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Lin X, Xu P, Tian Y, Xiao H, Dong X, Wang S. Establishing a Mouse Model of Chlorpromazine-Induced Corneal Trigeminal Denervation. Transl Vis Sci Technol 2023; 12:21. [PMID: 37906054 PMCID: PMC10619696 DOI: 10.1167/tvst.12.10.21] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Accepted: 09/24/2023] [Indexed: 11/02/2023] Open
Abstract
Purpose This study aimed to establish a mouse model of chlorpromazine-induced corneal trigeminal denervation (CCTD). Methods Retrobulbar chlorpromazine injections were administered to 6- to 8-week-old C57BL/6j mice to induce corneal denervation. Additionally, apoptosis was assessed in isolated primary trigeminal ganglion cells after culturing in a conditioned medium containing chlorpromazine. Finally, the success rate of model generation, mortality and complication rates, and model-preparation learning curves were compared between the CCTD model and the electrocoagulation and axotomy models. Results Chlorpromazine retrobulbar injections resulted in trigeminal denervation, leading to a reduced blink reflex, corneal nerve density, and corneal epithelium thickness. Furthermore, 90% (9/10) of the mice developed epithelial defects, accompanied by increased apoptosis and inhibited proliferation of corneal epithelial cells. In vitro, trigeminal ganglion cell apoptosis increased after culturing in a conditioned medium containing chlorpromazine. Moreover, the CCTD model exhibited a higher success rate, longer survival rate, and lower complication rate compared to the electrocoagulation and axotomy models. Crucially, the learning curve demonstrated that the method used to generate the CCTD model was easy to learn. Conclusions The CCTD model is a user-friendly mouse model for studying corneal trigeminal denervation that offers a less invasive alternative to existing models. Translational Relevance The CCTD model serves as a valuable tool for investigating the functional mechanisms of corneal trigeminal nerves and their interactions with corneal cells.
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Affiliation(s)
- Xiongshi Lin
- The Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, Guangdong Province, China
| | - Peipei Xu
- The Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, Guangdong Province, China
| | - Ying Tian
- The Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, Guangdong Province, China
| | - Haiqi Xiao
- The Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, Guangdong Province, China
| | - Xing Dong
- The Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, Guangdong Province, China
| | - Shuangyong Wang
- The Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, Guangdong Province, China
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2
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McGinnis A, Ji RR. The Similar and Distinct Roles of Satellite Glial Cells and Spinal Astrocytes in Neuropathic Pain. Cells 2023; 12:965. [PMID: 36980304 PMCID: PMC10047571 DOI: 10.3390/cells12060965] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2023] [Revised: 03/19/2023] [Accepted: 03/20/2023] [Indexed: 03/30/2023] Open
Abstract
Preclinical studies have identified glial cells as pivotal players in the genesis and maintenance of neuropathic pain after nerve injury associated with diabetes, chemotherapy, major surgeries, and virus infections. Satellite glial cells (SGCs) in the dorsal root and trigeminal ganglia of the peripheral nervous system (PNS) and astrocytes in the central nervous system (CNS) express similar molecular markers and are protective under physiological conditions. They also serve similar functions in the genesis and maintenance of neuropathic pain, downregulating some of their homeostatic functions and driving pro-inflammatory neuro-glial interactions in the PNS and CNS, i.e., "gliopathy". However, the role of SGCs in neuropathic pain is not simply as "peripheral astrocytes". We delineate how these peripheral and central glia participate in neuropathic pain by producing different mediators, engaging different parts of neurons, and becoming active at different stages following nerve injury. Finally, we highlight the recent findings that SGCs are enriched with proteins related to fatty acid metabolism and signaling such as Apo-E, FABP7, and LPAR1. Targeting SGCs and astrocytes may lead to novel therapeutics for the treatment of neuropathic pain.
