining in ipsilateral synovial tissue, lumbar DRG and spinal cord. The HSV-1 and transgene product expression were confined to ipsilateral lumbar DRG (HSV-1, met-ENK, beta-gal). Only transgene product (met-ENK and beta-gal) was seen in lumbar spinal cord sections. Targeted delivery of enkephalin-encoding HSV-1 vector generated safe, sustained opioid-induced analgesia with protective anti-inflammatory blunting in rat inflammatory arthritis.

    View details for DOI 10.1111/j.1460-9568.2008.06076.x

    View details for Web of Science ID 000254273400010

    View details for PubMedID 18364035

  • Enkephalin-encoding herpes simplex virus-1 decreases inflammation and hotplate sensitivity in a chronic pancreatitis model MOLECULAR PAIN Yang, H., McNearney, T. A., Chu, R., Lu, Y., Ren, Y., Yeomans, D. C., Wilson, S. P., Westlund, K. N. 2008; 4


    A chronic pancreatitis model was developed in young male Lewis rats fed a high-fat and alcohol liquid diet beginning at three weeks. The model was used to assess time course and efficacy of a replication defective herpes simplex virus type 1 vector construct delivering human cDNA encoding preproenkephalin (HSV-ENK).Most surprising was the relative lack of inflammation and tissue disruption after HSV-ENK treatment compared to the histopathology consistent with pancreatitis (inflammatory cell infiltration, edema, acinar cell hypertrophy, fibrosis) present as a result of the high-fat and alcohol diet in controls. The HSV-ENK vector delivered to the pancreatic surface at week 3 reversed pancreatitis-associated hotplate hypersensitive responses for 4-6 weeks, while control virus encoding beta-galactosidase cDNA (HSV-beta-gal) had no effect. Increased Fos expression seen bilaterally in pain processing regions in control animals with pancreatitis was absent in HSV-ENK-treated animals. Increased met-enkephalin staining was evident in pancreas and lower thoracic spinal cord laminae I-II in the HSV-ENK-treated rats.Thus, clear evidence is provided that site specific HSV-mediated transgene delivery of human cDNA encoding preproenkephalin ameliorates pancreatic inflammation and significantly reduces hypersensitive hotplate responses for an extended time consistent with HSV mediated overexpression, without tolerance or evidence of other opiate related side effects.

    View details for DOI 10.1186/1744-8069-4-8

    View details for Web of Science ID 000255479600001

    View details for PubMedID 18307791

    View details for PubMedCentralID PMC2292157

  • Chronic morphine administration enhances nociceptive sensitivity and local cytokine production after incision MOLECULAR PAIN Liang, D., Shi, X., Qiao, Y., Angst, M. S., Yeomans, D. C., Clark, J. D. 2008; 4


    The chronic use of opioids prior to surgery leads to lowered pain thresholds and exaggerated pain levels after these procedures. Several mechanisms have been proposed to explain this heightened sensitivity commonly termed opioid-induced hyperalgesia (OIH). Most of these proposed mechanisms involve plastic events in the central or peripheral nervous systems. Alterations in the abundance of peripheral mediators of nociception have not previously been explored.In these experiments mice were treated with saline (control) or ascending daily doses of morphine to generate a state of OIH followed by hind paw incision. In other experiments morphine treatment was initiated at the time of incision. Both mechanical allodynia and peri-incisional skin cytokine levels were measured. Myeloperoxidase (MPO) assays were used to determine neutrophil activity near the wounds. The cytokine production inhibitor pentoxifylline was used to determine the functional significance of the excess cytokines in previously morphine treated animals. Mice treated chronically treated with morphine prior to incision were found to have enhanced skin levels of IL-1beta, IL-6, G-CSF, KC and TNFalpha after incision at one or more time points compared to saline pretreated controls. The time courses of individual cytokines followed different patterns. There was no discernable effect of chronic morphine treatment on wound area neutrophil infiltration. Pentoxifylline reduced cytokine levels and reversed the excess mechanical sensitization caused by chronic morphine administration prior to incision. Morphine treatment initiated at the time of incision did not lead to a generalized enhancement of cytokine production or nociceptive sensitization in excess of the levels observed after incision alone.The enhanced level of nociceptive sensitization seen after incision in animals chronically exposed to morphine is associated with elevated levels of several cytokines previously reported to be relevant to this incisional pain model. The cytokines may be functional in supporting nociceptive sensitization because pentoxifylline reverses both peri-incisional skin cytokine levels and OIH. Opioid administration beginning at the time of incision does not seem to have the same cytokine enhancing effect. Approaches to postoperative pain control involving a reduction of cytokines may be an effective way to control excessive pain in patients chronically using opioids prior to surgical procedures.

    View details for DOI 10.1186/1744-8069-4-7

    View details for PubMedID 18294378

  • Human in-vivo bioassay for the tissue-specific measurement of nociceptive and inflammatory mediators. Journal of visualized experiments : JoVE Angst, M. S., Tingle, M., Schmelz, M., Carvalho, B., Yeomans, D. C. 2008


    This in-vivo human bioassay can be used to study human volunteers and patients. Samples are collected from pertinent tissue sites such as the skin via aseptically inserted microdialysis catheters (Dermal Dialysis, Erlangen, Germany). Illustrated in this example is the collection of interstitial fluid from experimentally inflamed skin in human volunteers. Sample collection can be combined with other experimental tests. For example, the simultaneous assessment of locally released biochemicals and subjective sensitivity to painful stimuli in experimentally inflamed skin provides the critical biochemical-behavioral link to identify biomarkers of pain and inflammation. Presented assay in the living human organism allows for mechanistic insight into tissue-specific processes underlying pain and/or inflammation. The method is also well suited to examine the effectiveness of existing or novel interventions--such as new drug candidates - targeting the treatment of painful and/or inflammatory conditions. This article will provide a detailed description on the use of microdialysis techniques for collecting interstitial fluid from experimentally inflamed skin lesion of human study subjects. Interstitial fluid samples are typically processed with aid of multiplex bead array immunoassays allowing assaying up to 100 analytes in samples as small in volume as 50 microliters.

    View details for DOI 10.3791/1074

    View details for PubMedID 19229167

  • Collecting and measuring nociceptive and inflammatory mediators in surgical wounds. Journal of visualized experiments : JoVE Carvalho, B., Clark, D. J., Yeomans, D., Angst, M. S. 2008


    We describe a methodology by which we are able to collect and measure inflammatory and nociceptive biochemical mediators at the surgical wound site. Collecting site-specific biochemical markers allows us to evaluate the relationship between surgical wound and serum levels;determine any associations between mediator release, pain and analgesic consumption; and evaluate the effect of systemic and peripheral drug administration on surgical wound biochemistry.This methodology has been applied to healthy women undergoing elective cesarean delivery with spinal anesthesia. Wound exudate and serum mediators, in conjunction with pain scores and analgesics consumption were measured at 1, 6, 24, and 48 hours post-cesarean delivery.Biochemical mediators that were detected included IL-1?, IL-2, IL-4, IL-6, IL-7, IL-8, IL-10, IL-12, IL-13, IL-17, TNF?, INF?, G-CSF, GM-CSF,MCP-1 and MIP-1?, nerve growth factor (NGF), prostaglandin E2 (PG-E2) and substance P. We found no correlations between wound and serum cytokines concentrations or time-release profiles (J Pain. 2008 Jul 9(7):650-7). This article describes and demonstrates the feasibility of collecting and assaying nociceptive and inflammatory mediators in surgical wounds at specific time points. The lack of significant correlations between serum and wound levels shows the importance of determining site-specific release if surgical wounds and localized pathologies are to be studied [corrected].

    View details for DOI 10.3791/962

    View details for PubMedID 19078937

  • Morphine reduces local cytokine expression and neutrophil infiltration after incision MOLECULAR PAIN Clark, J. D., Shi, X., Li, X., Qiao, Y., Liang, D., Angst, M. S., Yeomans, D. C. 2007; 3


    Inflammation and nociceptive sensitization are hallmarks of tissue surrounding surgical incisions. Recent studies demonstrate that several cytokines may participate in the enhancement of nociception near these wounds. Since opioids like morphine interact with neutrophils and other immunocytes, it is possible that morphine exerts some of its antinociceptive action after surgical incision by altering the vigor of the inflammatory response. On the other hand, keratinocytes also express opioid receptors and have the capacity to produce cytokines after injury. Our studies were directed towards determining if opioids alter cytokine production near incisions and to identify cell populations responsible for producing these cytokines.A murine incisional model was used to measure the effects of acute morphine administration (0.1-10 mg/kg) on nociceptive thresholds, neutrophil infiltration and cytokine production in hind paw skin 30 minutes and 2 hours after incision. Incised hind paws displayed profound allodynia which was reduced by morphine (0.1-10 mg/kg) in the 2 hours following incision. Skin samples harvested from these mice showed enhanced levels of 5 cytokines: IL-1 beta, IL-6, tumor necrosis factor alpha (TNFalpha), granulocyte colony stimulating factor (G-CSF) and keratinocyte-derived cytokine (KC). Morphine reduced these incision-stimulated levels. Separate analyses measuring myeloperoxidase (MPO) and using immunohistochemistry demonstrated that morphine dose-dependently reduced the infiltration of neutrophils into the peri-incisional tissue. The dose of morphine required for reduction of cytokine accumulation, however, was below that required for inhibition of peri-incisional neutrophil infiltration. Additional immunohistochemical studies revealed wound edge keratinocytes as being an important source of cytokines in the acute phase after incision.Acute morphine administration of doses as low as 0.1 mg/kg reduces peri-incisional cytokine expression. A reduction in neutrophil infiltration does not provide a complete explanation for this effect, and keratinocytes may be responsible for some incision area cytokine production. These studies suggest that morphine may alter the inflammatory milieu of incisional wounds, but these alterations do not likely contribute significantly to analgesia in the acute setting.

