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Kim SE, Kim YJ, Kim YW, Cheon YW. Heating Pretreatment of the Recipient Site Enhances Survival of Transplanted Fat in a Mouse Model. Plast Reconstr Surg 2023; 152:787-795. [PMID: 36847665 DOI: 10.1097/prs.0000000000010328] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/01/2023]
Abstract
BACKGROUND Despite several studies about the preparation of the recipient site in fat grafting, optimizing techniques with clinical usefulness is still necessary. Through previous animal studies reporting that heat can increase tissue vascular endothelial growth factor and vascular permeability, the authors hypothesize that pretreatment heating of the recipient site will increase retention of grafted fat. METHODS Twenty 6-week-old female BALB/c mice had two pretreatment sites on their back, one for the experimental temperatures (44°C and 48°C) and the other for the control. A digitally controlled aluminum block was used to apply the contact thermal damage. Human fat (0.5 mL) was grafted on each site and harvested on days 7, 14, and 49. The percentage volume and weight, histologic changes, and peroxisome proliferator-activated receptor gamma expression, a key regulator of adipogenesis, were measured by the water displacement method, light microscopy, and quantitative real-time polymerase chain reaction, respectively. RESULTS The harvested percentage volumes were 74.0% ± 3.4%, 82.5% ± 5.0%, and 67.5% ± 9.6% for the control, 44°C-pretreatment, and 48°C-pretreatment groups, respectively. The percentage volume and weight of the 44°C-pretreatment group was higher than the other groups ( P < 0.05). The 44°C-pretreatment group exhibited significantly higher integrity with fewer cysts and vacuoles than the other groups. Both heating pretreatment groups showed markedly higher rates of vascularity than the control group ( P < 0.017), and also increased the expression of peroxisome proliferator-activated receptor gamma over two-fold. CONCLUSION Heating preconditioning of the recipient site during fat grafting can increase the retention volume and improve the integrity, which is partly explained by increased adipogenesis in a short-term mouse model. CLINICAL RELEVANCE STATEMENT Tanning could be an alternative pretreatment for fat grafting.
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Affiliation(s)
- Sun Eung Kim
- From the Department of Plastic and Reconstructive Surgery, Gil Medical Center, Gachon University College of Medicine
| | - Yu Jin Kim
- From the Department of Plastic and Reconstructive Surgery, Gil Medical Center, Gachon University College of Medicine
| | - Yang Woo Kim
- From the Department of Plastic and Reconstructive Surgery, Gil Medical Center, Gachon University College of Medicine
| | - Young Woo Cheon
- From the Department of Plastic and Reconstructive Surgery, Gil Medical Center, Gachon University College of Medicine
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2
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Currò D, Navarra P, Samengo I, Martire M. P2X7 receptors exert a permissive effect on the activation of presynaptic AMPA receptors in rat trigeminal caudal nucleus glutamatergic nerve terminals. J Headache Pain 2020; 21:83. [PMID: 32615921 PMCID: PMC7330953 DOI: 10.1186/s10194-020-01153-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2020] [Accepted: 06/29/2020] [Indexed: 12/12/2022] Open
Abstract
Background Purine receptors play roles in peripheral and central sensitization and are associated with migraine headache. We investigated the possibility that ATP plays a permissive role in the activation of AMPA receptors thus inducing Glu release from nerve terminals isolated from the rat trigeminal caudal nucleus (TCN). Methods Nerve endings isolated from the rat TCN were loaded with [3H]D-aspartic acid ([3H]D-ASP), layered into thermostated superfusion chambers, and perfused continuously with physiological medium, alone or with various test drugs. Radioactivity was measured to assess [3H]D-ASP release under different experimental conditions. Results Synaptosomal [3H]D-ASP spontaneous release was stimulated by ATP and to an even greater extent by the ATP analogue benzoylbenzoylATP (BzATP). The stimulation of [3H]D-ASP basal release by the purinergic agonists was prevented by the selective P2X7 receptor antagonist A438079. AMPA had no effect on basal [3H]D-ASP release, but the release observed when synaptosomes were exposed to AMPA plus a purinoceptor agonist exceeded that observed with ATP or BzATP alone. The selective AMPA receptor antagonist NBQX blocked this “excess” release. Co-exposure to AMPA and BzATP, each at a concentration with no release-stimulating effects, evoked a significant increase in [3H]D-ASP basal release, which was prevented by exposure to a selective AMPA antagonist. Conclusions P2X7 receptors expressed on glutamatergic nerve terminals in the rat TCN can mediate Glu release directly and indirectly by facilitating the activation of presynaptic AMPA receptors. The high level of glial ATP that occurs during chronic pain states can promote widespread release of Glu as well as can increase the function of AMPA receptors. In this manner, ATP contributes to the AMPA receptor activation involved in the onset and maintenance of the central sensitization associated with chronic pain.
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Affiliation(s)
- Diego Currò
- Institute of Pharmacology, School of Medicine, Università Cattolica del Sacro Cuore, Largo Francesco Vito, 1, 00168, Rome, Italy
| | - Pierluigi Navarra
- Institute of Pharmacology, School of Medicine, Università Cattolica del Sacro Cuore, Largo Francesco Vito, 1, 00168, Rome, Italy
| | - Irene Samengo
- Institute of Pharmacology, School of Medicine, Università Cattolica del Sacro Cuore, Largo Francesco Vito, 1, 00168, Rome, Italy
| | - Maria Martire
- Institute of Pharmacology, School of Medicine, Università Cattolica del Sacro Cuore, Largo Francesco Vito, 1, 00168, Rome, Italy.
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3
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Morgan M, Deuis JR, Frøsig-Jørgensen M, Lewis RJ, Cabot PJ, Gray PD, Vetter I. Burn Pain: A Systematic and Critical Review of Epidemiology, Pathophysiology, and Treatment. PAIN MEDICINE 2019; 19:708-734. [PMID: 29036469 DOI: 10.1093/pm/pnx228] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Objective This review aims to examine the available literature on the epidemiology, pathophysiology, and treatment of burn-induced pain. Methods A search was conducted on the epidemiology of burn injury and treatment of burn pain utilizing the database Medline, and all relevant articles were systemically reviewed. In addition, a critical review was performed on the pathophysiology of burn pain and animal models of burn pain. Results The search on the epidemiology of burn injury yielded a total of 163 publications of interest, 72 of which fit the inclusion/exclusion criteria, with no publications providing epidemiological data on burn injury pain management outcomes. The search on the treatment of burn pain yielded a total of 213 publications, 14 of which fit the inclusion/exclusion criteria, highlighting the limited amount of evidence available on the treatment of burn-induced pain. Conclusions The pathophysiology of burn pain is poorly understood, with limited clinical trials available to assess the effectiveness of analgesics in burn patients. Further studies are needed to identify new pharmacological targets and treatments for the effective management of burn injury pain.
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Affiliation(s)
- Michael Morgan
- Centre for Pain Research, Institute for Molecular Bioscience, The University of Queensland, St Lucia, Queensland, Australia
| | - Jennifer R Deuis
- Centre for Pain Research, Institute for Molecular Bioscience, The University of Queensland, St Lucia, Queensland, Australia
| | - Majbrit Frøsig-Jørgensen
- Centre for Pain Research, Institute for Molecular Bioscience, The University of Queensland, St Lucia, Queensland, Australia
| | - Richard J Lewis
- Centre for Pain Research, Institute for Molecular Bioscience, The University of Queensland, St Lucia, Queensland, Australia
| | - Peter J Cabot
- School of Pharmacy, The University of Queensland, Wooloongabba, Queensland, Australia
| | - Paul D Gray
- Tess Cramond Multidisciplinary Pain Centre, Royal Brisbane & Women's Hospital, Metro North Health, Herston, Queensland, Australia.,School of Medicine, The University of Queensland, Herston, Queensland, Australia
| | - Irina Vetter
- Centre for Pain Research, Institute for Molecular Bioscience, The University of Queensland, St Lucia, Queensland, Australia.,School of Pharmacy, The University of Queensland, Wooloongabba, Queensland, Australia
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Yaksh TL, Fisher CJ, Hockman TM, Wiese AJ. Current and Future Issues in the Development of Spinal Agents for the Management of Pain. Curr Neuropharmacol 2017; 15:232-259. [PMID: 26861470 PMCID: PMC5412694 DOI: 10.2174/1570159x14666160307145542] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2015] [Revised: 12/02/2015] [Accepted: 02/05/2016] [Indexed: 11/22/2022] Open
Abstract
Targeting analgesic drugs for spinal delivery reflects the fact that while the conscious experience of pain is mediated supraspinally, input initiated by high intensity stimuli, tissue injury and/or nerve injury is encoded at the level of the spinal dorsal horn and this output informs the brain as to the peripheral environment. This encoding process is subject to strong upregulation resulting in hyperesthetic states and downregulation reducing the ongoing processing of nociceptive stimuli reversing the hyperesthesia and pain processing. The present review addresses the biology of spinal nociceptive processing as relevant to the effects of intrathecally-delivered drugs in altering pain processing following acute stimulation, tissue inflammation/injury and nerve injury. The review covers i) the major classes of spinal agents currently employed as intrathecal analgesics (opioid agonists, alpha 2 agonists; sodium channel blockers; calcium channel blockers; NMDA blockers; GABA A/B agonists; COX inhibitors; ii) ongoing developments in the pharmacology of spinal therapeutics focusing on less studied agents/targets (cholinesterase inhibition; Adenosine agonists; iii) novel intrathecal targeting methodologies including gene-based approaches (viral vectors, plasmids, interfering RNAs); antisense, and toxins (botulinum toxins; resniferatoxin, substance P Saporin); and iv) issues relevant to intrathecal drug delivery (neuraxial drug distribution), infusate delivery profile, drug dosing, formulation and principals involved in the preclinical evaluation of intrathecal drug safety.
