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Su Y, Verkhratsky A, Yi C. Targeting connexins: possible game changer in managing neuropathic pain? Trends Mol Med 2024:S1471-4914(24)00064-9. [PMID: 38594094 DOI: 10.1016/j.molmed.2024.03.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2024] [Revised: 03/08/2024] [Accepted: 03/18/2024] [Indexed: 04/11/2024]
Abstract
Neuropathic pain is a chronic debilitating condition caused by nerve injury or a variety of diseases. At the core of neuropathic pain lies the aberrant neuronal excitability in the peripheral and/or central nervous system (PNS and CNS). Enhanced connexin expression and abnormal activation of connexin-assembled gap junctional channels are prominent in neuropathic pain along with reactive gliosis, contributing to neuronal hypersensitivity and hyperexcitability. In this review, we delve into the current understanding of how connexin expression and function contribute to the pathogenesis and pathophysiology of neuropathic pain and argue for connexins as potential therapeutic targets for neuropathic pain management.
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Affiliation(s)
- Yixun Su
- Research Centre, Seventh Affiliated Hospital of Sun Yat-sen University, Shenzhen, China
| | - Alexei Verkhratsky
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK; Achucarro Center for Neuroscience, IKERBASQUE, Bilbao, Spain; Department of Stem Cell Biology, State Research Institute Centre for Innovative Medicine, Vilnius, Lithuania; Department of Forensic Analytical Toxicology, School of Forensic Medicine, China Medical University, Shenyang, China.
| | - Chenju Yi
- Research Centre, Seventh Affiliated Hospital of Sun Yat-sen University, Shenzhen, China; Guangdong Provincial Key Laboratory of Brain Function and Disease, Guangzhou, China; Shenzhen Key Laboratory of Chinese Medicine Active substance screening and Translational Research, Shenzhen, China.
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2
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Morioka N, Tsuruta M, Masuda N, Yamano K, Nakano M, Kochi T, Nakamura Y, Hisaoka-Nakashima K. Inhibition of Nuclear Receptor Related Orphan Receptor γ Ameliorates Mechanical Hypersensitivity Through the Suppression of Spinal Microglial Activation. Neuroscience 2023; 526:223-236. [PMID: 37419402 DOI: 10.1016/j.neuroscience.2023.07.002] [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: 01/29/2023] [Revised: 06/21/2023] [Accepted: 07/01/2023] [Indexed: 07/09/2023]
Abstract
Microglia are crucial in induction of central sensitization under a chronic pain state. Therefore, control of microglial activity is important to ameliorate nociceptive hypersensitivity. The nuclear receptor retinoic acid related orphan receptor γ (RORγ) contributes to the regulation of inflammation-related gene transcription in some immune cells, including T cells and macrophages. Their role and function in regulation of microglial activity and nociceptive transduction have yet to be elaborated. Treatment of cultured microglia with specific RORγ inverse agonists, SR2211 or GSK2981278, significantly suppressed lipopolysaccharide (LPS)-induced mRNA expression of pronociceptive molecules interleukin-1β (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor (TNF). Intrathecal treatment of naïve male mice with LPS markedly induced mechanical hypersensitivity and upregulation of ionized calcium-biding adaptor molecule (Iba1) in the spinal dorsal horn, indicating microglial activation. In addition, intrathecal treatment with LPS significantly induced mRNA upregulation of IL-1β and IL-6 in the spinal dorsal horn. These responses were prevented by intrathecal pretreatment with SR2211. In addition, intrathecal administration of SR2211 significantly ameliorated established mechanical hypersensitivity and upregulation of Iba1 immunoreactivity in the spinal dorsal horn of male mice following peripheral sciatic nerve injury. The current findings demonstrate that blockade of RORγ in spinal microglia exerts anti-inflammatory effects, and that RORγ may be an appropriate target for the treatment of chronic pain.
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Affiliation(s)
- Norimitsu Morioka
- Department of Pharmacology, Hiroshima University Graduate School of Biomedical and Health Sciences, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8553, Japan.
| | - Maho Tsuruta
- Department of Pharmacology, Hiroshima University Graduate School of Biomedical and Health Sciences, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8553, Japan
| | - Nao Masuda
- Department of Pharmacology, Hiroshima University Graduate School of Biomedical and Health Sciences, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8553, Japan
| | - Kiichi Yamano
- Department of Pharmacology, Hiroshima University Graduate School of Biomedical and Health Sciences, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8553, Japan
| | - Manaya Nakano
- Department of Pharmacology, Hiroshima University Graduate School of Biomedical and Health Sciences, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8553, Japan
| | - Takahiro Kochi
- Department of Pharmacology, Hiroshima University Graduate School of Biomedical and Health Sciences, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8553, Japan
| | - Yoki Nakamura
- Department of Pharmacology, Hiroshima University Graduate School of Biomedical and Health Sciences, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8553, Japan
| | - Kazue Hisaoka-Nakashima
- Department of Pharmacology, Hiroshima University Graduate School of Biomedical and Health Sciences, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8553, Japan
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Zhang FF, Wang H, Zhou YM, Yu HY, Zhang M, Du X, Wang D, Zhang F, Xu Y, Zhang JG, Zhang HT. Inhibition of phosphodiesterase-4 in the spinal dorsal horn ameliorates neuropathic pain via cAMP-cytokine-Cx43 signaling in mice. CNS Neurosci Ther 2022; 28:749-760. [PMID: 35156776 PMCID: PMC8981432 DOI: 10.1111/cns.13807] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2021] [Revised: 12/13/2021] [Accepted: 12/28/2021] [Indexed: 01/21/2023] Open
Abstract
Background The spinal phosphodiesterase‐4 (PDE4) plays an important role in chronic pain. Inhibition of PDE4, an enzyme catalyzing the hydrolysis of cyclic adenosine monophosphate AMP (cAMP), produces potent antinociceptive activity. However, the antinociceptive mechanism remains largely unknown. Connexin43 (Cx43), a gap junction protein, has been shown to be involved in controlling pain transduction at the spinal level; restoration of Cx43 expression in spinal astrocytes to the normal levels reduces nerve injury‐induced pain. Here, we evaluate the novel mechanisms involving spinal cAMP‐Cx43 signaling by which PDE4 inhibitors produce antinociceptive activity. Methods First, we determined the effect of PDE4 inhibitors rolipram and roflumilast on partial sciatic nerve ligation (PSNL)‐induced mechanical hypersensitivity. Next, we observed the role of cAMP‐Cx43 signaling in the effect of PDE4 inhibitors on PSNL‐induced mechanical hypersensitivity. Results Single or repeated, intraperitoneal or intrathecal administration of rolipram or roflumilast significantly reduced mechanical hypersensitivity in mice following PSNL. In addition, repeated intrathecal treatment with either of PDE4 inhibitors reduced PSNL‐induced downregulation of cAMP and Cx43, and upregulation of proinflammatory cytokines tumor necrosis factor‐α (TNF‐α) and interleukin‐1β. Furthermore, the antinociceptive effects of PDE4 inhibitors were attenuated by the protein kinase A (PKA) inhibitor H89, TNF‐α, or Cx43 antagonist carbenoxolone. Finally, PSNL‐induced upregulation of PDE4B and PDE4D, especially the PDE4B subtype, was reduced by treatment with either of the PDE4 inhibitors. Conclusions The results suggest that the antinociceptive effect of PDE4 inhibitors is contributed by increasing Cx43 expression via cAMP‐PKA‐cytokine signaling in the spinal dorsal horn.
