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Jazaeri SZ, Taghizadeh G, Babaei JF, Goudarzi S, Saadatmand P, Joghataei MT, Khanahmadi Z. Aquaporin 4 beyond a water channel; participation in motor, sensory, cognitive and psychological performances, a comprehensive review. Physiol Behav 2023; 271:114353. [PMID: 37714320 DOI: 10.1016/j.physbeh.2023.114353] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2023] [Revised: 08/15/2023] [Accepted: 09/13/2023] [Indexed: 09/17/2023]
Abstract
Aquaporin 4 (AQP4) is a protein highly expressed in the central nervous system (CNS) and peripheral nervous system (PNS) as well as various other organs, whose different sites of action indicate its importance in various functions. AQP4 has a variety of essential roles beyond water homeostasis. In this article, we have for the first time summarized different roles of AQP4 in motor and sensory functions, besides cognitive and psychological performances, and most importantly, possible physiological mechanisms by which AQP4 can exert its effects. Furthermore, we demonstrated that AQP4 participates in pathology of different neurological disorders, various effects depending on the disease type. Since neurological diseases involve a spectrum of dysfunctions and due to the difficulty of obtaining a treatment that can simultaneously affect these deficits, it is therefore suggested that future studies consider the role of this protein in different functional impairments related to neurological disorders simultaneously or separately by targeting AQP4 expression and/or polarity modulation.
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Affiliation(s)
- Seyede Zohreh Jazaeri
- Department of Neuroscience, Faculty of Advanced Technologies in Medicine, Iran University of Medical Sciences, Tehran, Iran; Division of Neuroscience, Cellular and Molecular Research Center, Iran University of Medical Sciences, Tehran, Iran
| | - Ghorban Taghizadeh
- Department of Occupational Therapy, School of Rehabilitation Sciences, Iran University of Medical Sciences, Tehran, Iran.
| | - Javad Fahanik Babaei
- Electrophysiology Research Center, Tehran University of Medical Sciences, Tehran, Iran
| | - Sepideh Goudarzi
- Experimental Medicine Research Center, Tehran University of medical Sciences, Tehran, Iran
| | - Pegah Saadatmand
- Department of Medical Physics, School of Medicine, Iran University of Medical Sciences, Tehran, Iran
| | - Mohammad Taghi Joghataei
- Department of Neuroscience, Faculty of Advanced Technologies in Medicine, Iran University of Medical Sciences, Tehran, Iran; Division of Neuroscience, Cellular and Molecular Research Center, Iran University of Medical Sciences, Tehran, Iran; Department of Anatomy, School of Medicine, Iran University of Medical Sciences, Tehran, Iran; Department of Innovation in Medical Education, Faculty of Medicine, Ottawa University, Ottawa, Canada.
| | - Zohreh Khanahmadi
- Department of Occupational Therapy, School of Rehabilitation Services, Isfahan University of Medical Sciences, Isfahan, Iran
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Zhang N, Jiang H, Wang H, Wang Y, Peng Y, Liu Y, Xia C, Yan X, Chu S, Zhang Y, Wang Z, Chen N. Novel Antidepressant Mechanism of Ginsenoside Rg1 in Regulating the Dysfunction of the Glutamatergic System in Astrocytes. Int J Mol Sci 2022; 24:ijms24010575. [PMID: 36614017 PMCID: PMC9820673 DOI: 10.3390/ijms24010575] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Revised: 12/19/2022] [Accepted: 12/23/2022] [Indexed: 12/31/2022] Open
Abstract
Ginsenoside Rg1, a traditional Chinese medicine monomer, has been shown to have antidepressant effects. We previously found that Rg1 exerts antidepressant effects by improving the gap junction channels (GJCs) dysfunction; however, the downstream mechanisms through which Rg1 ameliorates GJC dysfunction remain unclear. Since hemichannels directly release glutamate, GJC dysfunction decreases the expression levels of glutamate transporters in astrocytes, and glutamatergic system dysfunction plays an essential role in the pathogenesis of depression. The glutamatergic system may be a potential downstream target of Rg1 that exerts antidepressant effects. Therefore, in this study, we aimed to determine the downstream mechanisms by which Rg1 ameliorated GJC dysfunction and exerted its antidepressant effects. Corticosterone (CORT) is used to mimic high glucocorticoid levels in patients with depression in vitro. Primary cortical astrocytes were isolated and phosphorylation of connexin43 (Cx43) as well as the functions of hemichannels, GJCs, and the glutamatergic system were evaluated after drug treatment. Rg1 pretreatment reversed the anomalous activation of Cx43 phosphorylation as well as the dysfunction of hemichannels, GJCs, and the glutamatergic system induced by CORT. These results suggest that Rg1 can ameliorate CORT-induced dysfunction of the glutamatergic system in astrocytes by potentially reducing Cx43 phosphorylation and inhibiting opening of hemichannels, thereby improving GJC dysfunction.
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Affiliation(s)
- Ningning Zhang
- State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Institute of Materia Medica & Neuroscience Center, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100050, China
| | - Hong Jiang
- State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Institute of Materia Medica & Neuroscience Center, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100050, China
| | - Huiqin Wang
- School of Pharmacy, Hunan University of Traditional Chinese Medicine & Hunan Engineering Technology Center of Standardization and Function of Chinese Herbal Decoction Pieces, Changsha 410208, China
| | - Yating Wang
- Department of Anatomy, School of Chinese Medicine, Beijing University of Chinese Medicine, Beijing 102488, China
| | - Ye Peng
- School of Pharmacy, Hunan University of Traditional Chinese Medicine & Hunan Engineering Technology Center of Standardization and Function of Chinese Herbal Decoction Pieces, Changsha 410208, China
| | - Yangbo Liu
- School of Pharmacy, Hunan University of Traditional Chinese Medicine & Hunan Engineering Technology Center of Standardization and Function of Chinese Herbal Decoction Pieces, Changsha 410208, China
| | - Congyuan Xia
- State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Institute of Materia Medica & Neuroscience Center, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100050, China
| | - Xu Yan
- State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Institute of Materia Medica & Neuroscience Center, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100050, China
| | - Shifeng Chu
- State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Institute of Materia Medica & Neuroscience Center, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100050, China
| | - Yi Zhang
- Department of Anatomy, School of Chinese Medicine, Beijing University of Chinese Medicine, Beijing 102488, China
| | - Zhenzhen Wang
- State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Institute of Materia Medica & Neuroscience Center, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100050, China
- Correspondence: (Z.W.); (N.C.); Tel.: +86-10-6316-5182 (Z.W.); +86-10-6316-5177 (N.C.)