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Affiliation(s)
- Tony L. Yaksh
- University of California, San Diego, Anesthesia Research Lab 0818, 9500 Gilman Dr. LaJolla, CA 92093, USA
| | - Casey J. Fisher
- University of California, San Diego, Anesthesia Research Lab 0818, 9500 Gilman Dr. LaJolla, CA 92093, USA
| | - Tyler M. Hockman
- University of California, San Diego, Anesthesia Research Lab 0818, 9500 Gilman Dr. LaJolla, CA 92093, USA
| | - Ashley J. Wiese
- University of California, San Diego, Anesthesia Research Lab 0818, 9500 Gilman Dr. LaJolla, CA 92093, USA
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Ellis A, Grace PM, Wieseler J, Favret J, Springer K, Skarda B, Hutchinson MR, Falci S, Rice KC, Maier SF, Watkins LR, Watkins LR. Morphine amplifies mechanical allodynia via TLR4 in a rat model of spinal cord injury. Brain Behav Immun 2016; 58:348-356. [PMID: 27519154 PMCID: PMC5067205 DOI: 10.1016/j.bbi.2016.08.004] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/02/2016] [Revised: 08/07/2016] [Accepted: 08/07/2016] [Indexed: 01/09/2023] Open
Abstract
Central neuropathic pain (CNP) is a pervasive, debilitating problem that impacts thousands of people living with central nervous system disorders, including spinal cord injury (SCI). Current therapies for treating this type of pain are ineffective and often have dose-limiting side effects. Although opioids are one of the most commonly used CNP treatments, recent animal literature has indicated that administering opioids shortly after a traumatic injury can actually have deleterious effects on long-term health and recovery. In order to study the deleterious effects of administering morphine shortly after trauma, we employed our low thoracic (T13) dorsal root avulsion model (Spinal Neuropathic Avulsion Pain, SNAP). Administering a weeklong course of 10mg/kg/day morphine beginning 24h after SNAP resulted in amplified mechanical allodynia. Co-administering the non-opioid toll-like receptor 4 (TLR4) antagonist (+)-naltrexone throughout the morphine regimen prevented morphine-induced amplification of SNAP. Exploration of changes induced by early post-trauma morphine revealed that this elevated gene expression of TLR4, TNF, IL-1β, and NLRP3, as well as IL-1β protein at the site of spinal cord injury. These data suggest that a short course of morphine administered early after spinal trauma can exacerbate CNP in the long term. TLR4 initiates this phenomenon and, as such, may be potential therapeutic targets for preventing the deleterious effects of administering opioids after traumatic injury.
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Affiliation(s)
- Amanda Ellis
- University of Colorado Boulder, Department of Psychology and Neuroscience, Center for Neuroscience, Boulder, CO, USA
| | - Peter M. Grace
- University of Colorado Boulder, Department of Psychology and Neuroscience, Center for Neuroscience, Boulder, CO, USA,School of Medicine, University of Adelaide, Adelaide, SA, Australia
| | - Julie Wieseler
- University of Colorado Boulder, Department of Psychology and Neuroscience, Center for Neuroscience, Boulder, CO, USA
| | - Jacob Favret
- University of Colorado Boulder, Department of Psychology and Neuroscience, Center for Neuroscience, Boulder, CO, USA
| | - Kendra Springer
- University of Colorado Boulder, Department of Psychology and Neuroscience, Center for Neuroscience, Boulder, CO, USA
| | - Bryce Skarda
- University of Colorado Boulder, Department of Psychology and Neuroscience, Center for Neuroscience, Boulder, CO, USA
| | - Mark R. Hutchinson
- School of Medicine, University of Adelaide, Adelaide, SA, Australia,Australian Research Council Centre of Excellence for Nanoscale BioPhotonics, Australia
| | | | - Kenner C. Rice
- Chemical Biology Research Branch, National Institute on Drug Abuse and National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Rockville, MD, USA
| | - Steven F. Maier
- University of Colorado Boulder, Department of Psychology and Neuroscience, Center for Neuroscience, Boulder, CO, USA
| | - Linda R. Watkins
- University of Colorado Boulder, Department of Psychology and Neuroscience, Center for Neuroscience, Boulder, CO, USA,Corresponding author: Linda R. Watkins, Department of Psychology & Neuroscience, Campus Box 345, University of Colorado Boulder, Boulder, CO 80309-0345, , Phone: 303-492-7034, Fax: 303-492-2967
| | - Linda R Watkins
- University of Colorado Boulder, Department of Psychology and Neuroscience, Center for Neuroscience, Boulder, CO, USA.
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Green D, Ruparel S, Gao X, Ruparel N, Patil M, Akopian A, Hargreaves K. Central activation of TRPV1 and TRPA1 by novel endogenous agonists contributes to mechanical allodynia and thermal hyperalgesia after burn injury. Mol Pain 2016; 12:12/0/1744806916661725. [PMID: 27411353 PMCID: PMC4955965 DOI: 10.1177/1744806916661725] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The primary complaint of burn victims is an intense, often devastating spontaneous pain, with persistence of mechanical and thermal allodynia. The transient receptor potential channels, TRPV1 and TRPA1, are expressed by a subset of nociceptive sensory neurons and contribute to inflammatory hypersensitivity. Although their function in the periphery is well known, a role for these TRP channels in central pain mechanisms is less well defined. Lipid agonists of TRPV1 are released from peripheral tissues via enzymatic oxidation after burn injury; however, it is not known if burn injury triggers the release of oxidized lipids in the spinal cord. Accordingly, we evaluated whether burn injury evoked the central release of oxidized lipids. Analysis of lipid extracts of spinal cord tissue with HPLC-MS revealed a significant increase in levels of the epoxide and diol metabolites of linoleic acid: 9,10-DiHOME, 12,13-DiHOME, 9(10)-EpOME, and 12(13)-EpOME, that was reduced after intrathecal (i.t.) injection of the oxidative enzyme inhibitor ketoconazole. Moreover, we found that these four lipid metabolites were capable of specifically activating both TRPV1 and TRPA1. Intrathecal injection of specific antagonists to TRPV1 (AMG-517) or TRPA1 (HC-030031) significantly reduced post-burn mechanical and thermal allodynia. Finally, i.t. injection of ketoconazole significantly reversed post-burn mechanical and thermal allodynia. Our data indicate that spinal cord TRPV1 and TRPA1 contributes to pain after burn and identifies a novel class of oxidized lipids elevated in the spinal cord after burn injury. Since the management of burn pain is problematic, these findings point to a novel approach for treating post-burn pain.
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Affiliation(s)
- Dustin Green
- University of Texas Health Science Center at San Antonio
| | | | - Xiaoli Gao
- University of Texas Health Science Center at San Antonio
| | - Nikita Ruparel
- University of Texas Health Science Center at San Antonio
| | - Mayur Patil
- University of Texas Health Science Center at San Antonio
| | - Armen Akopian
- University of Texas Health Science Center at San AntonioUniversity of Texas Health Science Center at San AntonioUniversity of Texas Health Science Center at San AntonioUniversity of Texas Health Science Center at San AntonioUniversity of Texas Health Science Center at San AntonioUniversity of Texas Health Science Center at San Antonio
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7
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Kopach O, Krotov V, Goncharenko J, Voitenko N. Inhibition of Spinal Ca(2+)-Permeable AMPA Receptors with Dicationic Compounds Alleviates Persistent Inflammatory Pain without Adverse Effects. Front Cell Neurosci 2016; 10:50. [PMID: 26973464 PMCID: PMC4770326 DOI: 10.3389/fncel.2016.00050] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2015] [Accepted: 02/13/2016] [Indexed: 11/17/2022] Open
Abstract
Upregulation of Ca2+-permeable AMPA receptors (CP-AMPARs) in the dorsal horn (DH) neurons of the spinal cord has been causally linked to the maintenance of persistent inflammatory pain. Therefore, inhibition of CP-AMPARs could potentially alleviate an, otherwise, poorly treatable chronic pain. However, a loss of CP-AMPARs could produce considerable side effects because of the crucial role of CP-AMPARs in synaptic plasticity. Here we have tested whether the inhibition of spinal CP-AMPARs with dicationic compounds, the open-channel antagonists acting in an activity-dependent manner, can relieve inflammatory pain without adverse effects being developed. Dicationic compounds, N1-(1-phenylcyclohexyl)pentane-1,5-diaminium bromide (IEM-1925) and 1-trimethylammonio-5-1-adamantane-methyl-ammoniopentane dibromide (IEM-1460) were applied intrathecally (i.t.) as a post-treatment for inflammatory pain in the model of complete Freund’s adjuvant (CFA)-induced long-lasting peripheral inflammation. The capability of dicationic compounds to ameliorate inflammatory pain was tested in rats in vivo using the Hargreaves, the von Frey and the open-field tests. Treatment with IEM-1460 or IEM-1925 resulted in profound alleviation of inflammatory pain. The pain relief appeared shortly after compound administration. The effects were concentration-dependent, displaying a high potency of dicationic compounds for alleviation of inflammatory hyperalgesia in the micromolar range, for both acute and long-lasting responses. The period of pain maintenance was shortened following treatment. Treatment with IEM-1460 or IEM-1925 changed neither thermal and mechanical basal sensitivities nor animal locomotion, suggesting that inhibition of CP-AMPARs with dicationic compounds does not give rise to detectable side effects. Thus, the ability of dicationic compounds to alleviate persistent inflammatory pain may provide new routes in the treatment of chronic pain.
