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Charron A, Pepino L, Malapert P, Debrauwer V, Castets F, Salio C, Moqrich A. Sex-related exacerbation of injury-induced mechanical hypersensitivity in GAD67 haplodeficient mice. Pain 2024; 165:192-201. [PMID: 37578506 PMCID: PMC10723643 DOI: 10.1097/j.pain.0000000000003012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2023] [Revised: 05/13/2023] [Accepted: 06/05/2023] [Indexed: 08/15/2023]
Abstract
ABSTRACT Decreased GABA levels in injury-induced loss of spinal inhibition are still under intense interest and debate. Here, we show that GAD67 haplodeficient mice exhibited a prolonged injury-induced mechanical hypersensitivity in postoperative, inflammatory, and neuropathic pain models. In line with this, we found that loss of 1 copy of the GAD67-encoding gene Gad1 causes a significant decrease in GABA contents in spinal GABAergic neuronal profiles. Consequently, GAD67 haplodeficient males and females were unresponsive to the analgesic effect of diazepam. Remarkably, all these phenotypes were more pronounced in GAD67 haplodeficient females. These mice had significantly much lower amount of spinal GABA content, exhibited an exacerbated pain phenotype during the second phase of the formalin test, developed a longer lasting mechanical hypersensitivity in the chronic constriction injury of the sciatic nerve model, and were unresponsive to the pain relief effect of the GABA-transaminase inhibitor phenylethylidenehydrazine. Our study provides strong evidence for a role of GABA levels in the modulation of injury-induced mechanical pain and suggests a potential role of the GABAergic system in the prevalence of some painful diseases among females.
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Affiliation(s)
- Aude Charron
- Aix-Marseille-université, CNRS, Institut de Biologie du Développement de Marseille, UMR 7288, Case 907, Marseille, France
| | - Lucie Pepino
- Aix-Marseille-université, CNRS, Institut de Biologie du Développement de Marseille, UMR 7288, Case 907, Marseille, France
| | - Pascale Malapert
- Aix-Marseille-université, CNRS, Institut de Biologie du Développement de Marseille, UMR 7288, Case 907, Marseille, France
| | - Vincent Debrauwer
- Aix-Marseille-université, CNRS, Institut des Sciences Moléculaires de Marseille, UMR 7313, Campus Scientifique de St Jérôme, Marseille, France
| | - Francis Castets
- Aix-Marseille-université, CNRS, Institut de Biologie du Développement de Marseille, UMR 7288, Case 907, Marseille, France
| | - Chiara Salio
- Department of Veterinary Sciences, University of Turin, Grugliasco, Italy
| | - Aziz Moqrich
- Aix-Marseille-université, CNRS, Institut de Biologie du Développement de Marseille, UMR 7288, Case 907, Marseille, France
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Yang CT, Guan Y, Chen CC, Lin WT, Lu KH, Lin CR, Shyu BC, Wen YR. Novel Pulsed Ultrahigh-frequency Spinal Cord Stimulation Inhibits Mechanical Hypersensitivity and Brain Neuronal Activity in Rats after Nerve Injury. Anesthesiology 2023; 139:646-663. [PMID: 37428715 DOI: 10.1097/aln.0000000000004680] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/12/2023]
Abstract
BACKGROUND Spinal cord stimulation (SCS) is an important pain treatment modality. This study hypothesized that a novel pulsed ultrahigh-frequency spinal cord stimulation (pUHF-SCS) could safely and effectively inhibit spared nerve injury-induced neuropathic pain in rats. METHODS Epidural pUHF-SCS (± 3V, 2-Hz pulses comprising 500-kHz biphasic sinewaves) was implanted at the thoracic vertebrae (T9 to T11). Local field brain potentials after hind paw stimulation were recorded. Analgesia was evaluated by von Frey-evoked allodynia and acetone-induced cold allodynia. RESULTS The mechanical withdrawal threshold of the injured paw was 0.91 ± 0.28 g lower than that of the sham surgery (24.9 ± 1.2 g). Applying 5-, 10-, or 20-min pUHF-SCS five times every 2 days significantly increased the paw withdrawal threshold to 13.3 ± 6.5, 18.5 ± 3.6, and 21.0 ± 2.8 g at 5 h post-SCS, respectively (P = 0.0002, < 0.0001, and < 0.0001; n = 6 per group) and to 6.1 ± 2.5, 8.2 ± 2.7, and 14.3 ± 5.9 g on the second day, respectively (P = 0.123, 0.013, and < 0.0001). Acetone-induced paw response numbers decreased from pre-SCS (41 ± 12) to 24 ± 12 and 28 ± 10 (P = 0.006 and 0.027; n = 9) at 1 and 5 h after three rounds of 20-min pUHF-SCS, respectively. The areas under the curve from the C component of the evoked potentials at the left primary somatosensory and anterior cingulate cortices were significantly decreased from pre-SCS (101.3 ± 58.3 and 86.9 ± 25.5, respectively) to 39.7 ± 40.3 and 36.3 ± 20.7 (P = 0.021, and 0.003; n = 5) at 60 min post-SCS, respectively. The intensity thresholds for pUHF-SCS to induce brain and sciatic nerve activations were much higher than the therapeutic intensities and thresholds of conventional low-frequency SCS. CONCLUSIONS Pulsed ultrahigh-frequency spinal cord stimulation inhibited neuropathic pain-related behavior and paw stimulation evoked brain activation through mechanisms distinct from low-frequency SCS. EDITOR’S PERSPECTIVE
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Affiliation(s)
- Chin-Tsang Yang
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan; and Department of Leisure Industry and Health Promotion, National Ilan University, Yilan, Taiwan
| | - Yun Guan
- Department of Anesthesiology and Critical Care Medicine, Department of Neurological Surgery, The Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Chih-Cheng Chen
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan; Neuroscience Program of Academia Sinica, Academia Sinica, Taipei, Taiwan; and Taiwan Mouse Clinic, Biomedical Translational Research Center, Academia Sinica, Taipei, Taiwan
| | | | - Kuo-Hsiang Lu
- Kuo-Hsiang Lu, M.S.; Gimer Medical Co., New Taipei City, Taiwan
| | - Chung-Ren Lin
- Department of Anesthesiology, National Cheng Kung University Hospital, Tainan, Taiwan
| | - Bai-Chuang Shyu
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Yeong-Ray Wen
- Pain Management and Research Center, Department of Anesthesiology, China Medical University Hospital, Taichung, Taiwan; and College of Medicine, China Medical University, Taichung, Taiwan
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Perez-Gonzalez AP, Provost F, Rousse I, Piovesana R, Benzina O, Darabid H, Lamoureux B, Wang YS, Arbour D, Robitaille R. Functional adaptation of glial cells at neuromuscular junctions in response to injury. Glia 2022; 70:1605-1629. [PMID: 35474470 PMCID: PMC9543218 DOI: 10.1002/glia.24184] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Revised: 04/14/2022] [Accepted: 04/18/2022] [Indexed: 12/04/2022]
Abstract
Synaptic elements from neuromuscular junctions (NMJs) undergo massive morphological and functional changes upon nerve injury. While morphological changes of NMJ‐associated glia in response to injury has been investigated, their functional properties remain elusive. Perisynaptic Schwann cells (PSCs), glial cells at the NMJ, are essential for NMJ maintenance and repair, and are involved in synaptic efficacy and plasticity. Importantly, these functions are regulated by PSCs ability to detect synaptic transmission through, notably, muscarinic (mAChRs) and purinergic receptors' activation. Using Ca2+ imaging and electrophysiological recordings of synaptic transmission at the mouse NMJ, we investigated PSC receptors activation following denervation and during reinnervation in adults and at denervated NMJs in an ALS mouse model (SOD1G37R). We observed reduced PSCs mAChR‐mediated Ca2+ responses at denervated and reinnervating NMJs. Importantly, PSC phenotypes during denervation and reinnervation were distinct than the one observed during NMJ maturation. At denervated NMJs, exogenous activation of mAChRs greatly diminished galectin‐3 expression, a glial marker of phagocytosis. PSCs Ca2+ responses at reinnervating NMJs did not correlate with the number of innervating axons or process extensions. Interestingly, we observed an extended period of reduced PSC mAChRs activation after the injury (up to 60 days), suggesting a glial memory of injury. PSCs associated with denervated NMJs in an ALS model (SOD1G37R mice) did not show any muscarinic adaptation, a phenotype incompatible with NMJ repair. Understanding functional mechanisms that underlie this glial response to injury may contribute to favor complete NMJ and motor recovery.
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Affiliation(s)
- Anna P Perez-Gonzalez
- Département de Neurosciences, Université de Montréal, Montréal, Québec, Canada.,Groupe de Recherche sur le Système Nerveux Central, Université de Montréal, Montréal, Québec, Canada
| | - Frédéric Provost
- Département de Neurosciences, Université de Montréal, Montréal, Québec, Canada.,Groupe de Recherche sur le Système Nerveux Central, Université de Montréal, Montréal, Québec, Canada
| | - Isabelle Rousse
- Département de Neurosciences, Université de Montréal, Montréal, Québec, Canada.,Groupe de Recherche sur le Système Nerveux Central, Université de Montréal, Montréal, Québec, Canada
| | - Roberta Piovesana
- Département de Neurosciences, Université de Montréal, Montréal, Québec, Canada.,Groupe de Recherche sur le Système Nerveux Central, Université de Montréal, Montréal, Québec, Canada
| | - Ouafa Benzina
- Département de Neurosciences, Université de Montréal, Montréal, Québec, Canada.,Groupe de Recherche sur le Système Nerveux Central, Université de Montréal, Montréal, Québec, Canada
| | - Houssam Darabid
- Département de Neurosciences, Université de Montréal, Montréal, Québec, Canada.,Groupe de Recherche sur le Système Nerveux Central, Université de Montréal, Montréal, Québec, Canada
| | - Benoit Lamoureux
- Département de Neurosciences, Université de Montréal, Montréal, Québec, Canada.,Groupe de Recherche sur le Système Nerveux Central, Université de Montréal, Montréal, Québec, Canada
| | - Yu Shi Wang
- Département de Neurosciences, Université de Montréal, Montréal, Québec, Canada.,Groupe de Recherche sur le Système Nerveux Central, Université de Montréal, Montréal, Québec, Canada
| | - Danielle Arbour
- Département de Neurosciences, Université de Montréal, Montréal, Québec, Canada.,Groupe de Recherche sur le Système Nerveux Central, Université de Montréal, Montréal, Québec, Canada
| | - Richard Robitaille
- Département de Neurosciences, Université de Montréal, Montréal, Québec, Canada.,Groupe de Recherche sur le Système Nerveux Central, Université de Montréal, Montréal, Québec, Canada.,Centre Interdisciplinaire de Recherche sur le Cerveau et l'apprentissage, Montréal, Québec, Canada
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Mortensen D, Thoefner MS, Agerholm JS, Slumstrup L, Jensen TS, Bjerrum OJ, Berendt M, Nyengaard JR. Dorsal horn volume loss and pain pathway changes in Cavalier King Charles Spaniels with syringomyelia, signs of pain, and phantom scratching. Pain 2022; 163:2365-2379. [PMID: 35353770 DOI: 10.1097/j.pain.0000000000002630] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Accepted: 02/28/2022] [Indexed: 11/25/2022]
Abstract
ABSTRACT Central neuropathic pain is a core clinical sign of syringomyelia in humans and Cavalier King Charles Spaniel (CKCS) dogs. This histopathological study used spinal cords from CKCS with syringomyelia to investigate: 1) whether specific structural cervical spinal cord entities involved in nociception are affected by loss of neuroparenchyma or other pathological changes in CKCS with pain-related behaviour and phantom scratching, 2) if pain related behaviour or phantom scratching correlated with loss of a specific anatomical entity or upregulation of glia cells, and 3) if syringomyelia-related lesions affected specific functional spinal cord units of nociception.Spinal cord segments C1-C8 from CKCS with MRI-confirmed syringomyelia and clinical signs of pain and phantom scratch (n=8) were compared to CKCS without syringomyelia (n=4). Dogs with unilateral scratching (n=7) had a volume loss (P=0.043) of the dorsal horn laminae I-III in the ipsilateral side compared to the contralateral dorsal horn. A clear pattern of ipsilateral changes in the dorsal root entry zone characterised by deafferentation and reorganization of first-order axons into deeper laminae was found in cases with lateralised scratching. Significant changes in cell number density were not found for astrocytes or microglia, suggesting that the dogs represented cases of end-stage syringomyelia and thus could not reveal astrogliosis and microgliosis, which may be involved in the early phases of syrinx development and phantom scratch.The present relationship between clinical findings and dorsal horn and pain pathway pathology in CKCS suggests that these dogs may be of interest as a supplement to experimental model pain research.