| | - Naihong Chen
- State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Institute of Materia Medica & Neuroscience Center, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100050, China
- School of Pharmacy, Hunan University of Traditional Chinese Medicine & Hunan Engineering Technology Center of Standardization and Function of Chinese Herbal Decoction Pieces, Changsha 410208, China
- Correspondence: (Z.W.); (N.C.); Tel.: +86-10-6316-5182 (Z.W.); +86-10-6316-5177 (N.C.)
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Zhang NN, Zhang Y, Wang ZZ, Chen NH. Connexin 43: insights into candidate pathological mechanisms of depression and its implications in antidepressant therapy. Acta Pharmacol Sin 2022; 43:2448-2461. [PMID: 35145238 PMCID: PMC9525669 DOI: 10.1038/s41401-022-00861-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Accepted: 01/06/2022] [Indexed: 11/09/2022] Open
Abstract
Major depressive disorder (MDD), a chronic and recurrent disease characterized by anhedonia, pessimism or even suicidal thought, remains a major chronic mental concern worldwide. Connexin 43 (Cx43) is the most abundant connexin expressed in astrocytes and forms the gap junction channels (GJCs) between astrocytes, the most abundant and functional glial cells in the brain. Astrocytes regulate neurons' synaptic strength and function by expressing receptors and regulating various neurotransmitters. Astrocyte dysfunction causes synaptic abnormalities, which are related to various mood disorders, e.g., depression. Increasing evidence suggests a crucial role of Cx43 in the pathogenesis of depression. Depression down-regulates Cx43 expression in humans and rats, and dysfunction of Cx43 also induces depressive behaviors in rats and mice. Recently Cx43 has received considerable critical attention and is highly implicated in the onset of depression. However, the pathological mechanisms of depression-like behavior associated with Cx43 still remain ambiguous. In this review we summarize the recent progress regarding the underlying mechanisms of Cx43 in the etiology of depression-like behaviors including gliotransmission, metabolic disorders, and neuroinflammation. We also discuss the effects of antidepressants (monoamine antidepressants and ketamine) on Cx43. The clarity of the candidate pathological mechanisms of depression-like behaviors associated with Cx43 and its potential pharmacological roles for antidepressants will benefit the exploration of a novel antidepressant target.
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Affiliation(s)
- Ning-Ning Zhang
- State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Institute of Materia Medica & Neuroscience Center, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100050, China
| | - Yi Zhang
- Department of Anatomy, School of Chinese Medicine, Beijing University of Chinese Medicine, Beijing, 102488, China
| | - Zhen-Zhen Wang
- State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Institute of Materia Medica & Neuroscience Center, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100050, China.
| | - Nai-Hong Chen
- State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Institute of Materia Medica & Neuroscience Center, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100050, China.
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Levetiracetam treatment leads to functional recovery after thoracic or cervical injuries of the spinal cord. NPJ Regen Med 2021; 6:11. [PMID: 33654068 PMCID: PMC7977146 DOI: 10.1038/s41536-021-00121-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2020] [Accepted: 02/01/2021] [Indexed: 01/31/2023] Open
Abstract
Spinal cord injury (SCI) leads to dramatic impairments of motor, sensory, and autonomic functions of affected individuals. Following the primary injury, there is an increased release of glutamate that leads to excitotoxicity and further neuronal death. Therefore, modulating glutamate excitotoxicity seems to be a promising target to promote neuroprotection during the acute phase of the injury. In this study, we evaluated the therapeutic effect of a FDA approved antiepileptic drug (levetiracetam-LEV), known for binding to the synaptic vesicle protein SV2A in the brain and spinal cord. LEV therapy was tested in two models of SCI-one affecting the cervical and other the thoracic level of the spinal cord. The treatment was effective on both SCI models. Treated animals presented significant improvements on gross and fine motor functions. The histological assessment revealed a significant decrease of cavity size, as well as higher neuronal and oligodendrocyte survival on treated animals. Molecular analysis revealed that LEV acts by stabilizing the astrocytes allowing an effective uptake of the excess glutamate from the extracellular space. Overall, our results demonstrate that Levetiracetam may be a promising drug for acute management of SCI.