    View details for DOI 10.1186/1744-8069-3-28

    View details for PubMedID 17908329

  • Treatment of inflamed pancreas with enkephalin encoding HSV-1 recombinant vector reduces inflammatory damage and behavioral sequelae MOLECULAR THERAPY Lu, Y., McNearney, T. A., Lin, W., Wilson, S. P., Yeomans, D. C., Westlund, K. N. 2007; 15 (10): 1812-1819


    This study assessed the efficacy of pancreatic surface delivered enkephalin (ENK)-encoding herpes simplex virus type 1 (HSV-1) on spontaneous behaviors and spinal cord and pancreatic enkephalin expression in an experimental pancreatitis model. Replication-defective HSV-1 with proenkephalin complementary DNA (cDNA) (HSV-ENK) or control beta-galactosidase cDNA (HSV-beta-gal), or media vehicle (Veh) was applied to the pancreatic surface of rats with dibutyltin dichloride (DBTC)-induced pancreatitis. Spontaneous exploratory behavioral activity was monitored on days 0 and 6 post DBTC and vector treatments. The pancreas, thoracic dorsal root ganglia (DRG, T9-10), and spinal cord (T9-10) were immunostained for met-enkephalin (met-ENK), beta-gal, and HSV-1 proteins. Spinal cord was also immunostained for c-Fos, and pancreas was stained for the inflammatory marker regulated on activation, normal T-cells expressed and secreted (RANTES), mu-opioid receptor, and hemotoxylin/eosin. On day 6, compared to pancreatitis and vector controls, the DBTC/HSV-ENK treated rats had significantly improved spontaneous exploratory activities, increased met-ENK staining in the pancreas and spinal cord, and normalized c-Fos staining in the dorsal horn. Histopathology of pancreas in DBTC/HSV-ENK treated rats showed preservation of acinar cells and cytoarchitecture with minimal inflammatory cell infiltrates, compared to severe inflammation and acinar cell loss seen in DBTC/HSV-beta-gal and DBTC/Veh treated rats. Targeted transgene delivery and met-ENK expression successfully produced decreased inflammation in experimental pancreatitis.

    View details for DOI 10.1038/

    View details for Web of Science ID 000249778000015

    View details for PubMedID 17565349

    View details for PubMedCentralID PMC2592562

  • Antihyperalgesic effect of a recombinant herpes virus encoding antisense for calcitonin gene-related peptide ANESTHESIOLOGY Tzabazis, A. Z., Pirc, G., Votta-Velis, E., Wilson, S. P., Laurito, C. E., Yeomans, D. C. 2007; 106 (6): 1196-1203


    Calcitonin gene-related peptide (CGRP) is contained in and released by small-diameter, nociceptive primary afferent sensory neurons. Upon spinal release, one of the effects of CGRP seems to be to sensitize dorsal horn neurons to subsequent input from nociceptive afferents and, consequently, to induce a behavioral hyperalgesia. Therefore, attenuating evoked release of CGRP from central terminals of nociceptors should have an antihyperalgesic effect.The authors applied a recombinant herpes vector, encoding an antisense sequence to the whole CGRP gene, to the dorsal surface of the hind paw of mice to knock down expression of the peptide selectively in primary afferents innervating this tissue.Herpes virus-based vector encoding an antisense sequence for the whole CGRP clearly reduced CGRP immunoreactivity in the infected spinal dorsal horn levels as well as in cultured dorsal root ganglia neurons. Selective knockdown of CGRP in primary afferents significantly attenuated the thermal, C-fiber hyperalgesia normally observed after topical application of capsaicin. The effect of viral vector-mediated knockdown of CGRP was comparable to the effect of intrathecal application of the CGRP antagonist CGRP8-37, but lasted for 14 weeks after one single application.Viral vector-mediated knockdown of CGRP in primary afferent neurons provides a promising tool for treatment of chronic pain states as well as for studies investigating the pathophysiology underlying these conditions.

    View details for Web of Science ID 000246797500019

    View details for PubMedID 17525595

  • ASIC3 in muscle mediates mechanical, but not heat, hyperalgesia associated with muscle inflammation PAIN Sluka, K. A., Radhakrishnan, R., Benson, C. J., Eshcol, J. O., Price, M. P., Babinski, K., Audette, K. M., Yeomans, D. C., Wilson, S. P. 2007; 129 (1-2): 102-112


    Peripheral initiators of muscle pain are virtually unknown, but likely key to development of chronic pain after muscle insult. The current study tested the hypothesis that ASIC3 in muscle is necessary for development of cutaneous mechanical, but not heat, hyperalgesia induced by muscle inflammation. Using mechanical and heat stimuli, we assessed behavioral responses in ASIC3-/- and ASIC3+/+ mice after induction of carrageenan muscle inflammation. ASIC3-/- mice did not develop cutaneous mechanical hyperalgesia after muscle inflammation when compared to ASIC3+/+ mice; heat hyperalgesia developed similarly between groups. We then tested if the phenotype could be rescued in ASIC3-/- mice by using a recombinant herpes virus vector to express ASIC3 in skin (where testing occurred) or muscle (where inflammation occurred). Infection of mouse DRG neurons with ASIC3-encoding virus resulted in functional expression of ASICs. Injection of ASIC3-encoding virus into muscle or skin of ASIC3-/- mice resulted in ASIC3 mRNA in DRG and protein expression in DRG and the peripheral injection site. Injection of ASIC3-encoding virus into muscle, but not skin, resulted in development of mechanical hyperalgesia similar to that observed in ASIC3+/+ mice. Thus, ASIC3 in primary afferent fibers innervating muscle is critical to development of hyperalgesia that results from muscle insult.

    View details for DOI 10.1016/j.pain.2006.09.038

    View details for Web of Science ID 000246515300014

    View details for PubMedID 17134831

  • Blockade of the complement C5a receptor reduces incisional allodynia, edema, and cytokine expression ANESTHESIOLOGY Clark, J. D., Qiao, Y., Li, X., Shi, X., Angst, M. S., Yeomans, D. C. 2006; 104 (6): 1274-1282


    Activation of the complement system is one component of the inflammatory response. Various components of the complement system participate in killing foreign organisms, recruiting immune cells, enhancing edema, and stimulating cytokine formation. Complement-mediated enhancement of the inflammation surrounding surgical incisions may increase pain.In these studies, the authors used a murine hind paw incisional model to study the role of the complement C5a receptor in supporting incisional inflammation. At baseline and at various time points after incision, they measured the effects of a highly selective C5a receptor antagonist on nociceptive thresholds, edema formation, and cytokine production in the skin surrounding the incision. They also measured changes in C5a receptor expression near the incisions.The once-daily injection of the C5a receptor antagonist AcF-[OPdChaWR] reduced mechanical allodynia and edema in the incised hind paw. A multiplexed cytokine assay revealed that 8 of the 18 cytokines examined showed significant increases in skin tissue abundance after incision. Distinct time courses for the patterns of elevation were seen, though some degree of resolution occurred for all cytokines within 96 h. For 7 of these 8 cytokines, the C5a receptor antagonist reduced the enhancement of expression. In addition, the authors found that the C5a receptor messenger RNA level increased 15-fold in the skin surrounding the incisions within 24 h and then slowly declined.The tissue directly surrounding incisions in mouse hind paws undergoes large changes in the content of specific cytokines in addition to demonstrating edema and nociceptive sensitization. By blocking the receptor for one component of the complement system, C5a, all of these changes can be reduced. Complement receptor inhibitors may constitute a novel group of compounds useful in reducing the pain and swelling of surgical incisions.

    View details for PubMedID 16732100

  • Recombinant herpes vector-mediated analgesia in a primate model of hyperalgesia MOLECULAR THERAPY Yeomans, D. C., Lu, Y., Laurito, C. E., Peters, M. C., Vota-Vellis, G., Wilson, S. P., Pappas, G. D. 2006; 13 (3): 589-597


    Some chronic pain syndromes are characterized by episodes of intense burning and hyperalgesia in localized areas of skin. These sensations are thought to be mediated, at least in part, by the activity of damaged, unmyelinated C nociceptors. These phenomena were modeled by assaying responses of macaques to thermal and chemical stimuli that produced periodic activation and sensitization of C nociceptors. Upon validation of this method, a recombinant herpes simplex vector encoding human preproenkephalin was topically applied to the dorsal surface of the feet of the monkeys. Immunohistochemistry and radioimmunoassay revealed that enkephalin peptides were being produced in releasable pools in sensory neurons innervating the treated skin area. Behavioral responses evoked by periodic sensitization and activation of C nociceptors innervating the vector-treated skin area revealed a substantial and long-lasting (at least 20 weeks) antihyperalgesic and analgesic effect limited to the areas to which the virus was applied. This approach may be a viable means of treating localized cutaneous burning pain and hyperalgesia.