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Affiliation(s)
- Danny Mortensen
- Core Center for Molecular Morphology, Section for Stereology and Microscopy, Center for Stochastic Geometry and Advanced Bioimaging
| | - Maria Soendergaard Thoefner
- Department of Veterinary Clinical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark
| | - Joergen Steen Agerholm
- Department of Veterinary Clinical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark
| | - Lasse Slumstrup
- Core Center for Molecular Morphology, Section for Stereology and Microscopy, Center for Stochastic Geometry and Advanced Bioimaging
| | | | - Ole Jannik Bjerrum
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen
| | - Mette Berendt
- Department of Veterinary Clinical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark
| | - Jens Randel Nyengaard
- Core Center for Molecular Morphology, Section for Stereology and Microscopy, Center for Stochastic Geometry and Advanced Bioimaging.,Department of Pathology, Aarhus University Hospital, Denmark
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Liao MF, Lu KT, Hsu JL, Lee CH, Cheng MY, Ro LS. The Role of Autophagy and Apoptosis in Neuropathic Pain Formation. Int J Mol Sci 2022; 23:ijms23052685. [PMID: 35269822 PMCID: PMC8910267 DOI: 10.3390/ijms23052685] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2021] [Revised: 02/26/2022] [Accepted: 02/27/2022] [Indexed: 01/18/2023] Open
Abstract
Neuropathic pain indicates pain caused by damage to the somatosensory system and is difficult to manage and treat. A new treatment strategy urgently needs to be developed. Both autophagy and apoptosis are critical adaptive mechanisms when neurons encounter stress or damage. Recent studies have shown that, after nerve damage, both autophagic and apoptotic activities in the injured nerve, dorsal root ganglia, and spinal dorsal horn change over time. Many studies have shown that upregulated autophagic activities may help myelin clearance, promote nerve regeneration, and attenuate pain behavior. On the other hand, there is no direct evidence that the inhibition of apoptotic activities in the injured neurons can attenuate pain behavior. Most studies have only shown that agents can simultaneously attenuate pain behavior and inhibit apoptotic activities in the injured dorsal root ganglia. Autophagy and apoptosis can crosstalk with each other through various proteins and proinflammatory cytokine expressions. Proinflammatory cytokines can promote both autophagic/apoptotic activities and neuropathic pain formation, whereas autophagy can inhibit proinflammatory cytokine activities and further attenuate pain behaviors. Thus, agents that can enhance autophagic activities but suppress apoptotic activities on the injured nerve and dorsal root ganglia can treat neuropathic pain. Here, we summarized the evolving changes in apoptotic and autophagic activities in the injured nerve, dorsal root ganglia, spinal cord, and brain after nerve damage. This review may help in further understanding the treatment strategy for neuropathic pain during nerve injury by modulating apoptotic/autophagic activities and proinflammatory cytokines in the nervous system.
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Affiliation(s)
- Ming-Feng Liao
- Linkou Medical Center, Department of Neurology, Chang Gung Memorial Hospital, College of Medicine, Chang Gung University, Taoyuan 333, Taiwan; (M.-F.L.); (J.-L.H.); (C.-H.L.); (M.-Y.C.)
- Department of Life Science, School of Life Science, National Taiwan Normal University, Taipei 106, Taiwan;
| | - Kwok-Tung Lu
- Department of Life Science, School of Life Science, National Taiwan Normal University, Taipei 106, Taiwan;
| | - Jung-Lung Hsu
- Linkou Medical Center, Department of Neurology, Chang Gung Memorial Hospital, College of Medicine, Chang Gung University, Taoyuan 333, Taiwan; (M.-F.L.); (J.-L.H.); (C.-H.L.); (M.-Y.C.)
- Department of Neurology, New Taipei Municipal TuCheng Hospital, Chang Gung Memorial Hospital, Chang Gung University, New Taipei City 236, Taiwan
- Graduate Institute of Mind, Brain and Consciousness, Taipei Medical University, Taipei 110, Taiwan
- Brain and Consciousness Research Center, Shuang Ho Hospital, New Taipei City 235, Taiwan
| | - Chih-Hong Lee
- Linkou Medical Center, Department of Neurology, Chang Gung Memorial Hospital, College of Medicine, Chang Gung University, Taoyuan 333, Taiwan; (M.-F.L.); (J.-L.H.); (C.-H.L.); (M.-Y.C.)
| | - Mei-Yun Cheng
- Linkou Medical Center, Department of Neurology, Chang Gung Memorial Hospital, College of Medicine, Chang Gung University, Taoyuan 333, Taiwan; (M.-F.L.); (J.-L.H.); (C.-H.L.); (M.-Y.C.)
| | - Long-Sun Ro
- Linkou Medical Center, Department of Neurology, Chang Gung Memorial Hospital, College of Medicine, Chang Gung University, Taoyuan 333, Taiwan; (M.-F.L.); (J.-L.H.); (C.-H.L.); (M.-Y.C.)
- Correspondence: ; Tel.: +886-3-3281200 (ext. 8351)
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Zhang KL, Li SJ, Pu XY, Wu FF, Liu H, Wang RQ, Liu BZ, Li Z, Li KF, Qian NS, Yang YL, Yuan H, Wang YY. Targeted up-regulation of Drp1 in dorsal horn attenuates neuropathic pain hypersensitivity by increasing mitochondrial fission. Redox Biol 2021; 49:102216. [PMID: 34954498 PMCID: PMC8718665 DOI: 10.1016/j.redox.2021.102216] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Revised: 12/11/2021] [Accepted: 12/15/2021] [Indexed: 01/02/2023] Open
Abstract
Mitochondria play an essential role in pathophysiology of both inflammatory and neuropathic pain (NP), but the mechanisms are not yet clear. Dynamin-related protein 1 (Drp1) is broadly expressed in the central nervous system and plays a role in the induction of mitochondrial fission process. Spared nerve injury (SNI), due to the dysfunction of the neurons within the spinal dorsal horn (SDH), is the most common NP model. We explored the neuroprotective role of Drp1 within SDH in SNI. SNI mice showed pain behavior and anxiety-like behavior, which was associated with elevation of Drp1, as well as increased density of mitochondria in SDH. Ultrastructural analysis showed SNI induced damaged mitochondria into smaller perimeter and area, tending to be circular. Characteristics of vacuole in the mitochondria further showed SNI induced the increased number of vacuole, widened vac-perimeter and vac-area. Stable overexpression of Drp1 via AAV under the control of the Drp1 promoter by intraspinal injection (Drp1 OE) attenuated abnormal gait and alleviated pain hypersensitivity of SNI mice. Mitochondrial ultrastructure analysis showed that the increased density of mitochondria induced by SNI was recovered by Drp1 OE which, however, did not change mitochondrial morphology and vacuole parameters within SDH. Contrary to Drp1 OE, down-regulation of Drp1 in the SDH by AAV-Drp1 shRNA (Drp1 RNAi) did not alter painful behavior induced by SNI. Ultrastructural analysis showed the treatment by combination of SNI and Drp1 RNAi (SNI + Drp1 RNAi) amplified the damages of mitochondria with the decreased distribution density, increased perimeter and area, as well as larger circularity tending to be more circular. Vacuole data showed SNI + Drp1 RNAi increased vacuole density, perimeter and area within the SDH mitochondria. Our results illustrate that mitochondria within the SDH are sensitive to NP, and targeted mitochondrial Drp1 overexpression attenuates pain hypersensitivity. Drp1 offers a novel therapeutic target for pain treatment.
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Affiliation(s)
- Kun-Long Zhang
- Specific Lab for Mitochondrial Plasticity Underlying Nervous System Diseases, National Demonstration Center for Experimental Preclinical Medicine Education, The Fourth Military Medical University, Xi'an, 710032, China; Department of Rehabilitation Medicine, Xi-Jing Hospital, The Fourth Military Medical University, Xi'an, 710032, China
| | - Shu-Jiao Li
- Specific Lab for Mitochondrial Plasticity Underlying Nervous System Diseases, National Demonstration Center for Experimental Preclinical Medicine Education, The Fourth Military Medical University, Xi'an, 710032, China
| | - Xue-Yin Pu
- Specific Lab for Mitochondrial Plasticity Underlying Nervous System Diseases, National Demonstration Center for Experimental Preclinical Medicine Education, The Fourth Military Medical University, Xi'an, 710032, China
| | - Fei-Fei Wu
- Specific Lab for Mitochondrial Plasticity Underlying Nervous System Diseases, National Demonstration Center for Experimental Preclinical Medicine Education, The Fourth Military Medical University, Xi'an, 710032, China
| | - Hui Liu
- Department of Human Anatomy, Yan-An University, Yan'an, 716000, China
| | - Rui-Qing Wang
- Department of Human Anatomy, Yan-An University, Yan'an, 716000, China
| | - Bo-Zhi Liu
- Specific Lab for Mitochondrial Plasticity Underlying Nervous System Diseases, National Demonstration Center for Experimental Preclinical Medicine Education, The Fourth Military Medical University, Xi'an, 710032, China
| | - Ze Li
- Specific Lab for Mitochondrial Plasticity Underlying Nervous System Diseases, National Demonstration Center for Experimental Preclinical Medicine Education, The Fourth Military Medical University, Xi'an, 710032, China
| | - Kai-Feng Li
- Specific Lab for Mitochondrial Plasticity Underlying Nervous System Diseases, National Demonstration Center for Experimental Preclinical Medicine Education, The Fourth Military Medical University, Xi'an, 710032, China
| | - Nian-Song Qian
- Department of Oncology, First Medical Center, The General Hospital of the People's Liberation Army, Beijing, 100000, China
| | - Yan-Ling Yang
- Department of Liver and Gallbladder Surgery, Xi-Jing Hospital, The Fourth Military Medical University, Xi'an, 710032, China.
| | - Hua Yuan
- Department of Rehabilitation Medicine, Xi-Jing Hospital, The Fourth Military Medical University, Xi'an, 710032, China.
| | - Ya-Yun Wang
- Specific Lab for Mitochondrial Plasticity Underlying Nervous System Diseases, National Demonstration Center for Experimental Preclinical Medicine Education, The Fourth Military Medical University, Xi'an, 710032, China; State Key Laboratory of Military Stomatology, School of Stomatology, The Fourth Military Medical University, Xi'an, 710032, China.
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Stereological Study of Changes of GABA-Immunoreactive Neurons in Spinal Dorsal Horn of SNI Rats. BIOMED RESEARCH INTERNATIONAL 2021; 2021:6633834. [PMID: 34239929 PMCID: PMC8233084 DOI: 10.1155/2021/6633834] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/25/2020] [Revised: 04/30/2021] [Accepted: 06/04/2021] [Indexed: 11/18/2022]
Abstract
Objective To observe the changes in the mechanical withdrawal threshold (MWT) and the proportion of GABA-immunoreactive neurons in spinal dorsal horn (SDH) of the spared nerve injury (SNI) rat model. Methods Thirty-six healthy male SD rats were randomly divided into a sham-operated group (group D, n = 18) and an SNI group (group S, n = 18). The left sciatic nerve trunk and three branches were exposed, two of which, known as tibial and the peroneal nerve, were ligated and cut off. The sural nerve was preserved to build the SNI model in group S. The left sciatic nerve trunk and three branches were only exposed in group D. MWT tests were performed on the medial and lateral sides of the rats' left hindpaw 1 day before surgery and at 7th, 14th, and 28th day after surgery. Results In group S, compared with the baseline measured 1 day before surgery, MWT on the medial and lateral sides of the rats' left hindpaw decreased significantly on the 7th, 14th, and 28th days after surgery (P < 0.05), while in group D, there was no statistically significant difference (P > 0.05). Compared with right SDH, there were not statistically significant reductions in the proportions of GABAergic neurons of left SDH on 7th and 28th day after SNI (P > 0.05); however, the proportion of GABAergic neurons in left SDH significantly decreased, compared with that in right side on 14th day after SNI (P < 0.05). On the same way, the proportions of GABAergic neurons on 7th, 14th, and 28th day after surgery were not statistically different (P > 0.05) in group D. Conclusion The SNI model could reduce the proportion of GABA-immunoreactive neurons in the rat's spinal dorsal horn on the nerve-injured side, and this change was lasting, which might be related to the transformation of the GABA-immunoreactive neurons.
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Zhang Q, Zhou L, Xie H, Zhang H, Gao X. HAGLR aggravates neuropathic pain and promotes inflammatory response and apoptosis of lipopolysaccharide-treated SH-SY5Y cells by sequestering miR-182-5p from ATAT1 and activating NLRP3 inflammasome. Neurochem Int 2021; 145:105001. [PMID: 33626373 DOI: 10.1016/j.neuint.2021.105001] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Revised: 01/27/2021] [Accepted: 02/16/2021] [Indexed: 01/09/2023]
Abstract
BACKGROUND Chronic neuropathic pain is characterized by neuroinflammation. Previously, long noncoding RNA (lncRNA) HAGLR was reported to regulate the inflammatory response of SH-SY5Y cells. However, neither the specific function nor the potential mechanism of HAGLR in neuropathic pain has been explored. AIM OF THE STUDY Our study is aimed to figure out the role of HAGLR in neuropathic pain. METHODS SH-SY5Y cells were treated with lipopolysaccharide (LPS) to mimic neuron injury in vitro. The chronic constriction injury (CCI) rat models were established by ligation of sciatic nerve to mimic neuropathic pain in vivo. Behavioral assessment assays were performed to determine the effects of HAGLR on hypersensitivity in neuropathic pain. Enzyme-linked immunosorbent assay kits were used for detection of inflammatory cytokines. Flow cytometry analysis and Western blot were applied to detect apoptosis. RESULTS HAGLR displayed high levels in spinal cords of CCI rats and in LPS treated SH-SY5Y cells. Knockdown of HAGLR inhibited inflammation and neuron apoptosis of LPS treated SH-SY5Y cells. Mechanistically, HAGLR bound with miR-182-5p in SH-SY5Y cells. ATAT1 served as a target of miR-182-5p. HAGLR activated the NLRP3 inflammasome by ATAT1. Rescue assays demonstrated that overexpression of ATAT1 or NLRP3 reversed the suppressive effects of HAGLR silencing on apoptosis and inflammatory response in SH-SY5Y cells and in spinal cords of CCI rats. The inhibitory effects of silenced HAGLR on hypersensitivity in neuropathic pain were also rescued by ATAT1 or NLRP3. CONCLUSIONS HAGLR aggravates neuropathic pain by sequestering miR-182-5p from ATAT1 and activating NLRP3 inflammasome, which may provide a potential therapeutic target for neuropathic pain treatment.
