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Lu HF, Xu CY, Zhang L, Gan L, Chen C, Yan MY, Guo XN, Fang Q, Xu GY, Zhang YB, Ni JQ, Zhao HR. A new central post-stroke pain rat model: autologous blood injected thalamic hemorrhage involved increased expression of P2X4 receptor. Neurosci Lett 2018; 687:124-130. [PMID: 30267847 DOI: 10.1016/j.neulet.2018.09.023] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Revised: 08/31/2018] [Accepted: 09/12/2018] [Indexed: 12/22/2022]
Abstract
Stroke is the leading cause of disability and death in the world. Central post-stroke pain (CPSP), a central neuropathic pain syndrome occurring after cerebral stroke, is a serious problem. But on account of the lack of reliable animal models, the mechanisms underlying CPSP remains poorly understood. To better understand of the pathophysiological basis of CPSP, we developed and characterized a new rat model of CPSP. This model is based on a hemorrhagic stroke lesion with intra-thalamic autologous blood (ITAB) injection in the ventral posterolateral nucleus of the thalamus. Behavioral analysis demonstrated that the animals displayed a significant decrease in mechanical allodynia threshold. We found a significant increase in P2 × 4 receptor expression in microglia in thalamic peri-lesion tissues post-hemorrhage. The mechanical allodynia in rats with CPSP were reversed by blocking P2 × 4 receptors. A significant alleviation of mechanical allodynia was achieved following the administration of adrenergic antidepressants and antiepileptics. Meanwhile, we found a significant decrease in P2 × 4 receptor expression after treatment with these drugs. Taken together, our results suggest that targeting P2 × 4 receptor may be effective in the treatment of CPSP.
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Affiliation(s)
- Hai-Feng Lu
- Department of Neurology, The First Affiliated Hospital of Soochow University, Suzhou 215006, China
| | - Chun-Yang Xu
- Department of Neurology, The First Affiliated Hospital of Soochow University, Suzhou 215006, China
| | - Lei Zhang
- Department of Neurology, The First Affiliated Hospital of Soochow University, Suzhou 215006, China
| | - Lei Gan
- Department of Oncology, The Second Affiliated Hospital of Soochow University, Suzhou 215006, China
| | - Chan Chen
- Department of Neurology, The First Affiliated Hospital of Soochow University, Suzhou 215006, China
| | - Man-Yun Yan
- Department of Neurology, The First Affiliated Hospital of Soochow University, Suzhou 215006, China
| | - Xiao-Ning Guo
- Department of Neurology, The First Affiliated Hospital of Soochow University, Suzhou 215006, China
| | - Qi Fang
- Department of Neurology, The First Affiliated Hospital of Soochow University, Suzhou 215006, China
| | - Guang-Yin Xu
- Institute of Neuroscience, Soochow University, Suzhou 215123, China
| | - Yan-Bo Zhang
- Department of Neurology, Affiliated Hospital of Taishan Medical University, Taian 271000, China
| | - Jian-Qiang Ni
- Department of Neurology, The First Affiliated Hospital of Soochow University, Suzhou 215006, China.
| | - Hong-Ru Zhao
- Department of Neurology, The First Affiliated Hospital of Soochow University, Suzhou 215006, China.
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Kalozoumi G, Kel-Margoulis O, Vafiadaki E, Greenberg D, Bernard H, Soreq H, Depaulis A, Sanoudou D. Glial responses during epileptogenesis in Mus musculus point to potential therapeutic targets. PLoS One 2018; 13:e0201742. [PMID: 30114263 PMCID: PMC6095496 DOI: 10.1371/journal.pone.0201742] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2017] [Accepted: 07/21/2018] [Indexed: 01/21/2023] Open
Abstract
The Mesio-Temporal Lobe Epilepsy syndrome is the most common form of intractable epilepsy. It is characterized by recurrence of focal seizures and is often associated with hippocampal sclerosis and drug resistance. We aimed to characterize the molecular changes occurring during the initial stages of epileptogenesis in search of new therapeutic targets for Mesio-Temporal Lobe Epilepsy. We used a mouse model obtained by intra-hippocampal microinjection of kainate and performed hippocampal whole genome expression analysis at 6h, 12h and 24h post-injection, followed by multilevel bioinformatics analysis. We report significant changes in immune and inflammatory responses, neuronal network reorganization processes and glial functions, predominantly initiated during status epilepticus at 12h and persistent after the end of status epilepticus at 24h post-kainate. Upstream regulator analysis highlighted Cyba, Cybb and Vim as central regulators of multiple overexpressed genes implicated in glial responses at 24h. In silico microRNA analysis indicated that miR-9, miR-19b, miR-129, and miR-223 may regulate the expression of glial-associated genes at 24h. Our data support the hypothesis that glial-mediated inflammatory response holds a key role during epileptogenesis, and that microglial cells may participate in the initial process of epileptogenesis through increased ROS production via the NOX complex.
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Affiliation(s)
- Georgia Kalozoumi
- Clinical Genomics and Pharmacogenomics Unit, 4 Department of Internal Medicine, Attikon Hospital, Medical School, National and Kapodistrian University of Athens, Athens, Greece
| | | | - Elizabeth Vafiadaki
- Molecular Biology Division, Biomedical Research Foundation of the Academy of Athens, Athens, Greece
| | - David Greenberg
- The Edmond and Lily Safra Center for Brain Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
| | | | - Hermona Soreq
- The Edmond and Lily Safra Center for Brain Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Antoine Depaulis
- INSERM, Grenoble, France
- Univ. Grenoble Alpes, Grenoble Institut des Neurosciences, Grenoble, France
- CHU de Grenoble, Hôpital Michallon, Grenoble, France
| | - Despina Sanoudou
- Clinical Genomics and Pharmacogenomics Unit, 4 Department of Internal Medicine, Attikon Hospital, Medical School, National and Kapodistrian University of Athens, Athens, Greece
- Molecular Biology Division, Biomedical Research Foundation of the Academy of Athens, Athens, Greece
- * E-mail:
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53
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Bosco DB, Zheng J, Xu Z, Peng J, Eyo UB, Tang K, Yan C, Huang J, Feng L, Wu G, Richardson JR, Wang H, Wu LJ. RNAseq analysis of hippocampal microglia after kainic acid-induced seizures. Mol Brain 2018; 11:34. [PMID: 29925434 PMCID: PMC6011524 DOI: 10.1186/s13041-018-0376-5] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2018] [Accepted: 05/28/2018] [Indexed: 12/20/2022] Open
Abstract
Microglia have been shown to be of critical importance to the progression of temporal lobe epilepsy. However, the broad transcriptional changes that these cells undergo following seizure induction is not well understood. As such, we utilized RNAseq analysis upon microglia isolated from the hippocampus to determine expression pattern alterations following kainic acid induced seizure. We determined that microglia undergo dramatic changes to their expression patterns, particularly with regard to mitochondrial activity and metabolism. We also observed that microglia initiate immunological activity, specifically increasing interferon beta responsiveness. Our results provide novel insights into microglia transcriptional regulation following acute seizures and suggest potential therapeutic targets specifically in microglia for the treatment of seizures and epilepsy.
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Affiliation(s)
- Dale B. Bosco
- Department of Neurology, Mayo Clinic, 200 First Street SW, Rochester, MN 55905 USA
| | - Jiaying Zheng
- Department of Neurology, Mayo Clinic, 200 First Street SW, Rochester, MN 55905 USA
| | - Zhiyan Xu
- Department of Pharmacology, School of Pharmacy, Nantong University, 19 Qixiu Road, Nantong, 226001 Jiangsu China
| | - Jiyun Peng
- Department of Neurology, Mayo Clinic, 200 First Street SW, Rochester, MN 55905 USA
| | - Ukpong B. Eyo
- Department of Neurology, Mayo Clinic, 200 First Street SW, Rochester, MN 55905 USA
| | - Ke Tang
- Admera Health LLC, South Plainfield, NJ 07080 USA
| | - Cheng Yan
- Admera Health LLC, South Plainfield, NJ 07080 USA
| | - Jun Huang
- Admera Health LLC, South Plainfield, NJ 07080 USA
| | - Lijie Feng
- Department of Histology and Embryology, School of Basic Medical Sciences, Anhui Medical University, Hefei, 230032 Anhui China
| | - Gongxiong Wu
- One Harvard Street Institute of Health, Brookline, MA 02446 USA
| | - Jason R. Richardson
- Department of Pharmaceutical Sciences and Center for Neurodegenerative Disease and Aging, Northeast Ohio Medical University, Rootstown, OH 44272 USA
| | - Hui Wang
- Department of Pharmacology, School of Pharmacy, Nantong University, 19 Qixiu Road, Nantong, 226001 Jiangsu China
- Department of Neuroscience and Cell Biology, Rutgers-Robert Wood Johnson Medical School, Piscataway, NJ 08854 USA
| | - Long-Jun Wu
- Department of Neurology, Mayo Clinic, 200 First Street SW, Rochester, MN 55905 USA
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL 32224 USA
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Hiragi T, Ikegaya Y, Koyama R. Microglia after Seizures and in Epilepsy. Cells 2018; 7:cells7040026. [PMID: 29597334 PMCID: PMC5946103 DOI: 10.3390/cells7040026] [Citation(s) in RCA: 100] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Revised: 03/24/2018] [Accepted: 03/26/2018] [Indexed: 01/23/2023] Open
Abstract
Microglia are the resident immune cells in the brain that constitute the brain’s innate immune system. Recent studies have revealed various functions of microglia in the development and maintenance of the central nervous system (CNS) in both health and disease. However, the role of microglia in epilepsy remains largely undiscovered, partly because of the complex phenotypes of activated microglia. Activated microglia likely exert different effects on brain function depending on the phase of epileptogenesis. In this review, we mainly focus on the animal models of temporal lobe epilepsy (TLE) and discuss the proepileptic and antiepileptic roles of activated microglia in the epileptic brain. Specifically, we focus on the roles of microglia in the production of inflammatory cytokines, regulation of neurogenesis, and surveillance of the surrounding environment in epilepsy.
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Affiliation(s)
- Toshimitsu Hiragi
- Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-8654, Japan.
| | - Yuji Ikegaya
- Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-8654, Japan.
| | - Ryuta Koyama
- Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-8654, Japan.