    View details for DOI 10.1016/j.ymthe.2005.08.023

    View details for Web of Science ID 000236445000015

    View details for PubMedID 16288901

  • Opioid Modulation of Nociceptive Afferents in vivo Encyclopedic Reference of Pain Tzabazis, A. Z., Yeomans, D. C. 2006
  • Attenuation of pain perception after transposition of the greater omentum to the cauda equina region of rats - a preliminary observation NEUROLOGICAL RESEARCH Agner, C., Dujovny, M., Yeomans, D. C. 2005; 27 (6): 598-608


    This paper addresses a specific experimental design to suggest the possible role of the greater omentum in the modulation of pain in rats.Fifteen male Sprague-Dawley rats weighing between 275 and 325 g were selected. The animals were randomized and then anesthetized with pentobarbital (35 mg/kg) and divided into three groups: (1) sham: laparotomy followed by laminectomy with exposure of the spinal epidural space (n=5); (2) transposition of pedicled omentum (n=5) to the cauda equina epidural space; and (3) transposition of pedicled omentum (n=5) to the cauda equina intradural space. The animals were operated upon and once more randomized by an independent investigator, so that the groups were thought to be similar during post-operative testing. The latency of paw withdrawal to noxious heat stimulation was tested and the values (seconds) plotted for 1, 3, 6, 11, 14 and 30 days after surgery. Randomization codes were open after the animals were euthanized. The analysis of variance (ANOVA) without replication was applied for each of the dataset and comparisons established among the different study groups involved. The omenta were removed and standard immunohistochemistry was performed for gamma-amino-butyric acid (GABA), serotonin, calcitonin-gene related protein (CGRP), vascular intestinal peptide (VIP) and Met-enkephalin.The response to high heating rates of stimulation favored intradural versus sham and epidural omental transpositions. High and low noxious heat stimulation suggested an increased threshold to noxious stimulation after the 3 and 30 days of omental transposition. In the low heat stimulation series, responses were comparatively higher than in the sham animals.The suggested increased threshold of response to noxious stimulation after transposition of the greater omentum onto the spinal cord of rats suggested a novel role of the omentum and a potential future application in the clinical arena.

    View details for Web of Science ID 000231956300005

    View details for PubMedID 16157009

  • GABA(B) receptors on central terminals of C-afferents mediate intersegmental A delta-afferent evoked hypoalgesia EUROPEAN JOURNAL OF PAIN Jones, T. L., Sweitzer, S. M., Peters, M. C., Wilson, S. P., Yeomans, D. C. 2005; 9 (3): 233-242


    The current study tested the hypothesis that repetitive activation of sciatic Adelta-afferents evokes a saphenous C-afferent hypoalgesia mediated by pre-synaptic GABA(B) receptors. Tonic activation of sciatic Adelta-afferents was produced by cutaneous application of dimethyl sulfoxide (DMSO) followed by repetitive thermal activation of Adelta-afferents on the dorsolateral hind paw. The tonic activation of sciatic Adelta-afferents produced hypoalgesia in saphenous C-afferents. Intrathecal administration of the GABA(B) receptor antagonist, saclofen, attenuated saphenous hypoalgesia demonstrating at least partial mediation by central GABA(B) receptors. To determine if this central GABA(B) receptor activation occurs at pre-synaptic primary afferent terminals or postsynaptic spinal cord neurons, the dorsal hind paws of mice were infected with a recombinant herpes simplex virus type 1 (HSV-1) designed to selectively knock down expression of the GABA(B1a) receptor subunit (PAGB1a) in primary afferents or a control virus encoding the E. coli lacZ gene (PZ). Four weeks after infection, GABA(B) receptor immunoreactivity in the superficial dorsal horns ipsilateral to PAGB1a application was reduced and hypoalgesia in saphenous C-afferents was attenuated when compared to PZ-infected mice. These findings indicate an intersegmental, sciatic Adelta-afferent-evoked hypoalgesic effect on saphenous C-afferent responses that is mediated by pre-synaptic GABA(B) receptors on the terminals of those C-afferents.

    View details for DOI 10.1016/j.ejpain.2004.06.004

    View details for Web of Science ID 000229773000002

    View details for PubMedID 15862472

  • Antinociceptive effect of intrathecal transplantation of preproenkephalin encoding neural progenitor cells in rat 12th Annual Conference of the American-Society-for-Neural-Transplantation-and-Repair Lu, Y., Qu, T., Wilson, S. P., Yeomans, D. C., Pappas, G. D. ACADEMIC PRESS INC ELSEVIER SCIENCE. 2005: 251?52
  • Differential activation of trigeminal C or A delta nociceptors by infrared diode laser in rats: Behavioral evidence BRAIN RESEARCH Tzabazis, A., Klyukinov, M., Manering, N., Nemenov, M. I., Shafer, S. L., Yeomans, D. C. 2005; 1037 (1-2): 148-156


    Radiant heat is often used for studying thermal nociception, although inherent characteristics such as the broad spectrum of applied wavelengths of typical light sources limit control over and repeatability of stimuli. To overcome these problems, we used a diode infrared laser-based stimulator (wavelength: 980 nm) for selectively stimulating trigeminal Adelta or C thermonociceptors in rats. To provide indirect evidence for nociceptor-selective stimulation, we tested the effects of capsaicin, dimethylsulfoxide (DMSO), and morphine on withdrawal latencies for long pulses with a low current (hypothesized to selectively stimulate C nociceptors) and for threshold currents of short pulses with high current (hypothesized to selectively stimulate Adelta nociceptors) in lightly anesthetized rats. Nonmem analysis was used to perform pharmacodynamic modeling. The measured baseline withdrawal latency for long pulses was 12.5 +/- 0.3 s which was changed significantly to 6.7 +/- 0.4 s after applying topical capsaicin which selectively sensitizes C nociceptors and to 16.5 +/- 1.3 s after 1.0 mg/kg morphine which preferentially attenuates C fiber nociception. Topical DMSO which appears to selectively sensitize Adelta afferents did not significantly alter withdrawal latencies to the long pulses. Fitted threshold currents for short pulses after DMSO were however significantly lower (974 +/- 53 mA vs. 1113 +/- 12 mA for baseline) indicating Adelta sensitization. Capsaicin and morphine did not significantly change threshold currents. Best Nonmem fits for the long pulse were obtained using a model assuming no DMSO effect, but a different inter-individual variability after applying this substance. For the short pulse, a model assuming no capsaicin or morphine effect, but again allowing different inter-individual variabilities after applying these drugs, best described the data. We conclude that different settings of the stimulator used in this study were capable of selectively activating trigeminal Adelta or C thermonociceptors.

    View details for DOI 10.1016/j.brainres.2005.01.019

    View details for PubMedID 15777763

  • Decrease in inflammatory hyperalgesia by herpes vector-mediated knockdown of Na(v)1.7 sodium channels in primary afferents HUMAN GENE THERAPY Yeomans, D. C., Levinson, S. R., Peters, M. C., Koszowski, A. G., Tzabazis, A. Z., Gilly, W. F., Wilson, S. P. 2005; 16 (2): 271-277


    Induction of peripheral inflammation increases the expression of the Nav1.7 sodium channel in sensory neurons, potentially increasing their excitability. Peripheral inflammation also produces hyperalgesia in humans and an increase in nociceptive responsiveness in animals. To test the relationship between these two phenomena we applied a recombinant herpes simplex-based vector to the hindpaw skin of mice, which encoded both green fluorescent protein (GFP) as well as an antisense sequence to the Nav1.7 gene. The hindpaw was subsequently injected with complete Freund's adjuvant to induce robust inflammation. Application of the vector, but not a control vector encoding only GFP, prevented an increase in Nav1.7 expression in GFP-positive neurons and prevented development of hyperalgesia in both C and Adelta thermonociceptive tests. These results provide clear evidence of the involvement of an increased expression of the Nav1.7 channel in nociceptive neurons in the development of inflammatory hyperalgesia.

    View details for Web of Science ID 000227543900012

    View details for PubMedID 15761266

  • Peripheral and central p38 MAPK mediates capsaicin-induced hyperalgesia PAIN Sweitzer, S. M., Peters, M. C., Ma, J. Y., Kerr, I., Mangadu, R., CHAKRAVARTY, S., Dugar, S., Medicherla, S., Protter, A. A., Yeomans, D. C. 2004; 111 (3): 278-285


    The stress-activated mitogen-activated protein kinase (MAPK) p38 is emerging as an important mediator of pain. The present study examined the possible involvement of peripheral and spinal p38 MAPK in capsaicin-induced thermal hyperalgesia. Topical capsaicin produced phosphorylation of p38 MAPK in the skin from the affected hindpaw as well as the corresponding lumbar spinal cord in a time dependent manner. Topical capsaicin produced robust C-fiber mediated thermal hyperalgesia that was inhibited by systemic, local peripheral, or central intrathecal pre-treatment with the p38 MAPK inhibitor, SD-282. Intraperitoneal SD-282 (10-60 mg/kg) significantly and dose-dependently attenuated capsaicin-induced C-fiber mediated thermal hyperalgesia. Similarly, 0.1-5mg/kg subcutaneous SD-282 in the hindpaw dose-dependently attenuated capsaicin-induced thermal hyperalgesia. Intrathecal administration of 1microg SD-282 was also anti-hyperalgesic in this model. Functionally, SD-282 decreased capsaicin-induced release of calcitonin gene related peptide in an in vitro skin release assay, consistent with a role for p38 MAPK in peripheral nerve function. These results suggest that p38 MAPK plays a role in the development of hyperalgesic states, exerting effects both centrally in the spinal cord and peripherally in sensory C fibers.

    View details for DOI 10.1016/j.pain.2004.07.007

    View details for Web of Science ID 000224313700009

    View details for PubMedID 15363871

  • Porcine chromaffin cells, culture, and transplant for antinociceptive effects in rodents and primates NEUROLOGICAL RESEARCH Lu, Y., Jing, R. F., Yeomans, D. C., Pappas, G. D. 2004; 26 (7): 707-712


    It has been shown that xenografts and allografts of spinally transplanted adrenal chromaffin cells produce antinociception in animals and pain relief in patients with cancer pain. As there is a very limited availability of human adrenal tissue to serve as allografts, the clinical need for xenogeneic chromaffin cells as transplants is obvious. Bovine adrenal glands as a steady source of chromaffin cells have been extensively studied. There is however concern about the possible infection in humans with retrovirus following transplantation. The purpose of this study is to use the pig as a preferred donor animal species for xenotransplantation into rat and monkey. As pigs have been cloned, this opens the door to gene-targeted technologies and allows for genetic modifications, which possibly could improve the efficacy and safety of chromaffin cell transplantation. Porcine chromaffin cells were isolated from adrenal glands of 6-8-month-old pigs. After culturing cells for 1 week in a medium containing serum, the release of met-enkephalin and norepinephrine from the cells was detected by high-performance liquid chromatography and radioimmunoassay with nicotine stimulation, lasting approximately 3 weeks. Transplantation of these cells into the subarachnoid space of rats produced antinociceptive effects on Adelta and C fiber-mediated responses lasting 2-3 weeks. Similar findings were observed in studies with macaque monkeys. Compared with the same number of bovine chromaffin cells, porcine chromaffin cells showed a more robust and longer antinociceptive effect, and could be a better source of cells for human transplantation.