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Affiliation(s)
- QuanYun Zhang
- Department of Anesthesiology, Second Affiliated Hospital of Soochow University, Suzhou, 215000, Jiangsu, China; Department of Pain Medical Center, Lianyungang Second People's Hospital, Lianyungang, 222000, Jiangsu, China
| | - Li Zhou
- Department of Anaesthesia, Affiliated Hospital of Xuzhou Medical University, Xuzhou, 221006, Jiangsu, China
| | - Hong Xie
- Department of Anesthesiology, Second Affiliated Hospital of Soochow University, Suzhou, 215000, Jiangsu, China.
| | - HongJin Zhang
- Department of Anesthesiology, Second Affiliated Hospital of Soochow University, Suzhou, 215000, Jiangsu, China
| | - XuZhu Gao
- Department of Anesthesiology, Second Affiliated Hospital of Soochow University, Suzhou, 215000, Jiangsu, China
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9
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Locke S, Yousefpour N, Ribeiro-da-Silva A. Dorsal horn disinhibition and movement-induced behaviour in a rat model of inflammatory arthritis. Rheumatology (Oxford) 2021; 60:918-928. [PMID: 32910183 DOI: 10.1093/rheumatology/keaa396] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2020] [Revised: 06/08/2020] [Indexed: 01/08/2023] Open
Abstract
OBJECTIVES Alterations beyond joint inflammation such as changes in dorsal horn (DH) excitability contribute to pain in inflammatory arthritis (IA). More complete understanding of specific underlying mechanisms will be important to define novel targets for the treatment of IA pain. Pre-clinical models are useful, but relevant pain assays are vital for successful clinical translation. For this purpose, a method is presented to assess movement-induced pain-related behaviour changes that was subsequently used to investigate DH disinhibition in IA. METHODS IA was induced by intra-articular injection of complete Freund's adjuvant (CFA) in male rats, and weight distribution was assessed before and after walking on a treadmill. To confirm increased activity in nociception-related pathways, fos expression was assessed in the superficial DH, including in nociceptive neurons, identified by neurokinin 1 (NK1) immunoreactivity, and interneurons. Inhibitory terminal density onto NK1+ neurons was assessed and lastly, a cohort of animals was treated for 3 days with gabapentin. RESULTS At 4 weeks post-CFA, walking reduced weight distribution to the affected joint and increased DH fos expression, including in NK1+ neurons. Neuronal activity in inhibitory cells and inhibitory terminal density on NK1+ neurons were decreased in CFA-treated animals compared with controls. Treatment with gabapentin led to recovered behaviour and DH neuronal activity pattern in CFA-treated animals. CONCLUSION We describe an assay to assess movement-induced pain-related behaviour changes in a rodent IA model. Furthermore, our results suggest that disinhibition may contribute to pain related to movement in IA.
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Affiliation(s)
- Samantha Locke
- Department of Pharmacology and Therapeutics, Montreal, Quebec, Canada.,Alan Edwards Centre for Research on Pain, Montreal, Quebec, Canada
| | - Noosha Yousefpour
- Department of Pharmacology and Therapeutics, Montreal, Quebec, Canada.,Alan Edwards Centre for Research on Pain, Montreal, Quebec, Canada
| | - Alfredo Ribeiro-da-Silva
- Department of Pharmacology and Therapeutics, Montreal, Quebec, Canada.,Alan Edwards Centre for Research on Pain, Montreal, Quebec, Canada.,Department of Anatomy and Cell Biology, McGill University, Montreal, Quebec, Canada
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10
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Boyle KA, Gradwell MA, Yasaka T, Dickie AC, Polgár E, Ganley RP, Orr DPH, Watanabe M, Abraira VE, Kuehn ED, Zimmerman AL, Ginty DD, Callister RJ, Graham BA, Hughes DI. Defining a Spinal Microcircuit that Gates Myelinated Afferent Input: Implications for Tactile Allodynia. Cell Rep 2020; 28:526-540.e6. [PMID: 31291586 PMCID: PMC6635381 DOI: 10.1016/j.celrep.2019.06.040] [Citation(s) in RCA: 67] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Revised: 03/29/2019] [Accepted: 06/10/2019] [Indexed: 12/16/2022] Open
Abstract
Chronic pain presents a major unmet clinical problem. The development of more effective treatments is hindered by our limited understanding of the neuronal circuits underlying sensory perception. Here, we show that parvalbumin (PV)-expressing dorsal horn interneurons modulate the passage of sensory information conveyed by low-threshold mechanoreceptors (LTMRs) directly via presynaptic inhibition and also gate the polysynaptic relay of LTMR input to pain circuits by inhibiting lamina II excitatory interneurons whose axons project into lamina I. We show changes in the functional properties of these PV interneurons following peripheral nerve injury and that silencing these cells unmasks a circuit that allows innocuous touch inputs to activate pain circuits by increasing network activity in laminae I-IV. Such changes are likely to result in the development of tactile allodynia and could be targeted for more effective treatment of mechanical pain.
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Affiliation(s)
- Kieran A Boyle
- Spinal Cord Research Group, Institute of Neuroscience and Psychology, University of Glasgow, Glasgow G12 8QQ, UK
| | - Mark A Gradwell
- School of Biomedical Sciences and Pharmacy, University of Newcastle, Newcastle NSW 2308, Australia
| | - Toshiharu Yasaka
- Department of Anatomy and Physiology, Saga University, Saga 849-8501, Japan
| | - Allen C Dickie
- Spinal Cord Research Group, Institute of Neuroscience and Psychology, University of Glasgow, Glasgow G12 8QQ, UK
| | - Erika Polgár
- Spinal Cord Research Group, Institute of Neuroscience and Psychology, University of Glasgow, Glasgow G12 8QQ, UK
| | - Robert P Ganley
- Spinal Cord Research Group, Institute of Neuroscience and Psychology, University of Glasgow, Glasgow G12 8QQ, UK
| | - Desmond P H Orr
- Spinal Cord Research Group, Institute of Neuroscience and Psychology, University of Glasgow, Glasgow G12 8QQ, UK
| | - Masahiko Watanabe
- Department of Anatomy, Hokkaido University School of Medicine, Sapporo 060-8638, Japan
| | - Victoria E Abraira
- Department of Neurobiology, Howard Hughes Medical Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Emily D Kuehn
- Department of Neurobiology, Howard Hughes Medical Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Amanda L Zimmerman
- Department of Neurobiology, Howard Hughes Medical Institute, Harvard Medical School, Boston, MA 02115, USA
| | - David D Ginty
- Department of Neurobiology, Howard Hughes Medical Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Robert J Callister
- School of Biomedical Sciences and Pharmacy, University of Newcastle, Newcastle NSW 2308, Australia
| | - Brett A Graham
- School of Biomedical Sciences and Pharmacy, University of Newcastle, Newcastle NSW 2308, Australia.
| | - David I Hughes
- Spinal Cord Research Group, Institute of Neuroscience and Psychology, University of Glasgow, Glasgow G12 8QQ, UK.
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11
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Hughes DI, Todd AJ. Central Nervous System Targets: Inhibitory Interneurons in the Spinal Cord. Neurotherapeutics 2020; 17:874-885. [PMID: 33029722 PMCID: PMC7641291 DOI: 10.1007/s13311-020-00936-0] [Citation(s) in RCA: 43] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/22/2020] [Indexed: 12/15/2022] Open
Abstract
Pain is a percept of critical importance to our daily survival. In most cases, it serves both an adaptive function by helping us respond appropriately in a potentially hostile environment and also a protective role by alerting us to tissue damage. Normally, it is evoked by the activation of peripheral nociceptive nerve endings and the subsequent relay of information to distinct cortical and sub-cortical regions, but under pathological conditions that result in chronic pain, it can become spontaneous. Given that one in three chronic pain patients do not respond to the treatments currently available, the need for more effective analgesics is evident. Two principal obstacles to the development of novel analgesic therapies are our limited understanding of how neuronal circuits that comprise these pain pathways transmit and modulate sensory information under normal circumstances and how these circuits change under pathological conditions leading to chronic pain states. In this review, we focus on the role of inhibitory interneurons in setting pain thresholds and, in particular, how disinhibition in the spinal dorsal horn can lead to aberrant sensory processing associated with chronic pain states.
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Affiliation(s)
- David I Hughes
- Institute of Neuroscience and Psychology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, Scotland.
| | - Andrew J Todd
- Institute of Neuroscience and Psychology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, Scotland
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12
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Ward H, West SJ. Microglia: sculptors of neuropathic pain? ROYAL SOCIETY OPEN SCIENCE 2020; 7:200260. [PMID: 32742693 PMCID: PMC7353970 DOI: 10.1098/rsos.200260] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Accepted: 06/01/2020] [Indexed: 05/02/2023]
Abstract
Neuropathic pain presents a huge societal and individual burden. The limited efficacy of current analgesics, diagnostic markers and clinical trial outcome measures arises from an incomplete understanding of the underlying mechanisms. A large and growing body of evidence has established the important role of microglia in the onset and possible maintenance of neuropathic pain, and these cells may represent an important target for future therapy. Microglial research has further revealed their important role in structural remodelling of the nervous system. In this review, we aim to explore the evidence for microglia in sculpting nervous system structure and function, as well as their important role in neuropathic pain, and finally integrate these studies to synthesize a new model for microglia in somatosensory circuit remodelling, composed of six key and inter-related mechanisms. Summarizing the mechanisms through which microglia modulate nervous system structure and function helps to frame a better understanding of neuropathic pain, and provide a clear roadmap for future research.
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Affiliation(s)
- Harry Ward
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
| | - Steven J. West
- Sainsbury Wellcome Centre, University College London, 25 Howland St, London WC1E 6BT, UK
- Author for correspondence: Steven J. West e-mail:
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13
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Telailia N, Fisson S, Frih H. Compression of The Sciatic Nerve May not Contribute to Ipsilateral Hyperalgesia Development in Ovariectomized Female Rats! CELL JOURNAL 2020; 22:548-555. [PMID: 32347049 PMCID: PMC7211275 DOI: 10.22074/cellj.2021.6907] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/27/2019] [Accepted: 08/06/2019] [Indexed: 11/15/2022]
Abstract
Objective von Frey Filament (vFF) is an aesthesiometer to measure paw withdrawal thresholds. Our aim was to
validate the manually von Frey test technique for assessing neuropathic pain behavioral signs in a sciatic nerve ligation
model.
Materials and Methods In this experimental study, peripheral neuropathic pain associated with sciatic nerve chronic
ligation (SN-CL) was induced. Filaments used against posterior pad mid-plantar region using a simplified up-down
method (SUDO). In addition to baseline withdrawal thresholds, the behavioral test was repeated after surgery thrice
more with an interval of ten days. vFF (2 to 26 g) were used in ascending order for hyperalgesia assessment.
Results In SN-CL rats, the results validate a loss of pain sensation, resulted in, long-lasting ipsilateral allodynia with
the development of contralateral allodynia later and an extraterritorial development of neuropathic signs. Variability
for the development of ipsilateral and contralateral allodynia over time was noted in sham (SH) control rats. SN-CL
group showed a contralateral hyperalgesia development just at the 16th-day after surgery with an absence of ipsilateral
hyperalgesia development at the different days of paw withdrawal thresholds measurements.
Conclusion Manually vFF test technique was successfully used for assessing neuropathic pain behavioral signs in
sciatic a nerve ligation model with the absence of ipsilateral hyperalgesia development.