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Klement W, Garbelli R, Zub E, Rossini L, Tassi L, Girard B, Blaquiere M, Bertaso F, Perroy J, de Bock F, Marchi N. Seizure progression and inflammatory mediators promote pericytosis and pericyte-microglia clustering at the cerebrovasculature. Neurobiol Dis 2018; 113:70-81. [PMID: 29432809 DOI: 10.1016/j.nbd.2018.02.002] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2017] [Revised: 02/05/2018] [Accepted: 02/07/2018] [Indexed: 10/18/2022] Open
Abstract
BACKGROUND Cerebrovascular dysfunction and inflammation occur in epilepsy. Here we asked whether pericytes, a pivotal cellular component of brain capillaries, undergo pathological modifications during experimental epileptogenesis and in human epilepsy. We evaluated whether pro-inflammatory cytokines, present in the brain during seizures, contribute to pericyte morphological modifications. METHODS In vivo, unilateral intra-hippocampal kainic acid (KA) injections were performed in NG2DsRed/C57BL6 mice to induce status epilepticus (SE), epileptogenesis, and spontaneous recurrent seizures (SRS). NG2DsRed mice were used to visualize pericytes during seizure progression. The effect triggered by recombinant IL-1β, TNFα, or IL-6 on pericytes was evaluated in NG2DsRed hippocampal slices and in human-derived cell culture. Human brain specimens obtained from temporal lobe epilepsy (TLE) with or without sclerosis (HS) and focal cortical dysplasia (FCD-IIb) were evaluated for pericyte-microglial cerebrovascular assembly. RESULTS A disarray of NG2DsRed+ pericyte soma and ramifications was found 72 h post-SE and 1 week post-SE (epileptogenesis) in the hippocampus. Pericyte modifications topographically overlapped with IBA1+ microglia clustering around the capillaries with cases of pericytes lodged within the microglial cells. Microglial clustering around the NG2DsRed pericytes lingered at SRS. Pericyte proliferation (Ki67+) occurred 72 h post-SE and during epileptogenesis and returned towards control levels at SRS. Human epileptic brain tissues showed pericyte-microglia assemblies with IBA1/HLA microglial cells outlining the capillary wall in TLE-HS and FCD-IIb specimens. Inflammatory mediators contributed to pericyte modifications, in particular IL-1β elicited pericyte morphological changes and pericyte-microglia clustering in NG2DsRed hippocampal slices. Modifications also occurred when pro-inflammatory cytokines were added to an in vitro culture of pericytes. CONCLUSIONS These results indicate the occurrence of pericytosis during seizures and introduce a pericyte-microglial mediated mechanism of blood-brain barrier dysfunction in epilepsy.
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Affiliation(s)
- Wendy Klement
- Laboratory of Cerebrovascular Mechanisms of Brain Disorders, Institute of Functional Genomics (UMR 5203 CNRS - U 1191 INSERM, University of Montpellier), Montpellier, France
| | - Rita Garbelli
- Clinical Epileptology and Experimental Neurophysiology Unit, Fondazione IRCCS, Istituto Neurologico C. Besta, Milano, Italy
| | - Emma Zub
- Laboratory of Cerebrovascular Mechanisms of Brain Disorders, Institute of Functional Genomics (UMR 5203 CNRS - U 1191 INSERM, University of Montpellier), Montpellier, France
| | - Laura Rossini
- Clinical Epileptology and Experimental Neurophysiology Unit, Fondazione IRCCS, Istituto Neurologico C. Besta, Milano, Italy
| | - Laura Tassi
- C. Munari Epilepsy Surgery Centre, Ospedale Niguarda, Milano, Italy
| | - Benoit Girard
- Laboratory of Pathophysiology of Synaptic Transmission, Institute of Functional Genomics (UMR 5203 CNRS - U 1191 INSERM, University of Montpellier), Montpellier, France
| | - Marine Blaquiere
- Laboratory of Cerebrovascular Mechanisms of Brain Disorders, Institute of Functional Genomics (UMR 5203 CNRS - U 1191 INSERM, University of Montpellier), Montpellier, France
| | - Federica Bertaso
- Laboratory of Pathophysiology of Synaptic Transmission, Institute of Functional Genomics (UMR 5203 CNRS - U 1191 INSERM, University of Montpellier), Montpellier, France
| | - Julie Perroy
- Laboratory of Pathophysiology of Synaptic Transmission, Institute of Functional Genomics (UMR 5203 CNRS - U 1191 INSERM, University of Montpellier), Montpellier, France
| | - Frederic de Bock
- Laboratory of Cerebrovascular Mechanisms of Brain Disorders, Institute of Functional Genomics (UMR 5203 CNRS - U 1191 INSERM, University of Montpellier), Montpellier, France
| | - Nicola Marchi
- Laboratory of Cerebrovascular Mechanisms of Brain Disorders, Institute of Functional Genomics (UMR 5203 CNRS - U 1191 INSERM, University of Montpellier), Montpellier, France.
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Sensory neuronal P2RX4 receptors controls BDNF signaling in inflammatory pain. Sci Rep 2018; 8:964. [PMID: 29343707 PMCID: PMC5772667 DOI: 10.1038/s41598-018-19301-5] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2017] [Accepted: 12/27/2017] [Indexed: 11/09/2022] Open
Abstract
Chronic inflammatory and neuropathic pains are major public health concerns. Potential therapeutic targets include the ATP-gated purinergic receptors (P2RX) that contribute to these pathological types of pain in several different cell types. The purinergic receptors P2RX2 and P2RX3 are expressed by a specific subset of dorsal root ganglion neurons and directly shape pain processing by primary afferents. In contrast the P2RX4 and P2RX7 are mostly expressed in myeloid cells, where activation of these receptors triggers the release of various pro-inflammatory molecules. Here, we demonstrate that P2RX4 also controls calcium influx in mouse dorsal root ganglion neurons. P2RX4 is up-regulated in pain-processing neurons during long lasting peripheral inflammation and it co-localizes with Brain-Derived Neurotrophic Factor (BDNF). In the dorsal horn of the spinal cord, BDNF-dependent signaling pathways, phosphorylation of Erk1/2 and of the GluN1 subunit as well as the down regulation of the co-transporter KCC2, which are triggered by peripheral inflammation are impaired in P2RX4-deficient mice. Our results suggest that P2RX4, expressed by sensory neurons, controls neuronal BDNF release that contributes to hyper-excitability during chronic inflammatory pain and establish P2RX4 in sensory neurons as a new potential therapeutic target to treat hyperexcitability during chronic inflammatory pain.
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57
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Kambli L, Bhatt LK, Oza M, Prabhavalkar K. Novel therapeutic targets for epilepsy intervention. Seizure 2017; 51:27-34. [DOI: 10.1016/j.seizure.2017.07.014] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2017] [Revised: 07/23/2017] [Accepted: 07/24/2017] [Indexed: 12/11/2022] Open
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Suurväli J, Boudinot P, Kanellopoulos J, Rüütel Boudinot S. P2X4: A fast and sensitive purinergic receptor. Biomed J 2017; 40:245-256. [PMID: 29179879 PMCID: PMC6138603 DOI: 10.1016/j.bj.2017.06.010] [Citation(s) in RCA: 109] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2017] [Revised: 06/28/2017] [Accepted: 06/30/2017] [Indexed: 01/31/2023] Open
Abstract
Extracellular nucleotides have been recognized as important mediators of activation, triggering multiple responses via plasma membrane receptors known as P2 receptors. P2 receptors comprise P2X ionotropic receptors and G protein-coupled P2Y receptors. P2X receptors are expressed in many tissues, where they are involved in a number of functions including synaptic transmission, muscle contraction, platelet aggregation, inflammation, macrophage activation, differentiation and proliferation, neuropathic and inflammatory pain. P2X4 is one of the most sensitive purinergic receptors (at nanomolar ATP concentrations), about one thousand times more than the archetypal P2X7. P2X4 is widely expressed in central and peripheral neurons, in microglia, and also found in various epithelial tissues and endothelial cells. It localizes on the plasma membrane, but also in intracellular compartments. P2X4 is preferentially localized in lysosomes, where it is protected from proteolysis by its glycosylation. High ATP concentration in the lysosomes does not activate P2X4 at low pH; P2X4 gets activated by intra-lysosomal ATP only in its fully dissociated tetra-anionic form, when the pH increases to 7.4. Thus, P2X4 is functioning as a Ca2+-channel after the fusion of late endosomes and lysosomes. P2X4 modulates major neurotransmitter systems and regulates alcohol-induced responses in microglia. P2X4 is one of the key receptors mediating neuropathic pain. However, injury-induced upregulation of P2X4 expression is gender dependent and plays a key role in pain difference between males and females. P2X4 is also involved in inflammation. Extracellular ATP being a pro-inflammatory molecule, P2X4 can trigger inflammation in response to high ATP release. It is therefore involved in multiple pathologies, like post-ischemic inflammation, rheumatoid arthritis, airways inflammation in asthma, neurodegenerative diseases and even metabolic syndrome. Although P2X4 remains poorly characterized, more studies are needed as it is likely to be a potential therapeutic target in these multiple pathologies.
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Affiliation(s)
- Jaanus Suurväli
- Department of Chemistry and Biotechnology, Tallinn University of Technology, Tallinn, Estonia
| | - Pierre Boudinot
- Virologie et Immunologie Moléculaires, INRA, Université Paris-Saclay, Jouy-en-Josas, France
| | - Jean Kanellopoulos
- Institute for Integrative Biology of the Cell (I2BC) CEA, CNRS, Univ. Paris-Sud, Université Paris-Saclay, Gif-sur-Yvette cedex, France
| | - Sirje Rüütel Boudinot
- Department of Chemistry and Biotechnology, Tallinn University of Technology, Tallinn, Estonia.
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Stokes L, Layhadi JA, Bibic L, Dhuna K, Fountain SJ. P2X4 Receptor Function in the Nervous System and Current Breakthroughs in Pharmacology. Front Pharmacol 2017; 8:291. [PMID: 28588493 PMCID: PMC5441391 DOI: 10.3389/fphar.2017.00291] [Citation(s) in RCA: 100] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Accepted: 05/05/2017] [Indexed: 12/18/2022] Open
Abstract
Adenosine 5′-triphosphate is a well-known extracellular signaling molecule and neurotransmitter known to activate purinergic P2X receptors. Information has been elucidated about the structure and gating of P2X channels following the determination of the crystal structure of P2X4 (zebrafish), however, there is still much to discover regarding the role of this receptor in the central nervous system (CNS). In this review we provide an overview of what is known about P2X4 expression in the CNS and discuss evidence for pathophysiological roles in neuroinflammation and neuropathic pain. Recent advances in the development of pharmacological tools including selective antagonists (5-BDBD, PSB-12062, BX430) and positive modulators (ivermectin, avermectins, divalent cations) of P2X4 will be discussed.