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Affiliation(s)
- Aidan McGinnis
- Center for Translational Pain Medicine, Department of Anesthesiology, Duke University Medical Center, Durham, NC 27710, USA
| | - Ru-Rong Ji
- Center for Translational Pain Medicine, Department of Anesthesiology, Duke University Medical Center, Durham, NC 27710, USA
- Department of Cell Biology, Duke University Medical Center, Durham, NC 27710, USA
- Department of Neurobiology, Duke University Medical Center, Durham, NC 27710, USA
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Pozzi E, Ballarini E, Rodriguez-Menendez V, Canta A, Chiorazzi A, Monza L, Bossi M, Alberti P, Malacrida A, Meregalli C, Scuteri A, Cavaletti G, Carozzi VA. Paclitaxel, but Not Cisplatin, Affects Satellite Glial Cells in Dorsal Root Ganglia of Rats with Chemotherapy-Induced Peripheral Neurotoxicity. TOXICS 2023; 11:93. [PMID: 36850969 PMCID: PMC9961471 DOI: 10.3390/toxics11020093] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/19/2022] [Revised: 01/13/2023] [Accepted: 01/13/2023] [Indexed: 06/18/2023]
Abstract
Chemotherapy-induced peripheral neurotoxicity is one of the most common dose-limiting toxicities of several widely used anticancer drugs such as platinum derivatives (cisplatin) and taxanes (paclitaxel). Several molecular mechanisms related to the onset of neurotoxicity have already been proposed, most of them having the sensory neurons of the dorsal root ganglia (DRG) and the peripheral nerve fibers as principal targets. In this study we explore chemotherapy-induced peripheral neurotoxicity beyond the neuronocentric view, investigating the changes induced by paclitaxel (PTX) and cisplatin (CDDP) on satellite glial cells (SGC) in the DRG and their crosstalk. Rats were chronically treated with PTX (10 mg/Kg, 1qwx4) or CDDP (2 mg/Kg 2qwx4) or respective vehicles. Morpho-functional analyses were performed to verify the features of drug-induced peripheral neurotoxicity. Qualitative and quantitative immunohistochemistry, 3D immunofluorescence, immunoblotting, and transmission electron microscopy analyses were also performed to detect alterations in SGCs and their interconnections. We demonstrated that PTX, but not CDDP, produces a strong activation of SGCs in the DRG, by altering their interconnections and their physical contact with sensory neurons. SGCs may act as principal actors in PTX-induced peripheral neurotoxicity, paving the way for the identification of new druggable targets for the treatment and prevention of chemotherapy-induced peripheral neurotoxicity.
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Affiliation(s)
- Eleonora Pozzi
- School of Medicine and Surgery, University of Milano-Bicocca, 20216 Monza, Italy
- NeuroMI (Milan Center for Neuroscience), 20126 Milan, Italy
| | - Elisa Ballarini
- School of Medicine and Surgery, University of Milano-Bicocca, 20216 Monza, Italy
- NeuroMI (Milan Center for Neuroscience), 20126 Milan, Italy
| | - Virginia Rodriguez-Menendez
- School of Medicine and Surgery, University of Milano-Bicocca, 20216 Monza, Italy
- NeuroMI (Milan Center for Neuroscience), 20126 Milan, Italy
| | - Annalisa Canta
- School of Medicine and Surgery, University of Milano-Bicocca, 20216 Monza, Italy
- NeuroMI (Milan Center for Neuroscience), 20126 Milan, Italy
| | - Alessia Chiorazzi
- School of Medicine and Surgery, University of Milano-Bicocca, 20216 Monza, Italy
- NeuroMI (Milan Center for Neuroscience), 20126 Milan, Italy
| | - Laura Monza
- School of Medicine and Surgery, University of Milano-Bicocca, 20216 Monza, Italy
- NeuroMI (Milan Center for Neuroscience), 20126 Milan, Italy
| | - Mario Bossi
- School of Medicine and Surgery, University of Milano-Bicocca, 20216 Monza, Italy
- NeuroMI (Milan Center for Neuroscience), 20126 Milan, Italy
| | - Paola Alberti
- School of Medicine and Surgery, University of Milano-Bicocca, 20216 Monza, Italy
- NeuroMI (Milan Center for Neuroscience), 20126 Milan, Italy
| | - Alessio Malacrida
- School of Medicine and Surgery, University of Milano-Bicocca, 20216 Monza, Italy
- NeuroMI (Milan Center for Neuroscience), 20126 Milan, Italy
| | - Cristina Meregalli
- School of Medicine and Surgery, University of Milano-Bicocca, 20216 Monza, Italy
- NeuroMI (Milan Center for Neuroscience), 20126 Milan, Italy
| | - Arianna Scuteri
- School of Medicine and Surgery, University of Milano-Bicocca, 20216 Monza, Italy
- NeuroMI (Milan Center for Neuroscience), 20126 Milan, Italy
| | - Guido Cavaletti
- School of Medicine and Surgery, University of Milano-Bicocca, 20216 Monza, Italy
- NeuroMI (Milan Center for Neuroscience), 20126 Milan, Italy
| | - Valentina Alda Carozzi
- School of Medicine and Surgery, University of Milano-Bicocca, 20216 Monza, Italy
- NeuroMI (Milan Center for Neuroscience), 20126 Milan, Italy
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4
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Muñoz MF, Griffith TN, Contreras JE. Mechanisms of ATP release in pain: role of pannexin and connexin channels. Purinergic Signal 2021; 17:549-561. [PMID: 34792743 PMCID: PMC8677853 DOI: 10.1007/s11302-021-09822-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Accepted: 10/18/2021] [Indexed: 12/21/2022] Open
Abstract