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Prah J, Winters A, Chaudhari K, Hersh J, Liu R, Yang SH. A novel serum free primary astrocyte culture method that mimic quiescent astrocyte phenotype. J Neurosci Methods 2019; 320:50-63. [PMID: 30904500 DOI: 10.1016/j.jneumeth.2019.03.013] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2019] [Revised: 03/15/2019] [Accepted: 03/19/2019] [Indexed: 12/20/2022]
Abstract
BACKGROUND Primary astrocyte cultures have been used for decades to study astrocyte functions in health and disease. The current primary astrocyte cultures are mostly maintained in serum-containing medium which produces astrocytes with a reactive phenotype as compared to in vivo quiescent astrocytes. The aim of this study was to establish a serum-free astrocyte culture medium that maintains primary astrocytes in a quiescent state. NEW METHOD Serum free astrocyte base medium (ABM) supplemented with basic fibroblast growth factor 2 (FGF2) and epidermal growth factor (EGF) (ABM-FGF2-EGF) or serum supplemented DMEM (MD-10%FBS) was used to culture primary astrocytes isolated from cerebral cortex of postnatal day 1 C57BL/6 mice. RESULTS Compared to astrocytes cultured in MD-10%FBS medium, astrocytes in ABM-FGF2-EGF had higher process bearing morphologies similar to in vivo astrocytes. Western blot, immunostaining, quantitative polymerase chain reaction and metabolic assays revealed that astrocytes maintained in ABM-FGF2-EGF had enhanced glycolytic metabolism, higher glycogen content, lower GFAP expression, increased glutamine synthase, and glutamate transporter-1 mRNA levels as compared to astrocytes cultured in MD-10% FBS medium. COMPARISON TO EXISTING METHODS These observations suggest that astrocytes cultured in ABM-FGF2-EGF media compared to the usual FBS media promote quiescent and biosynthetic phenotype similar to in vivo astrocytes. CONCLUSION This media provides a novel method for studying astrocytes functions in vitro under physiological and pathological conditions.
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Affiliation(s)
- Jude Prah
- Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, Fort Worth, TX, 76107, USA
| | - Ali Winters
- Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, Fort Worth, TX, 76107, USA
| | - Kiran Chaudhari
- Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, Fort Worth, TX, 76107, USA
| | - Jessica Hersh
- Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, Fort Worth, TX, 76107, USA
| | - Ran Liu
- Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, Fort Worth, TX, 76107, USA
| | - Shao-Hua Yang
- Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, Fort Worth, TX, 76107, USA.
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Li K, Zhou H, Zhan L, Shi Z, Sun W, Liu D, Liu L, Liang D, Tan Y, Xu W, Xu E. Hypoxic Preconditioning Maintains GLT-1 Against Transient Global Cerebral Ischemia Through Upregulating Cx43 and Inhibiting c-Src. Front Mol Neurosci 2018; 11:344. [PMID: 30323740 PMCID: PMC6172853 DOI: 10.3389/fnmol.2018.00344] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2018] [Accepted: 09/03/2018] [Indexed: 01/06/2023] Open
Abstract
Transient global cerebral ischemia (tGCI) causes excessive release of glutamate from neurons. Astrocytic glutamate transporter-1 (GLT-1) and glutamine synthetase (GS) together play a predominant role in maintaining glutamate at normal extracellular concentrations. Though our previous studies reported the alleviation of tGCI-induced neuronal death by hypoxic preconditioning (HPC) in hippocampal Cornu Ammonis 1 (CA1) of adult rats, the underlying mechanism has not yet been fully elaborated. In this study, we aimed to investigate the roles of GLT-1 and GS in the neuroprotection mediated by HPC against tGCI and to ascertain whether these roles can be regulated by connexin 43 (Cx43) and cellular-Src (c-Src) activity. We found that HPC decreased the level of extracellular glutamate in CA1 after tGCI via maintenance of GLT-1 expression and GS activity. Inhibition of GLT-1 expression with dihydrokainate (DHK) or inhibition of GS activity with methionine sulfoximine (MSO) abolished the neuroprotection induced by HPC. Also, HPC markedly upregulated Cx43 and inhibited p-c-Src expression in CA1 after tGCI, whereas inhibition of Cx43 with Gap26 dramatically reversed this effect. Furthermore, inhibition of p-c-Src with 4-amino-5-(4-chlorophenyl)-7-(t-butyl) pyrazolo (3, 4-d) pyrimidine (PP2) decreased c-Src activity, increased protein levels of GLT-1 and Cx43, enhanced GS activity, and thus reduced extracellular glutamate level in CA1 after tGCI. Collectively, our data demonstrated that reduced extracellular glutamate induced by HPC against tGCI through preventing the reduction of GLT-1 expression and maintaining GS activity in hippocampal CA1, which was mediated by upregulating Cx43 expression and inhibiting c-Src activity.
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Affiliation(s)
- Kongping Li
- Institute of Neurosciences and Department of Neurology of the Second Affiliated Hospital of Guangzhou Medical University and Key Laboratory of Neurogenetics and Channelopathies of Guangdong Province and the Ministry of Education of China, Guangzhou, China
| | - Huarong Zhou
- Institute of Neurosciences and Department of Neurology of the Second Affiliated Hospital of Guangzhou Medical University and Key Laboratory of Neurogenetics and Channelopathies of Guangdong Province and the Ministry of Education of China, Guangzhou, China
| | - Lixuan Zhan
- Institute of Neurosciences and Department of Neurology of the Second Affiliated Hospital of Guangzhou Medical University and Key Laboratory of Neurogenetics and Channelopathies of Guangdong Province and the Ministry of Education of China, Guangzhou, China
| | - Zhe Shi
- Institute of Neurosciences and Department of Neurology of the Second Affiliated Hospital of Guangzhou Medical University and Key Laboratory of Neurogenetics and Channelopathies of Guangdong Province and the Ministry of Education of China, Guangzhou, China
| | - Weiwen Sun
- Institute of Neurosciences and Department of Neurology of the Second Affiliated Hospital of Guangzhou Medical University and Key Laboratory of Neurogenetics and Channelopathies of Guangdong Province and the Ministry of Education of China, Guangzhou, China
| | - Dandan Liu
- Institute of Neurosciences and Department of Neurology of the Second Affiliated Hospital of Guangzhou Medical University and Key Laboratory of Neurogenetics and Channelopathies of Guangdong Province and the Ministry of Education of China, Guangzhou, China