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Affiliation(s)
- Fang-Fang Zhang
- Institute of Pharmacology, Shandong First Medical University & Shandong Academy of Medical Sciences, Tai'an, China
| | - Hao Wang
- Institute of Pharmacology, Shandong First Medical University & Shandong Academy of Medical Sciences, Tai'an, China
| | - Yan-Meng Zhou
- Institute of Pharmacology, Shandong First Medical University & Shandong Academy of Medical Sciences, Tai'an, China
| | - Hai-Yang Yu
- Institute of Pharmacology, Shandong First Medical University & Shandong Academy of Medical Sciences, Tai'an, China
| | - Melanie Zhang
- Department of Neurobiology, Northwestern University Feinberg School of Medicine, Evanston, Illinois, USA
| | - Xian Du
- Institute of Pharmacology, Shandong First Medical University & Shandong Academy of Medical Sciences, Tai'an, China
| | - Dong Wang
- Institute of Pharmacology, Shandong First Medical University & Shandong Academy of Medical Sciences, Tai'an, China
| | - Feng Zhang
- Institute of Pharmacology, Shandong First Medical University & Shandong Academy of Medical Sciences, Tai'an, China
| | - Ying Xu
- Department of Pharmaceutical Sciences, School of Pharmacy & Pharmaceutical Sciences, University at Buffalo, the State University of New York, Buffalo, New York, USA
| | - Ji-Guo Zhang
- Institute of Pharmacology, Shandong First Medical University & Shandong Academy of Medical Sciences, Tai'an, China
| | - Han-Ting Zhang
- Institute of Pharmacology, Shandong First Medical University & Shandong Academy of Medical Sciences, Tai'an, China.,Department of Pharmacology, School of Pharmacy, Qingdao University, Qingdao, China
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Contreras-Hernández E, Chávez D, Hernández E, Rudomin P. Discrete field potentials produced by coherent activation of spinal dorsal horn neurons. Exp Brain Res 2022; 240:665-686. [PMID: 35001174 DOI: 10.1007/s00221-021-06286-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Accepted: 12/03/2021] [Indexed: 11/28/2022]
Abstract
In addition to the action potentials generated by the ongoing activation of single dorsal horn neurons in the anesthetized cat, we often recorded small negative field potentials with a fast-rising phase and a slow decay (dIFPs). These potentials could be separated in different classes, each with a specific and rather constant shape and amplitude. They were largest in spinal laminae III-V and gradually faded at deeper locations, without showing the polarity reversal displayed at these depths by the focal potentials produced by stimulation of muscle and cutaneous afferents. We propose that the dIFPs are postsynaptic field potentials generated by strongly coupled sets of dorsal horn neurons displaying a spatial orientation that generates closed field potentials in response to stimulation of high-threshold cutaneous and muscle afferents. These neuronal sets could form part of the spinal inhibitory circuitry that mediates presynaptic inhibition and Ib non-reciprocal postsynaptic inhibition and could be involved in the sensory-motor transformations activated by stimulation of high-threshold cutaneous afferents.
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Affiliation(s)
- Enrique Contreras-Hernández
- Department of Physiology, Biophysics and Neurosciences, Center for Research and Advanced Studies, National Polytechnic Institute, Ciudad de México, México
| | - Diógenes Chávez
- Department of Physiology, Biophysics and Neurosciences, Center for Research and Advanced Studies, National Polytechnic Institute, Ciudad de México, México
| | - Edson Hernández
- Department of Physiology, Biophysics and Neurosciences, Center for Research and Advanced Studies, National Polytechnic Institute, Ciudad de México, México
| | - Pablo Rudomin
- Department of Physiology, Biophysics and Neurosciences, Center for Research and Advanced Studies, National Polytechnic Institute, Ciudad de México, México. .,El Colegio Nacional, Ciudad de México, México.
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Perineural high-mobility group box 1 induces mechanical hypersensitivity through activation of spinal microglia: Involvement of glutamate-NMDA receptor dependent mechanism in spinal dorsal horn. Biochem Pharmacol 2021; 186:114496. [PMID: 33667472 DOI: 10.1016/j.bcp.2021.114496] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Revised: 02/24/2021] [Accepted: 02/25/2021] [Indexed: 01/15/2023]
Abstract
High mobility box 1 (HMGB1), a damage-associated molecular pattern, has crucial roles in induction of neuropathic pain. Upregulation of HMGB1 around the injured sciatic nerve contributes to mechanical hypersensitivity following partial sciatic nerve ligation (PSNL) of mice. However, central mechanisms mediating perineural HMGB1-induced nociceptive hypersensitivity, especially within the spinal dorsal horn, have not been determined. The current study shows that perineural treatment of naïve mice with recombinant HMGB1, which mimics increased HMGB1 around the injured sciatic nerve of PSNL mice, significantly induced activation of microglia, but not astrocytes, in the spinal dorsal horn. Intraperitoneal injection of minocycline, a microglial inhibitor, ameliorated perineural rHMGB1-induced mechanical hypersensitivity. In addition, blockade of spinal N-methyl-D-aspartate (NMDA) receptors significantly prevented perineural rHMGB1-induced mechanical hypersensitivity and microglial activation. In contrast, non-NMDA receptors, neurokinin 1 receptor, colony-stimulating factor 1 receptor and P2Y12 receptor were not involved in perineural rHMGB1-induced mechanical hypersensitivity. Furthermore, repeated perineural treatment with an anti-HMGB1 antibody blocked activation of spinal microglia in PSNL mice. Collectively, the current findings demonstrate that increased HMGB1 around injured sciatic nerve might induce nociceptive hypersensitivity through activation of spinal microglia. Thus, HMGB1-dependent mechanisms between the injured sciatic nerve and spinal dorsal horn could be crucial in induction of neuropathic pain.