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Affiliation(s)
- Leanne Stokes
- School of Pharmacy, University of East Anglia, Norwich Research ParkNorwich, United Kingdom.,School of Biomedical and Health Sciences, RMIT University, BundooraVIC, Australia
| | - Janice A Layhadi
- Biomedical Research Centre, School of Biological Sciences, University of East AngliaNorwich, United Kingdom
| | - Lucka Bibic
- School of Pharmacy, University of East Anglia, Norwich Research ParkNorwich, United Kingdom
| | - Kshitija Dhuna
- School of Biomedical and Health Sciences, RMIT University, BundooraVIC, Australia
| | - Samuel J Fountain
- Biomedical Research Centre, School of Biological Sciences, University of East AngliaNorwich, United Kingdom
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Ali I, Aertgeerts S, Le Blon D, Bertoglio D, Hoornaert C, Ponsaerts P, Dedeurwaerdere S. Intracerebral delivery of the M2 polarizing cytokine interleukin 13 using mesenchymal stem cell implants in a model of temporal lobe epilepsy in mice. Epilepsia 2017; 58:1063-1072. [PMID: 28374921 DOI: 10.1111/epi.13743] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/06/2017] [Indexed: 12/27/2022]
Abstract
OBJECTIVES Neuroinflammation plays a critical role in the pathophysiology of mesial temporal lobe epilepsy. We aimed to evaluate whether intracerebral transplantation of interleukin 13-producing mesenchymal stem cells (IL-13 MSCs) induces an M2 microglia/macrophage activation phenotype in the hippocampus with an epileptogenic insult, thereby providing a neuroprotective environment with reduced epileptogenesis. METHODS Genetically engineered syngeneic IL-13 MSCs or vehicle was injected within the hippocampus 1 week before the intrahippocampal kainic acid-induced status epilepticus (SE) in C57BL/6J mice. Neuroinflammation was evaluated at disease onset as well as during the chronic epilepsy period (9 weeks). In addition, continuous video-electroencephalography (EEG) (vEEG) monitoring was obtained during the chronic epilepsy period (between 6 and 9 weeks after SE). RESULTS Evaluation of vEEG recordings suggested that IL-13 MSC grafts did not affect the severity and duration of SE or the seizure burden during the chronic epilepsy period, when compared to the vehicle treated SE mice. An M2-activation phenotype was induced in microglia/macrophages that infiltrated the -13 MSC graft site, as evidenced by the arginase1 expression at the graft site at both the 2-week and 9-week time-points. However, M2-activated immune cells were rarely observed outside the graft site and, accordingly, the neuroinflammatory response or cell loss related to SE induction was not altered by IL-13 MSC grafting. Moreover, an increase in the proportion of F4/80+ cells was observed in the IL-13 MSC group compared to the controls. SIGNIFICANCE Our data suggest that MSC-based IL-13 delivery to induce M2 glial activation does not provide any neuroprotective or disease-modifying effects in a mouse model of epilepsy. Moreover, use of cell grafting to deliver bioactive compounds for modulating neuroinflammation may have confounding effects in disease pathology of epilepsy due to the additional immune response generated by the grafted cells.
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Affiliation(s)
- Idrish Ali
- Department of Translational Neurosciences, University of Antwerp, Antwerp, Belgium
| | - Stephanie Aertgeerts
- Department of Translational Neurosciences, University of Antwerp, Antwerp, Belgium
| | - Debbie Le Blon
- Laboratory of Experimental Hematology, Vaxinfectio, University of Antwerp, Antwerp, Belgium
| | - Daniele Bertoglio
- Department of Translational Neurosciences, University of Antwerp, Antwerp, Belgium
| | - Chloe Hoornaert
- Laboratory of Experimental Hematology, Vaxinfectio, University of Antwerp, Antwerp, Belgium
| | - Peter Ponsaerts
- Laboratory of Experimental Hematology, Vaxinfectio, University of Antwerp, Antwerp, Belgium
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Role of the purinergic signaling in epilepsy. Pharmacol Rep 2016; 69:130-138. [PMID: 27915186 DOI: 10.1016/j.pharep.2016.09.018] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2016] [Revised: 09/20/2016] [Accepted: 09/21/2016] [Indexed: 01/19/2023]
Abstract
Adenine nucleotides and adenosine are signaling molecules that activate purinergic receptors P1 and P2. Activation of A1 adenosine receptors has an anticonvulsant action, whereas activation of A2A receptors might initiate seizures. Therefore, a significant limitation to the use of A1 receptor agonists as drugs in the CNS might be their peripheral side effects. The anti-epileptic activity of adenosine is related to its increased concentration outside the cell. This increase might result from the inhibition of the equilibrative nucleoside transporters (ENTs). Moreover, the implantation of implants or stem cells into the brain might cause slow and persistent increases in adenosine concentrations in the extracellular spaces of the brain. The role of adenosine in seizure inhibition has been confirmed by results demonstrating that in patients with epilepsy, the adenosine kinase (ADK) present in astrocytes is the only purine-metabolizing enzyme that exhibits increased expression. Increased ADK activity causes intensified phosphorylation of adenosine to 5'-AMP, which therefore lowers the adenosine level in the extracellular spaces. These changes might initiate astrogliosis and epileptogenesis, which are the manifestations of epilepsy. Seizures might induce inflammatory processes and vice versa. Activation of P2X7 receptors causes intensified release of pro-inflammatory cytokines (IL-1β and TNF-α) and activates metabolic pathways that induce inflammatory processes in the CNS. Therefore, antagonists of P2X7 and the interleukin 1β receptor might be efficient drugs for recurring seizures and prolonged status epilepticus. Inhibitors of ADK would simultaneously inhibit the seizures, prevent the astrogliosis and epileptogenesis processes and prevent the formation of new epileptogenic foci. Therefore, these drugs might become beneficial seizure-suppressing drugs.
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Xu J, Bernstein AM, Wong A, Lu XH, Khoja S, Yang XW, Davies DL, Micevych P, Sofroniew MV, Khakh BS. P2X4 Receptor Reporter Mice: Sparse Brain Expression and Feeding-Related Presynaptic Facilitation in the Arcuate Nucleus. J Neurosci 2016; 36:8902-20. [PMID: 27559172 PMCID: PMC4995303 DOI: 10.1523/jneurosci.1496-16.2016] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2016] [Revised: 06/17/2016] [Accepted: 06/20/2016] [Indexed: 11/21/2022] Open
Abstract
UNLABELLED P2X4 receptors are ATP-gated cation channels that are widely expressed in the nervous system. To identify P2X4 receptor-expressing cells, we generated BAC transgenic mice expressing tdTomato under the control of the P2X4 receptor gene (P2rx4). We found sparse populations of tdTomato-positive neurons in most brain areas with patterns that matched P2X4 mRNA distribution. tdTomato expression within microglia was low but was increased by an experimental manipulation that triggered microglial activation. We found surprisingly high tdTomato expression in the hypothalamic arcuate nucleus (Arc) (i.e., within parts of the neural circuitry controlling feeding). Immunohistochemistry and genetic crosses of P2rx4 tdTomato mice with cell-specific GFP reporter lines showed that the tdTomato-expressing cells were mainly AgRP-NPY neurons and tanycytes. There was no electrophysiological evidence for functional expression of P2X4 receptors on AgRP-NPY neuron somata, but instead, we found clear evidence for functional presynaptic P2X4 receptor-mediated responses in terminals of AgRP-NPY neurons onto two of their postsynaptic targets (Arc POMC and paraventricular nucleus neurons), where ATP dramatically facilitated GABA release. The presynaptic responses onto POMC neurons, and the expression of tdTomato in AgRP-NPY neurons and tanycytes, were significantly decreased by food deprivation in male mice in a manner that was partially reversed by the satiety-related peptide leptin. Overall, we provide well-characterized tdTomato reporter mice to study P2X4-expressing cells in the brain, new insights on feeding-related regulation of presynaptic P2X4 receptor responses, and the rationale to explore extracellular ATP signaling in the control of feeding behaviors. SIGNIFICANCE STATEMENT Cells expressing ATP-gated P2X4 receptors have proven problematic to identify and study in brain slice preparations because P2X4 expression is sparse. To address this limitation, we generated and characterized BAC transgenic P2rx4 tdTomato reporter mice. We report the distribution of tdTomato-expressing cells throughout the brain and particularly strong expression in the hypothalamic arcuate nucleus. Together, our studies provide a new, well-characterized tool with which to study P2X4 receptor-expressing cells. The electrophysiological studies enabled by this mouse suggest previously unanticipated roles for ATP and P2X4 receptors in the neural circuitry controlling feeding.
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Affiliation(s)
- Ji Xu
- Departments of Physiology and
| | - Alexander M Bernstein
- Neurobiology, David Geffen School of Medicine, University of California-Los Angeles, Los Angeles, California 90095
| | - Angela Wong
- Neurobiology, David Geffen School of Medicine, University of California-Los Angeles, Los Angeles, California 90095
| | - Xiao-Hong Lu
- Center for Neurobehavioral Genetics, Semel Institute for Neuroscience and Human Behavior, University of California-Los Angeles, Los Angeles, California 90095
| | - Sheraz Khoja
- Department of Pharmacology and Pharmaceutical Sciences, University of Southern California, Los Angeles, California 90089
| | - X William Yang
- Center for Neurobehavioral Genetics, Semel Institute for Neuroscience and Human Behavior, University of California-Los Angeles, Los Angeles, California 90095, Department of Psychiatry and Biobehavioral Sciences, David Geffen School of Medicine, University of California-Los Angeles, Los Angeles, California 90095, and
| | - Daryl L Davies
- Titus Family Department of Clinical Pharmacy, School of Pharmacy, University of Southern California, Los Angeles, California 90089
| | - Paul Micevych
- Neurobiology, David Geffen School of Medicine, University of California-Los Angeles, Los Angeles, California 90095
| | - Michael V Sofroniew
- Neurobiology, David Geffen School of Medicine, University of California-Los Angeles, Los Angeles, California 90095
| | - Baljit S Khakh
- Departments of Physiology and Neurobiology, David Geffen School of Medicine, University of California-Los Angeles, Los Angeles, California 90095,
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Microglial Contact Prevents Excess Depolarization and Rescues Neurons from Excitotoxicity. eNeuro 2016; 3:eN-NWR-0004-16. [PMID: 27390772 PMCID: PMC4916329 DOI: 10.1523/eneuro.0004-16.2016] [Citation(s) in RCA: 81] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2016] [Revised: 04/29/2016] [Accepted: 05/18/2016] [Indexed: 12/20/2022] Open
Abstract
Microglia survey and directly contact neurons in both healthy and damaged brain, but the mechanisms and functional consequences of these contacts are not yet fully elucidated. Combining two-photon imaging and patch clamping, we have developed an acute experimental model for studying the role of microglia in CNS excitotoxicity induced by neuronal hyperactivity. Our model allows us to simultaneously examine the effects of repetitive supramaximal stimulation on axonal morphology, neuronal membrane potential, and microglial migration, using cortical brain slices from Iba-1 eGFP mice. We demonstrate that microglia exert an acute and highly localized neuroprotective action under conditions of neuronal hyperactivity. Evoking repetitive action potentials in individual layer 2/3 pyramidal neurons elicited swelling of axons, but not dendrites, which was accompanied by a large, sustained depolarization of soma membrane potential. Microglial processes migrated to these swollen axons in a mechanism involving both ATP and glutamate release via volume-activated anion channels. This migration was followed by intensive microglial wrapping of affected axons and, in some cases, the removal of axonal debris that induced a rapid soma membrane repolarization back to resting potentials. When the microglial migration was pharmacologically blocked, the activity-induced depolarization continued until cell death ensued, demonstrating that the microglia–axon contact served to prevent pathological depolarization of the soma and maintain neuronal viability. This is a novel aspect of microglia surveillance: detecting, wrapping, and rescuing neuronal soma from damage due to excessive activity.