Pain is a physiological response to bodily damage and serves as a warning of potential threat. Pain can also transform from an acute response to noxious stimuli to a chronic condition with notable emotional and psychological components that requires treatment. Indeed, the management of chronic pain is currently an important unmet societal need. Several reports have implicated the release of the neurotransmitter adenosine triphosphate (ATP) and subsequent activation of purinergic receptors in distinct pain etiologies. Purinergic receptors are broadly expressed in peripheral neurons and the spinal cord; thus, purinergic signaling in sensory neurons or in spinal circuits may be critical for pain processing. Nevertheless, an outstanding question remains: what are the mechanisms of ATP release that initiate nociceptive signaling? Connexin and pannexin channels are established conduits of ATP release and have been suggested to play important roles in a variety of pathologies, including several models of pain. As such, these large-pore channels represent a new and exciting putative pharmacological target for pain treatment. Herein, we will review the current evidence for a role of connexin and pannexin channels in ATP release during nociceptive signaling, such as neuropathic and inflammatory pain. Collectively, these studies provide compelling evidence for an important role of connexins and pannexins in pain processing.
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Affiliation(s)
- Manuel F. Muñoz
- Department of Physiology and Membrane Biology, School of Medicine, University of California, Davis, USA
| | - Theanne N. Griffith
- Department of Physiology and Membrane Biology, School of Medicine, University of California, Davis, USA
| | - Jorge E. Contreras
- Department of Physiology and Membrane Biology, School of Medicine, University of California, Davis, USA
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Common and discrete mechanisms underlying chronic pain and itch: peripheral and central sensitization. Pflugers Arch 2021; 473:1603-1615. [PMID: 34245379 DOI: 10.1007/s00424-021-02599-y] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2020] [Revised: 05/26/2021] [Accepted: 06/22/2021] [Indexed: 12/30/2022]
Abstract
Normally, an obvious antagonism exists between pain and itch. In normal conditions, painful stimuli suppress itch sensation, whereas pain killers often generate itch. Although pain and itch are mediated by separate pathways under normal conditions, most chemicals are not highly specific to one sensation in chronic pathologic conditions. Notably, in patients with neuropathic pain, histamine primarily induces pain rather than itch, while in patients with atopic dermatitis, bradykinin triggers itch rather than pain. Accordingly, repetitive scratching even enhances itch sensation in chronic itch conditions. Physicians often prescribe pain relievers to patients with chronic itch, suggesting common mechanisms underlying chronic pain and itch, especially peripheral and central sensitization. Rather than separating itch and pain, studies should investigate chronic itch and pain including neuropathic and inflammatory conditions. Here, we reviewed chronic sensitization leading to chronic pain and itch at both peripheral and central levels. Studies investigating the connection between pain and itch facilitate the development of new therapeutics against both chronic dysesthesias based on the underlying pathophysiology.
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6
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Gazerani P. Satellite Glial Cells in Pain Research: A Targeted Viewpoint of Potential and Future Directions. FRONTIERS IN PAIN RESEARCH 2021; 2:646068. [PMID: 35295432 PMCID: PMC8915641 DOI: 10.3389/fpain.2021.646068] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2020] [Accepted: 01/26/2021] [Indexed: 12/16/2022] Open
Abstract
Chronic pain is known to be caused by sensitization within the pain circuits. An imbalance occurs between excitatory and inhibitory transmission that enables this sensitization to form. In addition to neurons, the contribution of central glia, especially astrocytes and microglia, to the pathogenesis of pain induction and maintenance has been identified. This has led to the targeting of astrogliosis and microgliosis to restore the normal functions of astrocytes and microglia to help reverse chronic pain. Gliosis is broadly defined as a reactive response of glial cells in response to insults to the central nervous system (CNS). The role of glia in the peripheral nervous system (PNS) has been less investigated. Accumulating evidence, however, points to the contribution of satellite glial cells (SGCs) to chronic pain. Hence, understanding the potential role of these cells and their interaction with sensory neurons has become important for identifying the mechanisms underlying pain signaling. This would, in turn, provide future therapeutic options to target pain. Here, a viewpoint will be presented regarding potential future directions in pain research, with a focus on SGCs to trigger further research. Promising avenues and new directions include the potential use of cell lines, cell live imaging, computational analysis, 3D tissue prints and new markers, investigation of glia–glia and macrophage–glia interactions, the time course of glial activation under acute and chronic pathological pain compared with spontaneous pain, pharmacological and non-pharmacological responses of glia, and potential restoration of normal function of glia considering sex-related differences.