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Morioka N, Nakamura Y, Zhang FF, Hisaoka-Nakashima K, Nakata Y. Role of Connexins in Chronic Pain and Their Potential as Therapeutic Targets for Next-Generation Analgesics. Biol Pharm Bull 2019; 42:857-866. [PMID: 31155584 DOI: 10.1248/bpb.b19-00195] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Chronic pain, including inflammatory, neuropathic pain, is a serious clinical issue. There are increasing numbers of patients with chronic pain due to the growing number of elderly and it is estimated that about 25% of the global population will develop chronic pain. Chronic pain patients are refractory to medications used to treat acute pain such as opioids and non-steroidal anti-inflammatory drugs. Furthermore, the complexity and diversity of chronic pain mechanisms hinder the development of new analgesics. Thus, a better understanding of the mechanism of chronic pain is needed, which would facilitate the development of novel analgesics based on novel mechanisms. With this goal, connexins (Cxs) could be targeted for the development of new analgesics. Connexins are proteins with 20 subtypes, and function as channels, gap junctions between cells, and hemichannels that sample the extracellular space and release molecules such as neurotransmitters. Furthermore, Cxs could have functions independent of channel activity. Recent studies have shown that Cxs could be crucial in the induction and maintenance of chronic pain, and modulation of the activity or the expression of Cxs ameliorates nociceptive hypersensitivity in multiple chronic pain models. This review will cite novel findings on the role of of Cxs in the nociceptive transduction pathway under the chronic pain state and antinociceptive effects of various molecules modulating activity or expression of Cxs. Also, the potential of Cx modulation as a therapeutic strategy for intractable chronic pain will be discussed.
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Affiliation(s)
- Norimitsu Morioka
- Department of Pharmacology, Hiroshima University Graduate School of Biomedical & Health Sciences
| | - Yoki Nakamura
- Department of Pharmacology, Hiroshima University Graduate School of Biomedical & Health Sciences
| | - Fang Fang Zhang
- Department of Pharmacology, Hiroshima University Graduate School of Biomedical & Health Sciences.,Institute of Pharmacology, Taishan Medical University
| | - Kazue Hisaoka-Nakashima
- Department of Pharmacology, Hiroshima University Graduate School of Biomedical & Health Sciences
| | - Yoshihiro Nakata
- Department of Pharmacology, Hiroshima University Graduate School of Biomedical & Health Sciences
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Morioka N, Miyauchi K, Miyashita K, Kochi T, Zhang FF, Nakamura Y, Liu K, Wake H, Hisaoka‐Nakashima K, Nishibori M, Nakata Y. Spinal high‐mobility group box‐1 induces long‐lasting mechanical hypersensitivity through the toll‐like receptor 4 and upregulation of interleukin‐1β in activated astrocytes. J Neurochem 2019; 150:738-758. [DOI: 10.1111/jnc.14812] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2019] [Revised: 06/19/2019] [Accepted: 06/26/2019] [Indexed: 12/13/2022]
Affiliation(s)
- Norimitsu Morioka
- Department of Pharmacology Hiroshima University Graduate School of Biomedical & Health Sciences Minami‐ku Hiroshima Japan
| | - Kazuki Miyauchi
- Department of Pharmacology Hiroshima University Graduate School of Biomedical & Health Sciences Minami‐ku Hiroshima Japan
| | - Keita Miyashita
- Department of Pharmacology Hiroshima University Graduate School of Biomedical & Health Sciences Minami‐ku Hiroshima Japan
| | - Takahiro Kochi
- Department of Pharmacology Hiroshima University Graduate School of Biomedical & Health Sciences Minami‐ku Hiroshima Japan
| | - Fang Fang Zhang
- Department of Pharmacology Hiroshima University Graduate School of Biomedical & Health Sciences Minami‐ku Hiroshima Japan
- Institute of Pharmacology Taishan Medical University Taian Shandong China
| | - Yoki Nakamura
- Department of Pharmacology Hiroshima University Graduate School of Biomedical & Health Sciences Minami‐ku Hiroshima Japan
- Cellular Pathobiology Section, Integrative Neuroscience Research Branch National Institute on Drug Abuse IRP Baltimore Maryland USA
| | - Keyue Liu
- Department of Pharmacology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Okayama University Okayama Japan
| | - Hidenori Wake
- Department of Pharmacology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Okayama University Okayama Japan
| | - Kazue Hisaoka‐Nakashima
- Department of Pharmacology Hiroshima University Graduate School of Biomedical & Health Sciences Minami‐ku Hiroshima Japan
| | - Masahiro Nishibori
- Department of Pharmacology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Okayama University Okayama Japan
| | - Yoshihiro Nakata
- Department of Pharmacology Hiroshima University Graduate School of Biomedical & Health Sciences Minami‐ku Hiroshima Japan
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Morioka N, Kodama K, Tomori M, Yoshikawa K, Saeki M, Nakamura Y, Zhang FF, Hisaoka-Nakashima K, Nakata Y. Stimulation of nuclear receptor REV-ERBs suppresses production of pronociceptive molecules in cultured spinal astrocytes and ameliorates mechanical hypersensitivity of inflammatory and neuropathic pain of mice. Brain Behav Immun 2019; 78:116-130. [PMID: 30682503 DOI: 10.1016/j.bbi.2019.01.014] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/03/2018] [Revised: 01/15/2019] [Accepted: 01/19/2019] [Indexed: 11/15/2022] Open
Abstract
The orphan nuclear receptors REV-ERBα and REV-ERBβ (REV-ERBs) are crucial in the regulation of inflammatory-related gene transcription in astroglioma cells, but their role in nociceptive transduction has yet to be elaborated. Spinal dorsal horn astrocytes contribute to the maintenance of chronic pain. Treatment of cultured spinal astrocytes with specific REV-ERBs agonists SR9009 or GSK4112 significantly prevented lipopolysaccharide (LPS)-induced mRNA upregulation of pronociceptive molecules interleukin-1β (IL-1β) mRNA, interleukin-6 (IL-6) mRNA and matrix metalloprotease-9 (MMP-9) mRNA, but not CCL2 mRNA expression. Treatment with SR9009 also blocked tumor necrosis factor-induced IL-1β mRNA, IL-6 mRNA and MMP-9 mRNA. In addition, treatment with SR9009 significantly blocked LPS-induced upregulation of IL-1β protein, IL-6 protein and MMP-9 activity. The inhibitory effects of SR9009 on LPS-induced expression of pronociceptive molecules were blocked by knockdown of REV-ERBs expression with short interference RNA, confirming that SR9009 exerts its effect through REV-ERBs. Intrathecal LPS treatment in male mice induces hind paw mechanical hypersensitivity, and upregulation of IL-1β mRNA, IL-6 mRNA and glial fibrillary acidic protein (GFAP) expression in spinal dorsal horn. Intrathecal pretreatment of SR9009 prevented the onset of LPS-induced mechanical hypersensitivity, cytokine expression and GFAP expression. Intrathecal injection of SR9009 also ameliorated mechanical hypersensitivity during the maintenance phase of complete Freund's adjuvant-induced inflammatory pain and partial sciatic nerve ligation-, paclitaxel-, and streptozotocin-induced neuropathy in mice. The current findings suggest that spinal astrocytic REV-ERBs could be critical in the regulation of nociceptive transduction through downregulation of pronociceptive molecule expression. Thus, spinal REV-ERBs could be an effective therapeutic target in the treatment of chronic pain.