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Affiliation(s)
- Nafissa Telailia
- Department of Biology, Faculty of Natural Science, University of Badji Mokhtar, Annaba, Algeria. Electronic Address:
| | - Sylvain Fisson
- National Institute of Health and Medical Research, Joint Research Unit_S951, Evry, France.,Genethon, National Institute of Health and Medical Research, Joint Research Unit_S951, Evry, France.,Joint Research Unit_S951, University of Evry Val d'Essonne, Evry, France
| | - Hacène Frih
- Department of Biology, Faculty of Natural Science, University of Badji Mokhtar, Annaba, Algeria
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14
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Protein Kinase A Is Involved in Neuropathic Pain by Activating the p38MAPK Pathway to Mediate Spinal Cord Cell Apoptosis. Mediators Inflamm 2020; 2020:6420425. [PMID: 32273830 PMCID: PMC7125471 DOI: 10.1155/2020/6420425] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Revised: 02/26/2020] [Accepted: 03/03/2020] [Indexed: 12/18/2022] Open
Abstract
Neuropathic pain is a serious clinical problem to be solved. This study is aimed at investigating protein kinase A (PKA) expression in neuropathic pain and its possible mechanisms of involvement. A neuropathic pain-related gene expression dataset was downloaded from Gene Expression Omnibus, and differentially expressed genes were screened using the R software. cytoHubba was used to screen for hub genes. A spared nerve injury (SNI) rat model was established, and the paw withdrawal threshold was determined using von Frey filaments. Western blotting and immunofluorescence were used to detect the expression and cellular localization, respectively, of key proteins in the spinal cord. Western blot, ELISA, and TUNEL assays were used to detect cell signal transduction, inflammation, and apoptosis, respectively. Pka was identified as a key gene involved in neuropathic pain. After SNI, mechanical allodynia occurred, PKA expression in the spinal cord increased, the p38MAPK pathway was activated, and spinal cord inflammation and apoptosis occurred in rats. PKA colocalized with neurons, astrocytes, and microglia, and apoptotic cells were mainly neurons. Intrathecal injection of a PKA inhibitor not only relieved mechanical hyperalgesia, inflammatory reaction, and apoptosis in SNI rats but also inhibited p38MAPK pathway activation. However, intrathecal injection of a p38MAPK inhibitor attenuated mechanical hyperalgesia, inflammation, and apoptosis, but did not affect PKA expression. In conclusion, PKA is involved in neuropathic pain by activating the p38MAPK pathway to mediate spinal cord cell apoptosis.
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15
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Lorenzo LE, Godin AG, Ferrini F, Bachand K, Plasencia-Fernandez I, Labrecque S, Girard AA, Boudreau D, Kianicka I, Gagnon M, Doyon N, Ribeiro-da-Silva A, De Koninck Y. Enhancing neuronal chloride extrusion rescues α2/α3 GABA A-mediated analgesia in neuropathic pain. Nat Commun 2020; 11:869. [PMID: 32054836 PMCID: PMC7018745 DOI: 10.1038/s41467-019-14154-6] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Accepted: 12/16/2019] [Indexed: 02/06/2023] Open
Abstract
Spinal disinhibition has been hypothesized to underlie pain hypersensitivity in neuropathic pain. Apparently contradictory mechanisms have been reported, raising questions on the best target to produce analgesia. Here, we show that nerve injury is associated with a reduction in the number of inhibitory synapses in the spinal dorsal horn. Paradoxically, this is accompanied by a BDNF-TrkB-mediated upregulation of synaptic GABAARs and by an α1-to-α2GABAAR subunit switch, providing a mechanistic rationale for the analgesic action of the α2,3GABAAR benzodiazepine-site ligand L838,417 after nerve injury. Yet, we demonstrate that impaired Cl- extrusion underlies the failure of L838,417 to induce analgesia at high doses due to a resulting collapse in Cl- gradient, dramatically limiting the benzodiazepine therapeutic window. In turn, enhancing KCC2 activity not only potentiated L838,417-induced analgesia, it rescued its analgesic potential at high doses, revealing a novel strategy for analgesia in pathological pain, by combined targeting of the appropriate GABAAR-subtypes and restoring Cl- homeostasis.
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Affiliation(s)
- Louis-Etienne Lorenzo
- CERVO Brain Research Centre, Quebec Mental Health Institute, Québec, QC, Canada
- Department of Pharmacology & Therapeutics, McGill University, Montreal, QC, Canada
| | - Antoine G Godin
- CERVO Brain Research Centre, Quebec Mental Health Institute, Québec, QC, Canada
- Department of Psychiatry & Neuroscience, Université Laval, Québec, QC, Canada
- Graduate program in Neuroscience, Université Laval, Québec, QC, Canada
| | - Francesco Ferrini
- CERVO Brain Research Centre, Quebec Mental Health Institute, Québec, QC, Canada
- Department of Psychiatry & Neuroscience, Université Laval, Québec, QC, Canada
- Graduate program in Neuroscience, Université Laval, Québec, QC, Canada
- Department of Veterinary Sciences, University of Turin, Turin, Italy
| | - Karine Bachand
- CERVO Brain Research Centre, Quebec Mental Health Institute, Québec, QC, Canada
| | - Isabel Plasencia-Fernandez
- CERVO Brain Research Centre, Quebec Mental Health Institute, Québec, QC, Canada
- Graduate program in Neuroscience, Université Laval, Québec, QC, Canada
| | - Simon Labrecque
- CERVO Brain Research Centre, Quebec Mental Health Institute, Québec, QC, Canada
| | - Alexandre A Girard
- CERVO Brain Research Centre, Quebec Mental Health Institute, Québec, QC, Canada
- Ecole Polytechnique, IP Paris, Palaiseau, France
| | - Dominic Boudreau
- CERVO Brain Research Centre, Quebec Mental Health Institute, Québec, QC, Canada
- Graduate program in Neuroscience, Université Laval, Québec, QC, Canada
| | - Irenej Kianicka
- Chlorion Pharma, Laval, Québec, QC, Canada
- Laurent Pharmaceuticals Inc., Montreal, QC, Canada
| | - Martin Gagnon
- CERVO Brain Research Centre, Quebec Mental Health Institute, Québec, QC, Canada
- Centre for Innovation, University of Otago, Dunedin, New Zealand
| | - Nicolas Doyon
- CERVO Brain Research Centre, Quebec Mental Health Institute, Québec, QC, Canada
- Finite Element Interdisciplinary Research Group (GIREF), Université Laval, Québec, QC, Canada
| | - Alfredo Ribeiro-da-Silva
- Department of Pharmacology & Therapeutics, McGill University, Montreal, QC, Canada
- Department of Anatomy & Cell Biology, McGill University, Montreal, QC, Canada
- Alan Edwards Centre for Research on Pain, McGill University, Montreal, QC, Canada
| | - Yves De Koninck
- CERVO Brain Research Centre, Quebec Mental Health Institute, Québec, QC, Canada.
- Department of Pharmacology & Therapeutics, McGill University, Montreal, QC, Canada.
- Department of Psychiatry & Neuroscience, Université Laval, Québec, QC, Canada.
- Graduate program in Neuroscience, Université Laval, Québec, QC, Canada.
- Alan Edwards Centre for Research on Pain, McGill University, Montreal, QC, Canada.
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16
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Manion J, Waller MA, Clark T, Massingham JN, Neely GG. Developing Modern Pain Therapies. Front Neurosci 2019; 13:1370. [PMID: 31920521 PMCID: PMC6933609 DOI: 10.3389/fnins.2019.01370] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2019] [Accepted: 12/04/2019] [Indexed: 12/24/2022] Open
Abstract
Chronic pain afflicts as much as 50% of the population at any given time but our methods to address pain remain limited, ineffective and addictive. In order to develop new therapies an understanding of the mechanisms of painful sensitization is essential. We discuss here recent progress in the understanding of mechanisms underlying pain, and how these mechanisms are being targeted to produce modern, specific therapies for pain. Finally, we make recommendations for the next generation of targeted, effective, and safe pain therapies.
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Affiliation(s)
- John Manion
- The Dr. John and Anne Chong Lab for Functional Genomics, Charles Perkins Centre and School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW, Australia
| | - Matthew A. Waller
- The Dr. John and Anne Chong Lab for Functional Genomics, Charles Perkins Centre and School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW, Australia
| | - Teleri Clark
- The Dr. John and Anne Chong Lab for Functional Genomics, Charles Perkins Centre and School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW, Australia
| | - Joshua N. Massingham
- The Dr. John and Anne Chong Lab for Functional Genomics, Charles Perkins Centre and School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW, Australia
| | - G. Gregory Neely
- The Dr. John and Anne Chong Lab for Functional Genomics, Charles Perkins Centre and School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW, Australia
- Genome Editing Initiative, The University of Sydney, Sydney, NSW, Australia
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17
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NMDA Receptor Activation Underlies the Loss of Spinal Dorsal Horn Neurons and the Transition to Persistent Pain after Peripheral Nerve Injury. Cell Rep 2019; 23:2678-2689. [PMID: 29847798 PMCID: PMC6276118 DOI: 10.1016/j.celrep.2018.04.107] [Citation(s) in RCA: 73] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2017] [Revised: 03/12/2018] [Accepted: 04/26/2018] [Indexed: 12/31/2022] Open
Abstract
Peripheral nerve lesions provoke apoptosis in the dorsal horn of the spinal cord. The cause of cell death, the involvement of neurons, and the relevance for the processing of somatosensory information are controversial. Here, we demonstrate in a mouse model of sciatic nerve injury that glutamate-induced neurodegeneration and loss of γ-aminobutyric acid (GABA)ergic interneurons in the superficial dorsal horn promote the transition from acute to chronic neuropathic pain. Conditional deletion of Grin1, the essential subunit of N-methyl-d-aspartate-type glutamate receptors (NMDARs), protects dorsal horn neurons from excitotoxicity and preserves GABAergic inhibition. Mice deficient in functional NMDARs exhibit normal nociceptive responses and acute pain after nerve injury, but this initial increase in pain sensitivity is reversible. Eliminating NMDARs fully prevents persistent pain-like behavior. Reduced pain in mice lacking proapoptotic Bax confirmed the significance of neurodegeneration. We conclude that NMDAR-mediated neuron death contributes to the development of chronic neuropathic pain.
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18
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Gradwell MA, Callister RJ, Graham BA. Reviewing the case for compromised spinal inhibition in neuropathic pain. J Neural Transm (Vienna) 2019; 127:481-503. [PMID: 31641856 DOI: 10.1007/s00702-019-02090-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2019] [Accepted: 09/30/2019] [Indexed: 12/20/2022]
Abstract
A striking and debilitating property of the nervous system is that damage to this tissue can cause chronic intractable pain, which persists long after resolution of the initial insult. This neuropathic form of pain can arise from trauma to peripheral nerves, the spinal cord, or brain. It can also result from neuropathies associated with disease states such as diabetes, human immunodeficiency virus/AIDS, herpes, multiple sclerosis, cancer, and chemotherapy. Regardless of the origin, treatments for neuropathic pain remain inadequate. This continues to drive research into the underlying mechanisms. While the literature shows that dysfunction in numerous loci throughout the CNS can contribute to chronic pain, the spinal cord and in particular inhibitory signalling in this region have remained major research areas. This review focuses on local spinal inhibition provided by dorsal horn interneurons, and how such inhibition is disrupted during the development and maintenance of neuropathic pain.
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Affiliation(s)
- M A Gradwell
- School of Biomedical Sciences and Pharmacy, Faculty of Health, University of Newcastle, Callaghan, NSW, 2308, Australia
- Hunter Medical Research Institute (HMRI), New Lambton Heights, NSW, Australia
| | - R J Callister
- School of Biomedical Sciences and Pharmacy, Faculty of Health, University of Newcastle, Callaghan, NSW, 2308, Australia
- Hunter Medical Research Institute (HMRI), New Lambton Heights, NSW, Australia
| | - B A Graham
- School of Biomedical Sciences and Pharmacy, Faculty of Health, University of Newcastle, Callaghan, NSW, 2308, Australia.
- Hunter Medical Research Institute (HMRI), New Lambton Heights, NSW, Australia.
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19
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Functional Reorganization of Local Circuit Connectivity in Superficial Spinal Dorsal Horn with Neuropathic Pain States. eNeuro 2019; 6:ENEURO.0272-19.2019. [PMID: 31533959 PMCID: PMC6787342 DOI: 10.1523/eneuro.0272-19.2019] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2019] [Revised: 08/27/2019] [Accepted: 09/05/2019] [Indexed: 01/12/2023] Open
Abstract
The spinal dorsal horn is the first relay structure coding for pain transmission and modulation. Previous anatomical and electrophysiological studies have examined spinal dorsal horn circuit connections and network activity. Further work is required to understand spinal cord sensory information processing that underlies pathological neuropathic pain states. Our previous studies suggest that peripheral nerve injury enhances presynaptic excitatory input onto spinal superficial dorsal horn neurons, which in turn contributes to pathologic nociception. The potential changes in local postsynaptic circuits in the dorsal horn that lead to pathologically heightened behavioral responses to pain remain largely unexplored. We combined whole-cell electrophysiological recordings with laser-scanning photostimulation to test whether peripheral nerve injury in the spinal nerve ligation (SNL) mouse model of neuropathic pain leads to alterations in the functional connectivity of spinal cord circuits including lamina II excitatory interneurons. Here we show that SNL enhances excitation and decreases inhibition to lamina II excitatory interneurons along with their increased glutamate-evoked excitability. The enhanced excitatory postsynaptic input and connectivity evoked by SNL eventually return to normal levels concurrently with the resolution of the neuropathic pain states. The physiological pattern highly correlates with mouse pain behaviors following SNL, supporting a neurophysiological mechanism of central sensitization and neuropathic pain that is functionally localized to the spinal dorsal horn. Together, these data support that SNL induces functional changes in synaptic input and connectivity to lamina II excitatory interneurons that code for pain perception, and thus provide new insights into the mechanism and locus of pain hypersensitivity.