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Affiliation(s)
- Olga Kopach
- Laboratory of Sensory Signaling, Bogomoletz Institute of PhysiologyKyiv, Ukraine; Laboratory of Synaptic Imaging, Institute of Neurology, University College LondonLondon, UK
| | - Volodymyr Krotov
- Laboratory of Sensory Signaling, Bogomoletz Institute of Physiology Kyiv, Ukraine
| | - Julia Goncharenko
- Laboratory of Sensory Signaling, Bogomoletz Institute of Physiology Kyiv, Ukraine
| | - Nana Voitenko
- Laboratory of Sensory Signaling, Bogomoletz Institute of PhysiologyKyiv, Ukraine; International Center for Molecular Physiology, Bogomoletz Institute of PhysiologyKyiv, Ukraine
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8
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Yaksh TL, Woller SA, Ramachandran R, Sorkin LS. The search for novel analgesics: targets and mechanisms. F1000PRIME REPORTS 2015; 7:56. [PMID: 26097729 PMCID: PMC4447049 DOI: 10.12703/p7-56] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The management of the pain state is of great therapeutic relevance to virtually every medical specialty. Failure to manage its expression has deleterious consequence to the well-being of the organism. An understanding of the complex biology of the mechanisms underlying the processing of nociceptive information provides an important pathway towards development of novel and robust therapeutics. Importantly, preclinical models have been of considerable use in determining the linkage between mechanism and the associated behaviorally defined pain state. This review seeks to provide an overview of current thinking targeting pain biology, the use of preclinical models and the development of novel pain therapeutics. Issues pertinent to the strengths and weaknesses of current development strategies for analgesics are considered.
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9
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Challenor M, O'Hare Doig R, Fuller P, Giacci M, Bartlett C, Wale CH, Cozens GS, Hool L, Dunlop S, Swaminathan Iyer K, Rodger J, Fitzgerald M. Prolonged glutamate excitotoxicity increases GluR1 immunoreactivity but decreases mRNA of GluR1 and associated regulatory proteins in dissociated rat retinae in vitro. Biochimie 2015; 112:160-71. [DOI: 10.1016/j.biochi.2015.03.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2015] [Accepted: 03/06/2015] [Indexed: 12/15/2022]
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Garraway SM, Woller SA, Huie JR, Hartman JJ, Hook MA, Miranda RC, Huang YJ, Ferguson AR, Grau JW. Peripheral noxious stimulation reduces withdrawal threshold to mechanical stimuli after spinal cord injury: role of tumor necrosis factor alpha and apoptosis. Pain 2014; 155:2344-59. [PMID: 25180012 DOI: 10.1016/j.pain.2014.08.034] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2014] [Revised: 08/12/2014] [Accepted: 08/26/2014] [Indexed: 01/23/2023]
Abstract
We previously showed that peripheral noxious input after spinal cord injury (SCI) inhibits beneficial spinal plasticity and impairs recovery of locomotor and bladder functions. These observations suggest that noxious input may similarly affect the development and maintenance of chronic neuropathic pain, an important consequence of SCI. In adult rats with a moderate contusion SCI, we investigated the effect of noxious tail stimulation, administered 1 day after SCI on mechanical withdrawal responses to von Frey stimuli from 1 to 28 days after treatment. In addition, because the proinflammatory cytokine tumor necrosis factor alpha (TNFα) is implicated in numerous injury-induced processes including pain hypersensitivity, we assessed the temporal and spatial expression of TNFα, TNF receptors, and several downstream signaling targets after stimulation. Our results showed that unlike sham surgery or SCI only, nociceptive stimulation after SCI induced mechanical sensitivity by 24h. These behavioral changes were accompanied by increased expression of TNFα. Cellular assessments of downstream targets of TNFα revealed that nociceptive stimulation increased the expression of caspase 8 and the active subunit (12 kDa) of caspase 3, indicative of active apoptosis at a time point consistent with the onset of mechanical allodynia. In addition, immunohistochemical analysis revealed distinct morphological signs of apoptosis in neurons and microglia at 24h after stimulation. Interestingly, expression of the inflammatory mediator NFκB was unaltered by nociceptive stimulation. These results suggest that noxious input caudal to the level of SCI can increase the onset and expression of behavioral responses indicative of pain, potentially involving TNFα signaling.
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Affiliation(s)
- Sandra M Garraway
- Department of Psychology, Texas A&M University, College Station, TX 77843, USA.
| | - Sarah A Woller
- Department of Psychology, Texas A&M University, College Station, TX 77843, USA
| | - J Russell Huie
- Department of Neurological Surgery, Brain and Spinal Injury Center (BASIC), University of California, San Francisco, 1001 Potrero Ave, Bldg 1, Room 101, San Francisco, CA 94110, USA
| | - John J Hartman
- Department of Psychology, Texas A&M University, College Station, TX 77843, USA
| | - Michelle A Hook
- Department of Psychology, Texas A&M University, College Station, TX 77843, USA
| | - Rajesh C Miranda
- Department of Neuroscience and Experimental Therapeutics, Texas A&M Health Science Center, College of Medicine, Medical Research and Education Bldg, 8447 State Highway 47, Bryan, TX 77807-3260, USA
| | - Yung-Jen Huang
- Department of Psychology, Texas A&M University, College Station, TX 77843, USA
| | - Adam R Ferguson
- Department of Neurological Surgery, Brain and Spinal Injury Center (BASIC), University of California, San Francisco, 1001 Potrero Ave, Bldg 1, Room 101, San Francisco, CA 94110, USA
| | - James W Grau
- Department of Psychology, Texas A&M University, College Station, TX 77843, USA
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11
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Ellis A, Wieseler J, Favret J, Johnson KW, Rice KC, Maier SF, Falci S, Watkins LR. Systemic administration of propentofylline, ibudilast, and (+)-naltrexone each reverses mechanical allodynia in a novel rat model of central neuropathic pain. THE JOURNAL OF PAIN 2014; 15:407-21. [PMID: 24412802 DOI: 10.1016/j.jpain.2013.12.007] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2013] [Revised: 12/30/2013] [Accepted: 12/31/2013] [Indexed: 12/29/2022]
Abstract
UNLABELLED Central neuropathic pain (CNP) is a debilitating consequence of central nervous system damage for which current treatments are ineffective. To explore mechanisms underlying CNP, we developed a rat model involving T13/L1 dorsal root avulsion. The resultant dorsal horn damage creates bilateral below-level (L4-L6) mechanical allodynia. This allodynia, termed spinal neuropathic avulsion pain, occurs in the absence of confounding paralysis. To characterize this model, we undertook a series of studies aimed at defining whether spinal neuropathic avulsion pain could be reversed by any of 3 putative glial activation inhibitors, each with distinct mechanisms of action. Indeed, the phosphodiesterase inhibitor propentofylline, the macrophage migration inhibitory factor inhibitor ibudilast, and the toll-like receptor 4 antagonist (+)-naltrexone each reversed below-level allodynia bilaterally. Strikingly, none of these impacted spinal neuropathic avulsion pain upon first administration but required 1 to 2 weeks of daily administration before pain reversal was obtained. Given reversal of CNP by each of these glial modulatory agents, these results suggest that glia contribute to the maintenance of such pain and enduring release of macrophage migration inhibitory factor and endogenous agonists of toll-like receptor 4 is important for sustaining CNP. The markedly delayed efficacy of all 3 glial modulatory drugs may prove instructive for interpretation of apparent drug failures after shorter dosing regimens. PERSPECTIVE CNP that develops after trauma is often described by patients as severe and intolerable. Unfortunately, current treatments are not effective. This work suggests that using pharmacologic treatments that target glial cells could be an effective clinical treatment for CNP.