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Affiliation(s)
- Norimitsu Morioka
- Department of Pharmacology, Hiroshima University Graduate School of Biomedical & Health Sciences, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8553, Japan.
| | - Keitaro Kodama
- Department of Pharmacology, Hiroshima University Graduate School of Biomedical & Health Sciences, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8553, Japan
| | - Mizuki Tomori
- Department of Pharmacology, Hiroshima University Graduate School of Biomedical & Health Sciences, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8553, Japan
| | - Kanade Yoshikawa
- Department of Pharmacology, Hiroshima University Graduate School of Biomedical & Health Sciences, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8553, Japan
| | - Munenori Saeki
- Department of Pharmacology, Hiroshima University Graduate School of Biomedical & Health Sciences, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8553, Japan
| | - Yoki Nakamura
- Department of Pharmacology, Hiroshima University Graduate School of Biomedical & Health Sciences, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8553, Japan; Cellular Pathobiology Section, Integrative Neuroscience Research Branch, National Institute on Drug Abuse IRP, Triad Suite 3305, 333 Cassell Drive, Baltimore, MD 21224, United States
| | - Fang Fang Zhang
- Department of Pharmacology, Hiroshima University Graduate School of Biomedical & Health Sciences, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8553, Japan; Institute of Pharmacology, Taishan Medical University, 619 Changcheng Road, Taian, Shandong 271016, China
| | - Kazue Hisaoka-Nakashima
- Department of Pharmacology, Hiroshima University Graduate School of Biomedical & Health Sciences, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8553, Japan
| | - Yoshihiro Nakata
- Department of Pharmacology, Hiroshima University Graduate School of Biomedical & Health Sciences, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8553, Japan
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Ouachikh O, Hafidi A, Boucher Y, Dieb W. Electrical Synapses are Involved in Orofacial Neuropathic Pain. Neuroscience 2018; 382:69-79. [PMID: 29746991 DOI: 10.1016/j.neuroscience.2018.04.041] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2018] [Revised: 04/24/2018] [Accepted: 04/26/2018] [Indexed: 12/28/2022]
Abstract
Accumulated evidences suggest important roles of glial GAP-junctions in pain. However, only a few studies have explored the role of neuronal GAP-junctions or electrical synapses in neuropathic pain (NP). Therefore, the present study explores the role of connexin 36 (Cx36) in NP using the chronic constriction injury of the infraorbital nerve (CCI-IoN) model in rat. A significant increase in Cx36 labeling was observed in the medullary dorsal horn (MDH) of CCI-IoN-lesioned compared to sham rats. The expression of Cx36 in CCI-IoN-lesioned rats revealed a rostroventral gradient of punctuate labeling within lamina IIo of the MDH. Cx36-positive somata and processes were also observed in MDH laminae IIi and III-V. These somata were mostly of the Gamma aminobutyric acid (GABA) and occasionally Glycine transporter 2 (GlyT2) cell subtypes. Moreover the GABA cell subtypes are highly coupled in lamina IIo as revealed by the intense Cx36 staining in this lamina. Pharmacological Cx36 blockade by intracisternal administration of mefloquine decreased significantly the mechanical allodynia observed in CCI-IoN-lesioned rats. Altogether, our findings demonstrated that Cx36 play an important role in mechanical allodynia by coupling GABA cells. Increasing cell coupling by enhancing Cx36 expression favors neuropathic pain while disrupting this coupling alleviates it. This mechanism may constitute a novel target for the treatment of orofacial mechanical allodynia.
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Affiliation(s)
- Omar Ouachikh
- EA 7280 - Neuro-psycho-pharmacologie des systèmes dopaminergiques sous corticaux, Université Clermont Auvergne, Clermont-Ferrand 63000, France
| | - Aziz Hafidi
- EA 7280 - Neuro-psycho-pharmacologie des systèmes dopaminergiques sous corticaux, Université Clermont Auvergne, Clermont-Ferrand 63000, France.
| | - Yves Boucher
- Faculté d'odontologie (Garançière), Université Paris-Diderot, Paris, France; Hôpital Pitié-Salpétrière, AP-HP, Paris, France
| | - Wisam Dieb
- EA 7280 - Neuro-psycho-pharmacologie des systèmes dopaminergiques sous corticaux, Université Clermont Auvergne, Clermont-Ferrand 63000, France; Faculté d'odontologie (Garançière), Université Paris-Diderot, Paris, France; Hôpital Pitié-Salpétrière, AP-HP, Paris, France
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10
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Pérez Armendariz EM, Norcini M, Hernández-Tellez B, Castell-Rodríguez A, Coronel-Cruz C, Alquicira RG, Sideris A, Recio-Pinto E. Neurons and satellite glial cells in adult rat lumbar dorsal root ganglia express connexin 36. Acta Histochem 2018; 120:168-178. [PMID: 29224922 DOI: 10.1016/j.acthis.2017.11.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2017] [Revised: 11/02/2017] [Accepted: 11/15/2017] [Indexed: 01/08/2023]
Abstract
Previous studies have shown that following peripheral nerve injury there was a downregulation of the gap junction protein connexin 36 (Cx36) in the spinal cord; however, it is not known whether Cx36 protein is expressed in the dorsal root ganglia (DRGs), nor if its levels are altered following peripheral nerve injuries. Here we address these aspects in the adult rat lumbar DRG. Cx36 mRNA was detected using qRT-PCR, and Cx36 protein was identified in DRG sections using immunohistochemistry (IHC) and immunofluorescence (IF). Double staining revealed that Cx36 co-localizes with both anti-β-III tubulin, a neuronal marker, and anti-glutamine synthetase, a satellite glial cell (SGC) marker. In neurons, Cx36 staining was mostly uniform in somata and fibers of all sizes and its intensity increased at the cell membranes. This labeling pattern was in contrast with Cx36 IF dots mainly found at junctional membranes in islet beta cells used as a control tissue. Co-staining with anti-Cx43 and anti-Cx36 showed that whereas mostly uniform staining of Cx36 was found throughout neurons and SGCs, Cx43 IF puncta were localized to SGCs. Cx36 mRNA was expressed in normal lumbar DRG, and it was significantly down-regulated in L4 DRG of rats that underwent sciatic nerve injury resulting in persistent hypersensitivity. Collectively, these findings demonstrated that neurons and SGCs express Cx36 protein in normal DRG, and suggested that perturbation of Cx36 levels may contribute to chronic neuropathic pain resulting from a peripheral nerve injury.