    View details for DOI 10.1179/016164104225018018

    View details for Web of Science ID 000225115200001

    View details for PubMedID 15494107

  • Ameroid rings for gradual chronic constriction of the sciatic nerve in rats: contribution of different nerves to neuropathic pain BRAIN RESEARCH BULLETIN Tzabazis, A., Kim, P. H., Sweitzer, S. M., Yeomans, D. C. 2004; 64 (2): 127-132


    Mononeuropathy was induced by placing an ameroid ring around the sciatic nerve and was compared with chronic constriction injury (CCI) of the sciatic nerve [Pain 33 (1988) 87] in rats. Mechanical allodynia was assessed and the role of sciatic and saphenous afferents (Adelta and C) in thermal hyperalgesia investigated. A shorter duration of mechanical allodynia in ameroid rats as compared to CCI rats was observed. Thermal hyperalgesia was observed in the saphenous innervated skin of the hindpaw for Adelta and C nociceptors in ameroid and for Adelta nociceptors only in CCI rats, respectively. The sciatic innervated skin showed a thermal hypoalgesia with a fast onset for Adelta afferents and a slower onset for C afferents in CCI and ameroid rats. The duration of both thermal hypo- and hyperalgesia was longer in ameroid rats. We conclude that ameroid rings are a useful tool for the investigation of long-duration hyperalgesic effects of nerve injury, as the effects were more stable and seen for a longer time (>8 weeks) as compared to the CCI model. The uninjured saphenous afferents, in particular C fibers, mediate thermal hyperalgesia after chronic constriction of the sciatic nerve using an ameroid ring.

    View details for DOI 10.1016/j.brainresbull.2004.05.006

    View details for Web of Science ID 000224035600004

    View details for PubMedID 15342099

  • Antinociceptive action of a p38 alpha MAPK inhibitor, SD-282, in a diabetic neuropathy model 11th Congress of the International-Headache-Society Sweitzer, S. M., Medicherla, S., Almirez, R., Dugar, S. D., CHAKRAVARTY, S., Shumilla, J. A., Yeomans, D. C., Protter, A. A. ELSEVIER SCIENCE BV. 2004: 409?19


    Diabetes can induce a bewildering list of sensory changes, including alteration in pain sensitivity. Painful diabetic neuropathy is refractory to most common analgesics. This study examined the effect of a p38alpha MAPK inhibitor, SD-282, on mechanical allodynia, thermal hyperalgesia, and formalin-evoked nociception in streptozotocin-induced diabetic rats. Four-week diabetic rats exhibited mechanical allodynia, decreased mechanical thresholds, and C- and Adelta-fiber mediated thermal hyperalgesia. Mechanical and thermal responses were measured in diabetic rats following acute and repeated intraperitoneal administration of vehicle, 15 or 45 mg/kg SD-282. Mechanical allodynia was reversed by acute and repeated administration of 15 and 45 mg/kg SD-282. Repeated administration of 15 or 45 mg/kg SD-282 prevented the exacerbation of C-, but not Adelta-fiber, mediated thermal hyperalgesia. Repeated administration of 45 mg/kg SD-282 attenuated flinching behaviors during the quiescent period and the second phase of the formalin response in diabetic rats. Acute and repeated administration of 15 or 45 mg/kg SD-282 had no effect on mechanical, thermal or formalin responses in age-matched control rats. These results indicate a potential therapeutic value of p38alpha MAPK inhibitors in the treatment of aberrant pain sensitivity produced by diabetes.

    View details for DOI 10.1016/j.pain.2004.02.016

    View details for Web of Science ID 000222039400026

    View details for PubMedID 15157702

  • Protein kinase C epsilon and gamma: Involvement in formalin-induced nociception in neonatal rats JOURNAL OF PHARMACOLOGY AND EXPERIMENTAL THERAPEUTICS Sweitzer, S. M., Wong, S. M., Peters, M. C., Mochly-Rosen, D., Yeomans, D. C., Kendig, J. J. 2004; 309 (2): 616-625


    The central nervous system undergoes dynamic changes as it matures. However, until recently, very little was known about the impact of these changes on pain and analgesia. This study tested the hypothesis that the epsilon and gamma isozymes of protein kinase C (PKC) contribute to formalin-induced nociception in an age-dependent manner. Expression of epsilon and gamma PKC and the contributions of these isozymes in formalin-induced nociception was examined in postnatal day 7, 15, and 21 rats. epsilonPKC expression in dorsal root ganglion neurons and gammaPKC expression in lamina II of the spinal cord increased from the first to the third postnatal week. Coupling immunohistochemical and Western analysis, translocation of epsilonPKC followed intraplantar formalin in all ages. In contrast, formalin-induced gammaPKC translocation was observed only in postnatal day 21 rats. Behaviorally, intrathecal administration of the epsilonPKC-specific inhibitor (epsilonV1-2) attenuated phase 1 and phase 2 formalin behaviors at all ages. In contrast, intrathecal administration of the gammaPKC-specific inhibitor (gammaV5-3) attenuated only phase 2 responses in postnatal day 15 and 21 rats. Functionally, inhibition of epsilonPKC decreased capsaicin-stimulated release of glutamate and calcitonin gene-related peptide in spinal cords isolated from postnatal day 7 rats. These results suggest that epsilonPKC age independently mediates inflammatory pain produced by intraplantar formalin. In contrast, gammaPKC contributes to formalin-induced nociception in an age-dependent manner. Identifying the molecular mechanisms responsible for age-specific patterns of nociception is necessary for the rational development of novel therapeutic strategies for treating pediatric pain.

    View details for DOI 10.1124/jpet.103.060350

    View details for PubMedID 14762097

  • Porcine chromaffin cell isolation, culture, and transplant from antinociceptive effects. 11th Annual Conference of the American-Society-for-Neural-Transplantation-and-Repair Lu, Y., Jing, R., Yeomans, D. C., Pappas, G. D. ACADEMIC PRESS INC ELSEVIER SCIENCE. 2004: 213?14
  • Differential opioid inhibition of C- and A delta-fiber mediated thermonociception after stimulation of the nucleus raphe magnus ANESTHESIA AND ANALGESIA Lu, Y., Sweitzer, S. M., Laurito, C. E., Yeomans, D. C. 2004; 98 (2): 414-419


    Although the importance of the nucleus raphe magnus in descending inhibitory control of nociception is clear, it is not known whether these effects are equivalent for different types of nociception. Thus, we examined the differential inhibition of behavioral responses evoked by A delta or C fiber thermonociceptor activation by electrical stimulation of nucleus raphe magnus neurons as well as the involvement of different classes of opiate receptors in this inhibition. In general, it was necessary to apply twice as much current to the nucleus raphe magnus to produce criterion antinociception for A delta mediated versus C fiber mediated nociceptive responses. Intrathecal administration of the nonselective opioid receptor antagonist, naltrexone, or the delta(1) opioid receptor antagonist, naltrindole, attenuated both A delta and C fiber antinociception induced by nucleus raphe magnus stimulation with similar efficacy. In contrast, intrathecal administration of naloxonazine, a micro specific opioid receptor antagonist, or naltriben, a delta(2) specific opioid receptor antagonist, preferentially attenuated nucleus raphe magnus induced antinociception for C fiber responses when compared with A delta mediated responses. These findings suggest that nociception evoked by the activation of A delta or C fiber nociceptors is under pharmacologically distinguishable descending control from the nucleus raphe magnus.Opiates differentially inhibit pain produced by the activation of myelinated or unmyelinated pain sensing neurons, a distinction that is clinically important. This article demonstrates that the brain's own pain control system operates with similar selectivity, and that this selectivity is partly mediated by different opiate receptor subtypes.

    View details for DOI 10.1213/01.ANE.0000094334.12027.06

    View details for Web of Science ID 000188438700027

    View details for PubMedID 14742380

  • Reversal of ongoing thermal hyperalgesia in mice by a recombinant herpesvirus that encodes human preproenkephalin MOLECULAR THERAPY Yeomans, D. C., Jones, T., Laurito, C. E., Lu, Y., Wilson, S. P. 2004; 9 (1): 24-29


    Herpesvirus-mediated transfer of the human preproenkephalin gene to primary afferent nociceptors prevents phasic thermal allodynia/hyperalgesia in mice. It is not known, however, whether similar viral treatments would reverse ongoing or chronic pain and allodynia/hyperalgesia. To this end, mice were given intrathecal injections of pertussis toxin (PTX), which produces a weeks-long thermal hyperalgesia apparently by uncoupling certain G proteins from inhibitory neurotransmitter receptors. This treatment produced profound thermal hyperalgesia in both Adelta and C-fiber thermonociceptive tests lasting at least 6 weeks. However, treatment of skin surfaces with an enkephalin-encoding herpesvirus, but not control virus or vehicle, completely reversed this hyperalgesia. This profound anti-hyperalgesia was observed for both Adelta- and C-fiber-mediated responses. Interestingly, however, while the anti-hyperalgesic effect of the enkephalin-encoding virus on C-fiber-mediated responses was reversed by intrathecal application of micro or delta opioid antagonists, only delta antagonists reversed the effect of this virus on Adelta hyperalgesia. Thus, virus-mediated delivery of the proenkephalin cDNA reverses thermal hyperalgesia produced by PTX-induced ribosylation of inhibitory G proteins by an opioid-mediated mechanism. These results suggest that herpesvirus vectors encoding analgesic peptides may be useful in attenuating centrally mediated, ongoing neuropathic pain and/or hyperalgesia.