| | - Liu Liu
- Institute of Neurosciences and Department of Neurology of the Second Affiliated Hospital of Guangzhou Medical University and Key Laboratory of Neurogenetics and Channelopathies of Guangdong Province and the Ministry of Education of China, Guangzhou, China
| | - Donghai Liang
- Department of Environmental Health Sciences, Rollins School of Public Health, Emory University, Atlanta, GA, United States
| | - Yafu Tan
- Institute of Neurosciences and Department of Neurology of the Second Affiliated Hospital of Guangzhou Medical University and Key Laboratory of Neurogenetics and Channelopathies of Guangdong Province and the Ministry of Education of China, Guangzhou, China.,Department of Neurology, The First Affiliated Hospital of Guangxi Medical University, Nanning, China
| | - Wensheng Xu
- Institute of Neurosciences and Department of Neurology of the Second Affiliated Hospital of Guangzhou Medical University and Key Laboratory of Neurogenetics and Channelopathies of Guangdong Province and the Ministry of Education of China, Guangzhou, China
| | - En Xu
- Institute of Neurosciences and Department of Neurology of the Second Affiliated Hospital of Guangzhou Medical University and Key Laboratory of Neurogenetics and Channelopathies of Guangdong Province and the Ministry of Education of China, Guangzhou, China
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Lu C, Meng Z, He Y, Xiao D, Cai H, Xu Y, Liu X, Wang X, Mo L, Liang Z, Wei X, Ao Q, Liang B, Li X, Tang S, Guo S. Involvement of gap junctions in astrocyte impairment induced by manganese exposure. Brain Res Bull 2018; 140:107-113. [DOI: 10.1016/j.brainresbull.2018.04.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2017] [Revised: 03/16/2018] [Accepted: 04/13/2018] [Indexed: 11/28/2022]
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Abstract
Major depressive disorder (MDD) is a chronic and debilitating illness that affects over 350 million people worldwide; however, current treatments have failed to cure or prevent the progress of depression. Increasing evidence suggests a crucial role for connexins in MDD. In this review, we have summarised recent accomplishments regarding the role of connexins, gap junctions, and hemichannels in the aetiology of MDD, and discussed the limitations of current research. A blockage of gap junctions or hemichannels induces depressive behaviour. Possible underlying mechanisms include the regulation of neurosecretory functions and synaptic activity by gap junctions and hemichannels. Gap junctions are functionally inhibited under stress conditions. Conversely, hemichannel permeability is increased. Antidepressants inhibit hemichannel permeability; however, they have contrasting effects on the function of gap junctions under normal conditions and can protect them against stress. In conclusion, the blockage of hemichannels concurrent with improvements in gap junction functionality might be potential targets for depression treatment.
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Affiliation(s)
- Cong-Yuan Xia
- State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Institute of Materia Medica & Neuroscience Center, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100050, China
| | - Zhen-Zhen Wang
- State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Institute of Materia Medica & Neuroscience Center, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100050, China
| | - Tohru Yamakuni
- Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai 980-8578, Japan
| | - Nai-Hong Chen
- State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Institute of Materia Medica & Neuroscience Center, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100050, China; College of Pharmacy, Hunan University of Chinese Medicine, Changsha, Hunan 410208, China.
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Ren Q, Wang ZZ, Chu SF, Xia CY, Chen NH. Gap junction channels as potential targets for the treatment of major depressive disorder. Psychopharmacology (Berl) 2018; 235:1-12. [PMID: 29178009 DOI: 10.1007/s00213-017-4782-7] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/11/2017] [Accepted: 11/05/2017] [Indexed: 01/08/2023]
Abstract
BACKGROUND Major depressive disorder (MDD) remains a major public health problem worldwide. The association between MDD and the dysfunction of gap junction channels (GJCs) in glial cells, especially astrocytes, is still controversial. OBJECTIVE This review provides an overview of the role of astrocyte GJCs in LMDD. RESULTS Exposure to chronic unpredictable stress caused a reduction in connexin expression in the rat prefrontal cortex, a result that is consistent with clinical findings reported in postmortem studies of brains from MDD patients. Chronic antidepressant treatment in these rats increased the expression of connexins. However, pharmacological GJC blockade in normal rodents decreased connexin expression and caused depressive-like behaviors. Furthermore, GJC dysfunction affects electrical conductance, metabolic coupling and secondary messengers, and inflammatory responses, which are consistent with current hypotheses on MDD. All these results provide a comprehensive overview of the neurobiology of MDD. CONCLUSION This review supports the hypothesis that the regulation of GJCs between astrocytes could be an underlying mechanism for the therapeutic effect of antidepressants.
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Affiliation(s)
- Qian Ren
- State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Institute of Materia Medica & Neuroscience Center, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100050, China
| | - Zhen-Zhen Wang
- State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Institute of Materia Medica & Neuroscience Center, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100050, China
| | - Shi-Feng Chu
- State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Institute of Materia Medica & Neuroscience Center, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100050, China
| | - Cong-Yuan Xia
- State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Institute of Materia Medica & Neuroscience Center, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100050, China
| | - Nai-Hong Chen
- State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Institute of Materia Medica & Neuroscience Center, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100050, China. .,College of Pharmacy, Hunan University of Chinese Medicine, Changsha, Hunan, 410208, China.