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Affiliation(s)
- Amanda Ellis
- Department of Psychology and Neuroscience, University of Colorado Boulder, Boulder, Colorado.
| | - Julie Wieseler
- Department of Psychology and Neuroscience, University of Colorado Boulder, Boulder, Colorado
| | - Jacob Favret
- Department of Psychology and Neuroscience, University of Colorado Boulder, Boulder, Colorado
| | | | - Kenner C Rice
- Chemical Biology Research Branch, National Institute on Drug Abuse and National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Rockville, Maryland
| | - Steven F Maier
- Department of Psychology and Neuroscience, University of Colorado Boulder, Boulder, Colorado
| | | | - Linda R Watkins
- Department of Psychology and Neuroscience, University of Colorado Boulder, Boulder, Colorado
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Banerjee B, Medda BK, Pochiraju S, Kannampalli P, Lang IM, Sengupta JN, Shaker R. AMPA receptor subunits expression and phosphorylation in cingulate cortex in rats following esophageal acid exposure. Neurogastroenterol Motil 2013; 25:973-e776. [PMID: 24118589 PMCID: PMC4097166 DOI: 10.1111/nmo.12233] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/28/2013] [Accepted: 08/15/2013] [Indexed: 02/08/2023]
Abstract
BACKGROUND We recently reported an increase in N-methyl-d-aspartate (NMDA) receptor subunit expression and CaMKII-dependent phosphorylation of NR2B in the rostral cingulate cortical (rCC) neurons following esophageal acid exposure in rats. As α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) receptors mediate the fast excitatory transmission and play a critical role in synaptic plasticity, in this study, we investigated the effect of esophageal acid exposure in rats on the expression of AMPA receptor subunits and the involvement of these molecular alterations in acid-induced sensitization of neurons in the anterior cingulate (ACC) and midcingulate (MCC) cortices. METHODS In molecular study, we examined GluA1 and GluA2 expression and phosphorylation in membrane preparations and in the isolated postsynaptic densities (PSDs) from rats receiving acute esophageal exposure of either saline (control group) or 0.1 N HCl (experimental group). In electrophysiological study, the effect of selective AMPA receptor (Ca(2+) permeable) antagonist IEM-1460 and CaMKII inhibitor KN-93 was tested on responses of cortical neurons during acid infusion to address the underlying molecular mechanism of acid-induced sensitization. KEY RESULTS The acid exposure significantly increased expression of GluA1, pGluA1Ser(831) , and phosphorylated CaMKIIThr(286) , in the cortical membrane preparations. In isolated PSDs, a significant increase in pGluA1Ser(831) was observed in acid-treated rats compared with controls. Microinjection of IEM-1460 or KN-93 near the recording site significantly attenuated acid-induced sensitization of cortical neurons. CONCLUSIONS & INFERENCES The underlying mechanism of acid-induced cortical sensitization involves upregulation and CaMKII-mediated phosphorylation of GluA1. These molecular changes of AMPA receptors subunit GluA1 in the cortical neurons might play an important role in acid-induced esophageal hypersensitivity.
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Affiliation(s)
- B. Banerjee
- Division of Gastroenterology & Hepatology; Medical College of Wisconsin; Milwaukee WI USA
| | - B. K. Medda
- Division of Gastroenterology & Hepatology; Medical College of Wisconsin; Milwaukee WI USA
| | - S. Pochiraju
- Division of Gastroenterology & Hepatology; Medical College of Wisconsin; Milwaukee WI USA
| | - P. Kannampalli
- Division of Gastroenterology & Hepatology; Medical College of Wisconsin; Milwaukee WI USA
| | - I. M. Lang
- Division of Gastroenterology & Hepatology; Medical College of Wisconsin; Milwaukee WI USA
| | - J. N. Sengupta
- Division of Gastroenterology & Hepatology; Medical College of Wisconsin; Milwaukee WI USA
| | - R. Shaker
- Division of Gastroenterology & Hepatology; Medical College of Wisconsin; Milwaukee WI USA
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Ambriz-Tututi M, Palomero-Rivero M, Ramirez-López F, Millán-Aldaco D, Drucker-Colín AR. Role of glutamate receptors in the dorsal reticular nucleus in formalin-induced secondary allodynia. Eur J Neurosci 2013; 38:3008-17. [PMID: 23869620 DOI: 10.1111/ejn.12302] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2012] [Revised: 05/16/2013] [Accepted: 06/09/2013] [Indexed: 12/29/2022]
Abstract
The role of glutamate receptors present in the medullary dorsal reticular nucleus (DRt) in the formalin test and formalin-induced secondary nociception was studied in rats. Secondary mechanical allodynia was assessed with von Frey filaments applied to the rat's hindpaw, and secondary thermal hyperalgesia was evaluated with the tail-immersion test. The selective glutamate receptor antagonists MK801 (N-methyl-D-aspartate receptor antagonist), 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) (AMPA/KA receptor antagonist) and A841720 (metabotropic glutamate 1 receptor antagonist) were injected into the DRt before or 6 days after formalin injection in the rat. In the formalin test, the three antagonists significantly reduced the number of flinches in both phases of the test. DRt microinjection of MK801 or A841720, but not of CNQX, reduced both secondary nociceptive behaviors. Moreover, pre-treatment with the three antagonists injected into the DRt prevented the development of secondary mechanical allodynia and secondary thermal hyperalgesia. Similarly, in these rats, the number of c-Fos-like immunoreactive neurons were markedly reduced in both the superficial and deep lamina of the dorsal horn. Our findings support the role of DRt as a pain facilitator in acute and chronic pain states, and suggest a key role of glutamate receptors during the development and maintenance of formalin-induced secondary allodynia.
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Affiliation(s)
- Mónica Ambriz-Tututi
- División de Neurociencias, Departamento de Neuropatología Molecular, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, México DF, México
| | - Marcela Palomero-Rivero
- División de Neurociencias, Departamento de Neuropatología Molecular, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, México D.F, México
| | - Fernanda Ramirez-López
- División de Neurociencias, Departamento de Neuropatología Molecular, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, México D.F, México
| | - Diana Millán-Aldaco
- División de Neurociencias, Departamento de Neuropatología Molecular, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, México D.F, México
| | - And René Drucker-Colín
- División de Neurociencias, Departamento de Neuropatología Molecular, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, México D.F, México
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14
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Naka A, Gruber-Schoffnegger D, Sandkühler J. Non-Hebbian plasticity at C-fiber synapses in rat spinal cord lamina I neurons. Pain 2013; 154:1333-42. [PMID: 23707311 PMCID: PMC3708128 DOI: 10.1016/j.pain.2013.04.011] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2012] [Revised: 03/26/2013] [Accepted: 04/03/2013] [Indexed: 11/23/2022]
Abstract
Current concepts of memory storage are largely based on Hebbian-type synaptic long-term potentiation induced by concurrent activity of pre- and postsynaptic neurons. Little is known about non-Hebbian synaptic plasticity, which, if present in nociceptive pathways, could resolve a number of unexplained findings. We performed whole-cell patch-clamp recordings in rat spinal cord slices and found that a rise in postsynaptic [Ca2+]i due to postsynaptic depolarization was sufficient to induce synaptic long-term potentiation (LTP) in the absence of any presynaptic conditioning stimulation. LTP induction could be prevented by postsynaptic application of the Ca2+ chelator BAPTA (1,2-bis(o-aminophenoxy)ethane-N,N,N′,N′-tetraacetic acid), the L-type voltage-gated calcium channel (VGCC) antagonist nifedipine, and by postsynaptic application of the NMDA receptor antagonist MK801. This indicates that synaptic potentiation was induced postsynaptically by Ca2+ entry likely via L-type voltage-gated Ca2+ channels (VGCC) and via NMDA receptor channels. The paired pulse ratio and the coefficient of variation remained unchanged in neurons expressing LTP, suggesting that this form of synaptic potentiation was not only induced, but also expressed postsynaptically. Postsynaptic depolarization had no influence on firing patterns, action potential shape, or neuronal excitability. An increase in [Ca2+]i in spinal lamina I neurons induces a non-Hebbian form of synaptic plasticity in spinal nociceptive pathways without affecting neuronal active and passive membrane properties.
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Affiliation(s)
- Asami Naka
- Department of Neurophysiology, Center for Brain Research, Medical University of Vienna, Spitalgasse 4, 1090 Vienna, Austria
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15
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Lee DZ, Chung JM, Chung K, Kang MG. Reactive oxygen species (ROS) modulate AMPA receptor phosphorylation and cell-surface localization in concert with pain-related behavior. Pain 2012; 153:1905-1915. [PMID: 22770842 DOI: 10.1016/j.pain.2012.06.001] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2012] [Revised: 05/15/2012] [Accepted: 06/01/2012] [Indexed: 10/28/2022]
Abstract
Sensitization of dorsal horn neurons (DHNs) in the spinal cord is dependent on pain-related synaptic plasticity and causes persistent pain. The DHN sensitization is mediated by a signal transduction pathway initiated by the activation of N-methyl-d-aspartate receptors (NMDA-Rs). Recent studies have shown that elevated levels of reactive oxygen species (ROS) and phosphorylation-dependent trafficking of GluA2 subunit of α-amino-3-hydroxy-5-methyl-4-isoxazole propionate receptors (AMPA-Rs) are a part of the signaling pathway for DHN sensitization. However, the relationship between ROS and AMPA-R phosphorylation and trafficking is not known. Thus, this study investigated the effects of ROS scavengers on the phosphorylation and cell-surface localization of GluA1 and GluA2. Intrathecal NMDA- and intradermal capsaicin-induced hyperalgesic mice were used for this study since both pain models share the NMDA-R activation-dependent DHN sensitization in the spinal cord. Our behavioral, biochemical, and immunohistochemical analyses demonstrated that: 1) NMDA-R activation in vivo increased the phosphorylation of AMPA-Rs at GluA1 (S818, S831, and S845) and GluA2 (S880) subunits; 2) NMDA-R activation in vivo increased cell-surface localization of GluA1 but decreased that of GluA2; and 3) reduction of ROS levels by ROS scavengers PBN (N-tert-butyl-α-phenylnitrone) or TEMPOL (4-hydroxy-2, 2, 6, 6-tetramethylpiperidin-1-oxyl) reversed these changes in AMPA-Rs, as well as pain-related behavior. Given that AMPA-R trafficking to the cell surface and synapse is regulated by NMDA-R activation-dependent phosphorylation of GluA1 and GluA2, our study suggests that the ROS-dependent changes in the phosphorylation and cell-surface localization of AMPA-Rs are necessary for DHN sensitization and thus, pain-related behavior. We further suggest that ROS reduction will ameliorate these molecular changes and pain.