    View details for DOI 10.1016/j.ymthe.2003.10.008

    View details for Web of Science ID 000188659300009

    View details for PubMedID 14741774

  • Gene Therapy for Pain The Genetics of Pain Wilson, S. P., Yeomans, D. C. 2004
  • Afferent fiber-selective shift in opiate potency following targeted opioid receptor knockdown PAIN Jones, T. L., Sweitzer, S. M., Wilson, S. P., Yeomans, D. C. 2003; 106 (3): 365-371


    Spinal application of opiates is the cornerstone of potent analgesia. In the present study, opiate analgesia was investigated after cutaneous application of a recombinant herpes simplex virus type-1 (HSV-1) encoding micro-opioid receptor (microOR) cDNA in reverse orientation with respect to the human cytomegalovirus early enhancer-promoter. Hind paw application of this recombinant vector was used in order to attenuate expression of the microOR in primary afferents and determine whether recombinant vector application would differentially affect the antinociceptive effects of the specific microOR agonist, [D-Ala(2),N-MePhe(4),Gly-ol(5)] enkephalin (DAMGO), on behavioral responses mediated by C- and Adelta-thermonociceptors. The recombinant vector encoding the Escherichia coli lacZ gene marker, KHZ, served as a control virus. Dorsal hind paw surfaces of female Swiss-Webster mice were treated with one of these two viruses (1x10(8)pfu, 10 microl) or vehicle (uninfected). Immunohistochemistry and quantitative image analyses revealed decreased microOR expression in the superficial dorsal horns ipsilateral to hind paws treated with AMOR, but not KHZ. To add, behavioral foot withdrawal latencies of AMOR- and KHZ-treated hind paws demonstrated dose-dependent antinociception after intrathecal DAMGO administration. However, cutaneous application of dorsal hind paw surfaces treated with AMOR, but not KHZ, caused a rightward shift in the C-fiber dose-response, thus, indicating a loss of potency of intrathecal DAMGO. Loss or diminution of DAMGO potency during Adelta-fiber-mediated responses was not observed. These immunohistochemistry and behavioral results of novel, recombinant HSV-1 vector microOR 'knock-down' in nociceptor afferent fibers provide additional evidence for presynaptic localization of microORs on central C-, but not Adelta-terminals.

    View details for DOI 10.1016/j.pain.2003.08.006

    View details for Web of Science ID 000187209600017

    View details for PubMedID 14659519

  • Cutaneous application of HSV vectors encoding human preproenkephalin produces analgesia in primates. 10th Annual Conference of the American-Society-for-Neural-Transplantation-and-Repair Yeomans, D. C., Lu, Y., Laurito, C., Votta-Velis, G., Wilson, S. P. ACADEMIC PRESS INC ELSEVIER SCIENCE. 2003: 110?10
  • Conformation-dependent effects of VIP on nociception in rats PEPTIDES Yeomans, D. C., Onyuksel, H., Dagar, S., Ikezaki, H., Lu, Y., Rubinstein, I. 2003; 24 (4): 617-622


    The purpose of this study was to determine whether intrathecal injection of aqueous (random coil) vasoactive intestinal peptide (VIP) and VIP self-associated with sterically stabilized phospholipid micelles (alpha-helix VIP) at the lower lumbar vertebral level modulates foot withdrawal latency to low and high rate noxious radiant skin heating in anesthetized rats. We found that intrathecal random coil VIP evoked a significant bimodal, concentration-dependent response, early potent antinociception followed by hyperalgesia, during exposure to low and high rates of skin heating (P<0.05). Intrathecal alpha-helix VIP elicited a qualitatively similar response to that of random coil VIP except that the rate of decay of antinociception was faster and slower at low and high rates of skin heating, respectively. In addition, a low concentration of alpha-helix VIP evoked a potent late antinociception not observed with random coil VIP. Taken together, these data indicate that VIP modulates somatosensory processing in the lumbosacral spinal cord of rats in a complex fashion, and that this response is dependent, in part, on the conformation of VIP in the vicinity of target cells in the peripheral nervous system.

    View details for DOI 10.1016/S0196-9781(03)00102-5

    View details for Web of Science ID 000184329600016

    View details for PubMedID 12860207

  • Gene Therapy for Pain: Different Approaches Toward a Common Goal Pain Research and Therapy, Proceedings of the Tenth World Congress on Pain Yeomans, D. C., Saitoh, Y., Mannes, A. 2003
  • Pain and Genetics / Interspinal Drug Delivery for Chronic Pain Seminars in Pain Medicine Yeomans, D. C. Elsevier. 2003; 1 (4)
  • Gene therapy for pain: Different approaches toward a common goal 10th World Congress on Pain Yeomans, D. C., Mannes, A., Saitoh, Y. INT ASSOC STUDY PAIN (IASP) PRESS. 2003: 521?537
  • Virally Mediated Delivery of Enkephalin and Other Neuropeptide Transgenes Experimental Pain Models Wilson, S. P., Yeomans, D. C. 2003
  • Antibody-mediated lung endothelium targeting: in vivo model on primates 97th International Conference of the American-Thoracic-Society Balyasnikova, I. V., Yeomans, D. C., McDonald, T. B., Danilov, S. M. NATURE PUBLISHING GROUP. 2002: 282?90


    We have recently provided evidence that angiotensin-converting enzyme (ACE) is a rational target and anti-ACE monoclonal antibodies (mAbs) are suitable molecules for directing gene/drug delivery into the pulmonary endothelium of rodents. As a step towards gene therapy clinical trials using this approach, the present study evaluated the potential of anti-ACE mAbs for in vivo lung endothelium targeting in 10 species of primates. Cross-reactivity of 10 distinct mAbs directed to human ACE with ACE from baboon, macaques, cercopithecus and chimpanzee revealed that the highest binding with ACE from baboon and macaques was with mAb i2H5, from chimpanzee - mAb 9B9, and from human - 9B9 and i2H5. Thereafter, in vivo biodistribution of mAbs i2H5 and 9B9 was estimated in Macaca arctoides. MAb i2H5, which binds to macaque ACE with substantially higher affinity than mAb 9B9, also more effectively accumulates in their lungs than mAb 9B9. Immunospecificity of lung accumulation (mAb/control IgG ratio) was 37 for i2H5 and 0.5 for 9B9. Lung selectivity of i2H5 uptake (lung/blood ratio) was around 10. Therefore mAb i2H5 may be useful for in vivo lung targeting in non-human primates, whereas 9B9 may be most useful in primates that are closer to humans (chimpanzee). A combination of these two mAbs may be particularly useful for human clinical trials of gene/drug therapy for lung disorders such as pulmonary hypertension and lung metastases.

    View details for DOI 10.1038/sj/gt/3301657

    View details for Web of Science ID 000174314000006

    View details for PubMedID 11896467

  • Conditional analgesia from spinally transplanted adrenal chromaffin cells PAIN Yeomans, D. C., Lu, Y., Pappas, G. D. 2002; 95 (1-2): 191-191

    View details for Web of Science ID 000173772500022

    View details for PubMedID 11790482

  • The Management of Pain International Encyclopedia of Social and Behavioral Science Laurito, C. E., Yeomans, D. C., Pappas, G. D. 2002
  • Virally mediated delivery of enkephalin and other neuropeptide transgenes in experimental pain models 11th International Symposium on Chromaffin Cell Biology Wilson, S. P., Yeomans, D. C. NEW YORK ACAD SCIENCES. 2002: 515?521


    We have constructed recombinant herpes simplex virus type 1 vectors for delivery of genes to sensory neurons in an attempt to modulate nociception. Delivery of recombinant viruses to the skin of mice results in expression of encoded complementary DNA (cDNA) genes in DRG neurons within three to four days. Expression of marker genes persists for at least 10 weeks. Testing of baseline thermal nociceptive latencies at the site of virus application revealed no differences between a control virus and a virus encoding human preproenkephalin (hPPE) when performed at either low stimulus intensities (C-fiber activation) or high stimulus intensities (Adelta neurons). By contrast, sensitization of nociceptors by capsaicin or dimethylsulfoxide was reduced or abolished by infection with the virus encoding hPPE, but not by a control virus. These antihyperalgesic responses are mediated by opioids released at the central terminals of the primary afferents because they are blocked by intrathecal administration of the opioid antagonist naloxone. Similar experiments performed in macaques demonstrated an antihyperalgesic effect of the herpes virus vector encoding hPPE. This hPPE-encoding virus was also tested in a model of neuropathic pain in mice, with similar effect. A virus containing an antisense cDNA for calcitonin gene-related peptide precursor (ACGRP) has also been constructed and found to reverse C-fiber hyperalgesia caused by application of capsaicin to the skin for up to 14 weeks postinfection. These results raise the possibility that herpes-mediated, gene-based approaches to treat chronic pain states may be useful in therapy of chronic pain in humans.