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Dong H, Zhou XW, Wang X, Yang Y, Luo JW, Liu YH, Mao Q. Complex role of connexin 43 in astrocytic tumors and possible promotion of glioma‑associated epileptic discharge (Review). Mol Med Rep 2017; 16:7890-7900. [PMID: 28983585 DOI: 10.3892/mmr.2017.7618] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2016] [Accepted: 06/19/2017] [Indexed: 02/05/2023] Open
Abstract
Connexin (Cx)43 is a multifunction protein which forms gap junction channels and hemi‑channels. It also contains abundant binding domains which possess the ability to interact with certain Cx43‑associated proteins and therefore serve a fundamental role in various physiological and pathological functions. However, the understanding of the association between cancer and Cx43 along with Cx43‑gap junctions (GJ) remains unclear. All available data illustrate that Cx43 and its associated GJ serve important functions in cancers. The expression levels of Cx43 demonstrate a downward trend and an increase in the levels of malignancy, particularly in astrocytomas. The GJ intercellular communication activity in glioma cells can be adjusted via Cx43 phosphorylation and through the combination of Cx43 and its associated protein. Available evidence reveals Cx43 as a tumor‑inhibiting factor that suppresses glioma growth and proliferation. However, its mechanism is also regarded as complicated and ambiguous. Furthermore, it is apparent that Cx43‑GJ and the carboxyl tail may contribute to glioma growth and proliferation too. However, this valuable role could be weakened by its effects on migration and invasiveness. The detailed mechanism remains unclear and full of controversies. Cx43 can enhance the motor ability and invasiveness of astrocytic glioma cells. It is also able to influence glioma cells to detach from the tumor core to the peritumoral neocortex. This peritumoral region has recently been regarded as the basic focus of glioma‑associated seizure. Thus, Cx43 may take part in the onset and development of glioma‑associated epileptic discharge. In addition, change and increase of Cx43 expression in GJs has been observed in seizure perilesional tissue, which is associated with brain tumors. Cx43 or GJ/hemi‑channels exert enduring effects in the promotion of glioma‑associated epileptic release through direct mass effects and change of the tumor microenvironment. However, there are still a number of issues concerning this aspect that require further exploration. Cx43, as a potential treatment target against this incurable disease and its common symptom of epilepsy, requires further investigation.
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Affiliation(s)
- Hui Dong
- Department of Neurosurgery, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, P.R. China
| | - Xing-Wang Zhou
- Department of Neurosurgery, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, P.R. China
| | - Xiang Wang
- Department of Neurosurgery, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, P.R. China
| | - Yuan Yang
- Department of Neurosurgery, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, P.R. China
| | - Jie-Wen Luo
- Department of Neurosurgery, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, P.R. China
| | - Yan-Hui Liu
- Department of Neurosurgery, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, P.R. China
| | - Qing Mao
- Department of Neurosurgery, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, P.R. China
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Inhibition of Gap Junction Elevates Glutamate Uptake in Cultured Astrocytes. Neurochem Res 2017; 43:59-65. [PMID: 28589517 DOI: 10.1007/s11064-017-2316-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2017] [Revised: 05/26/2017] [Accepted: 05/27/2017] [Indexed: 10/19/2022]
Abstract
Glutamate uptake is a main function of astrocytes to keep extracellular glutamate levels low and protect neurons against glutamate-induced excitotoxicity. On the other hand, astrocyte networks formed by gap junctions, which are consisted with connexins and connecting neighboring cells, are reported to play a critical role in maintaining the homeostasis in the brain. In the present study, we examined the effects of gap junction inhibitors on the glutamate uptake activity in cultured rat cortical astrocytes. At first, we confirmed the effects of gap junction inhibitors, 1-octanol and carbenoxolone, on cell-cell communication by the scrape-loading assay using a fluorescent dye Lucifer yellow. Both of 1-octanol and carbenoxolone treatments for 20 min in cultured astrocytes significantly suppressed the cell-cell communication assessed as the distance of dye-spreading. 1-octanol and carbenoxolone increased the glutamate uptake by astrocytes and glutamate aspartate transporter (GLAST) expression on the cell membrane. These results suggest that gap junction inhibitors increase the glutamate uptake activity through the increase of GLAST proteins located on the cell membrane. The regulation of gap junction in astrocytes might protect neurons against glutamate-induced excitotoxicity.
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Haroon E, Miller AH, Sanacora G. Inflammation, Glutamate, and Glia: A Trio of Trouble in Mood Disorders. Neuropsychopharmacology 2017; 42:193-215. [PMID: 27629368 PMCID: PMC5143501 DOI: 10.1038/npp.2016.199] [Citation(s) in RCA: 307] [Impact Index Per Article: 43.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/13/2016] [Revised: 09/05/2016] [Accepted: 09/08/2016] [Indexed: 02/07/2023]
Abstract
Increasing data indicate that inflammation and alterations in glutamate neurotransmission are two novel pathways to pathophysiology in mood disorders. The primary goal of this review is to illustrate how these two pathways may converge at the level of the glia to contribute to neuropsychiatric disease. We propose that a combination of failed clearance and exaggerated release of glutamate by glial cells during immune activation leads to glutamate increases and promotes aberrant extrasynaptic signaling through ionotropic and metabotropic glutamate receptors, ultimately resulting in synaptic dysfunction and loss. Furthermore, glutamate diffusion outside the synapse can lead to the loss of synaptic fidelity and specificity of neurotransmission, contributing to circuit dysfunction and behavioral pathology. This review examines the fundamental role of glia in the regulation of glutamate, followed by a description of the impact of inflammation on glial glutamate regulation at the cellular, molecular, and metabolic level. In addition, the role of these effects of inflammation on glia and glutamate in mood disorders will be discussed along with their translational implications.