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Affiliation(s)
- Parisa Gazerani
- Laboratory of Molecular Pharmacology, Department of Health Science and Technology, Faculty of Medicine, Aalborg University, Aalborg, Denmark
- Pharmacy, Department of Life Sciences and Health, Faculty of Health Sciences, OsloMet, Oslo, Norway
- *Correspondence: Parisa Gazerani
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7
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Shinoda M, Kubo A, Hayashi Y, Iwata K. Peripheral and Central Mechanisms of Persistent Orofacial Pain. Front Neurosci 2019; 13:1227. [PMID: 31798407 PMCID: PMC6863776 DOI: 10.3389/fnins.2019.01227] [Citation(s) in RCA: 52] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Accepted: 10/30/2019] [Indexed: 12/25/2022] Open
Abstract
Neuroplastic changes in the neuronal networks involving the trigeminal ganglion (TG), trigeminal spinal subnucleus caudalis (Vc), and upper cervical spinal cord (C1/C2) are considered the mechanisms underlying the ectopic orofacial hypersensitivity associated with trigeminal nerve injury or orofacial inflammation. It has been reported that peripheral nerve injury causes injury discharges in the TG neurons, and a barrage of action potentials is generated in TG neurons and conveyed to the Vc and C1/C2 after trigeminal nerve injury. Long after trigeminal nerve injury, various molecules are produced in the TG neurons, and these molecules are released from the soma of TG neurons and are transported to the central and peripheral terminals of TG neurons. These changes within the TG cause neuroplastic changes in TG neurons and they become sensitized. The neuronal activity of TG neurons is further accelerated, and Vc and C1/C2 neurons are also sensitized. In addition to this cascade, non-neuronal glial cells are also involved in the enhancement of the neuronal activity of TG, Vc, and C1/C2 neurons. Satellite glial cells and macrophages are activated in the TG after trigeminal nerve injury and orofacial inflammation. Microglial cells and astrocytes are also activated in the Vc and C1/C2 regions. It is considered that functional interaction between non-neuronal cells and neurons in the TG, Vc, and C1/C2 regions is a key mechanism involved in the enhancement of neuronal excitability after nerve injury or inflammation. In this article, the detailed mechanisms underlying ectopic orofacial hyperalgesia associated with trigeminal nerve injury and orofacial inflammation are addressed.
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Affiliation(s)
- Masamichi Shinoda
- Department of Physiology, Nihon University School of Dentistry, Tokyo, Japan
| | - Asako Kubo
- Department of Physiology, Nihon University School of Dentistry, Tokyo, Japan
| | - Yoshinori Hayashi
- Department of Physiology, Nihon University School of Dentistry, Tokyo, Japan
| | - Koichi Iwata
- Department of Physiology, Nihon University School of Dentistry, Tokyo, Japan
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8
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Frederiksen SD, Haanes KA, Warfvinge K, Edvinsson L. Perivascular neurotransmitters: Regulation of cerebral blood flow and role in primary headaches. J Cereb Blood Flow Metab 2019; 39:610-632. [PMID: 29251523 PMCID: PMC6446417 DOI: 10.1177/0271678x17747188] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/05/2017] [Revised: 11/04/2017] [Accepted: 11/06/2017] [Indexed: 12/17/2022]
Abstract
In order to understand the nature of the relationship between cerebral blood flow (CBF) and primary headaches, we have conducted a literature review with particular emphasis on the role of perivascular neurotransmitters. Primary headaches are in general considered complex polygenic disorders (genetic and environmental influence) with pathophysiological neurovascular alterations. Identified candidate headache genes are associated with neuro- and gliogenesis, vascular development and diseases, and regulation of vascular tone. These findings support a role for the vasculature in primary headache disorders. Moreover, neuronal hyperexcitability and other abnormalities have been observed in primary headaches and related to changes in hemodynamic factors. In particular, this relates to migraine aura and spreading depression. During headache attacks, ganglia such as trigeminal and sphenopalatine (located outside the blood-brain barrier) are variably activated and sensitized which gives rise to vasoactive neurotransmitter release. Sympathetic, parasympathetic and sensory nerves to the cerebral vasculature are activated. During migraine attacks, altered CBF has been observed in brain regions such as the somatosensory cortex, brainstem and thalamus. In regulation of CBF, the individual roles of neurotransmitters are partly known, but much needs to be unraveled with respect to headache disorders.