    View details for Web of Science ID 000179509100091

    View details for PubMedID 12438172

  • The combined effects of N-type calcium channel blockers and morphine on A delta versus C fiber mediated nociception ANESTHESIA AND ANALGESIA Pirec, V., Laurito, C. E., Lu, Y., Yeomans, D. C. 2001; 92 (1): 239-243


    Intrathecal mu opiates produce analgesia presynaptically by inhibiting calcium ion influx and postsynaptically by increasing potassium flux. Mu receptors are expressed on presynaptic terminals of unmyelinated (C), but not myelinated (A delta) nociceptors. Thus, mu-opioids such as morphine may act presynaptically to inhibit C, but not A delta, neurotransmission, and postsynaptically on dorsal horn cells that receive input from A delta and/or C fiber nociceptors. N-type calcium ion channel blockers, such as omega-conotoxin GVIA (omega-CTX), produce analgesia by impeding flux of calcium ions into A delta and C fiber nociceptor terminals. Thus, morphine and omega-CTX attenuated C fiber nociception additively, possibly indicating the same presynaptic site of action. Conversely, morphine and omega- CTX were supraadditively analgesic on an A delta test, indicating that these agents probably have different sites of action. We conclude that although intrathecal application of either morphine or omega-CTX attenuates both A delta and C fiber mediated nociception in rats, the combined effects are quite different for the two fiber types. Specifically, although coadministration of morphine with omega-CTX produces an additive, apparently presynaptic antinociception for C fiber-mediated responses, the combination produces a clearly supraadditive, and likely synergistic effect on A delta mediated nociception, probably by acting at pre and postsynaptic sites, respectively. Implications: This study demonstrates that combined spinal administration of mu opioids and N-type calcium channel blockers may be useful in providing analgesia for A delta mediated (first, sharp) pain while minimizing the side effects of both drugs.

    View details for Web of Science ID 000166044300046

    View details for PubMedID 11133635

  • Differential Spinal Release of Amino Acid Neurotransmitters Following Selective Activation of C or A? Thermonociceptors Pain Research and Therapy, Proceedings of the Ninth World Congress on Pain Yeomans, D. C., Lu, Y., Peters, M., Whitely, M., Laurito, C. A. 2001
  • The neurochemical basis for the applications of the greater omentum in neurosurgery NEUROLOGICAL RESEARCH Agner, C., Yeomans, D., Dujovny, M. 2001; 23 (1): 7-15


    The omentum has been utilized in neurosurgery for over 30 years. However, the anatomical and physiological bases for its applications have not been described in great detail. In this paper, we will review the current status of the omentum applications for the management of central nervous system disorders.

    View details for Web of Science ID 000166612400002

    View details for PubMedID 11210434

  • Genetic therapy for pain management. Current review of pain Wilson, S. P., Yeomans, D. C. 2000; 4 (6): 445-450


    Two approaches to genetic therapy for the management of chronic pain have recently been investigated in animal models of pain. First, transgene-mediated delivery of antinociceptive molecules to the cerebrospinal fluid has been performed with engineered cell lines transplanted to the subarachnoid space and with recombinant adenoviruses that transduce pia mater cells. Second, the phenotype of nociceptive neurons has been altered by recombinant herpes viruses overexpressing antinociceptive peptides or reducing expression of endogenous nociceptive molecules. Both approaches attenuate or reverse persistent nociceptive states, suggesting use in the development of genetic therapy for pain management in humans.

    View details for PubMedID 11060590

  • Differential spinal release of amino acid neurotransmitters following selective activation of C or A delta thermonociceptors 9th World Congress on Pain Yeomans, D. C., Lu, Y., Peters, M., Whitely, M., Laurito, C. E. INT ASSOC STUDY PAIN (IASP) PRESS. 2000: 335?341
  • Antihyperalgesic effects of infection with a preproenkephalin-encoding herpes virus PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Wilson, S. P., Yeomans, D. C., Bender, M. A., Lu, Y., Goins, W. F., Glorioso, J. C. 1999; 96 (6): 3211-3216


    To test the utility of gene therapeutic approaches for the treatment of pain, a recombinant herpes simplex virus, type 1, has been engineered to contain the cDNA for an opioid peptide precursor, human preproenkephalin, under control of the human cytomegalovirus promoter. This virus and a similar recombinant containing the Escherichia coli lacZ gene were applied to the abraded skin of the dorsal hindpaw of mice. After infection, the presence of beta-galactosidase in neuronal cell bodies of the relevant spinal ganglia (lacZ-containing virus) and of human proenkephalin (preproenkephalin-encoding virus) in the central terminals of these neurons indicated appropriate gene delivery and expression. Baseline foot withdrawal responses to noxious radiant heat mediated by Adelta and C fibers were similar in animals infected with proenkephalin-encoding and beta-galactosidase-encoding viruses. Sensitization of the foot withdrawal response after application of capsaicin (C fibers) or dimethyl sulfoxide (Adelta fibers) observed in control animals was reduced or eliminated in animals infected with the proenkephalin-encoding virus for at least 7 weeks postinfection. Hence, preproenkephalin cDNA delivery selectively blocked hyperalgesia without disrupting baseline sensory neurotransmission. This blockade of sensitization was reversed by administration of the opioid antagonist naloxone, apparently acting in the spinal cord. The results demonstrate that the function of sensory neurons can be selectively altered by viral delivery of a transgene. Because hyperalgesic mechanisms may be important in establishing and maintaining neuropathic and other chronic pain states, this approach may be useful for treatment of chronic pain and hyperalgesia in humans.

    View details for Web of Science ID 000079224500117

    View details for PubMedID 10077663

  • Purification of adrenal chromaffin cells increases antinociceptive efficacy of xenotransplants without immunosuppression 5th Meeting of the American-Society-for-Neural-Transplantation Michalewicz, P., Laurito, C. E., Pappas, G. D., Lu, Y., Yeomans, D. C. COGNIZANT COMMUNICATION CORP. 1999: 103?9


    We have found that immunosuppression is necessary for the survival of xenogeneic adrenal medullary transplants. Because chromaffin cells are essentially nonimmunogenic, it is likely that the highly immunogenic "passenger" cells in the transplant preparation bring about rejection. This article describes a procedure that produces an essentially pure preparation of chromaffin cells for transplantation. Bovine adrenal medullary cells were isolated and differentially plated, resulting in a semipurified preparation of chromaffin cells. Ferromagnetic beads were added to the cell suspension, some of which were phagocytized by endothelial cells, which allowed their removal by exposure to a magnet. The remaining cells were then exposed to ferromagnetic beads coated with isolectin B4 from Griffonia simplicifolia and once again to a magnetic field. The "semipurified" preparation contained approximately 90% chromaffin cells, whereas the "highly purified" preparation was > 99.5% chromaffin cells as determined immunohistochemically. The immunogenicity of the two cell preparations was assessed in vitro by determining their capacity to evoke lymphocyte proliferation. Rat spleen lymphocytes were mixed with either a highly purified or semipurified population of bovine chromaffin cells. The results of this assay demonstrated that the highly purified preparation was a much weaker stimulant of lymphocyte proliferation than was the semipurified preparation and may demonstrate better graft survival in vivo. Transplantation via intrathecal catheter of either 80,000 or 250,000 cells from the highly or partially purified preparations onto the lumbar spinal cord of nonimmunosuppressed and non-nicotine-stimulated rats produced a cell number-dependent antinociception for both A(delta) and C fiber-mediated thermonociception at 6 days after transplantation. After 6 days and up to 28 days, only the "highly purified" preparation showed antinociception. These results suggest that nearly complete purification of bovine chromaffin cells minimizes immunorejection of xenogeneic transplants of these cells.

    View details for Web of Science ID 000080210700010

    View details for PubMedID 10338279

  • Assessment of cellular localization of the thomboxane A2 receptor by immunocytochemistry Eicosanoid Protocols Blackman, S., Borg, C., C David, LeBreton, G. C. 1999
  • Assessment of cellular localization of the thromboxane A2 receptor by immunocytochemistry. Methods in molecular biology (Clifton, N.J.) Blackman, S. C., Borg, C., Yeomans, D. C., Le Breton, G. C. 1999; 120: 145-171

    View details for PubMedID 10343316

  • Differential antinociceptive effects of spinal opioids on foot withdrawal responses evoked by C fibre or A delta nociceptor activation BRITISH JOURNAL OF PHARMACOLOGY Lu, Y., Pirec, V., Yeomans, D. C. 1997; 121 (6): 1210-1216


    1. Intrathecal application of mu, delta, and kappa opioids attenuate responses on several tests of animal nociception. However, the potency of these opioids differ depending on which tests were used. One factor contributing to these discrepancies is that different types of noxious stimuli activate different sets of nociceptor types, which may be differentially sensitive to opiate inhibition. To examine this hypothesis, we used a recently developed behavioural test which allows for differential assessment of nociception evoked by the activation of myelinated (A delta) and unmyelinated C thermonociceptors. 2. Administration of a kappa-selective agonist was ineffective on either type of response. Delta1 drugs were slightly more potent on C fibre-mediated responses than on A delta-mediated responses. 3. Intrathecal mu and delta2 drugs were antinociceptive on both A delta and C nociceptor-mediated responses. However, unlike the delta1 effects, the dose-response curves for mu and delta2 drugs were significantly more steep for A delta than for C fibre-mediated responses, potentially indicating differences in the mechanisms by which the drugs act on these 2 response types.