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Affiliation(s)
- Ebrahim Haroon
- Department of Psychiatry and Behavioral Sciences, Emory University School of Medicine, Atlanta, GA, USA
| | - Andrew H Miller
- Department of Psychiatry and Behavioral Sciences, Emory University School of Medicine, Atlanta, GA, USA
| | - Gerard Sanacora
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT, USA
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Sajja VSSS, Hlavac N, VandeVord PJ. Role of Glia in Memory Deficits Following Traumatic Brain Injury: Biomarkers of Glia Dysfunction. Front Integr Neurosci 2016; 10:7. [PMID: 26973475 PMCID: PMC4770450 DOI: 10.3389/fnint.2016.00007] [Citation(s) in RCA: 75] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2015] [Accepted: 02/05/2016] [Indexed: 12/15/2022] Open
Abstract
Historically, glial cells have been recognized as a structural component of the brain. However, it has become clear that glial cells are intimately involved in the complexities of neural networks and memory formations. Astrocytes, microglia, and oligodendrocytes have dynamic responsibilities which substantially impact neuronal function and activities. Moreover, the importance of glia following brain injury has come to the forefront in discussions to improve axonal regeneration and functional recovery. The numerous activities of glia following injury can either promote recovery or underlie the pathobiology of memory deficits. This review outlines the pathological states of glial cells which evolve from their positive supporting roles to those which disrupt synaptic function and neuroplasticity following injury. Evidence suggests that glial cells interact extensively with neurons both chemically and physically, reinforcing their role as pivotal for higher brain functions such as learning and memory. Collectively, this mini review surveys investigations of how glial dysfunction following brain injury can alter mechanisms of synaptic plasticity and how this may be related to an increased risk for persistent memory deficits. We also include recent findings, that demonstrate new molecular avenues for clinical biomarker discovery.
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Affiliation(s)
- Venkata S S S Sajja
- Cellular Imaging Section and Vascular Biology Program, Department of Radiology and Radiological Science, Institute for Cell Engineering, Johns Hopkins University School of Medicine Baltimore, MA, USA
| | - Nora Hlavac
- Department of Biomedical Engineering and Mechanics, Virginia Tech University Blacksburg, VA, USA
| | - Pamela J VandeVord
- Department of Biomedical Engineering and Mechanics, Virginia Tech University Blacksburg, VA, USA
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14
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Pinet-Charvet C, Geller S, Desroziers E, Ottogalli M, Lomet D, Georgelin C, Tillet Y, Franceschini I, Vaudin P, Duittoz A. GnRH Episodic Secretion Is Altered by Pharmacological Blockade of Gap Junctions: Possible Involvement of Glial Cells. Endocrinology 2016; 157:304-22. [PMID: 26562259 DOI: 10.1210/en.2015-1437] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Episodic release of GnRH is essential for reproductive function. In vitro studies have established that this episodic release is an endogenous property of GnRH neurons and that GnRH secretory pulses are associated with synchronization of GnRH neuron activity. The cellular mechanisms by which GnRH neurons synchronize remain largely unknown. There is no clear evidence of physical coupling of GnRH neurons through gap junctions to explain episodic synchronization. However, coupling of glial cells through gap junctions has been shown to regulate neuron activity in their microenvironment. The present study investigated whether glial cell communication through gap junctions plays a role in GnRH neuron activity and secretion in the mouse. Our findings show that Glial Fibrillary Acidic Protein-expressing glial cells located in the median eminence in close vicinity to GnRH fibers expressed Gja1 encoding connexin-43. To study the impact of glial-gap junction coupling on GnRH neuron activity, an in vitro model of primary cultures from mouse embryo nasal placodes was used. In this model, GnRH neurons possess a glial microenvironment and were able to release GnRH in an episodic manner. Our findings show that in vitro glial cells forming the microenvironment of GnRH neurons expressed connexin-43 and displayed functional gap junctions. Pharmacological blockade of the gap junctions with 50 μM 18-α-glycyrrhetinic acid decreased GnRH secretion by reducing pulse frequency and amplitude, suppressed neuronal synchronization and drastically reduced spontaneous electrical activity, all these effects were reversed upon 18-α-glycyrrhetinic acid washout.
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Affiliation(s)
- Caroline Pinet-Charvet
- Unité Mixte de Recherche (UMR) 85 Physiologie de la Reproduction et des Comportements (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), Institut National de la Recherche Agronomique (INRA); UMR7247 (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), Centre National de la Recherche Scientifique (CNRS); and Institut Français du Cheval et de l'Equitation (IFCE) (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), F-37380 Nouzilly, France; Physiologie de la Reproduction et des Comportements (PRC) UMR7247 INRA CNRS IFCE (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.) and CNRS UMR7350 (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), Laboratoire de Mathématiques et Physiques Théoriques, Université François Rabelais, F-37041 Tours, France; Fédération Denis Poisson (C.G.), F-37000 Tours, France; Structure Fédérative de Recherche (SFR) FED4226 Neuro-Imagerie Fonctionnelle (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), F-37044 Tours, France; and Université de Poitiers (C.P.-C.), Unité de Formation et de Recherche (UFR) Pharmacie, F-86000 Poitiers, France
| | - Sarah Geller
- Unité Mixte de Recherche (UMR) 85 Physiologie de la Reproduction et des Comportements (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), Institut National de la Recherche Agronomique (INRA); UMR7247 (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), Centre National de la Recherche Scientifique (CNRS); and Institut Français du Cheval et de l'Equitation (IFCE) (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), F-37380 Nouzilly, France; Physiologie de la Reproduction et des Comportements (PRC) UMR7247 INRA CNRS IFCE (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.) and CNRS UMR7350 (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), Laboratoire de Mathématiques et Physiques Théoriques, Université François Rabelais, F-37041 Tours, France; Fédération Denis Poisson (C.G.), F-37000 Tours, France; Structure Fédérative de Recherche (SFR) FED4226 Neuro-Imagerie Fonctionnelle (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), F-37044 Tours, France; and Université de Poitiers (C.P.-C.), Unité de Formation et de Recherche (UFR) Pharmacie, F-86000 Poitiers, France