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Affiliation(s)
- Daniel Z Lee
- Department of Neuroscience and Cell Biology, University of Texas Medical Branch, Galveston, TX 77555, USA
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16
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Ambriz-Tututi M, Sánchez-González V, Drucker-Colín R. Transcranial magnetic stimulation reduces nociceptive threshold in rats. J Neurosci Res 2012; 90:1085-95. [PMID: 22315163 DOI: 10.1002/jnr.22785] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2011] [Revised: 07/27/2011] [Accepted: 08/23/2011] [Indexed: 11/08/2022]
Abstract
Transcranial magnetic stimulation (TMS) is a procedure that uses magnetic fields to stimulate or inhibit nerve cells in the brain noninvasively. TMS induces an electromagnetic current in the underlying cortical neurons. Varying frequencies and intensities of TMS increase or decrease excitability in the cortical area directly targeted. It has been suggested that TMS has potential in the treatment of some neurological disorders such as Parkinson's disease, stroke, and depression. Initial case reports and open label trials reported by several groups support the use of TMS in pain treatment. In the present study, we evaluated the effect of TMS on the nociceptive threshold in the rat. The parameters used were a frequency of 60 Hz and an intensity of 2 and 6 mT for 2 hr twice per day. After 5 days of TMS treatment, rats were evaluated for mechanical, chemical, and cold stimulation. We observed a significant reduction in the nociceptive threshold in TMS-treated rats but not in sham-treated rats in all behavioral tests evaluated. When TMS treatment was stopped, a slow recovery to normal mechanic threshold was observed. Interestingly, i.c.v. MK-801 or CNQX administration reverted the TMS-induced pronociception. The results suggest that high-frequency TMS can alter the nociceptive threshold and produce allodynia in the rats; results suggest the involvement of NMDA and AMPA/KA receptors on TMS-induced allodynia in the rat.
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Affiliation(s)
- Mónica Ambriz-Tututi
- Departamento de Neuropatología Molecular, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, México D.F., México
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17
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Wieseler J, Ellis AL, McFadden A, Brown K, Starnes C, Maier SF, Watkins LR, Falci S. Below level central pain induced by discrete dorsal spinal cord injury. J Neurotrauma 2011; 27:1697-707. [PMID: 20649467 DOI: 10.1089/neu.2010.1311] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Central neuropathic pain occurs with multiple sclerosis, stroke, and spinal cord injury (SCI). Models of SCI are commonly used to study central neuropathic pain and are excellent at modeling gross physiological changes. Our goal was to develop a rat model of central neuropathic pain by traumatizing a discrete region of the dorsal spinal cord, thereby avoiding issues including paralysis, urinary tract infection, and autotomy. To this end, dorsal root avulsion was pursued. The model was developed by first determining the number of avulsed dorsal roots sufficient to induce below-level hindpaw mechanical allodynia. This was optimally achieved by unilateral T13 and L1 avulsion, which resulted in tissue damage confined to Lissauer's tract, dorsal horn, and dorsal columns, at the site of avulsion, with no gross physical changes at other spinal levels. Behavior following avulsion was compared to that following rhizotomy of the T13 and L1 dorsal roots, a commonly used model of neuropathic pain. Avulsion induced below-level allodynia that was more robust and enduring than that seen after rhizotomy. This, plus the lack of direct spinal cord damage associated with rhizotomy, suggests that avulsion is not synonymous with rhizotomy, and that avulsion (but not rhizotomy) is a model of central neuropathic pain. The new model described here is the first to use discrete dorsal horn damage by dorsal root avulsion to create below-level bilateral central neuropathic pain.
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Affiliation(s)
- Julie Wieseler
- Department of Psychology and Neuroscience and the Center for Neurosciences, Campus Box 345, University of Colorado at Boulder, Boulder, Colorado 80309-0345, USA.
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18
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Goforth PB, Ren J, Schwartz BS, Satin LS. Excitatory synaptic transmission and network activity are depressed following mechanical injury in cortical neurons. J Neurophysiol 2011; 105:2350-63. [PMID: 21346214 DOI: 10.1152/jn.00467.2010] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
In vitro and in vivo traumatic brain injury (TBI) alter the function and expression of glutamate receptors, yet the combined effect of these alterations on cortical excitatory synaptic transmission is unclear. We examined the effect of in vitro mechanical injury on excitatory synaptic function in cultured cortical neurons by assaying synaptically driven intracellular free calcium ([Ca(2+)](i)) oscillations in small neuronal networks as well as spontaneous and miniature excitatory postsynaptic currents (mEPSCs). We show that injury decreased the incidence and frequency of spontaneous neuronal [Ca(2+)](i) oscillations for at least 2 days post-injury. The amplitude of the oscillations was reduced immediately and 2 days post-injury, although a transient rebound at 4 h post-injury was observed due to increased activity of N-methyl-d-aspartate (NMDARs) and calcium-permeable α-amino-3-hydroxyl-5-methyl-4-isoxazole-propionate receptors (CP-AMPARs). Increased CP-AMPAR function was abolished by the inhibition of protein synthesis. In parallel, mEPSC amplitude decreased immediately, 4 h, and 2 days post-injury, with a transient increase in the contribution of synaptic CP-AMPARs observed at 4 h post-injury. Decreased mEPSC amplitude was evident after injury, even if NMDARs and CP-AMPARs were blocked pharmacologically, suggesting the decrease reflected alterations in synaptic Glur2-containing, calcium-impermeable AMPARs. Despite the transient increase in CP-AMPAR activity that we observed, the overriding effect of mechanical injury was long-term depression of excitatory neurotransmission that would be expected to contribute to the cognitive deficits of TBI.
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Affiliation(s)
- Paulette B Goforth
- University of Michigan Medical School, Department of Pharmacology, Ann Arbor, MI 48105, USA
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19
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Peripheral inflammation induces tumor necrosis factor dependent AMPA receptor trafficking and Akt phosphorylation in spinal cord in addition to pain behavior. Pain 2010; 149:243-253. [PMID: 20202754 DOI: 10.1016/j.pain.2010.02.008] [Citation(s) in RCA: 131] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2009] [Revised: 11/20/2009] [Accepted: 02/04/2010] [Indexed: 11/23/2022]
Abstract
In the present study, intraplantar carrageenan induced increased mechanical allodynia, phosphorylation of PKB/Akt and GluR1 ser 845 (PKA site) as well as GluR1, but not GluR2 movement into neuronal membranes. This change in membrane GluR1/GluR2 ratio is indicative of Ca(2+) permeable AMPA receptor insertion. Pain behavior was reduced and biochemical changes blocked by spinal pretreatment, but not post-treatment, with a tumor necrosis factor (TNF) antagonist, Etanercept (100microg). Pain behavior was also reduced by spinal inhibition of phosphatidylinositol 3-kinase (PI-3K) (wortmannin; 1 and 5microg) and LY294002; 50 and 100microg) and Akt (Akt inhibitor IV; 3microg). Phosphorylated Akt was found exclusively in neurons in grey matter and in oligodendrocytes in white matter. Interestingly, this increase was seen first in superficial dorsal horn and alpha-motor neurons (peak 45min) and later (peak 2h post-injection) in deep dorsal horn neurons. Akt and GluR1 phosphorylation, AMPA receptor trafficking and mechanical allodynia were all TNF dependent. Whether phosphorylation of Akt and of GluR1 are in series or in parallel or upstream of pain behavior remains to be determined. Certainly, TNF-mediated GluR1 trafficking appears to play a major role in inflammatory pain and TNF-mediated effects such as these could represent a path by which glia contribute to neuronal sensitization (spinal LTP) and pathological pain.