    View details for Web of Science ID A1997XL93600024

    View details for PubMedID 9249259

  • Low but not high rate noxious radiant skin heating evokes a capsaicin-sensitive increase in spinal cord dorsal horn release of substance P BRAIN RESEARCH Zachariou, V., Goldstein, B. D., Yeomans, D. C. 1997; 752 (1-2): 143-150


    Some kinds of nociception appear to be partially mediated by the release of substance P (SP) in the spinal cord dorsal horn from terminals of primary afferent nociceptors. Only some nociceptors contain and release SP however. Specifically, SP appears to be released by unmyelinated (C) nociceptive afferents when activated by noxious stimulation to the skin, but does not appear to be contained in cutaneous myelinated (A delta) nociceptive afferents. We have proposed a model of nociception in rats that uses different rates of noxious skin heating to allow for differential assessment on behavioral responses mediated by the activation of A delta or C fiber nociceptors. As one means of testing the validity of this model we have examined the effects of using high and low rate noxious skin heating on the dorsal horn release of substance P-like immunoreactivity (SPLI) in decerebrate/spinal transected animals. Consistent with the model, low rate skin heating evokes a significant increase in dorsal horn SPLI release indicating C fiber mediation, whereas high rate skin heating did not evoke SP release, indicating mediation by afferents other than C afferents, i.e. A delta nociceptive afferents. Also consistent with behavioral effects, topical application of capsaicin, which sensitizes C nociceptors, increased the SPLI release evoked by low but not high rate skin heating. These data provide additional evidence that foot withdrawals evoked by low rate skin heating are mediated by C fiber activation, whereas foot withdrawals evoked by high rate skin heating are evoked by A delta fiber activation.

    View details for Web of Science ID A1997WT62300016

    View details for PubMedID 9106450

  • Nociceptive responses to high and low rates of noxious cutaneous heating are mediated by different nociceptors in the rat: Electrophysiological evidence PAIN Yeomans, D. C., Proudfit, H. K. 1996; 68 (1): 141-150


    Behavioral nociceptive responses evoked by relatively high rates of noxious radiant skin heating appear to be mediated by A delta nociceptor activation, whereas responses evoked by low rates of skin heating appear to be mediated by the activation of C-fiber nociceptors. This hypothesis was confirmed by the results of single unit recordings of A delta and C nociceptive afferent fibers isolated from the saphenous nerves of pentobarbital anesthetized rats. Heating the hind paw skin of the rat at a relatively high rate of 6.5 degrees C/sec activated A delta units within 2 sec after the onset of the stimulus. This response latency is similar to the 2.5 sec latency of the foot withdrawal response to a similar stimulus. In contrast, C-fibers were only slightly activated at a longer latency of 5-6 sec. Conversely, heating the hind paw skin at a relatively low rate of 0.9 degrees C/sec activated C-fibers, but evoked only a few action potentials in A delta nociceptors. C-fibers began firing at a rate less than 1 Hz between 8 and 10 sec after the onset of heating and fired at a mean rate of 1.5 Hz between 10 and 12 sec, which corresponds to the latency of the foot withdrawal response. Topical application of capsaicin to the hind paw skin decreased the latency of C-fiber responses from control values of 8-12 sec to approximately 4 sec after topical capsaicin treatment. The mean latency of the foot withdrawal response to skin heating at the low rate is also reduced from control values of 12-14 sec to 4-5 sec after capsaicin treatment. In contrast, capsaicin treatment did not significantly affect the responses of A delta nociceptors. These results support the conclusion that nociceptive foot withdrawal responses to a low rate of skin heating are mediated predominantly by the activation of C-fiber nociceptors. These results provide direct evidence that, under the conditions of these experiments, nociceptive foot withdrawal responses evoked by high rates of skin heating are primarily mediated by A delta nociceptors, and foot withdrawal responses evoked by low rates of skin heating are primarily mediated by C-fiber nociceptors.

    View details for Web of Science ID A1996XF89500018

    View details for PubMedID 9252009

  • Nociceptive responses to high and low rates of noxious cutaneous heating are mediated by different nociceptors in the rat: Behavioral evidence PAIN Yeomans, D. C., Pirec, V., Proudfit, H. K. 1996; 68 (1): 133-140


    Several lines of evidence suggest that different classes of nociceptive afferents mediate the responses produced by different rates of noxious skin heating. More specifically, low skin heating rates evoke nociceptive responses that appear to be mediated by the activation of capsaicin-sensitive C-fiber nociceptors, whereas high skin heating rates appear to produce responses mediated by the activation of other nociceptors. This hypothesis was examined by both electrophysiological and behavioral experiments. This report describes the results of experiments designed to determine whether pharmacologic treatments that selectively alter the activity of C-fiber nociceptive afferents also produce selective effects on foot withdrawal responses to either high or low rates of noxious foot heating. The results of these experiments demonstrate that: (1) topical application of a low concentration of capsaicin, which sensitizes C-fiber nociceptors, selectively decreased the latency of responses to low heating rates; (2) topical application of a high concentration of capsaicin, that desensitizes C-fiber nociceptors, selectively increased the latency of responses to low heating rates; (3) low doses of systemic morphine, which selectively attenuate nociception produced by the activation of C-fiber nociceptors, selectively increased response latencies for low skin heating rates. These results support the conclusion that foot withdrawal responses evoked by low skin heating rates are mediated by the activation of capsaicin-sensitive C-fiber nociceptors and foot withdrawal responses evoked by high skin heating rates are mediated by the activation of other nociceptors. This conclusion is supported by the results of the accompanying electrophysiological study which provides direct evidence that low rates of skin heating preferentially activate C-fiber nociceptors while high rates of skin heating preferentially activate A delta nociceptors.

    View details for Web of Science ID A1996XF89500017

    View details for PubMedID 9252008

  • Effects of systemic morphine on responses of primates to first or second pain sensations PAIN Yeomans, D. C., Cooper, B. Y., Vierck, C. J. 1996; 66 (2-3): 253-263


    Despite evidence that systemic morphine preferentially attenuates second pain sensations that are presumed to result from activation of unmyelinated (C) nociceptors, most animal models of nociception elicit sensations that result from or are dominated by activation of myelinated (A-delta) nociceptors. Therefore, methods were developed to directly compare the effects of morphine on late (second) pain sensations and early onset (first) pain sensations in an animal model. In order to establish appropriate stimulus parameters, human psychophysical experiments compared characteristics of sensations evoked by brief (pulsed) thermal stimulation and ramp-and-hold thermal stimulation. Brief (500 msec) contact of a pre-heated thermode with the skin produced late pain sensations with peripheral conduction velocities in the range of C afferents, as estimated by latencies from stimulation of proximal and distal sites on the leg. The sensations evoked by brief contact increased with successive contacts (pulses) at 0.4 Hz, demonstrating temporal summation of sensation intensity. Pretreatment of the skin with capsaicin enhanced the late pain sensations from pulsed stimulation. In contrast, peak sensations evoked by ramp-and-hold thermal stimulation were evoked at similar latencies from disparate sites on the leg, and capsaicin pretreatment of the skin did not increase the magnitude of these sensations. The pulsed and ramp-and-hold forms of stimulation were used in a paradigm designed to test for differential effects of systemic morphine on operant responses of non-human primates. Low doses of morphine reduced operant responding to pulsed thermal contact, while higher doses were required to affect responses to ramp-and-hold thermal stimulation. The low doses of morphine did not suppress non-nociceptive (intertrial) motor responses, indicating that motor inhibition was not responsible for the effects on escape responses to pulsed stimulation. Measurements of skin temperature 10 cm from the site of stimulation showed that morphine had no effect on baseline temperature but attenuated changes in skin temperature that were elicited by pulsed and by ramp-and-hold stimulation. This effect of morphine on skin temperature responses could not account for the reduction of operant responsivity to thermal stimulation. These results support previous findings that systemic morphine preferentially attenuates second pain sensations, and a new animal model of morphine-sensitive thermal nociception is established. These findings demonstrate the importance of defining the sources of afferent input and the response measures in experiments which attempt to measure antinociceptive effects of pharmacological agents.

    View details for Web of Science ID A1996VG56100019

    View details for PubMedID 8880848



    Electromyographic activity and the force of reflex and operant responses were recorded following administration of morphine. Low doses facilitated reflex responses to input from A-delta afferents but not from A-beta input. Higher doses inhibited A-delta responses but not A-beta responses. Operant avoidance responses to visual cues were unchanged. Thus, depending on the dose, nociceptive reflexes were facilitated or inhibited, without associated effects on non-nociceptive input or on motor output.

    View details for Web of Science ID A1995QE83800012

    View details for PubMedID 7743193

  • The modulation of nociception by enkephalin-containing neurons in the brainstem Pharmacology of Opioid Peptides Proudfit, H., Yeomans, D. C. 1995


    The rat foot withdrawal response to noxious radiant heat has been used as a model of nociception that is particularly useful for measurements of unilateral changes in nociceptive responses. The purpose of these studies was to characterize the foot withdrawal response to graded rates of noxious skin heating. Response latencies and both surface and subsurface temperatures produced by 6 different intensities of radiant heat were measured to determine whether response latency is an appropriate measure of nociceptive threshold. With constant intensity heating, the temperature of the skin surface increased as logarithmic function of time, while subsurface temperature increased linearly with time. In contrast, a heating function that linearly increased the temperature at the skin surface increased the subsurface temperature as an exponential function of time. These results and published reports of nociceptive afferent recordings which used similar skin heating parameters, indicate that nociceptive foot withdrawal responses occur at about the same skin temperature as the activation of nociceptors. These results also indicate that since constant intensity heating produces linear increases in the subsurface temperature, then response latency can be used as an accurate measure of changes in nociceptive threshold produced by drug treatments. These observations lead to the conclusion that the foot withdrawal response latency is a valid and useful measure of nociceptive threshold in rodents.