| | - Elodie Desroziers
- Unité Mixte de Recherche (UMR) 85 Physiologie de la Reproduction et des Comportements (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), Institut National de la Recherche Agronomique (INRA); UMR7247 (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), Centre National de la Recherche Scientifique (CNRS); and Institut Français du Cheval et de l'Equitation (IFCE) (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), F-37380 Nouzilly, France; Physiologie de la Reproduction et des Comportements (PRC) UMR7247 INRA CNRS IFCE (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.) and CNRS UMR7350 (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), Laboratoire de Mathématiques et Physiques Théoriques, Université François Rabelais, F-37041 Tours, France; Fédération Denis Poisson (C.G.), F-37000 Tours, France; Structure Fédérative de Recherche (SFR) FED4226 Neuro-Imagerie Fonctionnelle (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), F-37044 Tours, France; and Université de Poitiers (C.P.-C.), Unité de Formation et de Recherche (UFR) Pharmacie, F-86000 Poitiers, France
| | - Monique Ottogalli
- Unité Mixte de Recherche (UMR) 85 Physiologie de la Reproduction et des Comportements (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), Institut National de la Recherche Agronomique (INRA); UMR7247 (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), Centre National de la Recherche Scientifique (CNRS); and Institut Français du Cheval et de l'Equitation (IFCE) (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), F-37380 Nouzilly, France; Physiologie de la Reproduction et des Comportements (PRC) UMR7247 INRA CNRS IFCE (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.) and CNRS UMR7350 (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), Laboratoire de Mathématiques et Physiques Théoriques, Université François Rabelais, F-37041 Tours, France; Fédération Denis Poisson (C.G.), F-37000 Tours, France; Structure Fédérative de Recherche (SFR) FED4226 Neuro-Imagerie Fonctionnelle (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), F-37044 Tours, France; and Université de Poitiers (C.P.-C.), Unité de Formation et de Recherche (UFR) Pharmacie, F-86000 Poitiers, France
| | - Didier Lomet
- Unité Mixte de Recherche (UMR) 85 Physiologie de la Reproduction et des Comportements (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), Institut National de la Recherche Agronomique (INRA); UMR7247 (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), Centre National de la Recherche Scientifique (CNRS); and Institut Français du Cheval et de l'Equitation (IFCE) (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), F-37380 Nouzilly, France; Physiologie de la Reproduction et des Comportements (PRC) UMR7247 INRA CNRS IFCE (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.) and CNRS UMR7350 (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), Laboratoire de Mathématiques et Physiques Théoriques, Université François Rabelais, F-37041 Tours, France; Fédération Denis Poisson (C.G.), F-37000 Tours, France; Structure Fédérative de Recherche (SFR) FED4226 Neuro-Imagerie Fonctionnelle (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), F-37044 Tours, France; and Université de Poitiers (C.P.-C.), Unité de Formation et de Recherche (UFR) Pharmacie, F-86000 Poitiers, France
| | - Christine Georgelin
- Unité Mixte de Recherche (UMR) 85 Physiologie de la Reproduction et des Comportements (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), Institut National de la Recherche Agronomique (INRA); UMR7247 (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), Centre National de la Recherche Scientifique (CNRS); and Institut Français du Cheval et de l'Equitation (IFCE) (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), F-37380 Nouzilly, France; Physiologie de la Reproduction et des Comportements (PRC) UMR7247 INRA CNRS IFCE (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.) and CNRS UMR7350 (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), Laboratoire de Mathématiques et Physiques Théoriques, Université François Rabelais, F-37041 Tours, France; Fédération Denis Poisson (C.G.), F-37000 Tours, France; Structure Fédérative de Recherche (SFR) FED4226 Neuro-Imagerie Fonctionnelle (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), F-37044 Tours, France; and Université de Poitiers (C.P.-C.), Unité de Formation et de Recherche (UFR) Pharmacie, F-86000 Poitiers, France
| | - Yves Tillet
- Unité Mixte de Recherche (UMR) 85 Physiologie de la Reproduction et des Comportements (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), Institut National de la Recherche Agronomique (INRA); UMR7247 (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), Centre National de la Recherche Scientifique (CNRS); and Institut Français du Cheval et de l'Equitation (IFCE) (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), F-37380 Nouzilly, France; Physiologie de la Reproduction et des Comportements (PRC) UMR7247 INRA CNRS IFCE (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.) and CNRS UMR7350 (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), Laboratoire de Mathématiques et Physiques Théoriques, Université François Rabelais, F-37041 Tours, France; Fédération Denis Poisson (C.G.), F-37000 Tours, France; Structure Fédérative de Recherche (SFR) FED4226 Neuro-Imagerie Fonctionnelle (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), F-37044 Tours, France; and Université de Poitiers (C.P.-C.), Unité de Formation et de Recherche (UFR) Pharmacie, F-86000 Poitiers, France
| | - Isabelle Franceschini
- Unité Mixte de Recherche (UMR) 85 Physiologie de la Reproduction et des Comportements (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), Institut National de la Recherche Agronomique (INRA); UMR7247 (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), Centre National de la Recherche Scientifique (CNRS); and Institut Français du Cheval et de l'Equitation (IFCE) (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), F-37380 Nouzilly, France; Physiologie de la Reproduction et des Comportements (PRC) UMR7247 INRA CNRS IFCE (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.) and CNRS UMR7350 (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), Laboratoire de Mathématiques et Physiques Théoriques, Université François Rabelais, F-37041 Tours, France; Fédération Denis Poisson (C.G.), F-37000 Tours, France; Structure Fédérative de Recherche (SFR) FED4226 Neuro-Imagerie Fonctionnelle (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), F-37044 Tours, France; and Université de Poitiers (C.P.-C.), Unité de Formation et de Recherche (UFR) Pharmacie, F-86000 Poitiers, France