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64
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Rassendren F, Audinat E. Purinergic signaling in epilepsy. J Neurosci Res 2016; 94:781-93. [PMID: 27302739 DOI: 10.1002/jnr.23770] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2016] [Revised: 04/28/2016] [Accepted: 04/29/2016] [Indexed: 12/24/2022]
Abstract
Until recently, analysis of the mechanisms underlying epilepsy was centered on neuron dysfunctions. Accordingly, most of the available pharmacological treatments aim at reducing neuronal excitation or at potentiating neuronal inhibition. These therapeutic options can lead to obvious secondary effects, and, moreover, seizures cannot be controlled by any known medication in one-third of the patients. A purely neurocentric view of brain functions and dysfunctions has been seriously questioned during the past 2 decades because of the accumulation of experimental data showing the functional importance of reciprocal interactions between glial cells and neurons. In the case of epilepsy, our current knowledge of the human disease and analysis of animal models clearly favor the involvement of astrocytes and microglial cells during the progression of the disease, including at very early stages, opening the way to the identification of new therapeutic targets. Purinergic signaling is a fundamental feature of neuron-glia interactions, and increasing evidence indicates that modifications of this pathway contribute to the functional remodeling of the epileptic brain. This Review discusses the recent experimental results indicating the roles of astrocytic and microglial P2X and P2Y receptors in epilepsy. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- François Rassendren
- CNRS, UMR 5203, Institut de Génomique Fonctionnelle, Montpellier, France.,INSERM, U1191, Montpellier, France.,Université de Montpellier, UMR5203, Montpellier, France.,Labex ICST, Montpellier, France
| | - Etienne Audinat
- INSERM, U1128, Paris, France.,Laboratory of Neurophysiology and New Microscopies, Paris Descartes University, Paris, France
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65
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Abiega O, Beccari S, Diaz-Aparicio I, Nadjar A, Layé S, Leyrolle Q, Gómez-Nicola D, Domercq M, Pérez-Samartín A, Sánchez-Zafra V, Paris I, Valero J, Savage JC, Hui CW, Tremblay MÈ, Deudero JJP, Brewster AL, Anderson AE, Zaldumbide L, Galbarriatu L, Marinas A, Vivanco MDM, Matute C, Maletic-Savatic M, Encinas JM, Sierra A. Neuronal Hyperactivity Disturbs ATP Microgradients, Impairs Microglial Motility, and Reduces Phagocytic Receptor Expression Triggering Apoptosis/Microglial Phagocytosis Uncoupling. PLoS Biol 2016; 14:e1002466. [PMID: 27228556 PMCID: PMC4881984 DOI: 10.1371/journal.pbio.1002466] [Citation(s) in RCA: 114] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2016] [Accepted: 04/21/2016] [Indexed: 12/24/2022] Open
Abstract
Phagocytosis is essential to maintain tissue homeostasis in a large number of inflammatory and autoimmune diseases, but its role in the diseased brain is poorly explored. Recent findings suggest that in the adult hippocampal neurogenic niche, where the excess of newborn cells undergo apoptosis in physiological conditions, phagocytosis is efficiently executed by surveillant, ramified microglia. To test whether microglia are efficient phagocytes in the diseased brain as well, we confronted them with a series of apoptotic challenges and discovered a generalized response. When challenged with excitotoxicity in vitro (via the glutamate agonist NMDA) or inflammation in vivo (via systemic administration of bacterial lipopolysaccharides or by omega 3 fatty acid deficient diets), microglia resorted to different strategies to boost their phagocytic efficiency and compensate for the increased number of apoptotic cells, thus maintaining phagocytosis and apoptosis tightly coupled. Unexpectedly, this coupling was chronically lost in a mouse model of mesial temporal lobe epilepsy (MTLE) as well as in hippocampal tissue resected from individuals with MTLE, a major neurological disorder characterized by seizures, excitotoxicity, and inflammation. Importantly, the loss of phagocytosis/apoptosis coupling correlated with the expression of microglial proinflammatory, epileptogenic cytokines, suggesting its contribution to the pathophysiology of epilepsy. The phagocytic blockade resulted from reduced microglial surveillance and apoptotic cell recognition receptor expression and was not directly mediated by signaling through microglial glutamate receptors. Instead, it was related to the disruption of local ATP microgradients caused by the hyperactivity of the hippocampal network, at least in the acute phase of epilepsy. Finally, the uncoupling led to an accumulation of apoptotic newborn cells in the neurogenic niche that was due not to decreased survival but to delayed cell clearance after seizures. These results demonstrate that the efficiency of microglial phagocytosis critically affects the dynamics of apoptosis and urge to routinely assess the microglial phagocytic efficiency in neurodegenerative disorders. Phagocytosis by microglia is tightly coupled to apoptosis, swiftly removing apoptotic cells and actively maintaining tissue homeostasis, but the neuronal hyperactivity associated with epilepsy disrupts the ATP gradients that drive phagocytosis, leading to the accumulation of apoptotic cells and inflammation. Phagocytosis, the engulfment and digestion of cellular debris, is at the core of the regenerative response of the damaged tissue, because it prevents the spillover of toxic intracellular contents and is actively anti-inflammatory. In the brain, the professional phagocytes are microglia, whose dynamic processes rapidly engulf and degrade cells undergoing apoptosis—programmed cell death—in physiological conditions. Thus, microglia hold the key to brain regeneration, but their efficiency as phagocytes in the diseased brain is only presumed. Here, we have discovered a generalized response of microglia to apoptotic challenge induced by excitotoxicity and inflammation, in which they boost their phagocytic efficiency to account for the increase in apoptosis. To our surprise, this apoptosis/microglial phagocytosis coupling was lost in the hippocampus from human and experimental mesial temporal lobe epilepsy (MTLE), a major neurodegenerative disorder characterized by excitotoxicity, inflammation, and seizures. This uncoupling was due to widespread ATP release during neuronal hyperactivity, which “blinded” microglia to the ATP microgradients released by apoptotic cells as “find-me” signals. The impairment of phagocytosis led to the accumulation of apoptotic cells and the build-up of a detrimental inflammatory reaction. Our data advocates for systematic assessment of the efficiency of microglial phagocytosis in brain disorders.
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Affiliation(s)
- Oihane Abiega
- Achucarro Basque Center for Neuroscience, Bizkaia Science and Technology Park, Zamudio, Spain
- University of the Basque Country, Leioa, Spain
| | - Sol Beccari
- Achucarro Basque Center for Neuroscience, Bizkaia Science and Technology Park, Zamudio, Spain
- University of the Basque Country, Leioa, Spain
| | - Irune Diaz-Aparicio
- Achucarro Basque Center for Neuroscience, Bizkaia Science and Technology Park, Zamudio, Spain
- University of the Basque Country, Leioa, Spain
| | | | - Sophie Layé
- Université Bordeaux Segalen, Bordeaux, France
| | | | - Diego Gómez-Nicola
- Centre for Biological Sciences, University of Southampton, Southampton, United Kingdom
| | - María Domercq
- Achucarro Basque Center for Neuroscience, Bizkaia Science and Technology Park, Zamudio, Spain
- University of the Basque Country, Leioa, Spain
| | - Alberto Pérez-Samartín
- Achucarro Basque Center for Neuroscience, Bizkaia Science and Technology Park, Zamudio, Spain
- University of the Basque Country, Leioa, Spain
| | - Víctor Sánchez-Zafra
- Achucarro Basque Center for Neuroscience, Bizkaia Science and Technology Park, Zamudio, Spain
- University of the Basque Country, Leioa, Spain
| | - Iñaki Paris
- Achucarro Basque Center for Neuroscience, Bizkaia Science and Technology Park, Zamudio, Spain
- University of the Basque Country, Leioa, Spain
| | - Jorge Valero
- Achucarro Basque Center for Neuroscience, Bizkaia Science and Technology Park, Zamudio, Spain
- University of the Basque Country, Leioa, Spain
- Ikerbasque Foundation, Bilbao, Spain
| | - Julie C. Savage
- Centre de recherche du CHU de Québec, Axe Neurosciences, Québec, Canada
- Université Laval, Département de médecine moléculaire, Québec, Canada
| | - Chin-Wai Hui
- Centre de recherche du CHU de Québec, Axe Neurosciences, Québec, Canada
- Université Laval, Département de médecine moléculaire, Québec, Canada
| | - Marie-Ève Tremblay
- Centre de recherche du CHU de Québec, Axe Neurosciences, Québec, Canada
- Université Laval, Département de médecine moléculaire, Québec, Canada
| | - Juan J. P. Deudero
- Baylor College of Medicine, The Jan and Dan Duncan Neurological Research Institute at Texas Children’s Hospital, Houston, Texas, United States of America
| | - Amy L. Brewster
- Baylor College of Medicine, The Jan and Dan Duncan Neurological Research Institute at Texas Children’s Hospital, Houston, Texas, United States of America
| | - Anne E. Anderson
- Baylor College of Medicine, The Jan and Dan Duncan Neurological Research Institute at Texas Children’s Hospital, Houston, Texas, United States of America
| | | | | | | | | | - Carlos Matute
- Achucarro Basque Center for Neuroscience, Bizkaia Science and Technology Park, Zamudio, Spain
- University of the Basque Country, Leioa, Spain
| | | | - Juan M. Encinas
- Achucarro Basque Center for Neuroscience, Bizkaia Science and Technology Park, Zamudio, Spain
- University of the Basque Country, Leioa, Spain
- Baylor College of Medicine, The Jan and Dan Duncan Neurological Research Institute at Texas Children’s Hospital, Houston, Texas, United States of America
| | - Amanda Sierra
- Achucarro Basque Center for Neuroscience, Bizkaia Science and Technology Park, Zamudio, Spain
- University of the Basque Country, Leioa, Spain
- Baylor College of Medicine, The Jan and Dan Duncan Neurological Research Institute at Texas Children’s Hospital, Houston, Texas, United States of America
- * E-mail:
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66
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Eyo UB, Murugan M, Wu LJ. Microglia-Neuron Communication in Epilepsy. Glia 2016; 65:5-18. [PMID: 27189853 DOI: 10.1002/glia.23006] [Citation(s) in RCA: 179] [Impact Index Per Article: 22.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Revised: 04/20/2016] [Accepted: 04/28/2016] [Indexed: 12/22/2022]
Abstract
Epilepsy has remained a significant social concern and financial burden globally. Current therapeutic strategies are based primarily on neurocentric mechanisms that have not proven successful in at least a third of patients, raising the need for novel alternative and complementary approaches. Recent evidence implicates glial cells and neuroinflammation in the pathogenesis of epilepsy with the promise of targeting these cells to complement existing strategies. Specifically, microglial involvement, as a major inflammatory cell in the epileptic brain, has been poorly studied. In this review, we highlight microglial reaction to experimental seizures, discuss microglial control of neuronal activities, and propose the functions of microglia during acute epileptic phenotypes, delayed neurodegeneration, and aberrant neurogenesis. Future research that would help fill in the current gaps in our knowledge includes epilepsy-induced alterations in basic microglial functions, neuro-microglial interactions during chronic epilepsy, and microglial contribution to developmental seizures. Studying the role of microglia in epilepsy could inform therapies to better alleviate the disease. GLIA 2016;65:5-18.