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Affiliation(s)
- E Martha Pérez Armendariz
- Departamento de Biología Celular y Tisular, Facultad de Medicina, Universidad Nacional Autónoma de México, Torre de Investigación 5to piso, Avenida Universidad 3000, Circuito Interior, Ciudad Universitaria, Colonia Universidad Nacional Autónoma de México, CU, D.F., 04510, Mexico.
| | - Monica Norcini
- Department of Anesthesiology, NYULMC, 180 Varick Street, Room 677, New York, NY 10014, USA.
| | - Beatriz Hernández-Tellez
- Departamento de Biología Celular y Tisular, Facultad de Medicina, Universidad Nacional Autónoma de México, Torre de Investigación 5to piso, Avenida Universidad 3000, Circuito Interior, Ciudad Universitaria, Colonia Universidad Nacional Autónoma de México, CU, D.F., 04510, Mexico.
| | - Andrés Castell-Rodríguez
- Departamento de Biología Celular y Tisular, Facultad de Medicina, Universidad Nacional Autónoma de México, Torre de Investigación 5to piso, Avenida Universidad 3000, Circuito Interior, Ciudad Universitaria, Colonia Universidad Nacional Autónoma de México, CU, D.F., 04510, Mexico.
| | - Cristina Coronel-Cruz
- Departamento de Biología Celular y Tisular, Facultad de Medicina, Universidad Nacional Autónoma de México, Torre de Investigación 5to piso, Avenida Universidad 3000, Circuito Interior, Ciudad Universitaria, Colonia Universidad Nacional Autónoma de México, CU, D.F., 04510, Mexico.
| | - Raquel Guerrero Alquicira
- Departamento de Biología Celular y Tisular, Facultad de Medicina, Universidad Nacional Autónoma de México, Torre de Investigación 5to piso, Avenida Universidad 3000, Circuito Interior, Ciudad Universitaria, Colonia Universidad Nacional Autónoma de México, CU, D.F., 04510, Mexico.
| | - Alexandra Sideris
- Department of Anesthesiology, NYULMC, 180 Varick Street, Room 677, New York, NY 10014, USA.
| | - Esperanza Recio-Pinto
- Department of Anesthesiology, NYULMC, 180 Varick Street, Room 677, New York, NY 10014, USA; Departments of Anesthesiology, Biochemistry & Molecular Pharmacology, NYULMC, 180 Varick Street, Room 677, New York, NY 10014 USA.
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11
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Morioka N, Fujii S, Kondo S, Zhang FF, Miyauchi K, Nakamura Y, Hisaoka-Nakashima K, Nakata Y. Downregulation of spinal astrocytic connexin43 leads to upregulation of interleukin-6 and cyclooxygenase-2 and mechanical hypersensitivity in mice. Glia 2017; 66:428-444. [DOI: 10.1002/glia.23255] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2017] [Revised: 10/13/2017] [Accepted: 10/13/2017] [Indexed: 12/19/2022]
Affiliation(s)
- Norimitsu Morioka
- Department of Pharmacology; Hiroshima University Graduate School of Biomedical & Health Sciences, 1-2-3 Kasumi; Minami-ku Hiroshima 734-8553 Japan
| | - Shiori Fujii
- Department of Pharmacology; Hiroshima University Graduate School of Biomedical & Health Sciences, 1-2-3 Kasumi; Minami-ku Hiroshima 734-8553 Japan
| | - Syun Kondo
- Department of Pharmacology; Hiroshima University Graduate School of Biomedical & Health Sciences, 1-2-3 Kasumi; Minami-ku Hiroshima 734-8553 Japan
| | - Fang Fang Zhang
- Department of Pharmacology; Hiroshima University Graduate School of Biomedical & Health Sciences, 1-2-3 Kasumi; Minami-ku Hiroshima 734-8553 Japan
- Institute of Pharmacology, Taishan Medical University, 619 Changcheng Road; Taian Shandong 271016 China
| | - Kazuki Miyauchi
- Department of Pharmacology; Hiroshima University Graduate School of Biomedical & Health Sciences, 1-2-3 Kasumi; Minami-ku Hiroshima 734-8553 Japan
| | - Yoki Nakamura
- Department of Pharmacology; Hiroshima University Graduate School of Biomedical & Health Sciences, 1-2-3 Kasumi; Minami-ku Hiroshima 734-8553 Japan
- Cellular Pathobiology Section, Integrative Neuroscience Research Branch, National Institute on Drug Abuse IRP, Triad Suite 3305, 333 Cassell Drive; Baltimore MD 21224
| | - Kazue Hisaoka-Nakashima
- Department of Pharmacology; Hiroshima University Graduate School of Biomedical & Health Sciences, 1-2-3 Kasumi; Minami-ku Hiroshima 734-8553 Japan
| | - Yoshihiro Nakata
- Department of Pharmacology; Hiroshima University Graduate School of Biomedical & Health Sciences, 1-2-3 Kasumi; Minami-ku Hiroshima 734-8553 Japan
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12
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Reversal of TRESK Downregulation Alleviates Neuropathic Pain by Inhibiting Activation of Gliocytes in the Spinal Cord. Neurochem Res 2017; 42:1288-1298. [PMID: 28160200 DOI: 10.1007/s11064-016-2170-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2016] [Revised: 11/03/2016] [Accepted: 12/28/2016] [Indexed: 10/20/2022]
Abstract
Despite the consensus that activation of TWIK-related spinal cord K+ (TRESK) might contribute to the pathogenesis of chronic pain, the specific mechanisms underlying the transfer and development of pain signals still remain obscure. In the present study, we validated that TRESK was expressed in neurons instead of glial cells. Furthermore, in the SNI model of neuropathic pain (NP), downregulation of TRESK in spinal cord neurons resulted in upregulation of connexin 36 (Cx36) and connexin 43 (Cx43), both being subtypes of gap junctions in the spinal cord, with gliocytes in the spinal cord activated ultimately. Compared with SNI rats, intrathecal injection of TRESK gene recombinant adenovirus significantly downregulated the expression levels of Cx36 and Cx43 and suppressed the activation of gliocytes in the spinal cord, with hyperalgesia significantly reduced. In conclusion, TRESK contributes to the pathogenesis of NP by upregulation of synaptic transmission and activation of gliocytes.