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20
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Caspases orchestrate microglia instrumental functions. Prog Neurobiol 2018; 171:50-71. [DOI: 10.1016/j.pneurobio.2018.09.007] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Revised: 09/21/2018] [Accepted: 09/29/2018] [Indexed: 12/16/2022]
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21
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Shehab S, Rehmathulla S, Javed H. A single GABA neuron receives contacts from myelinated primary afferents of two adjacent peripheral nerves. A possible role in neuropathic pain. J Comp Neurol 2018; 526:2984-2999. [PMID: 30069880 DOI: 10.1002/cne.24509] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Revised: 07/19/2018] [Accepted: 07/20/2018] [Indexed: 12/19/2022]
Abstract
GAD67-EGFP mice were used in a series of experiments to provide anatomical evidence for the role of the reduction in myelinated primary afferent input to GABA spinal neurons in the production of neuropathic pain following peripheral L5 nerve injury. First, we confirmed that L5 injury in these mice produced mechanical and thermal hyperalgesia in the ipsilateral foot. Second, we injected a mixture of cholera toxin subunit-B (CTb) and isolectin B4 (IB4) in the sciatic nerve to selectively label its myelinated and unmyelinated primary afferents. Results showed that primary afferents of sciatic nerve extend from L2-L6 spinal segments. Third, we determined the central terminations of myelinated primary afferents of L4 and L5 spinal nerves following CTb injection in either nerve. The myelinated primary afferents of both nerves terminated in the corresponding and two to three rostral spinal segments with some fibers descending to terminate in the segment caudal to the level at which they entered indicating an intermingling of their terminals at the dorsal horn of the spinal cord. Fourthly, we injected CTb in L5 nerve and CTb HRP-conjugate in L4 nerve. Confocal microscopy and subsequent image analyses showed that individual EGFP-labeled neurons in L4 segment receive myelinated primary afferent contacts from both L4 and L5 nerves. Eliminating inputs from L5 nerve following its injury would result in less involvement of spinal GABA neurons which would very likely initiate neuronal sensitization in L4 segment. This could lead to the development of hyperalgesia in response to the stimulation of the adjacent uninjured L4 nerve.
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Affiliation(s)
- Safa Shehab
- Department of Anatomy, College of Medicine and Health Sciences, United Arab Emirates University, Al-Ain, United Arab Emirates
| | - Sumisha Rehmathulla
- Department of Anatomy, College of Medicine and Health Sciences, United Arab Emirates University, Al-Ain, United Arab Emirates
| | - Hayate Javed
- Department of Anatomy, College of Medicine and Health Sciences, United Arab Emirates University, Al-Ain, United Arab Emirates
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22
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Tan W, Yao WL, Zhang B, Hu R, Wan L, Zhang CH, Zhu C. Neuronal loss in anterior cingulate cortex in spared nerve injury model of neuropathic pain. Neurochem Int 2018; 118:127-133. [PMID: 29894700 DOI: 10.1016/j.neuint.2018.06.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2017] [Revised: 05/29/2018] [Accepted: 06/06/2018] [Indexed: 12/23/2022]
Affiliation(s)
- Wei Tan
- Department of Anesthesiology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China.
| | - Wen-Long Yao
- Department of Anesthesiology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China.
| | - Bo Zhang
- Department of Anesthesiology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China.
| | - Rong Hu
- Department of Anesthesiology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China.
| | - Li Wan
- Department of Anesthesiology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China.
| | - Chuan-Han Zhang
- Department of Anesthesiology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China.
| | - Chang Zhu
- Department of Anesthesiology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China.
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Zhang H, Li Y, Yang Q, Liu XG, Dougherty PM. Morphological and Physiological Plasticity of Spinal Lamina II GABA Neurons Is Induced by Sciatic Nerve Chronic Constriction Injury in Mice. Front Cell Neurosci 2018; 12:143. [PMID: 29881336 PMCID: PMC5976754 DOI: 10.3389/fncel.2018.00143] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2018] [Accepted: 05/09/2018] [Indexed: 11/21/2022] Open
Abstract
Mice with transgenic insertion of code for enhanced green fluorescent protein (EGFP) at the locus for glutamic acid decarboxylase 67 (GAD67), one of two key enzymes for the synthesis of γ-aminobutyric acid (GABA) were used to test whether the morphological properties of these neurons show plasticity with nerve injury. Physiological properties and the delivery of intracellular label to EGFP-expressing lamina II neurons was done using whole-cell patch-clamp in spinal cord slices from sham and chronic constriction injury (CCI) mice. As well, whole cell recordings were made of non-EGFP labeled cells to ascertain changes in overall inhibitory signaling following CCI. The EGFP labeled neurons in both sham and CCI mice exhibited islet, central and vertical cell morphological profiles but no radial cell profiles were observed. The length of cell dendrites was found to be significantly shorter in CCI mice for all cell profile types. The longest neurites averaged 155.96 ± 18.29 μm in CCI mice compared to 334.93 ± 29.48 μm in sham control mice. No change was observed in either passive or evoked membrane properties of EGFP-expressing neurons in CCI versus sham mice. Meanwhile, the frequency of miniature inhibitory post-synaptic currents of non-EGFP expressing spinal lamina II neurons was significantly reduced. These results suggest that reduced inhibitory output from GABA neurons occurs with nerve injury in part due to altered cell morphology.
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Affiliation(s)
- Hongmei Zhang
- Division of Anesthesiology and Critical Care Medicine, Department of Pain Medicine, University of Texas MD Anderson Cancer Center, Houston, TX, United States
| | - Yan Li
- Division of Anesthesiology and Critical Care Medicine, Department of Pain Medicine, University of Texas MD Anderson Cancer Center, Houston, TX, United States
| | - Qing Yang
- Department of Integrative Biology and Pharmacology, The University of Texas Health Science Center at Houston, Houston, TX, United States
| | - Xian-Guo Liu
- Department of Physiology and Pain Research Center, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China
| | - Patrick M Dougherty
- Division of Anesthesiology and Critical Care Medicine, Department of Pain Medicine, University of Texas MD Anderson Cancer Center, Houston, TX, United States
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Microglia in neuropathic pain: cellular and molecular mechanisms and therapeutic potential. Nat Rev Neurosci 2018; 19:138-152. [DOI: 10.1038/nrn.2018.2] [Citation(s) in RCA: 365] [Impact Index Per Article: 60.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Zeilhofer HU, Acuña MA, Gingras J, Yévenes GE. Glycine receptors and glycine transporters: targets for novel analgesics? Cell Mol Life Sci 2018; 75:447-465. [PMID: 28791431 PMCID: PMC11105467 DOI: 10.1007/s00018-017-2622-x] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2017] [Revised: 07/14/2017] [Accepted: 08/04/2017] [Indexed: 01/29/2023]
Abstract
Glycinergic neurotransmission has long been known for its role in spinal motor control. During the last two decades, additional functions have become increasingly recognized-among them is a critical contribution to spinal pain processing. Studies in rodent pain models provide proof-of-concept evidence that enhancing inhibitory glycinergic neurotransmission reduces chronic pain symptoms. Apparent strategies for pharmacological intervention include positive allosteric modulators of glycine receptors and modulators or inhibitors of the glial and neuronal glycine transporters GlyT1 and GlyT2. These prospects have led to drug discovery efforts in academia and in industry aiming at compounds that target glycinergic neurotransmission with high specificity. Available data show promising analgesic efficacy. Less is currently known about potential unwanted effects but the presence of glycinergic innervation in CNS areas outside the nociceptive system prompts for a careful evaluation not only of motor function, but also of potential respiratory impairment and addictive properties.
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Affiliation(s)
- Hanns Ulrich Zeilhofer
- Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland.
- Institute of Pharmaceutical Sciences, Swiss Federal Institute of Technology (ETH) Zürich, Vladimir-Prelog-Weg 1-5/10, 8093, Zurich, Switzerland.
| | - Mario A Acuña
- Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland
| | | | - Gonzalo E Yévenes
- Department of Physiology, University of Concepción, Concepción, Chile
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27
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Zhou YQ, Chen SP, Liu DQ, Manyande A, Zhang W, Yang SB, Xiong BR, Fu QC, Song ZP, Rittner H, Ye DW, Tian YK. The Role of Spinal GABAB Receptors in Cancer-Induced Bone Pain in Rats. THE JOURNAL OF PAIN 2017; 18:933-946. [PMID: 28323246 DOI: 10.1016/j.jpain.2017.02.438] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2016] [Revised: 02/21/2017] [Accepted: 02/26/2017] [Indexed: 12/19/2022]
Abstract
Cancer-induced bone pain (CIBP) remains a major challenge in advanced cancer patients because of our lack of understanding of its mechanisms. Previous studies have shown the vital role of γ-aminobutyric acid B receptors (GABABRs) in regulating nociception and various neuropathic pain models have shown diminished activity of GABABRs. However, the role of spinal GABABRs in CIBP remains largely unknown. In this study, we investigated the specific cellular mechanisms of GABABRs in the development and maintenance of CIBP in rats. Our behavioral results show that acute as well as chronic intrathecal treatment with baclofen, a GABABR agonist, significantly attenuated CIBP-induced mechanical allodynia and ambulatory pain. The expression levels of GABABRs were significantly decreased in a time-dependent manner and colocalized mostly with neurons and a minority with astrocytes and microglia. Chronic treatment with baclofen restored the expression of GABABRs and markedly inhibited the activation of cyclic adenosine monophosphate (cAMP)-dependent protein kinase and the cAMP-response element-binding protein signaling pathway. PERSPECTIVE Our findings provide, to our knowledge, the first evidence that downregulation of GABABRs contribute to the development and maintenance of CIBP and restored diminished GABABRs attenuate CIBP-induced pain behaviors at least partially by inhibiting the protein kinase/cAMP-response element-binding protein signaling pathway. Therefore, spinal GABABR may become a potential therapeutic target for the management of CIBP.
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Affiliation(s)
- Ya-Qun Zhou
- Anesthesiology Institute, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China; Department of Anesthesiology and Pain Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Shu-Ping Chen
- Anesthesiology Institute, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China; Department of Anesthesiology and Pain Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Dai-Qiang Liu
- Anesthesiology Institute, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China; Department of Anesthesiology and Pain Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Anne Manyande
- School of Human and Social Sciences, University of West London, London, UK
| | - Wen Zhang
- Anesthesiology Institute, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China; Department of Anesthesiology and Pain Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Shao-Bing Yang
- Anesthesiology Institute, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China; Department of Anesthesiology and Pain Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Bing-Rui Xiong
- Anesthesiology Institute, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China; Department of Anesthesiology and Pain Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Qiao-Chu Fu
- Anesthesiology Institute, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China; Department of Anesthesiology and Pain Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Zhen-Peng Song
- Anesthesiology Institute, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China; Department of Anesthesiology and Pain Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Heike Rittner
- Department of Anesthesiology, University Hospital of Würzburg, Würzburg, Germany
| | - Da-Wei Ye
- Cancer Center, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
| | - Yu-Ke Tian
- Anesthesiology Institute, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China; Department of Anesthesiology and Pain Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
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Unconventional Role of Caspase-6 in Spinal Microglia Activation and Chronic Pain. Mediators Inflamm 2017; 2017:9383184. [PMID: 28270702 PMCID: PMC5320069 DOI: 10.1155/2017/9383184] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2016] [Accepted: 11/06/2016] [Indexed: 12/30/2022] Open
Abstract
Chronic pain affects ~20% of the worldwide population. The clinical management of chronic pain is mostly palliative and results in limited success. Current treatments mostly target the symptoms or neuronal signaling of chronic pain. It has been increasingly recognized that glial cells, such as microglia, and inflammatory signaling play a major role in the pathogenesis of chronic pain. Caspases (CASPs) are a family of protease enzymes involved in apoptosis and inflammation. They are pivotal components in a variety of neurological diseases. However, little is known about the role of CASPs in microglial modulation as to chronic pain. In particular, our recent studies have shown that CASP6 regulates chronic pain via microglial inflammatory signaling. Inhibition of microglia and CASP signaling might provide a new strategy for the prevention and treatment of chronic pain.