    View details for Web of Science ID A1994PL95600009

    View details for PubMedID 7854807



    In the present study, a new polyclonal antibody (TxAb) was raised against native thromboxane A2 (TXA2)/prostaglandin H2 (PGH2) receptor protein. Previously developed anti-peptide antibodies (P1Ab, P2Ab) and TxAb were then used to prepare immunoaffinity columns to purify TXA2/PGH2 receptors from platelets, brain, and aorta. In platelets, SDS-polyacrylamide gel electrophoresis revealed the purification of a 55-kDa protein by each affinity column. Identification of this protein as the TXA2/PGH2 receptor was based on: 1) an identical electrophoretic mobility to authentic receptor; 2) immunoblotting of TxAb against P1Ab and P2Ab-purified protein; 3) immunoblotting of P1Ab/P2Ab against TxAb-purified protein; and 4) specific [3H]SQ29,548 binding to TxAb-purified protein. P1Ab/TxAb purification of receptors from brain revealed a major protein band at 55 kDa. Furthermore, the eluates from ligand affinity chromatography confirmed the presence of this 55-kDa protein in brain (which was immunoblotted with TxAb), and contained specific [3H]SQ29,548 binding. In addition to the 55-kDa protein, P1Ab/TxAb also purified a minor protein in brain at 52 kDa, which when concentrated, cross-blotted with TxAb and P1Ab. This finding indicates sequence homology between the 55- and 52-kDa proteins. Independent identification of brain TXA2/PGH2 receptors was provided by P2Ab/TxAb immunohistochemistry, which demonstrated specific labeling of discrete myelin-containing fiber tracts. P2Ab/TxAb purification of TXA2/PGH2 receptors from aorta also revealed a major protein band at 55 kDa and a minor band at 52 kDa. These results represent the first purification of TXA2/PGH2 receptors from either brain or aorta.

    View details for Web of Science ID A1994MY84000095

    View details for PubMedID 8119956



    Although noradrenergic neurons in the nucleus locus coeruleus are known to project to the spinal cord, these neurons appear to innervate different regions of the spinal cord in Sprague-Dawley rats obtained from two different vendors. Recent anatomical studies demonstrated that the noradrenergic neurons in the locus coeruleus in Sasco Sprague-Dawley rats primarily innervate the ventral horn, whereas Harlan Sprague-Dawley rats have coeruleospinal projections that terminate in the dorsal horn of the spinal cord. This report describes the results of behavioral experiments that were designed to determine the functional significance of these anatomical differences. Electrical stimulation of neurons in the locus coeruleus produced antinociception in both Harlan and Sasco rats. The antinociception in Harlan rats was readily reversed by intrathecal injection of yohimbine, a selective alpha 2-adrenoceptor antagonist, or by phentolamine, a non-selective alpha 2-adrenoceptor antagonist. In contrast, these antagonists did not alter the antinociception produced by locus coeruleus stimulation in Sasco rats. Finally, the alpha 2-antagonist, idazoxan, did not alter the antinociceptive effect of locus coeruleus stimulation in either group of rats. These observations indicate that coeruleospinal noradrenergic neurons in Harlan and Sasco Sprague-Dawley rats have different physiological functions. Thus, electrical stimulation of noradrenergic neurons in the locus coeruleus that innervate the spinal cord dorsal horn (Harlan rats) produces antinociception, but stimulation of coeruleospinal noradrenergic neurons that project to the ventral horn (Sasco rats) does not produce antinociception. It is likely that genetic differences between these outbred stocks of rats account for the fundamental differences in the projections of coeruleospinal neurons and their function in controlling nociception.

    View details for Web of Science ID A1993MC80100016

    View details for PubMedID 7904225



    Stimulation of neurons in the ventromedial medulla produces antinociception that is mediated in part by indirect activation of pontospinal noradrenergic neurons. Substance P-containing neurons located in the ventromedial medulla project to the A7 catecholamine cell group and may serve as an excitatory link between these two cell groups. Thus, the antinociception induced by stimulation of the neurons in ventromedial medulla may be mediated by substance P released from these projections which activates spinally projecting noradrenergic neurons in the A7 cell group. This hypothesis was tested by determining whether microinjection of various doses of substance P into the A7 cell group of the rat could induce antinociception. The results indicated that substance P induced dose-dependent antinociception that was more pronounced in the hindlimb ipsilateral to the microinjections. This observation is consistent with anatomical observations that noradrenergic A7 neurons project predominantly to the ipsilateral spinal cord dorsal horn. Moreover, the antinociceptive effects of substance P microinjection appear to be mediated at least in part by activation of spinally projecting noradrenergic neurons in the A7 cell group, because intrathecal injections of the alpha-2 noradrenergic antagonists yohimbine and idazoxan blocked these antinociceptive effects. The results of these experiments support the hypothesis that the antinociception induced by stimulation of neurons in the ventromedial medulla is mediated in part by activation of substance P-containing neurons that project to, and activate, spinally projecting noradrenergic neurons located in the A7 catecholamine cell group.

    View details for Web of Science ID A1992JE54600015

    View details for PubMedID 1380137



    Recent anatomical evidence indicates that the pontine A7 catecholamine cell group provides the major noradrenergic innervation of the spinal cord dorsal horn (laminae I-IV). The experiments described in this report were designed to determine if these neurons modulate nociception at the level of the spinal cord. To this end, the antinociceptive effect of electrical stimulation applied at various sites along several tracks through the dorsolateral pontine tegmentum was determined in lightly anesthetized rats. The latency of the withdrawal response of the hind feet to noxious radiant thermal stimulation applied to the dorsal surface was used as a measure of nociception. The results indicated that the most potent and consistent antinociception was produced at sites near the A7 cell group. In addition, intrathecal injection of alpha-noradrenergic antagonists blocked the antinociception produced by electrical stimulation at sites near the A7 group. These observations indicate that the antinociception produced by stimulation near the A7 cell group was mediated by spinally projecting noradrenergic neurons. The results of these experiments provide evidence that pontospinal noradrenergic neurons located in the A7 cell group are important components of the descending neuronal system that modulates nociception.

    View details for Web of Science ID A1992HM57100023

    View details for PubMedID 1594267



    We have recently described the spinal cord terminations of noradrenergic neurons located in the A5, A6 and A7 cell groups. However, recent reports from another laboratory, using similar experimental methods, have described results that are profoundly different. The present experiments were designed to determine whether these discrepant results are due to fundamental differences between the substrains of rats used in the conflicting experiments. To this end, retrograde tract tracing experiments were done using Sprague-Dawley rats from either Sasco, Inc. or Harlan Sprague-Dawley, Inc. The results indicate that noradrenergic neurons in the pontine catecholamine cell groups exhibit remarkably different spinal cord projections in these two substrains of Sprague-Dawley derived rats.

    View details for Web of Science ID A1991FL17600015

    View details for PubMedID 1715531



    Stimulation of neurons located in the ventromedial medulla (VMM), including the nucleus raphe magnus (RMg), produces antinociception which appears to be mediated in part by activation of spinally-projecting noradrenergic neurons located in the A7 catecholamine nucleus. Although the identity of the VMM neurons that project to the A7 nucleus is not known, there is indirect evidence that these neurons contain substance P. This possibility was examined by injecting the retrograde tracer Fluoro-Gold into the A7 nucleus and determining whether substance P-immunoreactive neurons in the VMM were labeled with Fluoro-Gold. The results of these experiments demonstrated that numerous substance P-immunoreactive cells in the RMg, gigantocellular reticular nucleus pars alpha and the paragigantocellular reticular nucleus were retrogradely labeled by an injection of Fluoro-Gold into the A7 nucleus. These observations indicate that substance P-containing neurons in these areas of the VMM project to the A7 nucleus. Thus, the antinociception induced by stimulation of the VMM may be mediated by activation of substance P-containing neurons that project to and activate spinally projecting noradrenergic neurons in the A7 nucleus.

    View details for Web of Science ID A1990EK05900045

    View details for PubMedID 1704291



    A variety of forms of painful stimulation were delivered to human subjects in order to determine whether therapeutic dosages of systemic morphine might produce significant attenuation of some forms of phasic pain that are tolerable for experimental usage. Consistent with previous reports, simple application of thermal or electrical energy to the skin (for 3 sec) produced sensations of pain that were not significantly reduced by prior administration of morphine. Similarly, subjects that were trained to focus their attention on the magnitude of the immediate (first) pain sensation evoked by brief electrical or mechanical stimulation did not report reduction by morphine of pain attributed to conduction in myelinated peripheral nociceptors. In contrast, the magnitude of late (second) pain sensations produced by brief pulses of electrical, thermal or mechanical stimuli to the same subjects was consistently reduced significantly by doses of 5 or 10 mg of morphine. The simplest interpretation of the effect on second pain intensity is that morphine preferentially attenuates input from unmyelinated nociceptors. This conclusion was reinforced by an experiment in which chemicals were applied to the skin. Morphine reduced pain produced by capsaicin (presumed to selectively excite unmyelinated peripheral afferents) but did not diminish pain elicited by bradykinin (presumed to excite A delta and C nociceptors). Comparing long duration pains from chemical stimulation (lasting in excess of 5 min) with briefer pains elicited by 50 msec to 3 sec of stimulation did not support the notion that morphine acts selectively on tonic pain. Also, after-sensations that could be discerned following second pain were not eliminated by morphine, and paired pulse facilitation of first pain sensations remained after administration of morphine, indicating that temporal summation is not preferentially reduced. Regardless of duration, frequency or latency, pain arising exclusively from unmyelinated nociceptors was attenuated substantially, but other elicited sensations were not reliably affected. For example, detection thresholds for warmth were unaffected by morphine, demonstrating that input from all unmyelinated afferents is not reduced.

    View details for Web of Science ID A1986A042400009

    View details for PubMedID 3951883

  • The spinal pathways contributing to the ascending conduction and the descending modulation of pain sensations and reactions Spinal Afferent Processing Vierck, C. C., Greenspan, J. D., Ritz, L., Yeomans, D. C. 1986: 275?329
  • Effects of systemic morphine on monkeys and man Somatosensory Mechanisms Vierck, C., Cooper, B. Y., Cohen, R., Yeomans, D. C., Franzen, O. MacMillan Press. 1984: 309?321

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