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Affiliation(s)
- Simona D Frederiksen
- Department of Clinical Experimental Research, Glostrup Research Institute, Rigshospitalet Glostrup, Glostrup, Denmark
| | - Kristian A Haanes
- Department of Clinical Experimental Research, Glostrup Research Institute, Rigshospitalet Glostrup, Glostrup, Denmark
| | - Karin Warfvinge
- Department of Clinical Experimental Research, Glostrup Research Institute, Rigshospitalet Glostrup, Glostrup, Denmark
- Division of Experimental Vascular Research, Department of Clinical Sciences, Lund University, Lund, Sweden
| | - Lars Edvinsson
- Department of Clinical Experimental Research, Glostrup Research Institute, Rigshospitalet Glostrup, Glostrup, Denmark
- Division of Experimental Vascular Research, Department of Clinical Sciences, Lund University, Lund, Sweden
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Diabetes-induced Neuropathic Mechanical Hyperalgesia Depends on P2X4 Receptor Activation in Dorsal Root Ganglia. Neuroscience 2018; 398:158-170. [PMID: 30537520 DOI: 10.1016/j.neuroscience.2018.12.003] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2018] [Revised: 11/30/2018] [Accepted: 12/03/2018] [Indexed: 12/14/2022]
Abstract
Peripheral diabetic neuropathy (PDN) manifests in 50-60% of type I and II diabetic patients and is the major cause of limb amputation. Adequate therapy for PDN is a current challenge. There are evidences that the activation of the P2X4 receptor (P2X4R) expressed on microglial cells of the central nervous system takes part in the development of neuropathic pain. However, there is an open question: Is P2X4R activation on dorsal root ganglia (DRG) involved in the development of neuropathic pain? To answer this question, this study verified the involvement of P2X4R expressed in DRG cells on diabetes-induced neuropathic mechanical hyperalgesia in rats. We found that intrathecal or ganglionar (L5-DRG) administration of a novel P2X4R antagonist (PSB-15417) or intrathecal administration of oligodeoxynucleotides (ODN)-antisense against the P2X4R reversed diabetes-induced neuropathic mechanical hyperalgesia. The DRG of the diabetic neuropathic rats showed an increase in P2X4R expression, and the DRG immunofluorescence suggested that P2X4R is expressed mainly in satellite glial cells (SGC). Finally, our study showed a functional expression of P2X4R in SGCs of the rat's DRG, because the P2X4R agonist BzATP elicits an increase in intracellular calcium concentration in SGCs, which was reduced by PSB-15417. These findings indicate that P2X4R activation in DRG is essential to diabetes-induced neuropathic mechanical hyperalgesia. Therefore, this purinergic receptor in DRG could be an interesting therapeutic target for quaternary P2X4R antagonists that do not cross the hematoencephalic barrier, for the control of neuropathic pain, preserving central nervous system functions.
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Fan W, Zhu X, He Y, Zhu M, Wu Z, Huang F, He H. The role of satellite glial cells in orofacial pain. J Neurosci Res 2018; 97:393-401. [PMID: 30450738 DOI: 10.1002/jnr.24341] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2018] [Revised: 08/29/2018] [Accepted: 09/21/2018] [Indexed: 12/14/2022]
Abstract
Some chronic pain conditions in the orofacial region are common, the mechanisms underlying which are unresolved. Satellite glial cells (SGCs) are the glial cells of the peripheral nervous system. In the sensory ganglia, each neuronal body is surrounded by SGCs forming distinct functional units. The unique structural organization enables SGCs to communicate with each other and with their enwrapped neurons via a variety of ways. There is a growing body of evidence that SGCs can influence the level of neuronal excitability and are involved in the development and/or maintenance of pain. The aim of this review was to summarize the latest advances made about the implication of SGCs in orofacial pain. It may offer new targets for the development of orofacial pain treatment.