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Recombinant neural progenitor transplants in the spinal dorsal horn alleviate chronic central neuropathic pain. Pain 2017; 157:977-989. [PMID: 26761378 DOI: 10.1097/j.pain.0000000000000471] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Neuropathic pain induced by spinal cord injury (SCI) is clinically challenging with inadequate long-term treatment options. Partial pain relief offered by pharmacologic treatment is often counterbalanced by adverse effects after prolonged use in chronic pain patients. Cell-based therapy for neuropathic pain using GABAergic neuronal progenitor cells (NPCs) has the potential to overcome untoward effects of systemic pharmacotherapy while enhancing analgesic potency due to local activation of GABAergic signaling in the spinal cord. However, multifactorial anomalies underlying chronic pain will likely require simultaneous targeting of multiple mechanisms. Here, we explore the analgesic potential of genetically modified rat embryonic GABAergic NPCs releasing a peptidergic NMDA receptor antagonist, Serine-histogranin (SHG), thus targeting both spinal hyperexcitability and reduced inhibitory processes. Recombinant NPCs were designed using either lentiviral or adeno-associated viral vectors (AAV2/8) encoding single and multimeric (6 copies of SHG) cDNA. Intraspinal injection of recombinant cells elicited enhanced analgesic effects compared with nonrecombinant NPCs in SCI-induced pain in rats. Moreover, potent and sustained antinociception was achieved, even after a 5-week postinjury delay, using recombinant multimeric NPCs. Intrathecal injection of SHG antibody attenuated analgesic effects of the recombinant grafts suggesting active participation of SHG in these antinociceptive effects. Immunoblots and immunocytochemical assays indicated ongoing recombinant peptide production and secretion in the grafted host spinal cords. These results support the potential for engineered NPCs grafted into the spinal dorsal horn to alleviate chronic neuropathic pain.
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Roza C, Mazo I, Rivera-Arconada I, Cisneros E, Alayón I, López-García JA. Analysis of spontaneous activity of superficial dorsal horn neurons in vitro: neuropathy-induced changes. Pflugers Arch 2016; 468:2017-2030. [PMID: 27726011 DOI: 10.1007/s00424-016-1886-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2016] [Revised: 09/06/2016] [Accepted: 09/26/2016] [Indexed: 01/17/2023]
Abstract
The superficial dorsal horn contains large numbers of interneurons which process afferent and descending information to generate the spinal nociceptive message. Here, we set out to evaluate whether adjustments in patterns and/or temporal correlation of spontaneous discharges of these neurons are involved in the generation of central sensitization caused by peripheral nerve damage. Multielectrode arrays were used to record from discrete groups of such neurons in slices from control or nerve damaged mice. Whole-cell recordings of individual neurons were also obtained. A large proportion of neurons recorded extracellularly showed well-defined patterns of spontaneous firing. Clock-like neurons (CL) showed regular discharges at ∼6 Hz and represented 9 % of the sample in control animals. They showed a tonic-firing pattern to direct current injection and depolarized membrane potentials. Irregular fast-burst neurons (IFB) produced short-lasting high-frequency bursts (2-5 spikes at ∼100 Hz) at irregular intervals and represented 25 % of the sample. They showed bursting behavior upon direct current injection. Of the pairs of neurons recorded, 10 % showed correlated firing. Correlated pairs always included an IFB neuron. After nerve damage, the mean spontaneous firing frequency was unchanged, but the proportion of CL increased significantly (18 %) and many of these neurons appeared to acquire a novel low-threshold A-fiber input. Similarly, the percentage of IFB neurons was unaltered, but synchronous firing was increased to 22 % of the pairs studied. These changes may contribute to transform spinal processing of nociceptive inputs following peripheral nerve damage. The specific roles that these neurons may play are discussed.
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Affiliation(s)
- Carolina Roza
- Dpto. Biología de Sistemas, Edificio de Medicina, Universidad de Alcalá, Campus Universitario, 28871, Alcalá de Henares, Madrid, Spain
| | - Irene Mazo
- Dpto. Biología de Sistemas, Edificio de Medicina, Universidad de Alcalá, Campus Universitario, 28871, Alcalá de Henares, Madrid, Spain
| | - Iván Rivera-Arconada
- Dpto. Biología de Sistemas, Edificio de Medicina, Universidad de Alcalá, Campus Universitario, 28871, Alcalá de Henares, Madrid, Spain
| | - Elsa Cisneros
- Dpto. Biología de Sistemas, Edificio de Medicina, Universidad de Alcalá, Campus Universitario, 28871, Alcalá de Henares, Madrid, Spain
| | - Ismel Alayón
- Dpto. Biología de Sistemas, Edificio de Medicina, Universidad de Alcalá, Campus Universitario, 28871, Alcalá de Henares, Madrid, Spain
| | - José A López-García
- Dpto. Biología de Sistemas, Edificio de Medicina, Universidad de Alcalá, Campus Universitario, 28871, Alcalá de Henares, Madrid, Spain.
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31
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Dias QM, Prado WA. The lesion of dorsolateral funiculus changes the antiallodynic effect of the intrathecal muscimol and baclofen in distinct phases of neuropathic pain induced by spinal nerve ligation in rats. Brain Res Bull 2016; 124:103-15. [DOI: 10.1016/j.brainresbull.2016.04.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2015] [Revised: 03/31/2016] [Accepted: 04/04/2016] [Indexed: 12/20/2022]
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Iura A, Takahashi A, Hakata S, Mashimo T, Fujino Y. Reductions in tonic GABAergic current in substantia gelatinosa neurons and GABAAreceptor δ subunit expression after chronic constriction injury of the sciatic nerve in mice. Eur J Pain 2016; 20:1678-1688. [DOI: 10.1002/ejp.891] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/28/2016] [Indexed: 11/09/2022]
Affiliation(s)
- A. Iura
- Department of Anesthesiology and Intensive Care Medicine; Graduate School of Medicine; Osaka University; Japan
| | - A. Takahashi
- Department of Anesthesiology and Intensive Care Medicine; Graduate School of Medicine; Osaka University; Japan
| | - S. Hakata
- Department of Anesthesiology and Intensive Care Medicine; Graduate School of Medicine; Osaka University; Japan
| | - T. Mashimo
- Toyonaka Municipal Hospital; Osaka Japan
| | - Y. Fujino
- Department of Anesthesiology and Intensive Care Medicine; Graduate School of Medicine; Osaka University; Japan
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Jergova S, Gajavelli S, Varghese MS, Shekane P, Sagen J. Analgesic Effect of Recombinant GABAergic Cells in a Model of Peripheral Neuropathic Pain. Cell Transplant 2016; 25:629-43. [DOI: 10.3727/096368916x690782] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Chronic neuropathic pain represents a clinically challenging state with a poor response to current treatment options. Long-term management of chronic pain is often associated with the development of tolerance, addiction, and other side effects, reducing the therapeutic value of treatment. Alternative strategies based on cell therapy and gene manipulation, balancing the inhibitory and excitatory events in the spinal cord, may provide sustained pain relief in the long term. Transplantation of GABAergic cells has been successfully used to enhance inhibition and to restore physiological spinal pain processing. However, since the underlying mechanism of chronic pain development involves changes in several pain-signaling pathways, it is essential to develop an approach that targets several components of pain signaling. Recombinant cell therapy offers the possibility to deliver additional analgesic substances to the restricted area in the nervous system. The current study explores the analgesic potential of genetically modified rat embryonic GABAergic cells releasing a peptidergic NMDA receptor antagonist, Serine1-histogranin (SHG). Overactivation of glutamate NMDA receptors contributes to the hyperexcitability of spinal neurons observed in chronic pain models. Our approach allows us to simultaneously target spinal hyperexcitability and reduced inhibitory processes. Transplantable cells were transduced by viral vectors encoding either one or six copies of SHG cDNAs. The analgesic potential of recombinant cells after their intraspinal transplantation was evaluated in a model of peripheral nerve injury. Enhanced reduction of hypersensitivity to thermal and mechanical stimuli was observed in animals treated by recombinant cells compared to the nonrecombinant group. The recombinant peptide was detected in the spinal tissue, suggesting its successful production by transplanted cells. Our results demonstrate the feasibility of using recombinant cells releasing adjunct analgesic peptides in the therapy of neuropathic pain.
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Affiliation(s)
- Stanislava Jergova
- Miller School of Medicine, Miami Project, University of Miami, Miami, FL, USA
| | - Shyam Gajavelli
- Miller School of Medicine, Miami Project, University of Miami, Miami, FL, USA
| | - Mathew S. Varghese
- Miller School of Medicine, Miami Project, University of Miami, Miami, FL, USA
| | - Paul Shekane
- Miller School of Medicine, Miami Project, University of Miami, Miami, FL, USA
| | - Jacqueline Sagen
- Miller School of Medicine, Miami Project, University of Miami, Miami, FL, USA
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Kami K, Taguchi Ms S, Tajima F, Senba E. Improvements in impaired GABA and GAD65/67 production in the spinal dorsal horn contribute to exercise-induced hypoalgesia in a mouse model of neuropathic pain. Mol Pain 2016; 12:12/0/1744806916629059. [PMID: 27030712 PMCID: PMC4956002 DOI: 10.1177/1744806916629059] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2015] [Accepted: 12/04/2015] [Indexed: 11/16/2022] Open
Abstract
Background Physical exercise effectively attenuates neuropathic pain, and multiple events including the inhibition of activated glial cells in the spinal dorsal horn, activation of the descending pain inhibitory system, and reductions in pro-inflammatory cytokines in injured peripheral nerves may contribute to exercise-induced hypoalgesia. Since fewer GABAergic hypoalgesic interneurons exist in the dorsal horn in neuropathic pain model animals, the recovery of impaired GABAergic inhibition in the dorsal horn may improve pain behavior. We herein determined whether the production of gamma-aminobutyric acid (GABA) and glutamic acid decarboxylase (GAD) in the dorsal horn is restored by treadmill running and contributes to exercise-induced hypoalgesia in neuropathic pain model mice. C57BL/6 J mice underwent partial sciatic nerve ligation (PSL). PSL-Runner mice ran on a treadmill at 7 m/min for 60 min/day, 5 days/week, from two days after PSL. Results Mechanical allodynia and heat hyperalgesia developed in PSL-Sedentary mice but were significantly attenuated in PSL-Runner mice. PSL markedly decreased GABA and GAD65/67 levels in neuropils in the ipsilateral dorsal horn, while treadmill running inhibited these reductions. GABA+ neuronal nuclei+ interneuron numbers in the ipsilateral dorsal horn were significantly decreased in PSL-Sedentary mice but not in PSL-Runner mice. Pain behavior thresholds positively correlated with GABA and GAD65/67 levels and GABAergic interneuron numbers in the ipsilateral dorsal horns of PSL-Sedentary and -Runner mice. Conclusions Treadmill running prevented PSL-induced reductions in GAD65/67 production, and, thus, GABA levels may be retained in interneurons and neuropils in the superficial dorsal horn. Therefore, improvements in impaired GABAergic inhibition may be involved in exercise-induced hypoalgesia.
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Affiliation(s)
- Katsuya Kami
- Department of Rehabilitation Medicine, Wakayama Medical University, Wakayama City, Wakayama, Japan
| | - Satoru Taguchi Ms
- Department of Rehabilitation Medicine, Wakayama Medical University, Wakayama City, Wakayama, Japan
| | - Fumihiro Tajima
- Department of Rehabilitation Medicine, Wakayama Medical University, Wakayama City, Wakayama, Japan
| | - Emiko Senba
- Department of Rehabilitation Medicine, Wakayama Medical University, Wakayama City, Wakayama, Japan Department of Physical Therapy, Osaka Yukioka College of Health Science, Ibaraki City, Osaka, Japan
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Effects of chronic constriction injury and spared nerve injury, two models of neuropathic pain, on the numbers of neurons and glia in the rostral ventromedial medulla. Neurosci Lett 2016; 617:82-7. [PMID: 26861198 DOI: 10.1016/j.neulet.2016.02.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2015] [Revised: 01/15/2016] [Accepted: 02/02/2016] [Indexed: 12/26/2022]
Abstract
In previous studies we have reported that spinal nerve ligation (SNL), a model of neuropathic pain, results in the loss of over 20% of neurons in the rostral portion of the ventromedial medulla (RVM) in rats, 10 days after SNL. The RVM is involved in pain modulation and we have proposed that loss of pain inhibition from the RVM, including loss of RVM serotonin neurons, contributes to the increased hypersensitivity observed after SNL. In the present study we examined whether RVM neuronal loss occurs in two other models of neuropathic pain, chronic constriction injury (CCI) and spared nerve injury (SNI). We found no evidence for neuronal loss 10 days after either nerve injury, a time when robust tactile hypersensitivity is present in both CCI and SNI. We conclude that loss of RVM neurons appears not to be required for expression of tactile hypersensitivity in these models of neuropathic pain.
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West S, Bannister K, Dickenson A, Bennett D. Circuitry and plasticity of the dorsal horn – Toward a better understanding of neuropathic pain. Neuroscience 2015; 300:254-75. [DOI: 10.1016/j.neuroscience.2015.05.020] [Citation(s) in RCA: 73] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2015] [Revised: 05/07/2015] [Accepted: 05/08/2015] [Indexed: 11/24/2022]
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Rusanescu G, Mao J. Immature spinal cord neurons are dynamic regulators of adult nociceptive sensitivity. J Cell Mol Med 2015. [PMID: 26223362 PMCID: PMC4594677 DOI: 10.1111/jcmm.12648] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Chronic pain is a debilitating condition with unknown mechanism. Nociceptive sensitivity may be regulated by genetic factors, some of which have been separately linked to neuronal progenitor cells and neuronal differentiation. This suggests that genetic factors that interfere with neuronal differentiation may contribute to a chronic increase in nociceptive sensitivity, by extending the immature, hyperexcitable stage of spinal cord neurons. Although adult rodent spinal cord neurogenesis was previously demonstrated, the fate of these progenitor cells is unknown. Here, we show that peripheral nerve injury in adult rats induces extensive spinal cord neurogenesis and a long-term increase in the number of spinal cord laminae I–II neurons ipsilateral to injury. The production and maturation of these new neurons correlates with the time course and modulation of nociceptive behaviour, and transiently mimics the cellular and behavioural conditions present in genetically modified animal models of chronic pain. This suggests that the number of immature neurons present at any time in the spinal cord dorsal horns contributes to the regulation of nociceptive sensitivity. The continuous turnover of these neurons, which can fluctuate between normal and injured states, is a dynamic regulator of nociceptive sensitivity. In support of this hypothesis, we find that promoters of neuronal differentiation inhibit, while promoters of neurogenesis increase long-term nociception. TrkB agonists, well-known promoters of nociception in the short-term, significantly inhibit long-term nociception by promoting the differentiation of newly produced immature neurons. These findings suggest that promoters of neuronal differentiation may be used to alleviate chronic pain.