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Affiliation(s)
- Ukpong B Eyo
- Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, New Jersey
| | - Madhuvika Murugan
- Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, New Jersey
| | - Long-Jun Wu
- Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, New Jersey
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67
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Sabilallah M, Fontanaud P, Linck N, Boussadia B, Peyroutou R, Lasgouzes T, Rassendren FA, Marchi N, Hirbec HE. Evidence for Status Epilepticus and Pro-Inflammatory Changes after Intranasal Kainic Acid Administration in Mice. PLoS One 2016; 11:e0150793. [PMID: 26963100 PMCID: PMC4786335 DOI: 10.1371/journal.pone.0150793] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Accepted: 02/21/2016] [Indexed: 12/04/2022] Open
Abstract
Kainic acid (KA) is routinely used to elicit status epilepticus (SE) and epileptogenesis. Among the available KA administration protocols, intranasal instillation (IN) remains understudied. Dosages of KA were instilled IN in mice. Racine Scale and Video-EEG were used to assess and quantify SE onset. Time spent in SE and spike activity was quantified for each animal and confirmed by power spectrum analysis. Immunohistochemistry and qPCR were performed to define brain inflammation occurring after SE, including activated microglial phenotypes. Long term video-EEG recording was also performed. Titration of IN KA showed that a dose of 30 mg/kg was associated with low mortality while eliciting SE. IN KA provoked at least one behavioral and electrographic SE in the majority of the mice (>90%). Behavioral and EEG SE were accompanied by a rapid and persistent microglial-astrocytic cell activation and hippocampal neurodegeneration. Specifically, microglial modifications involved both pro- (M1) and anti-inflammatory (M2) genes. Our initial long-term video-EEG exploration conducted using a small cohort of mice indicated the appearance of spike activity or SE. Our study demonstrated that induction of SE is attainable using IN KA in mice. Typical pro-inflammatory brain changes were observed in this model after SE, supporting disease pathophysiology. Our results are in favor of the further development of IN KA as a means to study seizure disorders. A possibility for tailoring this model to drug testing or to study mechanisms of disease is offered.
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Affiliation(s)
- Mounira Sabilallah
- CNRS, UMR 5203, Institut de Génomique Fonctionnelle, Montpellier, France
- INSERM, U1191, Montpellier, France
- Université de Montpellier, UMR5203, Montpellier, France
- Labex ICST, Montpellier, France
| | - Pierre Fontanaud
- CNRS, UMR 5203, Institut de Génomique Fonctionnelle, Montpellier, France
- INSERM, U1191, Montpellier, France
- Université de Montpellier, UMR5203, Montpellier, France
- Plateforme Imagerie du Petit Animal Montpellier, Biocampus, Montpellier, France
| | - Nathalie Linck
- CNRS, UMR 5203, Institut de Génomique Fonctionnelle, Montpellier, France
- INSERM, U1191, Montpellier, France
- Université de Montpellier, UMR5203, Montpellier, France
- Labex ICST, Montpellier, France
| | - Badreddine Boussadia
- CNRS, UMR 5203, Institut de Génomique Fonctionnelle, Montpellier, France
- INSERM, U1191, Montpellier, France
- Université de Montpellier, UMR5203, Montpellier, France
| | - Ronan Peyroutou
- CNRS, UMR 5203, Institut de Génomique Fonctionnelle, Montpellier, France
- INSERM, U1191, Montpellier, France
- Université de Montpellier, UMR5203, Montpellier, France
- Labex ICST, Montpellier, France
| | - Thibault Lasgouzes
- CNRS, UMR 5203, Institut de Génomique Fonctionnelle, Montpellier, France
- INSERM, U1191, Montpellier, France
- Université de Montpellier, UMR5203, Montpellier, France
- Labex ICST, Montpellier, France
| | - François A. Rassendren
- CNRS, UMR 5203, Institut de Génomique Fonctionnelle, Montpellier, France
- INSERM, U1191, Montpellier, France
- Université de Montpellier, UMR5203, Montpellier, France
- Labex ICST, Montpellier, France
| | - Nicola Marchi
- CNRS, UMR 5203, Institut de Génomique Fonctionnelle, Montpellier, France
- INSERM, U1191, Montpellier, France
- Université de Montpellier, UMR5203, Montpellier, France
| | - Helene E. Hirbec
- CNRS, UMR 5203, Institut de Génomique Fonctionnelle, Montpellier, France
- INSERM, U1191, Montpellier, France
- Université de Montpellier, UMR5203, Montpellier, France
- Labex ICST, Montpellier, France
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68
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Jacobson KA, Müller CE. Medicinal chemistry of adenosine, P2Y and P2X receptors. Neuropharmacology 2015; 104:31-49. [PMID: 26686393 DOI: 10.1016/j.neuropharm.2015.12.001] [Citation(s) in RCA: 184] [Impact Index Per Article: 20.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2015] [Revised: 11/30/2015] [Accepted: 12/01/2015] [Indexed: 12/13/2022]
Abstract
Pharmacological tool compounds are now available to define action at the adenosine (ARs), P2Y and P2X receptors. We present a selection of the most commonly used agents to study purines in the nervous system. Some of these compounds, including A1 and A3 AR agonists, P2Y1R and P2Y12R antagonists, and P2X3, P2X4 and P2X7 antagonists, are potentially of clinical use in treatment of disorders of the nervous system, such as chronic pain, neurodegeneration and brain injury. Agonists of the A2AAR and P2Y2R are already used clinically, P2Y12R antagonists are widely used antithrombotics and an antagonist of the A2AAR is approved in Japan for treating Parkinson's disease. The selectivity defined for some of the previously introduced compounds has been revised with updated pharmacological characterization, for example, various AR agonists and antagonists were deemed A1AR or A3AR selective based on human data, but species differences indicated a reduction in selectivity ratios in other species. Also, many of the P2R ligands still lack bioavailability due to charged groups or hydrolytic (either enzymatic or chemical) instability. X-ray crystallographic structures of AR and P2YRs have shifted the mode of ligand discovery to structure-based approaches rather than previous empirical approaches. The X-ray structures can be utilized either for in silico screening of chemically diverse libraries for the discovery of novel ligands or for enhancement of the properties of known ligands by chemical modification. Although X-ray structures of the zebrafish P2X4R have been reported, there is scant structural information about ligand recognition in these trimeric ion channels. In summary, there are definitive, selective agonists and antagonists for all of the ARs and some of the P2YRs; while the pharmacochemistry of P2XRs is still in nascent stages. The therapeutic potential of selectively modulating these receptors is continuing to gain interest in such fields as cancer, inflammation, pain, diabetes, ischemic protection and many other conditions. This article is part of the Special Issue entitled 'Purines in Neurodegeneration and Neuroregeneration'.
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Key Words
- 2-MeSADP, (PubChem CID: 121990)
- A-740003, (PubChem CID: 23232014)
- ATP
- Agonists
- Antagonists
- DPCPX, (PubChem CID: 1329)
- GPCR
- IB-MECA, (PubChem CID: 123683)
- Ion channel
- LUF6000, (PubChem CID: 11711282)
- MRS2500, (PubChem CID: 44448831)
- Nucleosides
- Nucleotides
- PPTN, (PubChem CID: 42611190)
- PSB-1114, (PubChem CID: 52952605)
- PSB-603, (PubChem CID: 44185871)
- SCH442416, (PubChem CID: 10668061)
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Affiliation(s)
- Kenneth A Jacobson
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, 20892, Bethesda, USA.
| | - Christa E Müller
- PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, Bonn, Germany
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69
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ATPergic signalling during seizures and epilepsy. Neuropharmacology 2015; 104:140-53. [PMID: 26549853 DOI: 10.1016/j.neuropharm.2015.11.001] [Citation(s) in RCA: 74] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2015] [Revised: 11/01/2015] [Accepted: 11/02/2015] [Indexed: 10/22/2022]
Abstract
Much progress has been made over the last few decades in the identification of new anti-epileptic drugs (AEDs). However, 30% of epilepsy patients suffer poor seizure control. This underscores the need to identify alternative druggable neurotransmitter systems and drugs with novel mechanisms of action. An emerging concept is that seizure generation involves a complex interplay between neurons and glial cells at the tripartite synapse and neuroinflammation has been proposed as one of the main drivers of epileptogenesis. The ATP-gated purinergic receptor family is expressed throughout the brain and is functional on neurons and glial cells. ATP is released in high amounts into the extracellular space after increased neuronal activity and during chronic inflammation and cell death to act as a neuro- and gliotransmitter. Emerging work shows pharmacological targeting of ATP-gated purinergic P2 receptors can potently modulate seizure generation, inflammatory processes and seizure-induced brain damage. To date, work showing the functional contribution of P2 receptors has been mainly performed in animal models of acute seizures, in particular, by targeting the ionotropic P2X7 receptor subtype. Other ionotropic P2X and metabotropic P2Y receptor family members have also been implicated in pathological processes following seizures such as the P2X4 receptor and the P2Y12 receptor. However, during epilepsy, the characterization of P2 receptors was mostly restricted to the study of expressional changes of the different receptor subtypes. This review summarizes the work to date on ATP-mediated signalling during seizures and the functional impact of targeting the ATP-gated purinergic receptors on seizures and seizure-induced pathology. This article is part of the Special Issue entitled 'Purines in Neurodegeneration and Neuroregeneration'.