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20
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Spicarova D, Palecek J. Modulation of AMPA excitatory postsynaptic currents in the spinal cord dorsal horn neurons by insulin. Neuroscience 2009; 166:305-11. [PMID: 20005924 DOI: 10.1016/j.neuroscience.2009.12.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2009] [Revised: 11/16/2009] [Accepted: 12/02/2009] [Indexed: 11/17/2022]
Abstract
Glutamate AMPA receptors are critical for sensory transmission at the spinal cord dorsal horn (DH). Plasma membrane AMPA receptor endocytosis that can be induced by insulin may underlie long term modulation of synaptic transmission. Insulin receptors (IRs) are known to be expressed on spinal cord DH neurons, but their possible role in sensory transmission has not been studied. In this work the effect of insulin application on fast excitatory postsynaptic currents (EPSCs) mediated by AMPA receptors evoked in DH neurons was evaluated. Acute spinal cord slices from 6 to 10 day old mice were used to record EPSCs evoked in visually identified superficial DH neurons by dorsal root primary afferent stimulation. AMPA EPSCs could be evoked in all of the tested neurons. In 75% of the neurons the size of the AMPA EPSCs was reduced to 62.1% and to 68.9% of the control values when 0.5 or 10 microM insulin was applied. There was no significant change in the size of the AMPA EPSCs in the remaining 25% of DH neurons. The membrane permeable protein tyrosine kinase inhibitor, lavendustin A (10 microM), prevented the insulin induced AMPA EPSC depression. Our results suggest a possible role of the insulin pathway in modulation of sensory and nociceptive synaptic transmission in the spinal cord.
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Affiliation(s)
- D Spicarova
- Department of Functional Morphology, Institute of Physiology, Academy of Sciences of the Czech Republic, Videnska 1083, 14220 Prague 4, Czech Republic
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21
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Larsson M. Ionotropic glutamate receptors in spinal nociceptive processing. Mol Neurobiol 2009; 40:260-88. [PMID: 19876771 DOI: 10.1007/s12035-009-8086-8] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2009] [Accepted: 09/29/2009] [Indexed: 02/07/2023]
Abstract
Glutamate is the predominant excitatory transmitter used by primary afferent synapses and intrinsic neurons in the spinal cord dorsal horn. Accordingly, ionotropic glutamate receptors mediate basal spinal transmission of sensory, including nociceptive, information that is relayed to supraspinal centers. However, it has become gradually more evident that these receptors are also crucially involved in short- and long-term plasticity of spinal nociceptive transmission, and that such plasticity have an important role in the pain hypersensitivity that may result from tissue or nerve injury. This review will cover recent findings on pre- and postsynaptic regulation of synaptic function by ionotropic glutamate receptors in the dorsal horn and how such mechanisms contribute to acute and chronic pain.
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Affiliation(s)
- Max Larsson
- Department of Anatomy and Centre for Molecular Biology and Neuroscience, University of Oslo, Norway.
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22
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Sorkin L, Svensson CI, Jones-Cordero TL, Hefferan MP, Campana WM. Spinal p38 mitogen-activated protein kinase mediates allodynia induced by first-degree burn in the rat. J Neurosci Res 2009; 87:948-55. [PMID: 18855936 DOI: 10.1002/jnr.21905] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Activation of p38 mitogen-activated protein kinase (MAPK) in the spinal cord has been implicated in the development and maintenance of pain states. In this study, we tested whether p38 MAPK is involved in the response to first-degree burn of the hind paw. This injury induces central sensitization leading to tactile allodynia and is mediated by activation of Ca(2+) permeable AMPA/kainate receptors through PKC and PKA. We demonstrate that p38 MAPK is rapidly and robustly activated in the superficial spinal dorsal horn after mild thermal injury to the hind paw. Activated p38 MAPK was localized primarily to microglia and to a lesser extent in oligodendrocytes and lamina II neurons. Astrocytes were not involved in the p38 MAPK response. Intrathecal pretreatment of pharmacological inhibitors of p38 MAPK (SB203580, SD-282) dose-dependently blocked development of tactile allodynia, a characteristic of the first-degree burn model. The effects of the inhibitors on tactile allodynia were lost when they were administered after injury. These studies identify p38 MAPK as a major mediator of tactile allodynia, most likely activated downstream of AMPA/kainate receptors.
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Affiliation(s)
- Linda Sorkin
- Department of Anesthesiology, University of California-San Diego, La Jolla, California, USA.
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23
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Spaethling JM, Klein DM, Singh P, Meaney DF. Calcium-permeable AMPA receptors appear in cortical neurons after traumatic mechanical injury and contribute to neuronal fate. J Neurotrauma 2009; 25:1207-16. [PMID: 18986222 DOI: 10.1089/neu.2008.0532] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Traumatic brain injury (TBI) is one of the most disabling injuries in the population, with 1.5 million Americans new cases each year and 5.3 million Americans overall requiring long-term daily care as a result of their injuries. One critical aspect in developing effective treatments for TBI is determining if new, specific receptor populations emerge in the early phase after injury that can subsequently be targeted to reduce neuronal death after injury. One specific glutamate receptor subtype, the calcium-permeable AMPA receptor (CP-AMPAR), is becoming increasingly recognized for its role in physiological and pathophysiological processes. Although present in relatively low levels in the mature brain, recent studies show that CP-AMPARs can appear following ischemic brain injury or status epilepticus, and the mechanisms that regulate the appearance of these receptors include alterations in transcription, RNA editing, and receptor trafficking. In this report, we use an in vitro model of TBI to show a gradual appearance of CP-AMPARs four hours following injury to cortical neurons. Moreover, the appearance of these receptors is mediated by the phosphorylation of CaMKIIalpha following injury. Selectively blocking CP-AMPARs after mechanical injury leads to a significant reduction in the cell death that occurs 24 h following injury in untreated controls, and is similar in protection offered by broad-spectrum NMDA and AMPA receptor antagonists. These data point to a potentially new and more targeted therapeutic approach for treating TBI.
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Affiliation(s)
- Jennifer M Spaethling
- Department of Pharmacology, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6321, USA
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24
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Park JS, Yaster M, Guan X, Xu JT, Shih MH, Guan Y, Raja SN, Tao YX. Role of spinal cord alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors in complete Freund's adjuvant-induced inflammatory pain. Mol Pain 2008; 4:67. [PMID: 19116032 PMCID: PMC2628655 DOI: 10.1186/1744-8069-4-67] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2008] [Accepted: 12/30/2008] [Indexed: 11/10/2022] Open
Abstract
Spinal cord alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (AMPARs) mediate acute spinal processing of nociceptive and non-nociceptive information, but whether and how their activation contributes to the central sensitization that underlies persistent inflammatory pain are still unclear. Here, we examined the role of spinal AMPARs in the development and maintenance of complete Freund's adjuvant (CFA)-induced persistent inflammatory pain. Intrathecal application of two selective non-competitive AMPAR antagonists, CFM-2 (25 and 50 microg) and GYKI 52466 (50 microg), significantly attenuated mechanical and thermal hypersensitivities on the ipsilateral hind paw at 2 and 24 h post-CFA injection. Neither CFM-2 nor GYKI 52466 affected the contralateral basal responses to thermal and mechanical stimuli. Locomotor activity was not altered in any of the drug-treated animals. CFA-induced inflammation did not change total expression or distribution of AMPAR subunits GluR1 and GluR2 in dorsal horn but did alter their subcellular distribution. The amount of GluR2 was markedly increased in the crude cytosolic fraction and decreased in the crude membrane fraction from the ipsilateral L4-5 dorsal horn at 24 h (but not at 2 h) post-CFA injection. Conversely, the level of GluR1 was significantly decreased in the crude cytosolic fraction and increased in the crude membrane fraction from the ipsilateral L4-5 dorsal horn at 24 h (but not at 2 h) post-CFA injection. These findings suggest that spinal AMPARs might participate in the central spinal mechanism of persistent inflammatory pain.
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Affiliation(s)
- Jang-Su Park
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA.
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25
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26
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Secondary hyperalgesia in the rat first degree burn model is independent of spinal cyclooxygenase and nitric oxide synthase. Eur J Pharmacol 2008; 587:118-23. [PMID: 18440503 DOI: 10.1016/j.ejphar.2008.03.033] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2007] [Revised: 02/28/2008] [Accepted: 03/13/2008] [Indexed: 10/22/2022]
Abstract
Various animal models of pain are dependent on activation of different glutamate receptor subtypes. First degree burn of the paw elicits a secondary hyperalgesia that is dependent on Ca2+ permeable alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA), but not N-methyl-D-aspartate (NMDA) receptors. The present study takes advantage of that specificity by examining the effects of spinal pretreatments of agents on this secondary hyperalgesia. Rats with indwelling intrathecal catheters were pretreated with agents prior to paw injury. Mechanical withdrawal thresholds were measured before, and for three h after the injury. Spinal pretreatment with cyclooxygenase (10 and 30 microg (S)-(+)-ibuprofen; and 3 and 30 microg ketorolac) and nitric oxide synthase (33 and 100 microg N(G) Nitro-L-arginine methyl ester hydrochloride (L-NAME) and 10 microg thiocitrulline) inhibitors resulted in no specific anti-allodynia. In contrast, ziconotide (0.3, 1.0 and 3 microg), the N-type voltage gated calcium channel antagonist was very effective in blocking burn-induced sensitivity at all doses used. l-type (Diltiazam 230 microg) and P-type (Agatoxin IVA 0.3 microg) calcium channel blockers produced intermediate effects. Thus, cyclooxygenase and nitric oxide synthase are assumed not to be downstream of Ca2+ permeable AMPA receptors. Voltage gated calcium channels blockers could exert their effects either pre- or post-synaptically.