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13
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Zhang FF, Morioka N, Abe H, Fujii S, Miyauchi K, Nakamura Y, Hisaoka-Nakashima K, Nakata Y. Stimulation of spinal dorsal horn β2-adrenergic receptor ameliorates neuropathic mechanical hypersensitivity through a reduction of phosphorylation of microglial p38 MAP kinase and astrocytic c-jun N-terminal kinase. Neurochem Int 2016; 101:144-155. [PMID: 27840124 DOI: 10.1016/j.neuint.2016.11.004] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2016] [Revised: 10/21/2016] [Accepted: 11/01/2016] [Indexed: 12/22/2022]
Abstract
The noradrenaline-adrenergic system has a crucial role in controlling nociceptive transduction at the spinal level. While α-adrenergic receptors are known to regulate nociceptive neurotransmitter release at the spinal presynaptic level, it is not entirely clear whether β-adrenergic receptors are involved in controlling pain transduction at the spinal level as well. The current study elucidated a role of β-adrenergic receptors in neuropathic pain in mice following a partial sciatic nerve ligation (PSNL). In addition, the cellular and intracellular signaling cascade induced by β-adrenergic receptors in neuropathic mice was elaborated. Intrathecal injection of isoproterenol (1 nmol), a nonselective β-adrenergic receptor agonist, briefly ameliorated hind paw mechanical hypersensitivity of PSNL mice. Isoproterenol's antinociceptive effect was mediated through β2-adrenergic receptors since pretreatment with ICI118551, a selective β2-adrenergic receptor antagonist, but not with CGP20712A, a selective β1-adrenergic receptor antagonist, significantly attenuated isoproterenol's effect. Furthermore, intrathecal treatment with a selective β2-adrenergic receptor agonist, terbutaline, but not a selective β1-adrenergic receptor agonist, dobutamine, also significantly ameliorated neuropathic pain. Fourteen days after PSNL, increased phosphorylation of both p38 Mitogen-activated protein kinase (MAPK) in microglia and c-jun N-terminal kinase (JNK) in astrocytes of ipsilateral spinal dorsal horn were observed. Phosphorylation of both microglial p38 MAPK and astrocytic JNK were downregulated by stimulation of the β2-adrenergic receptor. Together, these results suggest that spinal β2-adrenergic receptor have an inhibitory role in neuropathic nociceptive transduction at the spinal level through a downregulation of glial activity, perhaps through modulation of MAP kinases phosphorylation. Thus, targeting of β2-adrenergic receptors could be an effective therapeutic strategy in treating neuropathic pain.
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Affiliation(s)
- Fang Fang Zhang
- Department of Pharmacology, Hiroshima University Graduate School of Biomedical & Health Sciences, 1-2-3 Kasumi, Minami-ku, Hiroshima, 734-8553, Japan; Institute of Pharmacology, Taishan Medical University, 619 Changcheng Road, Taian, Shandong, 271016, China
| | - Norimitsu Morioka
- Department of Pharmacology, Hiroshima University Graduate School of Biomedical & Health Sciences, 1-2-3 Kasumi, Minami-ku, Hiroshima, 734-8553, Japan.
| | - Hiromi Abe
- Department of Pharmacology, Hiroshima University Graduate School of Biomedical & Health Sciences, 1-2-3 Kasumi, Minami-ku, Hiroshima, 734-8553, Japan
| | - Shiori Fujii
- Department of Pharmacology, Hiroshima University Graduate School of Biomedical & Health Sciences, 1-2-3 Kasumi, Minami-ku, Hiroshima, 734-8553, Japan
| | - Kazuki Miyauchi
- Department of Pharmacology, Hiroshima University Graduate School of Biomedical & Health Sciences, 1-2-3 Kasumi, Minami-ku, Hiroshima, 734-8553, Japan
| | - Yoki Nakamura
- Department of Pharmacology, Hiroshima University Graduate School of Biomedical & Health Sciences, 1-2-3 Kasumi, Minami-ku, Hiroshima, 734-8553, Japan
| | - Kazue Hisaoka-Nakashima
- Department of Pharmacology, Hiroshima University Graduate School of Biomedical & Health Sciences, 1-2-3 Kasumi, Minami-ku, Hiroshima, 734-8553, Japan
| | - Yoshihiro Nakata
- Department of Pharmacology, Hiroshima University Graduate School of Biomedical & Health Sciences, 1-2-3 Kasumi, Minami-ku, Hiroshima, 734-8553, Japan
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Kay CWP, Ursu D, Sher E, King AE. The role of Cx36 and Cx43 in 4-aminopyridine-induced rhythmic activity in the spinal nociceptive dorsal horn: an electrophysiological study in vitro. Physiol Rep 2016; 4:e12852. [PMID: 27462070 PMCID: PMC4962069 DOI: 10.14814/phy2.12852] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Revised: 06/10/2016] [Accepted: 06/13/2016] [Indexed: 01/09/2023] Open
Abstract
Connexin (Cx) proteins and gap junctions support the formation of neuronal and glial syncytia that are linked to different forms of rhythmic firing and oscillatory activity in the CNS. In this study, quantitative reverse transcription polymerase chain reaction (RT-qPCR) was used to profile developmental expression of two specific Cx proteins, namely glial Cx43 and neuronal Cx36, in postnatal lumbar spinal cord aged 4, 7, and 14 days. Extracellular electrophysiology was used to determine the contribution of Cx36 and Cx43 to a previously described form of 4-aminopyridine (4-AP)-induced 4-12 Hz rhythmic activity within substantia gelatinosa (SG) of rat neonatal dorsal horn (DH) in vitro. The involvement of Cx36 and Cx43 was probed pharmacologically using quinine, a specific uncoupler of Cx36 and the mimetic peptide blocker Gap 26 which targets Cx43. After establishment of 4-12 Hz rhythmic activity by 4-AP (25 μmol/L), coapplication of quinine (250 μmol/L) reduced 4-AP-induced 4-12 Hz rhythmic activity (P < 0.05). Preincubation of spinal cord slices with Gap 26 (100 μmol/L), compromised the level of 4-AP-induced 4-12 Hz rhythmic activity in comparison with control slices preincubated in ACSF alone (P < 0.05). Conversely, the nonselective gap junction "opener" trimethylamine (TMA) enhanced 4-12 Hz rhythmic behavior (P < 0.05), further supporting a role for Cx proteins and gap junctions. These data have defined a physiological role for Cx36 and Cx43 in rhythmic firing in SG, a key nociceptive processing area of DH. The significance of these data in the context of pain and Cx proteins as a future analgesic drug target requires further study.