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70
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Avignone E, Lepleux M, Angibaud J, Nägerl UV. Altered morphological dynamics of activated microglia after induction of status epilepticus. J Neuroinflammation 2015; 12:202. [PMID: 26538404 PMCID: PMC4634193 DOI: 10.1186/s12974-015-0421-6] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2015] [Accepted: 10/26/2015] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND Microglia cells are the resident macrophages of the central nervous system and are considered its first line of defense. In the normal brain, their ramified processes are highly motile, constantly scanning the surrounding brain tissue and rapidly moving towards sites of acute injury or danger signals. These microglial dynamics are thought to be critical for brain homeostasis. Under pathological conditions, microglial cells undergo "activation," which modifies many of their molecular and morphological properties. Investigations of the effects of activation on motility are limited and have given mixed results. In particular, little is known about how microglial motility is altered in epilepsy, which is characterized by a strong inflammatory reaction and microglial activation. METHODS We used a mouse model of status epilepticus induced by kainate injections and time-lapse two-photon microscopy to image GFP-labeled microglia in acute hippocampal brain slices. We studied how microglial activation affected the motility of microglial processes, including basal motility, and their responses to local triggering stimuli. RESULTS Our study reveals that microglial motility was largely preserved in kainate-treated animals, despite clear signs of microglial activation. In addition, whereas the velocities of microglial processes during basal scanning and towards a laser lesion were unaltered 48 h after status epilepticus, we observed an increase in the size of the territory scanned by single microglial processes during basal motility and an elevated directional velocity towards a pipette containing a purinergic agonist. CONCLUSIONS Microglial activation differentially impacted the dynamic scanning behavior of microglia in response to specific acute noxious stimuli, which may be an important feature of the adaptive behavior of microglia during pathophysiological conditions.
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Affiliation(s)
- Elena Avignone
- Interdisciplinary Institute for Neurosciences, CNRS UMR 5297, 33077, Bordeaux, France. .,Université de Bordeaux, CNRS UMR 5297, 33077, Bordeaux, France.
| | - Marilyn Lepleux
- Interdisciplinary Institute for Neurosciences, CNRS UMR 5297, 33077, Bordeaux, France.,Université de Bordeaux, CNRS UMR 5297, 33077, Bordeaux, France
| | - Julie Angibaud
- Interdisciplinary Institute for Neurosciences, CNRS UMR 5297, 33077, Bordeaux, France.,Université de Bordeaux, CNRS UMR 5297, 33077, Bordeaux, France
| | - U Valentin Nägerl
- Interdisciplinary Institute for Neurosciences, CNRS UMR 5297, 33077, Bordeaux, France. .,Université de Bordeaux, CNRS UMR 5297, 33077, Bordeaux, France.
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71
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Madry C, Attwell D. Receptors, ion channels, and signaling mechanisms underlying microglial dynamics. J Biol Chem 2015; 290:12443-50. [PMID: 25855789 DOI: 10.1074/jbc.r115.637157] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Microglia, the innate immune cells of the CNS, play a pivotal role in brain injury and disease. Microglia are extremely motile; their highly ramified processes constantly survey the brain parenchyma, and they respond promptly to brain damage with targeted process movement toward the injury site. Microglia play a key role in brain development and function by pruning synapses during development, phagocytosing apoptotic newborn neurons, and regulating neuronal activity by direct microglia-neuron or indirect microglia-astrocyte-neuron interactions, which all depend on their process motility. This review highlights recent discoveries about microglial dynamics, focusing on the receptors, ion channels, and signaling pathways involved.
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Affiliation(s)
- Christian Madry
- From the Department of Neuroscience, Physiology & Pharmacology, University College London, Gower Street, London WC1E 6BT, United Kingdom
| | - David Attwell
- From the Department of Neuroscience, Physiology & Pharmacology, University College London, Gower Street, London WC1E 6BT, United Kingdom
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Hyperbaric oxygen treatment at various stages following chronic constriction injury produces different antinociceptive effects via regulation of P2X4R expression and apoptosis. PLoS One 2015; 10:e0120122. [PMID: 25789619 PMCID: PMC4366063 DOI: 10.1371/journal.pone.0120122] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2014] [Accepted: 02/04/2015] [Indexed: 01/23/2023] Open
Abstract
PURPOSE The aims of this study were to investigate the effect of hyperbaric oxygen (HBO) treatment at various stages following chronic constriction injury (CCI) and to explore the underlying mechanisms of HBO treatment. METHODS Forty adult male Sprague-Dawley rats were randomly assigned to five groups (n = 8 for each group): the sham group, CCI group, HBO1 group, HBO2 group, and HBO3 group. Neuropathic pain was induced by CCI of the sciatic nerve. HBO treatment began on postoperative days 1, 6, and 11 and continued for 5 days. The mechanical withdrawal threshold and thermal withdrawal latency were tested on preoperative day 3 and postoperative days 1, 3, 5, 7, 10, 14, and 21. The expression of P2X4R was determined by immunohistochemistry and western blot analysis. Cell apoptosis was measured using TUNEL staining. The expression of caspase 3 was measured using reverse transcription polymerase chain reaction (RT-PCR). Electron microscopy was used to determine the ultrastructural changes. RESULTS Early HBO treatment beginning on postoperative day 1 produced a persistent antinociceptive effect and inhibited the CCI-induced increase in the expression of P2X4R without changing CCI-induced apoptosis. In contrast, late HBO treatment beginning on postoperative day 11 produced a persistent antinociceptive effect and inhibited CCI-induced apoptosis and upregulation of caspase-3 without changing the expression of P2X4R. In addition, late HBO treatment reduced CCI-induced ultrastructural damage. However, HBO treatment beginning on postoperative day 6 produced a transient antinociceptive effect without changing the expression of P2X4R or CCI-induced apoptosis. CONCLUSION HBO treatment at various stages following CCI can produce antinociceptive effects via different mechanisms. Early HBO treatment is associated with inhibition of P2X4R expression, and late HBO treatment is associated with inhibition of cell apoptosis.
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73
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Migration and Phagocytic Ability of Activated Microglia During Post-natal Development is Mediated by Calcium-Dependent Purinergic Signalling. Mol Neurobiol 2015; 53:944-954. [PMID: 25575683 DOI: 10.1007/s12035-014-9064-3] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Accepted: 12/09/2014] [Indexed: 01/10/2023]
Abstract
Microglia play an important role in synaptic pruning and controlled phagocytosis of neuronal cells during developmental stages. However, the mechanisms that regulate these functions are not completely understood. The present study was designed to investigate the role of purinergic signalling in microglial migration and phagocytic activity during post-natal brain development. One-day-old BALB/c mice received lipopolysaccharide (LPS) and/or a purinergic analogue (2-methylthioladenosine-5'-diphosphate; 2MeSADP), intracerebroventrically (i.c.v.). Combined administration of LPS and 2MeSADP resulted in activation of microglia as evident from increased expression of ionised calcium-binding adapter molecule 1 (Iba1). Activated microglia showed increased expression of purinergic receptors (P2Y2, P2Y6 and P2Y12). LPS either alone or in combination with 2MeSADP induced the expression of Na(+)/Ca(2+) exchanger (NCX-1) and P/Q-type Ca(2+) channels along with MARCKS-related protein (MRP), which is an integral component of cell migration machinery. In addition, LPS and 2MeSADP administration induced the expression of microglial CD11b and DAP12 (DNAX-activation protein 12), which are known to be involved in phagocytosis of neurons during development. Interestingly, administration of thapsigargin (TG), a specific Ca(2+)-ATPase inhibitor of endoplasmic reticulum, prevented the LPS/2MeSADP-induced microglial activation and migration by down-regulating the expression of Iba1 and MRP, respectively. Moreover, TG also reduced the LPS/2MeSADP-induced expression of CD11b/DAP12. Taken together, the findings reveal for the first time that Ca(2+)-mediated purinergic receptors regulate the migration and phagocytic ability of microglia during post-natal brain development.
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74
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P2X and P2Y receptors—role in the pathophysiology of the nervous system. Int J Mol Sci 2014; 15:23672-704. [PMID: 25530618 PMCID: PMC4284787 DOI: 10.3390/ijms151223672] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2014] [Revised: 12/03/2014] [Accepted: 12/06/2014] [Indexed: 12/16/2022] Open
Abstract
Purinergic signalling plays a crucial role in proper functioning of the nervous system. Mechanisms depending on extracellular nucleotides and their P2 receptors also underlie a number of nervous system dysfunctions. This review aims to present the role of purinergic signalling, with particular focus devoted to role of P2 family receptors, in epilepsy, depression, neuropathic pain, nervous system neoplasms, such as glioma and neuroblastoma, neurodegenerative diseases like Parkinson’s disease, Alzheimer’s disease and multiple sclerosis. The above-mentioned conditions are associated with changes in expression of extracellular ectonucleotidases, P2X and P2Y receptors in neurons and glial cells, as well as releasing considerable amounts of nucleotides from activated or damaged nervous tissue cells into the extracellular space, which contributes to disturbance in purinergic signalling. The numerous studies indicate a potential possibility of using synthetic agonists/antagonists of P2 receptors in treatment of selected nervous system diseases. This is of particular significance, since numerous available agents reveal a low effectiveness and often produce side effects.
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75
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Ali I, Chugh D, Ekdahl CT. Role of fractalkine-CX3CR1 pathway in seizure-induced microglial activation, neurodegeneration, and neuroblast production in the adult rat brain. Neurobiol Dis 2014; 74:194-203. [PMID: 25461978 DOI: 10.1016/j.nbd.2014.11.009] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2014] [Revised: 10/21/2014] [Accepted: 11/12/2014] [Indexed: 10/24/2022] Open
Abstract
Temporal lobe seizures lead to an acute inflammatory response in the brain primarily characterized by activation of parenchymal microglial cells. Simultaneously, degeneration of pyramidal cells and interneurons is evident together with a seizure-induced increase in the production of new neurons within the dentate gyrus of the hippocampus. We have previously shown a negative correlation between the acute seizure-induced inflammation and the survival of newborn hippocampal neurons. Here, we aimed to evaluate the role of the fractalkine-CX3CR1 pathway for these acute events. Fractalkine is a chemokine expressed by both neurons and glia, while its receptor, CX3CR1 is primarily expressed on microglia. Electrically-induced partial status epilepticus (SE) was induced in adult rats through stereotaxically implanted electrodes in the hippocampus. Recombinant rat fractalkine or CX3CR1 antibody was infused intraventricularly during one week post-SE. A significant increase in the expression of CX3CR1, but not fractalkine, was observed in the dentate gyrus at one week. CX3CR1 antibody treatment resulted in a reduction in microglial activation, neurodegeneration, as well as neuroblast production. In contrast, fractalkine treatment had only minor effects. This study provides evidence for a role of the fractalkine-CX3CR1 signaling pathway in seizure-induced microglial activation and suggests that neuroblast production following seizures may partly occur as a result of microglial activation.