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Affiliation(s)
- Wenguo Fan
- Guangdong Provincial Key Laboratory of Stomatology, Institute of Stomatological Research, Sun Yat-sen University, Guangzhou, China.,Department of Anesthesiology, Guanghua School of Stomatology, Hospital of Stomatology, Sun Yat-sen University, Guangzhou, China
| | - Xiao Zhu
- The Public Service Platform of South China Sea for R&D Marine Biomedicine Resources, Marine Biomedical Research Institute, Guangdong Medical University, Zhanjiang, China
| | - Yifan He
- Guangdong Provincial Key Laboratory of Stomatology, Institute of Stomatological Research, Sun Yat-sen University, Guangzhou, China
| | - Mengzhu Zhu
- Department of Rheumatology, Chinese Medicine Hospital in Linyi City, Shandong, China
| | - Zhi Wu
- Guangdong Provincial Key Laboratory of Stomatology, Institute of Stomatological Research, Sun Yat-sen University, Guangzhou, China
| | - Fang Huang
- Guangdong Provincial Key Laboratory of Stomatology, Institute of Stomatological Research, Sun Yat-sen University, Guangzhou, China
| | - Hongwen He
- Guangdong Provincial Key Laboratory of Stomatology, Institute of Stomatological Research, Sun Yat-sen University, Guangzhou, China
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Retamal MA, Riquelme MA, Stehberg J, Alcayaga J. Connexin43 Hemichannels in Satellite Glial Cells, Can They Influence Sensory Neuron Activity? Front Mol Neurosci 2017; 10:374. [PMID: 29200997 PMCID: PMC5696352 DOI: 10.3389/fnmol.2017.00374] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2017] [Accepted: 10/27/2017] [Indexed: 12/30/2022] Open
Abstract
In this review article, we summarize the current insight on the role of Connexin- and Pannexin-based channels as modulators of sensory neurons. The somas of sensory neurons are located in sensory ganglia (i.e., trigeminal and nodose ganglia). It is well known that within sensory ganglia, sensory neurons do not form neither electrical nor chemical synapses. One of the reasons for this is that each soma is surrounded by glial cells, known as satellite glial cells (SGCs). Recent evidence shows that connexin43 (Cx43) hemichannels and probably pannexons located at SGCs have an important role in paracrine communication between glial cells and sensory neurons. This communication may be exerted via the release of bioactive molecules from SGCs and their subsequent action on receptors located at the soma of sensory neurons. The glio-neuronal communication seems to be relevant for the establishment of chronic pain, hyperalgesia and pathologies associated with tissue inflammation. Based on the current literature, it is possible to propose that Cx43 hemichannels expressed in SGCs could be a novel pharmacological target for treating chronic pain, which need to be directly evaluated in future studies.
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Affiliation(s)
- Mauricio A Retamal
- Centro de Fisiología Celular e Integrativa, Facultad de Medicina, Clinica Alemana Universidad del Desarrollo, Santiago, Chile.,Department of Cell Physiology and Molecular Biophysics, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, United States
| | - Manuel A Riquelme
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center, San Antonio, TX, United States
| | - Jimmy Stehberg
- Laboratorio de Neurobiología, Centro de Investigaciones Biomedicas, Universidad Andres Bello, Santiago, Chile
| | - Julio Alcayaga
- Department of Biology, Cell Physiology Center, University of Chile, Santiago, Chile
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12
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Abstract
Enhanced expression and function of gap junctions and pannexin (Panx) channels have been associated with both peripheral and central mechanisms of pain sensitization. At the level of the sensory ganglia, evidence includes augmented gap junction and pannexin1 expression in glial cells and neurons in inflammatory and neuropathic pain models and increased synchrony and enhanced cross-excitation among sensory neurons by gap junction-mediated coupling. In spinal cord and in suprapinal areas, evidence is largely limited to increased expression of relevant proteins, although in several rodent pain models, hypersensitivity is reduced by treatment with gap junction/Panx1 channel blocking compounds. Moreover, targeted modulation of Cx43 expression was shown to modulate pain thresholds, albeit in somewhat contradictory ways, and mice lacking Panx1 expression globally or in specific cell types show depressed hyperalgesia. We here review the evidence for involvement of gap junctions and Panx channels in a variety of animal pain studies and then discuss ways in which gap junctions and Panx channels may mediate their action in pain processing. This discussion focusses on spread of signals among satellite glial cells, in particular intercellular Ca2+ waves, which are propagated through both gap junction and Panx1-dependent routes and have been associated with the phenomenon of spreading depression and the malady of migraine headache with aura.
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