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Affiliation(s)
- Christopher W P Kay
- School of Biomedical Sciences, University of Leeds, Leeds, LS2 9JT, United Kingdom
| | - Daniel Ursu
- Eli Lilly & Co., Lilly Research Centre Erl Wood Manor, Windlesham, Surrey, GU20 6PH, United Kingdom
| | - Emanuele Sher
- Eli Lilly & Co., Lilly Research Centre Erl Wood Manor, Windlesham, Surrey, GU20 6PH, United Kingdom
| | - Anne E King
- School of Biomedical Sciences, University of Leeds, Leeds, LS2 9JT, United Kingdom
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15
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Zhang FF, Morioka N, Kitamura T, Fujii S, Miyauchi K, Nakamura Y, Hisaoka-Nakashima K, Nakata Y. Lycopene ameliorates neuropathic pain by upregulating spinal astrocytic connexin 43 expression. Life Sci 2016; 155:116-22. [DOI: 10.1016/j.lfs.2016.05.021] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2016] [Revised: 05/02/2016] [Accepted: 05/14/2016] [Indexed: 12/16/2022]
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16
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Downregulation of the spinal dorsal horn clock gene Per1 expression leads to mechanical hypersensitivity via c-jun N-terminal kinase and CCL2 production in mice. Mol Cell Neurosci 2016; 72:72-83. [DOI: 10.1016/j.mcn.2016.01.007] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2015] [Revised: 12/22/2015] [Accepted: 01/20/2016] [Indexed: 12/17/2022] Open
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17
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Chen ZY, Shen FY, Jiang L, Zhao X, Shen XL, Zhong W, Liu S, Wang ZR, Wang YW. Attenuation of Neuropathic Pain by Inhibiting Electrical Synapses in the Anterior Cingulate Cortex. Anesthesiology 2016; 124:169-83. [PMID: 26566282 DOI: 10.1097/aln.0000000000000942] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
BACKGROUND Synaptic mechanisms and neuronal oscillations have been proposed to be responsible for neuropathic pain formation. Many studies have also highlighted the important role of electrical synapses in synaptic plasticity and in neuronal oscillations. Thus, electrical synapses may contribute to neuropathic pain generation. However, previous studies have primarily focused on the role of chemical synapses, while ignoring the role of electrical synapses, in neuropathic pain generation. METHODS The authors adopted microinjection, RNA interference techniques, and behavioral tests to verify the link between connexin 36 (Cx36) and neuropathic pain. They also studied the selective Cx36 blocker mefloquine in rat chronic constriction injury and spared nerve injury model of neuropathic pain. Electrophysiologic recordings were used to further confirm the behavioral data. RESULTS The authors found that Cx36, which constitutes the neuron-neuron electrical synapses, was up-regulated in the anterior cingulate cortex after nerve injury (n = 5). Meanwhile, Cx36-mediated neuronal oscillations in the gamma frequency range (30 to 80 Hz) (n = 7 to 8) and the neuronal synaptic transmission (n = 13 to 19) were also enhanced. Neuropathic pain was relieved by disrupting Cx36 function or expression in the anterior cingulate cortex. They also found that mefloquine, which are clinically used for treating malaria, affected gamma oscillations and synaptic plasticity, leading to a sustained pain relief in chronic constriction injury and spared nerve injury models (n = 7 to 12). CONCLUSION The electrical synapses blocker mefloquine could affect gamma oscillations and synaptic plasticity in the anterior cingulate cortex and relieve neuropathic pain. Cx36 may be a new therapeutic target for treating chronic pain.
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Affiliation(s)
- Zhi-Yu Chen
- From the Department of Anesthesiology and Intensive Care Medicine, Xinhua Hospital, College of Medicine, Shanghai Jiaotong University, Shanghai, China (Z.-Y.C., F.-Y.S., L.J., X.Z., X.-L.S., Y.-W.W.); and Laboratory of Neural Circuit Plasticity & Memory, Institute of Brain Functional Genomics, East China Normal University, Shanghai, China (W.Z., S.L., Z.-R.W.)
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18
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Zhang FF, Morioka N, Harano S, Nakamura Y, Liu K, Nishibori M, Hisaoka-Nakashima K, Nakata Y. Perineural expression of high-mobility group box-1 contributes to long-lasting mechanical hypersensitivity via matrix metalloprotease-9 up-regulation in mice with painful peripheral neuropathy. J Neurochem 2015; 136:837-850. [PMID: 26578177 DOI: 10.1111/jnc.13434] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2015] [Revised: 10/06/2015] [Accepted: 11/02/2015] [Indexed: 12/21/2022]
Abstract
High-mobility group box-1 (HMGB1) has been shown to be critical in the modulation of nociceptive transduction following a peripheral neuropathy. However, the precise role of peripherally expressed HMGB1 in neuropathic pain has yet to be fully elaborated. Following a partial sciatic nerve ligation (PSNL) in mice, a persistent ipsilateral up-regulation of HMGB1 was observed from 3 to 21 days after PSNL, in paralleled with a robust ipsilateral hind paw mechanical hypersensitivity. Increased HMGB1 was detected in both infiltrating macrophages and proliferating Schwann cells in the ipsilateral nerve 14 days following PSNL. Repeated perineural treatment with anti-HMGB1 antibody significantly ameliorated PSNL-induced mechanical hypersensitivity. Several pronociceptive molecules, including matrix metalloprotease-9 (MMP-9), tumor necrosis factor-α, interleukin-1β (IL-1β), and cyclooxygenase-2, were up-regulated in injured sciatic nerve 14 days following PSNL. Repeated perineural treatment with an anti-HMGB1 antibody significantly suppressed expression of MMP-9, but not other pronociceptive molecules. Perineural treatment with a selective MMP-9 inhibitor ameliorated PSNL-induced mechanical hypersensitivity. The current findings demonstrate that the maintenance of the neuropathic state following an injured nerve is dependent on the up-regulation of HMGB1 and MMP-9. Thus, blocking HMGB1 function in sciatic nerve could be a potent therapeutic strategy for the treatment of neuropathic pain. Increased peripheral high-mobility group box-1 (HMGB1) is involved in the modulation of nociceptive transduction following a peripheral neuropathy. Following nerve injury in mice, increased HMGB1 is detected in both infiltrating macrophages and proliferating Schwann cells in the ipsilateral nerve. Repeated perineural treatment with anti-HMGB1 antibody significantly ameliorates nerve injury-induced mechanical hypersensitivity, and suppresses expression of matrix metalloprotease-9 (MMP-9). The findings demonstrate that the maintenance of the neuropathic state following an injury nerve is dependent on the up-regulation of HMGB1 and MMP-9.