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Affiliation(s)
- Idrish Ali
- Inflammation and Stem Cell Therapy Group, Wallenberg Neuroscience Center, Division of Clinical Neurophysiology, Lund University, Sweden; Lund Epilepsy Center, Lund University, SE-221 84 Lund, Sweden
| | - Deepti Chugh
- Inflammation and Stem Cell Therapy Group, Wallenberg Neuroscience Center, Division of Clinical Neurophysiology, Lund University, Sweden; Lund Epilepsy Center, Lund University, SE-221 84 Lund, Sweden
| | - Christine T Ekdahl
- Inflammation and Stem Cell Therapy Group, Wallenberg Neuroscience Center, Division of Clinical Neurophysiology, Lund University, Sweden; Lund Epilepsy Center, Lund University, SE-221 84 Lund, Sweden.
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Zeng J, Wang G, Liu X, Wang C, Tian H, Liu A, Jin H, Luo X, Chen Y. P2Y13 receptor-mediated rapid increase in intracellular calcium induced by ADP in cultured dorsal spinal cord microglia. Neurochem Res 2014; 39:2240-50. [PMID: 25186167 DOI: 10.1007/s11064-014-1426-8] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2014] [Revised: 07/11/2014] [Accepted: 08/27/2014] [Indexed: 12/18/2022]
Abstract
P2Y receptors have been implicated in the calcium mobilization by the response to neuroexcitatory substances in neurons and astrocytes, but little is known about P2Y receptors in microglia cells. In the present study, the effects of ADP on the intracellular calcium concentration ([Ca(2+)]i) in cultured dorsal spinal cord microglia were detected with confocal laser scanning microscopy using fluo-4/AM as a calcium fluorescence indicator that could monitor real-time alterations of [Ca(2+)]i. Here we show that ADP (0.01-100 μM) causes a rapid increase in [Ca(2+)]i with a dose-dependent manner in cultured microglia. The action of ADP on [Ca(2+)]i was significantly blocked by MRS2211 (a selective P2Y13 receptor antagonist), but was unaffected by MRS2179 (a selective P2Y1 receptor antagonist) or MRS2395 (a selective P2Y12 receptor antagonist), which suggest that P2Y13 receptor may be responsible for ADP-evoked Ca(2+) mobilization in cultured microglia. P2Y13-evoked Ca(2+) response can be obviously inhibited by BAPTA-AM and U-73122, respectively. Moreover, removal of extracellular Ca(2+) (by EGTA) also can obvious suppress the Ca(2+) mobilization. These results means both intracellular calcium and extracellular calcium are potentially important mechanisms in P2Y13 receptor-evoked Ca(2+) mobilization. However, P2Y13 receptor-evoked Ca(2+) response was not impaired after CdCl2 and verapamil administration, which suggest that voltage-operated Ca(2+) channels may be not related with P2Y13-evoked Ca(2+) response. In addition, Ca(2+) mobilization induced by ADP was abolished by different store-operated Ca(2+) channels (SOCs) blocker, 2-APB (50 μM) and SKF-96365 (1 mM), respectively. These observations suggest that the activation of P2Y13 receptor might be involved in the effect of ADP on [Ca(2+)]i in cultured dorsal spinal cord microglia. Furthermore, our results raise a possibility that P2Y13 receptor activation causes Ca(2+) release from Ca(2+) store, which leads to the opening of SOCs.
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Affiliation(s)
- Junwei Zeng
- Department of Physiology, Guizhou Key Laboratory of Anesthesia and Organ Protection, Zunyi Medical College, 201 Dalian Street, Zunyi, 563000, Guizhou Province, People's Republic of China,
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77
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Franklin KM, Asatryan L, Jakowec MW, Trudell JR, Bell RL, Davies DL. P2X4 receptors (P2X4Rs) represent a novel target for the development of drugs to prevent and/or treat alcohol use disorders. Front Neurosci 2014; 8:176. [PMID: 25009459 PMCID: PMC4068020 DOI: 10.3389/fnins.2014.00176] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2014] [Accepted: 06/05/2014] [Indexed: 12/19/2022] Open
Abstract
Alcohol use disorders (AUDs) have a staggering socioeconomic impact. Few therapeutic options are available, and they are largely inadequate. These shortcomings highlight the urgent need to develop effective medications to prevent and/or treat AUDs. A critical barrier is the lack of information regarding the molecular target(s) by which ethanol (EtOH) exerts its pharmacological activity. This review highlights findings implicating P2X4 receptors (P2X4Rs) as a target for the development of therapeutics to treat AUDs and discusses the use of ivermectin (IVM) as a potential clinical tool for treatment of AUDs. P2XRs are a family of ligand-gated ion channels (LGICs) activated by extracellular ATP. Of the P2XR subtypes, P2X4Rs are expressed the most abundantly in the CNS. Converging evidence suggests that P2X4Rs are involved in the development and progression of AUDs. First, in vitro studies report that pharmacologically relevant EtOH concentrations can negatively modulate ATP-activated currents. Second, P2X4Rs in the mesocorticolimbic dopamine system are thought to play a role in synaptic plasticity and are located ideally to modulate brain reward systems. Third, alcohol-preferring (P) rats have lower functional expression of the p2rx4 gene than alcohol-non-preferring (NP) rats suggesting an inverse relationship between alcohol intake and P2X4R expression. Similarly, whole brain p2rx4 expression has been shown to relate inversely to innate 24 h alcohol preference across 28 strains of rats. Fourth, mice lacking the p2rx4 gene drink more EtOH than wildtype controls. Fifth, IVM, a positive modulator of P2X4Rs, antagonizes EtOH-mediated inhibition of P2X4Rs in vitro and reduces EtOH intake and preference in vivo. These findings suggest that P2X4Rs contribute to EtOH intake. The present review summarizes recent findings focusing on the P2X4R as a molecular target of EtOH action, its role in EtOH drinking behavior and modulation of its activity by IVM as a potential therapy for AUDs.
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Affiliation(s)
- Kelle M Franklin
- Department of Psychiatry, Institute of Psychiatric Research, Indiana University School of Medicine Indianapolis, IN, USA
| | - Liana Asatryan
- Titus Family Department of Clinical Pharmacy and Pharmaceutical Economics and Policy, School of Pharmacy, University of Southern California Los Angeles, CA, USA
| | - Michael W Jakowec
- Department of Neurology, University of Southern California Los Angeles, CA, USA
| | - James R Trudell
- Beckman Program for Molecular and Genetic Medicine, Department of Anesthesia, Stanford University Palo Alto, CA, USA
| | - Richard L Bell
- Department of Psychiatry, Institute of Psychiatric Research, Indiana University School of Medicine Indianapolis, IN, USA
| | - Daryl L Davies
- Titus Family Department of Clinical Pharmacy and Pharmaceutical Economics and Policy, School of Pharmacy, University of Southern California Los Angeles, CA, USA
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Xu J, Chai H, Ehinger K, Egan TM, Srinivasan R, Frick M, Khakh BS. Imaging P2X4 receptor subcellular distribution, trafficking, and regulation using P2X4-pHluorin. ACTA ACUST UNITED AC 2014; 144:81-104. [PMID: 24935743 PMCID: PMC4076521 DOI: 10.1085/jgp.201411169] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
A P2X4 receptor labeled with the pH-sensitive GFP superecliptic pHluorin represents a useful probe to investigate P2X4 receptor distribution, trafficking, and up-regulation. P2X4 receptors are adenosine triphosphate (ATP)-gated cation channels present on the plasma membrane (PM) and also within intracellular compartments such as vesicles, vacuoles, lamellar bodies (LBs), and lysosomes. P2X4 receptors in microglia are up-regulated in epilepsy and in neuropathic pain; that is to say, their total and/or PM expression levels increase. However, the mechanisms underlying up-regulation of microglial P2X4 receptors remain unclear, in part because it has not been possible to image P2X4 receptor distribution within, or trafficking between, cellular compartments. Here, we report the generation of pH-sensitive fluorescently tagged P2X4 receptors that permit evaluations of cell surface and total receptor pools. Capitalizing on information gained from zebrafish P2X4.1 crystal structures, we designed a series of mouse P2X4 constructs in which a pH-sensitive green fluorescent protein, superecliptic pHluorin (pHluorin), was inserted into nonconserved regions located within flexible loops of the P2X4 receptor extracellular domain. One of these constructs, in which pHluorin was inserted after lysine 122 (P2X4-pHluorin123), functioned like wild-type P2X4 in terms of its peak ATP-evoked responses, macroscopic kinetics, calcium flux, current–voltage relationship, and sensitivity to ATP. P2X4-pHluorin123 also showed pH-dependent fluorescence changes, and was robustly expressed on the membrane and within intracellular compartments. P2X4-pHluorin123 identified cell surface and intracellular fractions of receptors in HEK-293 cells, hippocampal neurons, C8-B4 microglia, and alveolar type II (ATII) cells. Furthermore, it showed that the subcellular fractions of P2X4-pHluorin123 receptors were cell and compartment specific, for example, being larger in hippocampal neuron somata than in C8-B4 cell somata, and larger in C8-B4 microglial processes than in their somata. In ATII cells, P2X4-pHluorin123 showed that P2X4 receptors were secreted onto the PM when LBs undergo exocytosis. Finally, the use of P2X4-pHluorin123 showed that the modulator ivermectin did not increase the PM fraction of P2X4 receptors and acted allosterically to potentiate P2X4 receptor responses. Collectively, our data suggest that P2X4-pHluorin123 represents a useful optical probe to quantitatively explore P2X4 receptor distribution, trafficking, and up-regulation.