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Schoffnegger D, Ruscheweyh R, Sandkühler J. Spread of excitation across modality borders in spinal dorsal horn of neuropathic rats. Pain 2008; 135:300-310. [PMID: 18262362 DOI: 10.1016/j.pain.2007.12.016] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2007] [Revised: 12/13/2007] [Accepted: 12/20/2007] [Indexed: 01/27/2023]
Abstract
Under physiological conditions, nociceptive information is mainly processed in superficial laminae of the spinal dorsal horn, whereas non-nociceptive information is processed in deeper laminae. Neuropathic pain patients often suffer from touch-evoked pain (allodynia), suggesting that modality borders are disrupted in their nervous system. We studied whether excitation evoked in deep dorsal horn neurons either via stimulation of primary afferent Abeta-fibres, by direct electrical stimulation or via glutamate microinjection leads to activation of neurons in the superficial dorsal horn. We used Ca(2+)-imaging in transversal spinal cord slices of neuropathic and control animals to monitor spread of excitation from the deep to the superficial spinal dorsal horn. In neuropathic but not control animals, a spread of excitation occurred from the deep to the superficial dorsal horn. The spread of excitation was synaptically mediated as it was blocked by the AMPA receptor antagonist CNQX. In contrast, block of NMDA receptors was ineffective. In control animals, the violation of modality borders could be reproduced by bath application of GABA(A) and glycine receptor antagonists. Furthermore, we could show that neuropathic animals were more prone to synchronous network activity than control animals. Thus, following peripheral nerve injury, excitation generated in dorsal horn areas which process non-nociceptive information can invade superficial dorsal horn areas which normally receive nociceptive input. This may be a spinal mechanism of touch-evoked pain.
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Affiliation(s)
- Doris Schoffnegger
- Department for Neurophysiology, Center for Brain Research, Medical University Vienna, Spitalgasse 4, 1090 Vienna, Austria
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28
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Jones TL, Lustig AC, Sorkin LS. Secondary hyperalgesia in the postoperative pain model is dependent on spinal calcium/calmodulin-dependent protein kinase II alpha activation. Anesth Analg 2007; 105:1650-6, table of contents. [PMID: 18042863 DOI: 10.1213/01.ane.0000287644.00420.49] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
BACKGROUND Spinally administered non-N-methyl-D-aspartate (NMDA), but not NMDA, receptor antagonists block primary (1 degree) and secondary (2 degrees) mechanical hyperalgesia and spontaneous pain after plantar incision. Hyperalgesia after thermal stimulation is also mediated by non-NMDA, but not NMDA, receptors. Although previous pain behavior studies in the thermal stimulus model demonstrated distinct protein kinase involvement downstream from spinal non-NMDA receptor activation, protein kinase signaling mechanisms have not been examined in the postoperative pain model. In the present study, we investigated whether spinal calcium/calmodulin-dependent protein kinase IIalpha (CaMKIIalpha) mediates 1 degree and/or 2 degrees hyperalgesia and spontaneous pain behavior after plantar incision. METHODS Catheterized rats received a 1 cm incision in the hindpaw and were tested over 2 days for responses to mechanical stimulation adjacent to or 1 cm away from the incision site. Some rats received intrathecal (IT) pretreatment with a CaMKIIalpha inhibitor (14, 34, or 104 nmol KN-93) or vehicle (5% dimethyl sulfoxide in sterile saline). Separate groups received IT 34 nmol or 104 nmol KN-93 and were tested for hindpaw weight bearing. Lumbar spinal cords were extracted 1 h after incision or sham treatment to measure phosphorylated CaMKIIalpha and alpha-amino-3-hydroxy-5-methylisoxazole-4-proprionic acid GLUR1-831 in Western immunoblots. RESULTS Incision increased spinal CaMKIIalpha and GLUR1-831 phosphorylation. Although pretreatment with all doses of IT KN-93 reduced the development of 2 degrees hyperalgesia, only 34 nmol KN-93 appeared to have an effect on 1 degrees hyperalgesia. IT KN-93 did not affect nonevoked pain. CONCLUSION Spinal sensitization underlying incision-evoked hyperalgesia involves spinal CaMKIIalpha activation and enhanced spinal alpha-amino-3-hydroxy-5-methylisoxazole-4-proprionic acid receptor (AMPA) function.
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Affiliation(s)
- Toni L Jones
- Department of Anesthesiology, University of California San Diego, La Jolla, California 92093-0818, USA.
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29
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Youn DH, Royle G, Kolaj M, Vissel B, Randić M. Enhanced LTP of primary afferent neurotransmission in AMPA receptor GluR2-deficient mice. Pain 2007; 136:158-67. [PMID: 17826911 DOI: 10.1016/j.pain.2007.07.001] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2006] [Revised: 06/29/2007] [Accepted: 07/09/2007] [Indexed: 11/26/2022]
Abstract
Ca(2+)-permeable-AMPA receptors (AMPARs) are expressed in the superficial dorsal horn (SDH, laminae I/II) of the spinal cord, the area involved in transmission and modulation of sensory information, including nociception. A possible role of Ca(2+)-permeable-AMPARs in synaptic strengthening has been suggested in postnatal DH cultures, but their role in the long-lasting activity-dependent synaptic plasticity of primary afferent neurotransmission in the adult mouse SDH has not been investigated. In the present study the role of Ca(2+)-permeable-AMPARs in the regulation of long-lasting synaptic plasticity, specifically long-term potentiation (LTP) and long-term depression (LTD) in the SDH, was investigated using mice deficient in AMPAR GluR2 subunit. We show here that the GluR2 mutants exhibited no changes in passive membrane properties, but a significant increase in rectification of excitatory postsynaptic currents, the finding suggesting increased expression of Ca(2+)-permeable-AMPARs. In the absence of GluR2, high-frequency stimulation (HFS) of small-diameter primary afferent fibers induced LTP that is enhanced and non-saturating in the SDH at both primary afferent Adelta- and/or C-fibers monosynaptic and polysynaptic pathways, whereas neuronal excitability and paired-pulse depression were normal. The LTP could be induced in the presence of the NMDA receptor antagonist d-AP5, and L-type Ca(2+) channel blockers, suggesting that Ca(2+)-permeable-AMPARs are sufficient to induce LTP in the SDH neurons of adult mouse spinal cord. In contrast, the induction of HFS-LTD is reduced in the SDH of GluR2 mutants. These results suggest an important role for AMPAR GluR2 subunit in regulating synaptic plasticity with potential relevance for long-lasting hypersensitivity in pathological states.
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Affiliation(s)
- Dong-Ho Youn
- Department of Biomedical Sciences, Iowa State University, Ames, IA 50011, USA
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30
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Summer GJ, Dina OA, Levine JD. Enhanced inflammatory hyperalgesia after recovery from burn injury. Burns 2007; 33:1021-6. [PMID: 17707592 DOI: 10.1016/j.burns.2007.02.007] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2006] [Accepted: 02/22/2007] [Indexed: 11/30/2022]
Abstract
Severe burn induces severe pain. While chronic as well as acute pain syndromes are reported, the peripheral mechanisms of burn-induced chronic pain syndromes have not been studied. We tested the hypothesis that burn induces plastic changes in primary afferent nociceptors that predispose to chronic pain states. Mechanical nociceptive thresholds were measured using the Randall-Selitto paw-withdrawal test in male Sprague-Dawley rats, before and following a small (<1% total body surface area) partial-thickness thermal injury to the dorsal surface of one hind paw. This burn induced mechanical hyperalgesia, which lasted over 2 weeks. After recovery, local injection of prostaglandin E2 (PGE2), to mimic re-injury, induced an enhanced and markedly prolonged mechanical hyperalgesia compared to the hyperalgesic effect of PGE2 in the control contralateral paw. This prolonged PGE2-induced hyperalgesia was reversed by a selective inhibitor of protein kinase C-epsilon (PKCepsilon). Our findings suggest PKCepsilon as a peripheral mechanism for burn-induced chronic pain syndromes.
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Affiliation(s)
- Gretchen J Summer
- Department of Physiological Nursing, School of Nursing, University of California, San Francisco 94143, USA.
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31
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Estrada G, Villegas E, Corzo G. Spider venoms: a rich source of acylpolyamines and peptides as new leads for CNS drugs. Nat Prod Rep 2007; 24:145-61. [PMID: 17268611 DOI: 10.1039/b603083c] [Citation(s) in RCA: 104] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Advances in NMR and mass spectrometry as well as in peptide biochemistry coupled to modern methods in electrophysiology have permitted the isolation and identification of numerous products from spider venoms, previously explored due to technical limitations. The chemical composition of spider venoms is diverse, ranging from low molecular weight organic compounds such as acylpolyamines to complex peptides. First, acylpolyamines (< 1000 Da) have an aromatic moiety linked to a hydrophilic lateral chain. They were characterized for the first time in spider venoms and are ligand-gated ion channel antagonists, which block mainly postsynaptic glutamate receptors in invertebrate and vertebrate nervous systems. Acylpolyamines represent the vast majority of organic components from the spider venom. Acylpolyamine analogues have proven to suppress hippocampal epileptic discharges. Moreover, acylpolyamines could suppress excitatory postsynaptic currents inducing Ca+ accumulation in neurons leading to protection against a brain ischemic insult. Second, short spider peptides (< 6000 Da) modulate ionic currents in Ca2+, Na+, or K+ voltage-gated ion channels. Such peptides may contain from three to four disulfide bridges. Some spider peptides act specifically to discriminate among Ca2+, Na+, or K+ ion channel subtypes. Their selective affinities for ion channel subfamilies are functional for mapping excitable cells. Furthermore, several of these peptides have proven to hyperpolarize peripheral neurons, which are associated with supplying sensation to the skin and skeletal muscles. Some spider N-type calcium ion channel blockers may be important for the treatment of chronic pain. A special group of spider peptides are the amphipathic and positively charged peptides. Their secondary structure is alpha-helical and they insert into the lipid cell membrane of eukaryotic or prokaryotic cells leading to the formation of pores and subsequently depolarizing the cell membrane. Acylpolyamines and peptides from spider venoms represent an interesting source of molecules for the design of novel pharmaceutical drugs.