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Affiliation(s)
- Gabriel Rusanescu
- MGH Center for Translational Pain Research, Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Jianren Mao
- MGH Center for Translational Pain Research, Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
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Nguyen HTT, Bhattarai JP, Park SJ, Lee JC, Cho DH, Han SK. Enhanced GABA action on the substantia gelatinosa neurons of the medullary dorsal horn in the offspring of streptozotocin-injected mice. J Diabetes Complications 2015; 29:629-36. [PMID: 25891974 DOI: 10.1016/j.jdiacomp.2015.03.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/12/2014] [Revised: 03/06/2015] [Accepted: 03/11/2015] [Indexed: 11/20/2022]
Abstract
Peripheral neuropathy is a frequent complication of diabetes mellitus and a common symptom of neuropathic pain, the mechanism of which is complex and involves both peripheral and central components of the sensory system. The lamina II of the medullary dorsal horn, called the substantia gelatinosa (SG), is well known to be a critical site for processing of orofacial nociceptive information. Although there have been a number of studies done on diabetic neuropathy related to the orofacial region, the action of neurotransmitter receptors on SG neurons in the diabetic state is not yet fully understood. Therefore, we used the whole-cell patch clamp technique to investigate this alteration on SG neurons in both streptozotocin (STZ)-induced diabetic mice and offspring from diabetic female mice. STZ (200 mg/kg)-injected mice showed a small decrease in body weight and a significant increase in blood glucose level when compared with their respective control group. However, application of different concentrations of glycine, gamma-aminobutyric acid (GABA) and glutamate on SG neurons from STZ-injected mice did not induce any significant differences in inward currents when compared to their control counterparts. On the other hand, the offspring of diabetic female mice (induced by multiple injections of STZ (40 mg/kg) for 5 consecutive days) led to a significant decrease in both body weight and blood glucose level compared to the control offspring. Glycine and glutamate responses in the SG neurons of the offspring from diabetic female mice were similar to those of control offspring. However, the GABA response in SG neurons of offspring from diabetic female mice was greater than that of control offspring. Furthermore, the GABA-mediated responses in offspring from diabetic and control mice were examined at different concentrations ranging from 3 to 1,000 μM. At each concentration, the GABA-induced mean inward currents in the SG neurons of offspring from diabetic female mice were larger than those of control mice. These results demonstrate that SG neurons in offspring from diabetic mice are more sensitive to GABA compared to control mice, suggesting that GABA sensitivity may alter orofacial pain processing in offspring from diabetic female mice.
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Affiliation(s)
- Hoang Thi Thanh Nguyen
- Department of Oral Physiology, School of Dentistry and Institute of Oral Bioscience, Chonbuk National University, Jeonju, Republic of Korea
| | - Janardhan Prasad Bhattarai
- Department of Oral Physiology, School of Dentistry and Institute of Oral Bioscience, Chonbuk National University, Jeonju, Republic of Korea
| | - Soo Joung Park
- Department of Oral Physiology, School of Dentistry and Institute of Oral Bioscience, Chonbuk National University, Jeonju, Republic of Korea
| | - Jeong Chae Lee
- Department of Orthodontics, School of Dentistry and Institute of Oral Bioscience, Chonbuk National University, Jeonju, Republic of Korea
| | - Dong Hyu Cho
- Department of Obstetrics and Gynecology, Chonbuk National University Hospital and School of Medicine, Jeonju, Republic of Korea.
| | - Seong Kyu Han
- Department of Oral Physiology, School of Dentistry and Institute of Oral Bioscience, Chonbuk National University, Jeonju, Republic of Korea.
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Inflammatory-induced changes in synaptic drive and postsynaptic AMPARs in lamina II dorsal horn neurons are cell-type specific. Pain 2015; 156:428-438. [DOI: 10.1097/01.j.pain.0000460318.65734.00] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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Zhou C, Luo ZD. Nerve injury-induced calcium channel alpha-2-delta-1 protein dysregulation leads to increased pre-synaptic excitatory input into deep dorsal horn neurons and neuropathic allodynia. Eur J Pain 2015; 19:1267-76. [PMID: 25691360 DOI: 10.1002/ejp.656] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/28/2014] [Indexed: 01/13/2023]
Abstract
BACKGROUND Up-regulation of voltage-gated calcium channel α2 δ1 subunit post spinal nerve ligation (SNL) injury or in α2 δ1 -overexpressing transgenic (Tg) mice correlates with tactile allodynia, a pain state mediated mainly by Aβ sensory fibres forming synaptic connections with deep dorsal horn (DDH) neurons. It is not clear, however, whether dysregulated α2 δ1 alters DDH synaptic neurotransmission that underlies tactile allodynia development post nerve injury. METHODS Tactile allodynia was tested in the SNL and α2 δ1 Tg models. Miniature excitatory/inhibitory post-synaptic currents were recorded in DDH neurons from these animal models using whole-cell patch clamp slice recording techniques. RESULTS There was a significant increase in the frequency, but not amplitude, of miniature excitatory post-synaptic currents (mEPSC) in DDH neurons that correlated with tactile allodynia in SNL and α2 δ1 Tg mice. Gabapentin, an α2 δ1 ligand that is known to block tactile allodynia in these models, also normalized mEPSC frequency dose-dependently in DDH neurons from SNL and α2 δ1 Tg mice. In contrast, neither frequency nor amplitude of miniature inhibitory post-synaptic currents was altered in DDH neurons from SNL and α2 δ1 Tg mice. CONCLUSION Our data suggest that α2 δ1 dysregulation is highly likely contributing to tactile allodynia through a pre-synaptic mechanism involving facilitation of excitatory synaptic neurotransmission in DDH of spinal cord.
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Affiliation(s)
- C Zhou
- Department of Pharmacology, School of Medicine, University of California Irvine, USA
| | - Z D Luo
- Department of Pharmacology, School of Medicine, University of California Irvine, USA.,Department of Anesthesiology and Perioperative Care, School of Medicine, University of California Irvine, USA
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Abstract
Inhibitory interneurons, which use GABA and/or glycine as their principal transmitter, have numerous roles in regulating the transmission of sensory information through the spinal dorsal horn. These roles are likely to be performed by different populations of interneurons, each with specific locations in the synaptic circuitry of the region. Peripheral nerve injury frequently leads to neuropathic pain, and it is thought that loss of function of inhibitory interneurons in the dorsal horn contributes to this condition. Several mechanisms have been proposed for this disinhibition, including death of inhibitory interneurons, decreased transmitter release, diminished activity of these cells and reduced effectiveness of GABA and glycine as inhibitory transmitters. However, despite numerous studies on this important topic, it is still not clear which (if any) of these mechanisms contributes to neuropathic pain after nerve injury.
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Lian Y, Wang Y, Ma K, Zhao L, Zhang Z, Shang Y, Si J, Li L. Expression of gamma-aminobutyric acid type A receptor α2 subunit in the dorsal root ganglion of rats with sciatic nerve injury. Neural Regen Res 2014; 7:2492-9. [PMID: 25337100 PMCID: PMC4200704 DOI: 10.3969/j.issn.1673-5374.2012.32.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2012] [Accepted: 10/23/2012] [Indexed: 12/15/2022] Open
Abstract
The γ-aminobutyric acid neurotransmitter in the spinal cord dorsal horn plays an important role in pain modulation through primary afferent-mediated presynaptic inhibition. The weakening of γ-aminobutyric acid-mediated presynaptic inhibition may be an important cause of neuropathic pain. γ-aminobutyric acid-mediated presynaptic inhibition is related to the current strength of γ-aminobutyric acid A receptor activation. In view of this, the whole-cell patch-clamp technique was used here to record the change in muscimol activated current of dorsal root ganglion neurons in a chronic constriction injury model. Results found that damage in rat dorsal root ganglion neurons following application of muscimol caused concentration-dependent activation of current, and compared with the sham group, its current strength and γ-aminobutyric acid A receptor protein expression decreased. Immunofluorescence revealed that γ-aminobutyric acid type A receptor α2 subunit protein expression decreased and was most obvious at 12 and 15 days after modeling. Our experimental findings confirmed that the γ-aminobutyric acid type A receptor α2 subunit in the chronic constriction injury model rat dorsal root ganglion was downregulated, which may be one of the reasons for the reduction of injury in dorsal root ganglion neurons following muscimol-activated currents.
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Affiliation(s)
- Yu Lian
- Department of Physiology, Shihezi University School of Medicine, Shihezi 832002, Xinjiang Uygur Autonomous Region, China ; Key Laboratory of Xinjiang Endemic and Ethnic Disease, Shihezi University School of Medicine, Shihezi 832002, Xinjiang Uygur Autonomous Region, China
| | - Yang Wang
- Department of Physiology, Shihezi University School of Medicine, Shihezi 832002, Xinjiang Uygur Autonomous Region, China ; Key Laboratory of Xinjiang Endemic and Ethnic Disease, Shihezi University School of Medicine, Shihezi 832002, Xinjiang Uygur Autonomous Region, China ; Fundamental Medical School of Wuhan University, Wuhan 430071, Hubei Province, China
| | - Ketao Ma
- Department of Physiology, Shihezi University School of Medicine, Shihezi 832002, Xinjiang Uygur Autonomous Region, China ; Key Laboratory of Xinjiang Endemic and Ethnic Disease, Shihezi University School of Medicine, Shihezi 832002, Xinjiang Uygur Autonomous Region, China
| | - Lei Zhao
- Department of Physiology, Shihezi University School of Medicine, Shihezi 832002, Xinjiang Uygur Autonomous Region, China ; Key Laboratory of Xinjiang Endemic and Ethnic Disease, Shihezi University School of Medicine, Shihezi 832002, Xinjiang Uygur Autonomous Region, China
| | - Zhongshuang Zhang
- Department of Physiology, Shihezi University School of Medicine, Shihezi 832002, Xinjiang Uygur Autonomous Region, China ; Key Laboratory of Xinjiang Endemic and Ethnic Disease, Shihezi University School of Medicine, Shihezi 832002, Xinjiang Uygur Autonomous Region, China
| | - Yuanyuan Shang
- Department of Physiology, Shihezi University School of Medicine, Shihezi 832002, Xinjiang Uygur Autonomous Region, China ; Key Laboratory of Xinjiang Endemic and Ethnic Disease, Shihezi University School of Medicine, Shihezi 832002, Xinjiang Uygur Autonomous Region, China
| | - Junqiang Si
- Department of Physiology, Shihezi University School of Medicine, Shihezi 832002, Xinjiang Uygur Autonomous Region, China ; Key Laboratory of Xinjiang Endemic and Ethnic Disease, Shihezi University School of Medicine, Shihezi 832002, Xinjiang Uygur Autonomous Region, China ; Fundamental Medical School of Wuhan University, Wuhan 430071, Hubei Province, China
| | - Li Li
- Department of Physiology, Shihezi University School of Medicine, Shihezi 832002, Xinjiang Uygur Autonomous Region, China ; Key Laboratory of Xinjiang Endemic and Ethnic Disease, Shihezi University School of Medicine, Shihezi 832002, Xinjiang Uygur Autonomous Region, China
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Lorenzo LE, Magnussen C, Bailey AL, St Louis M, De Koninck Y, Ribeiro-da-Silva A. Spatial and temporal pattern of changes in the number of GAD65-immunoreactive inhibitory terminals in the rat superficial dorsal horn following peripheral nerve injury. Mol Pain 2014; 10:57. [PMID: 25189404 PMCID: PMC4164746 DOI: 10.1186/1744-8069-10-57] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2014] [Accepted: 08/26/2014] [Indexed: 01/12/2023] Open
Abstract
Inhibitory interneurons are an important component of dorsal horn circuitry where they serve to modulate spinal nociception. There is now considerable evidence indicating that reduced inhibition in the spinal dorsal horn contributes to neuropathic pain. A loss of these inhibitory neurons after nerve injury is one of the mechanisms being proposed to account for reduced inhibition; however, this remains controversial. This is in part because previous studies have focused on global measurements of inhibitory neurons without assessing the number of inhibitory synapses. To address this, we conducted a quantitative analysis of the spatial and temporal changes in the number of inhibitory terminals, as detected by glutamic acid decarboxylase 65 (GAD65) immunoreactivity, in the superficial dorsal horn of the spinal cord following a chronic constriction injury (CCI) to the sciatic nerve in rats. Isolectin B4 (IB4) labelling was used to define the location within the dorsal horn directly affected by the injury to the peripheral nerve. The density of GAD65 inhibitory terminals was reduced in lamina I (LI) and lamina II (LII) of the spinal cord after injury. The loss of GAD65 terminals was greatest in LII with the highest drop occurring around 3–4 weeks and a partial recovery by 56 days. The time course of changes in the number of GAD65 terminals correlated well with both the loss of IB4 labeling and with the altered thresholds to mechanical and thermal stimuli. Our detailed analysis of GAD65+ inhibitory terminals clearly revealed that nerve injury induced a transient loss of GAD65 immunoreactive terminals and suggests a potential involvement for these alterations in the development and amelioration of pain behaviour.