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Affiliation(s)
- Ji Xu
- Department of Physiology and Department of Neurobiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095
| | - Hua Chai
- Department of Physiology and Department of Neurobiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095
| | | | - Terrance M Egan
- Department of Pharmacological and Physiological Science and The Center for Excellence in Neuroscience, Saint Louis University School of Medicine, St. Louis, MO 63130 Department of Pharmacological and Physiological Science and The Center for Excellence in Neuroscience, Saint Louis University School of Medicine, St. Louis, MO 63130
| | - Rahul Srinivasan
- Department of Physiology and Department of Neurobiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095
| | - Manfred Frick
- Institute of General Physiology, University of Ulm, 89081 Ulm, Germany
| | - Baljit S Khakh
- Department of Physiology and Department of Neurobiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095Department of Physiology and Department of Neurobiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095
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Ficker C, Rozmer K, Kató E, Andó RD, Schumann L, Krügel U, Franke H, Sperlágh B, Riedel T, Illes P. Astrocyte-neuron interaction in the substantia gelatinosa of the spinal cord dorsal horn via P2X7 receptor-mediated release of glutamate and reactive oxygen species. Glia 2014; 62:1671-86. [PMID: 24895290 DOI: 10.1002/glia.22707] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2014] [Revised: 05/23/2014] [Accepted: 05/23/2014] [Indexed: 12/14/2022]
Abstract
The substantia gelatinosa (SG) of the spinal cord processes incoming painful information to ascending projection neurons. Whole-cell patch clamp recordings from SG spinal cord slices documented that in a low Ca(2+) /no Mg(2+) (low X(2+) ) external medium adenosine triphosphate (ATP)/dibenzoyl-ATP, Bz-ATP) caused inward current responses, much larger in amplitude than those recorded in a normal X(2+) -containing bath medium. The effect of Bz-ATP was antagonized by the selective P2X7 receptor antagonist A-438079. Neuronal, but not astrocytic Bz-ATP currents were strongly inhibited by a combination of the ionotropic glutamate receptor antagonists AP-5 and CNQX. In fact, all neurons and some astrocytes responded to NMDA, AMPA, and muscimol with inward current, demonstrating the presence of the respective receptors. The reactive oxygen species H2 O2 potentiated the effect of Bz-ATP at neurons but not at astrocytes. Hippocampal CA1 neurons exhibited a behavior similar to, but not identical with SG neurons. Although a combination of AP-5 and CNQX almost abolished the effect of Bz-ATP, H2 O2 was inactive. A Bz-ATP-dependent and A-438079-antagonizable reactive oxygen species production in SG slices was proven by a microelectrode biosensor. Immunohistochemical investigations showed the colocalization of P2X7-immunoreactivity with microglial (Iba1), but not astrocytic (GFAP, S100β) or neuronal (MAP2) markers in the SG. It is concluded that SG astrocytes possess P2X7 receptors; their activation leads to the release of glutamate, which via NMDA- and AMPA receptor stimulation induces cationic current in the neighboring neurons. P2X7 receptors have a very low density under resting conditions but become functionally upregulated under pathological conditions.
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Affiliation(s)
- Christoph Ficker
- Rudolf Boehm Institute for Pharmacology und Toxicology, University of Leipzig, Leipzig, Germany
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80
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Widespread activation of microglial cells in the hippocampus of chronic epileptic rats correlates only partially with neurodegeneration. Brain Struct Funct 2014; 220:2423-39. [PMID: 24878824 DOI: 10.1007/s00429-014-0802-0] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2014] [Accepted: 05/14/2014] [Indexed: 12/30/2022]
Abstract
Activation of microglial cells (brain macrophages) soon after status epilepticus has been suggested to be critical for the pathogenesis of mesial temporal lobe epilepsy (MTLE). However, microglial activation in the chronic phase of experimental MTLE has been scarcely addressed. In this study, we questioned whether microglial activation persists in the hippocampus of pilocarpine-treated, epileptic Wistar rats and to which extent it is associated with segmental neurodegeneration. Microglial cells were immunostained for the universal microglial marker, ionized calcium-binding adapter molecule-1 and the activation marker, CD11b (also known as OX42, Mac-1). Using quantitative morphology, i.e., stereology and Neurolucida-based reconstructions, we investigated morphological correlates of microglial activation such as cell number, ramification, somatic size and shape. We find that microglial cells in epileptic rats feature widespread, activation-related morphological changes such as increase in cell number density, massive up-regulation of CD11b and de-ramification. The parameters show heterogeneity in different hippocampal subregions. For instance, de-ramification is most prominent in the outer molecular layer of the dentate gyrus, whereas CD11b expression dominates in hilus. Interestingly, microglial activation only partially correlates with segmental neurodegeneration. Major neuronal death in the hilus, CA3 and CA1 coincides with strong up-regulation of CD11b. However, microglial activation is also observed in subregions that do not feature neurodegeneration, such as the molecular and granular layer of the dentate gyrus. This in vivo study provides solid experimental evidence that microglial cells feature widespread heterogeneous activation that only partially correlates with hippocampal segmental neuronal loss in experimental MTLE.
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81
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Tian M, Abdelrahman A, Weinhausen S, Hinz S, Weyer S, Dosa S, El-Tayeb A, Müller CE. Carbamazepine derivatives with P2X4 receptor-blocking activity. Bioorg Med Chem 2013; 22:1077-88. [PMID: 24411477 DOI: 10.1016/j.bmc.2013.12.035] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2013] [Revised: 12/15/2013] [Accepted: 12/16/2013] [Indexed: 12/28/2022]
Abstract
Antagonists for the P2 receptor subtype P2X4, an ATP-activated cation channel receptor, have potential as novel drugs for the treatment of neuropathic pain and other inflammatory diseases. In the present study, a series of 47 carbamazepine derivatives including 32 novel compounds were designed, synthesized, and evaluated as P2X4 receptor antagonists. Their potency to inhibit ATP-induced calcium influx in 1321N1 astrocytoma cells stably transfected with the human P2X4 receptor was determined. Additionally, species selectivity (human, rat, mouse) and receptor subtype selectivity (P2X4 vs P2X1, 2, 3, 7) were investigated for selected derivatives. The most potent compound of the present series, which exhibited an allosteric mechanism of P2X4 inhibition, was N,N-diisopropyl-5H-dibenz[b,f]azepine-5-carboxamide (34, IC50 of 3.44μM). The present study extends the so far very limited knowledge on structure-activity relationships of P2X4 receptor antagonists.
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Affiliation(s)
- Maoqun Tian
- PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, An der Immenburg 4, D-53121 Bonn, Germany
| | - Aliaa Abdelrahman
- PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, An der Immenburg 4, D-53121 Bonn, Germany
| | - Stephanie Weinhausen
- PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, An der Immenburg 4, D-53121 Bonn, Germany
| | - Sonja Hinz
- PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, An der Immenburg 4, D-53121 Bonn, Germany
| | - Stefanie Weyer
- PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, An der Immenburg 4, D-53121 Bonn, Germany
| | - Stefan Dosa
- PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, An der Immenburg 4, D-53121 Bonn, Germany
| | - Ali El-Tayeb
- PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, An der Immenburg 4, D-53121 Bonn, Germany
| | - Christa E Müller
- PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, An der Immenburg 4, D-53121 Bonn, Germany.
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The known knowns of microglia–neuronal signalling in neuropathic pain. Neurosci Lett 2013; 557 Pt A:37-42. [DOI: 10.1016/j.neulet.2013.08.037] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2013] [Accepted: 08/16/2013] [Indexed: 12/30/2022]
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Henshall DC, Diaz-Hernandez M, Miras-Portugal MT, Engel T. P2X receptors as targets for the treatment of status epilepticus. Front Cell Neurosci 2013; 7:237. [PMID: 24324404 PMCID: PMC3840793 DOI: 10.3389/fncel.2013.00237] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2013] [Accepted: 11/08/2013] [Indexed: 11/26/2022] Open
Abstract
Prolonged seizures are amongst the most common neurological emergencies. Status epilepticus is a state of continuous seizures that is life-threatening and prompt termination of status epilepticus is critical to protect the brain from permanent damage. Frontline treatment comprises parenteral administration of anticonvulsants such as lorazepam that facilitate γ-amino butyric acid (GABA) transmission. Because status epilepticus can become refractory to anticonvulsants in a significant proportion of patients, drugs which act on different neurotransmitter systems may represent potential adjunctive treatments. P2X receptors are a class of ligand-gated ion channel activated by ATP that contributes to neuro- and glio-transmission. P2X receptors are expressed by both neurons and glia in various brain regions, including the hippocampus. Electrophysiology, pharmacology and genetic studies suggest certain P2X receptors are activated during pathologic brain activity. Expression of several members of the family including P2X2, P2X4, and P2X7 receptors has been reported to be altered in the hippocampus following status epilepticus. Recent studies have shown that ligands of the P2X7 receptor can have potent effects on seizure severity during status epilepticus and mice lacking this receptor display altered seizures in response to chemoconvulsants. Antagonists of the P2X7 receptor also modulate neuronal death, microglial responses and neuroinflammatory signaling. Recent work also found altered neuronal injury and inflammation after status epilepticus in mice lacking the P2X4 receptor. In summary, members of the P2X receptor family may serve important roles in the pathophysiology of status epilepticus and represent novel targets for seizure control and neuroprotection.
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Affiliation(s)
- David C Henshall
- Department of Physiology and Medical Physics, Royal College of Surgeons in Ireland Dublin, Ireland ; Centre for the Study of Neurological Disorders, Royal College of Surgeons in Ireland Dublin, Ireland
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Tsuda M, Masuda T, Tozaki-Saitoh H, Inoue K. P2X4 receptors and neuropathic pain. Front Cell Neurosci 2013; 7:191. [PMID: 24191146 PMCID: PMC3808787 DOI: 10.3389/fncel.2013.00191] [Citation(s) in RCA: 97] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2013] [Accepted: 10/07/2013] [Indexed: 12/16/2022] Open
Abstract
Neuropathic pain, a debilitating pain condition, is a common consequence of damage to the nervous system. Neuropathic pain is often resistant to currently available analgesics. A growing body of evidence indicates that spinal microglia react and undergo a series of changes that directly influence the establishment of neuropathic pain states. After nerve injury, P2X4 receptors (P2X4Rs) are upregulated in spinal microglia by several factors at the transcriptional and translational levels. Those include the CC chemokine CCL21 derived from damaged neurons, the extracellular matrix protein fibronectin in the spinal cord, and the transcription factor interferon regulatory factor 8 (IRF8) expressed in microglia. P2X4R expression in microglia is also regulated at the post-translational level by signaling from other cell-surface receptors such as CC chemokine receptor (CCR2). Importantly, inhibiting the function or expression of P2X4Rs and P2X4R-regulating molecules suppresses the aberrant excitability of dorsal horn neurons and neuropathic pain. These findings indicate that P2X4R-positive microglia are a central player in mechanisms for neuropathic pain. Thus, microglial P2X4Rs are a potential target for treating the chronic pain state.
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Affiliation(s)
- Makoto Tsuda
- Department of Molecular and System Pharmacology, Graduate School of Pharmaceutical Sciences, Kyushu University Fukuoka, Japan
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