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Affiliation(s)
- Georgina Estrada
- Instituto de Biotecnología, UNAM, Avenida Universidad 2001, Cuernavaca, Morelos 62210, México
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Abstract
Pain is an important survival and protection mechanism for animals. However, chronic/persistent pain may be differentiated from normal physiological pain in that it confers no obvious advantage. An accumulating body of pharmacological, electrophysiological, and behavioral evidence is emerging in support of the notion that glutamate receptors play a crucial role in pain pathways and that modulation of glutamate receptors may have potential for therapeutic utility in several categories of persistent pain, including neuropathic pain resulting from injury and/or disease of central (e.g., spinal cord injury) or peripheral nerves (e.g., diabetic neuropathy, radiculopathy) and inflammatory or joint-related pain (e.g., rheumatoid arthritis, osteoarthritis). This review focuses on the role of glutamate receptors, including both ionotropic (AMPA, NMDA and kainate) and metabotropic (mGlu1-8) receptors in persistent pain states with particular emphasis on their expression patterns in nociceptive pathways and their potential as targets for pharmacological intervention strategies.
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Affiliation(s)
- David Bleakman
- Neuroscience Division, Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, IN 46285, USA.
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33
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Tao F, Skinner J, Su Q, Johns RA. New role for spinal Stargazin in alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor-mediated pain sensitization after inflammation. J Neurosci Res 2006; 84:867-73. [PMID: 16791853 DOI: 10.1002/jnr.20973] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Considerable evidence has demonstrated that alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor blockade has an antinociceptive effect on inflammatory pain. Stargazin (STG) is the first transmembrane protein known to associate with AMPA receptors and regulate their synaptic targeting. However, it is not known whether STG is involved in inflammatory pain processing by regulating AMPA receptor function. In the present study, we investigated the effect of knockdown of spinal STG on AMPA receptor-mediated pain sensitization after inflammation. Antisense technology was employed to knock down STG expression in the spinal cord. We show that STG was expressed and interacted with AMPA receptor subunit GluR2 in the spinal cord. Intrathecally injected STG antisense oligodeoxyribonucleotide (ODN) specifically decreased STG expression in the lumbar spinal cord and dose dependently inhibited formalin-induced inflammatory pain in the second phase. More important was our finding for the first time that this specific STG antisense ODN diminished AMPA (0.1 mug)-enhanced formalin pain and lost its effect if pretreated with AMPA receptor antagonist CNQX. Our results demonstrate a new role for STG in central sensitization of inflammatory pain by interacting with AMPA receptors in the spinal cord.
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Affiliation(s)
- Feng Tao
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA
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Tong CK, MacDermott AB. Both Ca2+-permeable and -impermeable AMPA receptors contribute to primary synaptic drive onto rat dorsal horn neurons. J Physiol 2006; 575:133-44. [PMID: 16763002 PMCID: PMC1819427 DOI: 10.1113/jphysiol.2006.110072] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Blockade of Ca2+-permeable AMPA receptors in the rat spinal cord diminishes the development of hyperalgesia and allodynia associated with peripheral injury. Cobalt uptake studies reveal that Ca2+-permeable AMPA receptors are expressed by some substance P receptor-expressing (NK1R+) neurons in lamina I, as well as other neurons throughout the superficial dorsal horn. Selective elimination of NK1R+ neurons in lamina I and lamina III/IV of the dorsal horn also suppresses development of hyperalgesia and allodynia. These observations raise the possibility that Ca2+-permeable AMPA receptors contribute to excitatory synaptic drive onto the NK1R+ neurons associated with allodynia and hyperalgesia. The first synapse in the pain pathway is the glutamatergic excitatory drive from the primary afferent fibres onto dorsal horn neurons. Therefore, we tested whether Ca2+-permeable AMPA receptors are located on lamina I and lamina III/IV NK1R+ neurons postsynaptic to primary afferent fibres, using inward rectification and polyamine toxins for receptor identification. We examined three different populations of dorsal horn neurons; lamina I NK1R+ neurons, including projection neurons, and non-NK1R+ (NK1R-) neurons including interneurons, and lamina III/IV NK1R+ neurons, believed to contribute to the low-threshold mechanosensory pathway. The majority of synapses in all three groups had rectification indices less than 1.0 and greater than 0.4, indicating that the AMPA receptors at these synapses are a mixture of Ca2+-permeable and -impermeable forms. Lamina III/IV NK1R+ neurons and lamina I NK1R- neurons have a significantly higher proportion of postsynaptic Ca2+-permeable AMPA receptors than lamina I NK1R+ neurons. Thus synaptically positioned Ca2+-permeable AMPA receptors directly contribute to low-threshold sensory afferent drive into the dorsal horn, and can mediate afferent input onto interneurons such as GABAergic neurons. These receptors also contribute to high-threshold primary afferent drive onto NK1R+ neurons in the superficial dorsal horn, but do so less consistently.
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Affiliation(s)
- Chi-Kun Tong
- Department of Physiology and Cellular Biophysics, Columbia University, 630 W. 168th St, Room 1109, New York, NY 10032, USA.
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35
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Miller BA, Sun F, Christensen RN, Ferguson AR, Bresnahan JC, Beattie MS. A sublethal dose of TNFalpha potentiates kainate-induced excitotoxicity in optic nerve oligodendrocytes. Neurochem Res 2006; 30:867-75. [PMID: 16187221 DOI: 10.1007/s11064-005-6880-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/12/2005] [Indexed: 01/06/2023]
Abstract
Glutamate receptor-induced cell death, known as excitotoxicity in both neurons and oligodendrocytes, has been implicated as a common pathway of cell death in numerous central nervous system (CNS) diseases and trauma. Research in both neuronal and oligodendrocyte excitotoxicity has examined glutamate's receptor-mediated effects on CNS cells, and explored strategies to protect cells exposed to the elevated glutamate levels that occur in CNS trauma and disease. Proinflammatory cytokines are also elevated in the injured CNS, and have also been implicated in CNS cell death. Recently, several laboratories have examined cytokines' effects on neuronal and glial excitotoxicity. Here, we review literature concerning the dynamic susceptibility of both neurons and oligodendrocytes to excitotoxicity, and present new data from our laboratory showing that the susceptibility of oligodendrocytes to excitotoxicity is acutely potentiated by the proinflammatory cytokine TNFalpha.
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Affiliation(s)
- Brandon A Miller
- Department of Neuroscience, The Ohio State University, College of Medicine, 333 W. 10th Ave, Columbus, OH 43210, USA
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36
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Abstract
Damage to the nervous system can cause neuropathic pain, which is in general poorly treated and involves mechanisms that are incompletely known. Currently available animal models for neuropathic pain mainly involve partial injury of peripheral nerves. Multiple inflammatory mediators released from damaged tissue not only acutely excite primary sensory neurons in the peripheral nervous system, producing ectopic discharge, but also lead to a sustained increase in their excitability. Hyperexcitability also develops in the central nervous system (for instance, in dorsal horn neurons), and both peripheral and spinal elements contribute to neuropathic pain, so that spontaneous pain may occur or normally innocuous stimuli may produce pain. Inflammatory mediators and aberrant neuronal activity activate several signaling pathways [including protein kinases A and C, calcium/calmodulin-dependent protein kinase, and mitogen-activated protein kinases (MAPKs)] in primary sensory and dorsal horn neurons that mediate the induction and maintenance of neuropathic pain through both posttranslational and transcriptional mechanisms. In particular, peripheral nerve lesions result in activation of MAPKs (p38, extracellular signal-regulated kinase, and c-Jun N-terminal kinase) in microglia or astrocytes in the spinal cord, or both, leading to the production of inflammatory mediators that sensitize dorsal horn neurons. Activity of dorsal horn neurons, in turn, enhances activation of spinal glia. This neuron-glia interaction involves positive feedback mechanisms and is likely to enhance and prolong neuropathic pain even in the absence of ongoing peripheral external stimulation or injury. The goal of this review is to present evidence for signaling cascades in these cell types that not only will deepen our understanding of the genesis of neuropathic pain but also may help to identify new targets for pharmacological intervention.
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Affiliation(s)
- Ru-Rong Ji
- Pain Research Center, Department of Anesthesiology, Perioperative and Pain Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA.
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