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Affiliation(s)
| | | | | | | | | | - Alfredo Ribeiro-da-Silva
- Department of Pharmacology and Therapeutics, McGill University, 3655 Promenade Sir-William-Osler, Montreal, Quebec H3G 1Y6, Canada.
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Dieb W, Hafidi A. Mechanism of GABA involvement in post-traumatic trigeminal neuropathic pain: activation of neuronal circuitry composed of PKCγ interneurons and pERK1/2 expressing neurons. Eur J Pain 2014; 19:85-96. [PMID: 24890317 DOI: 10.1002/ejp.525] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/04/2014] [Indexed: 01/27/2023]
Abstract
BACKGROUND GABA disinhibition within the spinal dorsal horn has been implicated in pain hypersensitivity on injury in different neuropathic models. However, GABA alteration has been explored in only one study on trigeminal neuropathic pain. METHODS The present study investigated the implication of GABA in trigeminal dynamic mechanical allodynia (DMA) obtained after chronic constriction of the infraorbital nerve (CCI-IoN), and explored the cellular and molecular mechanisms by which GABA dysfunction induced DMA. RESULTS Our data demonstrated a significant decrease in labelling in two GABA cell markers, glutamate acid decarboxylase (GAD67), and parvalbumin, in the medullary dorsal horn (MDH) of allodynic rats in comparison to sham rats. Increasing GABA by intracisternal injections of vigabatrin (VGB), a blocker of the catabolic enzyme GABA transaminase, alleviated pain behaviour and restored normal GABA cell marker expression in allodynic MDH. Interestingly, intracisternal VGB administration also significantly decreased PKCγ staining, i.e., of its phosphorylated active form and the number of pERK1/2 positive cells within the MDH. These two markers were highly expressed in allodynic MDH. CONCLUSION The circuitry composed of PKCγ and pERK1/2 cells is silent under physiological conditions but is activated after CCI-IoN, therefore, switching touch stimuli to pain sensation. The decrease of GABA transmission constituted a key factor in the activation of this neuronal circuitry, which opens the gate for non-noxious stimuli to reach nociceptive projection neurons in lamina I.
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Affiliation(s)
- W Dieb
- Neuropsycho-pharmacologie des systèmes dopaminergiques sous corticaux, Université d'Auvergne, Clermont-Ferrand, France
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45
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Lavertu G, Côté SL, De Koninck Y. Enhancing K–Cl co-transport restores normal spinothalamic sensory coding in a neuropathic pain model. Brain 2013; 137:724-38. [DOI: 10.1093/brain/awt334] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
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46
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A quantitative study of inhibitory interneurons in laminae I-III of the mouse spinal dorsal horn. PLoS One 2013; 8:e78309. [PMID: 24205193 PMCID: PMC3808353 DOI: 10.1371/journal.pone.0078309] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2013] [Accepted: 09/20/2013] [Indexed: 11/19/2022] Open
Abstract
Laminae I-III of the spinal dorsal horn contain many inhibitory interneurons that use GABA and/or glycine as a neurotransmitter. Distinct neurochemical populations can be recognised among these cells, and these populations are likely to have differing roles in inhibiting pain or itch. Quantitative studies in rat have shown that inhibitory interneurons account for 25-40% of all neurons in this region. The sst2A receptor is expressed by around half the inhibitory interneurons in laminae I-II, and is associated with particular neurochemically-defined populations. Although much of the work on spinal pain mechanisms has been performed on rat, the mouse is now increasingly used as a model, due to the availability of genetically altered lines. However, quantitative information on the arrangement of interneurons is lacking in the mouse, and it is possible that there are significant species differences in neuronal organisation. In this study, we show that as in the rat, nearly all neurons in laminae I-III that are enriched with glycine also contain GABA, which suggests that GABA-immunoreactivity can be used to identify inhibitory interneurons in this region. These cells account for 26% of the neurons in laminae I-II and 38% of those in lamina III. As in the rat, the sst2A receptor is only expressed by inhibitory interneurons in laminae I-II, and is present on just over half (54%) of these cells. Antibody against the neurokinin 1 receptor was used to define lamina I, and we found that although the receptor was concentrated in this lamina, it was expressed by many fewer cells than in the rat. By estimating the total numbers of neurons in each of these laminae in the L4 segment of the mouse, we show that there are around half as many neurons in each lamina as are present in the corresponding segment of the rat.
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47
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Zhou C, Luo ZD. Electrophysiological characterization of spinal neuron sensitization by elevated calcium channel alpha-2-delta-1 subunit protein. Eur J Pain 2013; 18:649-58. [PMID: 24151064 DOI: 10.1002/j.1532-2149.2013.00416.x] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/10/2013] [Indexed: 12/21/2022]
Abstract
BACKGROUND Voltage-gated calcium channel α2 δ1 subunit is the binding site for gabapentin, an effective drug in controlling neuropathic pain states including thermal hyperalgesia. Hyperalgesia to noxious thermal stimuli in both spinal nerve-ligated (SNL) and voltage-gated calcium channel α2 δ1 overexpressing transgenic (Tg) mice correlates with higher α2 δ1 levels in dorsal root ganglia and dorsal spinal cord. In this study, we investigated whether abnormal synaptic transmission is responsible for thermal hyperalgesia induced by elevated α2 δ1 expression in these models. METHODS Behavioural sensitivities to thermal stimuli were test in L4 SNL and sham mice, as well as in α2 δ1 Tg and wild-type mice. Miniature excitatory (mEPSC) and inhibitory (mIPSC) post-synaptic currents were recorded in superficial dorsal spinal cord neurons from these models using whole-cell patch clamp slice recording techniques. RESULTS The frequency, but not amplitude, of mEPSC in superficial dorsal horn neurons was increased in SNL and α2 δ1 Tg mice, which could be attenuated by gabapentin dose dependently. Intrathecal α2 δ1 antisense oligodeoxynucleotide treatment diminished increased mEPSC frequency and gabapentin's inhibitory effects in elevated mEPSC frequency in the SNL mice. In contrast, neither the frequency nor the amplitude of mIPSC was altered in superficial dorsal horn neurons from the SNL and α2 δ1 Tg mice. CONCLUSIONS Our findings support a role of peripheral nerve injury-induced α2 δ1 in enhancing pre-synaptic excitatory input onto superficial dorsal spinal cord neurons that contributes to nociception development.
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Affiliation(s)
- C Zhou
- Department of Pharmacology, School of Medicine, University of California Irvine, USA
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48
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Decreased expression and role of GRK6 in spinal cord of rats after chronic constriction injury. Neurochem Res 2013; 38:2168-79. [PMID: 23979726 DOI: 10.1007/s11064-013-1125-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2012] [Revised: 07/17/2013] [Accepted: 07/31/2013] [Indexed: 10/26/2022]
Abstract
Nerve injury and inflammation can both induce neuropathic pain via the production of pro-inflammatory cytokines. In the process, G protein-coupled receptors (GPCRs) were involved in pain signal transduction. GPCR kinase (GRK) 6 is a member of the GRK family that regulates agonist-induced desensitization and signaling of GPCRs. However, its expression and function in neuropathic pain have not been reported. In this study, we performed a chronic constriction injury (CCI) model in adult male rats and investigated the dynamic change of GRK6 expression in spinal cord. GRK6 was predominantly expressed in the superficial layers of the lumbar spinal cord dorsal horn neurons and its expression was decreased bilaterally following induction of CCI. The changes of GRK6 were mainly in IB4 and P substrate positive areas in spinal cord dorsal horn. And over-expression of GRK6 in spinal cord by lentivirus intrathecal injection attenuated the pain response induced by CCI. In addition, the level of TNF-α underwent the negative pattern of GRK6 in spinal cord. And neutralized TNF-α by antibody intrathecal injection up-regulated GRK6 expression and attenuated the mechanical allodynia and heat hyperalgesia in CCI model. All the data indicated that down-regulation of neuronal GRK6 expression induced by cytokine may be a potential mechanism that contributes to increasing neuronal signaling in neuropathic pain.
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Yowtak J, Wang J, Kim HY, Lu Y, Chung K, Chung JM. Effect of antioxidant treatment on spinal GABA neurons in a neuropathic pain model in the mouse. Pain 2013; 154:2469-2476. [PMID: 23880056 DOI: 10.1016/j.pain.2013.07.024] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2013] [Revised: 07/11/2013] [Accepted: 07/17/2013] [Indexed: 12/23/2022]
Abstract
One feature of neuropathic pain is a reduced spinal gamma-aminobutyric acid (GABA)-ergic inhibitory function. However, the mechanisms behind this attenuation remain to be elucidated. This study investigated the involvement of reactive oxygen species in the spinal GABA neuron loss and reduced GABA neuron excitability in spinal nerve ligation (SNL) model of neuropathic pain in mice. The importance of spinal GABAergic inhibition in neuropathic pain was tested by examining the effects of intrathecally administered GABA receptor agonists and antagonists in SNL and naïve mice, respectively. The effects of SNL and antioxidant treatment on GABA neuron loss and functional changes were examined in transgenic GAD67-enhanced green fluorescent protein positive (EGFP+) mice. GABA receptor agonists transiently reversed mechanical hypersensitivity of the hind paw in SNL mice. On the other hand, GABA receptor antagonists made naïve mice mechanically hypersensitive. Stereological analysis showed that the numbers of enhanced green fluorescent protein positive (EGFP+) GABA neurons were significantly decreased in the lateral superficial laminae (I-II) on the ipsilateral L5 spinal cord after SNL. Repeated antioxidant treatments significantly reduced the pain behaviors and prevented the reduction in EGFP+ GABA neurons. The response rate of the tonic firing GABA neurons recorded from SNL mice increased with antioxidant treatment, whereas no change was seen in those recorded from naïve mice, which suggested that oxidative stress impaired some spinal GABA neuron activity in the neuropathic pain condition. Together the data suggest that neuropathic pain, at least partially, is attributed to oxidative stress, which induces both a GABA neuron loss and dysfunction of surviving GABA neurons.
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Affiliation(s)
- June Yowtak
- Department of Neuroscience and Cell Biology, University of Texas Medical Branch, Galveston, TX, USA
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50
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Polgár E, Sardella TCP, Tiong SYX, Locke S, Watanabe M, Todd AJ. Functional differences between neurochemically defined populations of inhibitory interneurons in the rat spinal dorsal horn. Pain 2013; 154:2606-2615. [PMID: 23707280 PMCID: PMC3858808 DOI: 10.1016/j.pain.2013.05.001] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2013] [Revised: 04/24/2013] [Accepted: 05/01/2013] [Indexed: 11/25/2022]
Abstract
In order to understand how nociceptive information is processed in the spinal dorsal horn we need to unravel the complex synaptic circuits involving interneurons, which constitute the vast majority of the neurons in laminae I-III. The main limitation has been the difficulty in defining functional populations among these cells. We have recently identified 4 non-overlapping classes of inhibitory interneuron, defined by expression of galanin, neuropeptide Y (NPY), neuronal nitric oxide synthase (nNOS) and parvalbumin, in the rat spinal cord. In this study we demonstrate that these form distinct functional populations that differ in terms of sst(2A) receptor expression and in their responses to painful stimulation. The sst(2A) receptor was expressed by nearly all of the nNOS- and galanin-containing inhibitory interneurons but by few of those with NPY and none of the parvalbumin cells. Many galanin- and NPY-containing cells exhibited phosphorylated extracellular signal-regulated kinases (pERK) after mechanical, thermal or chemical noxious stimuli, but very few nNOS-containing cells expressed pERK after any of these stimuli. However, many nNOS-positive inhibitory interneurons up-regulated Fos after noxious thermal stimulation or injection of formalin, but not after capsaicin injection. Parvalbumin cells did not express either activity-dependent marker following any of these stimuli. These results suggest that interneurons belonging to the NPY, nNOS and galanin populations are involved in attenuating pain, and for NPY and nNOS cells this is likely to result from direct inhibition of nociceptive projection neurons. They also suggest that the nociceptive inputs to the nNOS cells differ from those to the galanin and NPY populations.
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Affiliation(s)
- Erika Polgár
- Spinal Cord Group, Institute of Neuroscience and Psychology, University of Glasgow, Glasgow G12 8QQ, United Kingdom Department of Anatomy, Hokkaido University School of Medicine, Sapporo 060-8638, Japan
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