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Affiliation(s)
- Fang Fang Zhang
- Department of Pharmacology, Hiroshima University Graduate School of Biomedical & Health Sciences, Minami-ku, Hiroshima, Japan
| | - Norimitsu Morioka
- Department of Pharmacology, Hiroshima University Graduate School of Biomedical & Health Sciences, Minami-ku, Hiroshima, Japan
| | - Sakura Harano
- Department of Pharmacology, Hiroshima University Graduate School of Biomedical & Health Sciences, Minami-ku, Hiroshima, Japan
| | - Yoki Nakamura
- Department of Pharmacology, Hiroshima University Graduate School of Biomedical & Health Sciences, Minami-ku, Hiroshima, Japan
| | - Keyue Liu
- Department of Pharmacology, Hiroshima University Graduate School of Biomedical & Health Sciences, Minami-ku, Hiroshima, Japan
| | - Masahiro Nishibori
- Department of Pharmacology, Graduate School of Medicine, Density and Pharmaceutical Sciences, Okayama University, Shikata, Okayama, Japan
| | - Kazue Hisaoka-Nakashima
- Department of Pharmacology, Hiroshima University Graduate School of Biomedical & Health Sciences, Minami-ku, Hiroshima, Japan
| | - Yoshihiro Nakata
- Department of Pharmacology, Hiroshima University Graduate School of Biomedical & Health Sciences, Minami-ku, Hiroshima, Japan
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Morioka N, Zhang FF, Nakamura Y, Kitamura T, Hisaoka-Nakashima K, Nakata Y. Tumor necrosis factor-mediated downregulation of spinal astrocytic connexin43 leads to increased glutamatergic neurotransmission and neuropathic pain in mice. Brain Behav Immun 2015; 49:293-310. [PMID: 26116449 DOI: 10.1016/j.bbi.2015.06.015] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/13/2015] [Revised: 06/05/2015] [Accepted: 06/16/2015] [Indexed: 11/29/2022] Open
Abstract
Spinal cord astrocytes are critical in the maintenance of neuropathic pain. Connexin 43 (Cx43) expressed on spinal dorsal horn astrocytes modulates synaptic neurotransmission, but its role in nociceptive transduction has yet to be fully elaborated. In mice, Cx43 is mainly expressed in astrocytes, not neurons or microglia, in the spinal dorsal horn. Hind paw mechanical hypersensitivity was observed beginning 3days after partial sciatic nerve ligation (PSNL), but a persistent downregulation of astrocytic Cx43 in ipsilateral lumbar spinal dorsal horn was not observed until 7days post-PSNL, suggesting that Cx43 downregulation mediates the maintenance and not the initiation of nerve injury-induced hypersensitivity. Downregulation of Cx43 expression by intrathecal treatment with Cx43 siRNA also induced mechanical hypersensitivity. Conversely, restoring Cx43 by an adenovirus vector expressing Cx43 (Ad-Cx43) ameliorated PSNL-induced mechanical hypersensitivity. The sensitized state following PSNL is likely maintained by dysfunctional glutamatergic neurotransmission, as Cx43 siRNA-induced mechanical hypersensitivity was attenuated with intrathecal treatment of glutamate receptor antagonists MK801 and CNQX, but not neurokinin-1 receptor antagonist CP96345 or the Ca(2+) channel subunit α2δ1 blocker gabapentin. The source of this dysfunctional glutamatergic neurotransmission is likely decreased clearance of glutamate from the synapse rather than increased glutamate release into the synapse. Astrocytic expression of glutamate transporter GLT-1, but not GLAST, and activity of glutamate transport were markedly decreased in mice intrathecally injected with Cx43-targeting siRNA but not non-targeting siRNA. Glutamate release from spinal synaptosomes prepared from mice treated with either Cx43-targeting siRNA or non-targeting siRNA was unchanged. Intrathecal injection of Ad-Cx43 in PSNL mice restored astrocytic GLT-1 expression. The cytokine tumor necrosis factor (TNF) has been implicated in the induction of central sensitization, particularly through its actions on astrocytes, in the spinal cord following peripheral injury. Intrathecal injection of TNF in naïve mice induced the downregulation of both Cx43 and GLT-1 in spinal dorsal horn, as well as hind paw mechanical hypersensitivity, as observed in PSNL mice. Conversely, intrathecal treatment of PSNL mice with the TNF inhibitor etanercept prevented not only mechanical hypersensitivity but also the downregulation of Cx43 and GLT-1 expression in astrocytes. The current findings indicate that spinal astrocytic Cx43 are essential for the maintenance of neuropathic pain following peripheral nerve injury and suggest modulation of Cx43 as a novel target for developing analgesics for neuropathic pain.
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Affiliation(s)
- Norimitsu Morioka
- Department of Pharmacology, Hiroshima University Graduate School of Biomedical & Health Sciences, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8553, Japan.
| | - Fang Fang Zhang
- Department of Pharmacology, Hiroshima University Graduate School of Biomedical & Health Sciences, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8553, Japan
| | - Yoki Nakamura
- Department of Pharmacology, Hiroshima University Graduate School of Biomedical & Health Sciences, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8553, Japan
| | - Tomoya Kitamura
- Department of Pharmacology, Hiroshima University Graduate School of Biomedical & Health Sciences, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8553, Japan
| | - Kazue Hisaoka-Nakashima
- Department of Pharmacology, Hiroshima University Graduate School of Biomedical & Health Sciences, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8553, Japan
| | - Yoshihiro Nakata
- Department of Pharmacology, Hiroshima University Graduate School of Biomedical & Health Sciences, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8553, Japan
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