| | - Pascal Vaudin
- Unité Mixte de Recherche (UMR) 85 Physiologie de la Reproduction et des Comportements (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), Institut National de la Recherche Agronomique (INRA); UMR7247 (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), Centre National de la Recherche Scientifique (CNRS); and Institut Français du Cheval et de l'Equitation (IFCE) (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), F-37380 Nouzilly, France; Physiologie de la Reproduction et des Comportements (PRC) UMR7247 INRA CNRS IFCE (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.) and CNRS UMR7350 (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), Laboratoire de Mathématiques et Physiques Théoriques, Université François Rabelais, F-37041 Tours, France; Fédération Denis Poisson (C.G.), F-37000 Tours, France; Structure Fédérative de Recherche (SFR) FED4226 Neuro-Imagerie Fonctionnelle (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), F-37044 Tours, France; and Université de Poitiers (C.P.-C.), Unité de Formation et de Recherche (UFR) Pharmacie, F-86000 Poitiers, France
| | - Anne Duittoz
- Unité Mixte de Recherche (UMR) 85 Physiologie de la Reproduction et des Comportements (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), Institut National de la Recherche Agronomique (INRA); UMR7247 (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), Centre National de la Recherche Scientifique (CNRS); and Institut Français du Cheval et de l'Equitation (IFCE) (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), F-37380 Nouzilly, France; Physiologie de la Reproduction et des Comportements (PRC) UMR7247 INRA CNRS IFCE (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.) and CNRS UMR7350 (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), Laboratoire de Mathématiques et Physiques Théoriques, Université François Rabelais, F-37041 Tours, France; Fédération Denis Poisson (C.G.), F-37000 Tours, France; Structure Fédérative de Recherche (SFR) FED4226 Neuro-Imagerie Fonctionnelle (C.P.-C., S.G., E.D., M.O., D.L., Y.T., I.F., P.V., A.D.), F-37044 Tours, France; and Université de Poitiers (C.P.-C.), Unité de Formation et de Recherche (UFR) Pharmacie, F-86000 Poitiers, France
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Morioka N, Zhang FF, Nakamura Y, Kitamura T, Hisaoka-Nakashima K, Nakata Y. Tumor necrosis factor-mediated downregulation of spinal astrocytic connexin43 leads to increased glutamatergic neurotransmission and neuropathic pain in mice. Brain Behav Immun 2015; 49:293-310. [PMID: 26116449 DOI: 10.1016/j.bbi.2015.06.015] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/13/2015] [Revised: 06/05/2015] [Accepted: 06/16/2015] [Indexed: 11/29/2022] Open
Abstract
Spinal cord astrocytes are critical in the maintenance of neuropathic pain. Connexin 43 (Cx43) expressed on spinal dorsal horn astrocytes modulates synaptic neurotransmission, but its role in nociceptive transduction has yet to be fully elaborated. In mice, Cx43 is mainly expressed in astrocytes, not neurons or microglia, in the spinal dorsal horn. Hind paw mechanical hypersensitivity was observed beginning 3days after partial sciatic nerve ligation (PSNL), but a persistent downregulation of astrocytic Cx43 in ipsilateral lumbar spinal dorsal horn was not observed until 7days post-PSNL, suggesting that Cx43 downregulation mediates the maintenance and not the initiation of nerve injury-induced hypersensitivity. Downregulation of Cx43 expression by intrathecal treatment with Cx43 siRNA also induced mechanical hypersensitivity. Conversely, restoring Cx43 by an adenovirus vector expressing Cx43 (Ad-Cx43) ameliorated PSNL-induced mechanical hypersensitivity. The sensitized state following PSNL is likely maintained by dysfunctional glutamatergic neurotransmission, as Cx43 siRNA-induced mechanical hypersensitivity was attenuated with intrathecal treatment of glutamate receptor antagonists MK801 and CNQX, but not neurokinin-1 receptor antagonist CP96345 or the Ca(2+) channel subunit α2δ1 blocker gabapentin. The source of this dysfunctional glutamatergic neurotransmission is likely decreased clearance of glutamate from the synapse rather than increased glutamate release into the synapse. Astrocytic expression of glutamate transporter GLT-1, but not GLAST, and activity of glutamate transport were markedly decreased in mice intrathecally injected with Cx43-targeting siRNA but not non-targeting siRNA. Glutamate release from spinal synaptosomes prepared from mice treated with either Cx43-targeting siRNA or non-targeting siRNA was unchanged. Intrathecal injection of Ad-Cx43 in PSNL mice restored astrocytic GLT-1 expression. The cytokine tumor necrosis factor (TNF) has been implicated in the induction of central sensitization, particularly through its actions on astrocytes, in the spinal cord following peripheral injury. Intrathecal injection of TNF in naïve mice induced the downregulation of both Cx43 and GLT-1 in spinal dorsal horn, as well as hind paw mechanical hypersensitivity, as observed in PSNL mice. Conversely, intrathecal treatment of PSNL mice with the TNF inhibitor etanercept prevented not only mechanical hypersensitivity but also the downregulation of Cx43 and GLT-1 expression in astrocytes. The current findings indicate that spinal astrocytic Cx43 are essential for the maintenance of neuropathic pain following peripheral nerve injury and suggest modulation of Cx43 as a novel target for developing analgesics for neuropathic pain.
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Affiliation(s)
- Norimitsu Morioka
- Department of Pharmacology, Hiroshima University Graduate School of Biomedical & Health Sciences, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8553, Japan.
| | - Fang Fang Zhang
- Department of Pharmacology, Hiroshima University Graduate School of Biomedical & Health Sciences, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8553, Japan
| | - Yoki Nakamura
- Department of Pharmacology, Hiroshima University Graduate School of Biomedical & Health Sciences, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8553, Japan
| | - Tomoya Kitamura
- Department of Pharmacology, Hiroshima University Graduate School of Biomedical & Health Sciences, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8553, Japan
| | - Kazue Hisaoka-Nakashima
- Department of Pharmacology, Hiroshima University Graduate School of Biomedical & Health Sciences, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8553, Japan
| | - Yoshihiro Nakata
- Department of Pharmacology, Hiroshima University Graduate School of Biomedical & Health Sciences, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8553, Japan
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16
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Activity-Dependent Plasticity of Astroglial Potassium and Glutamate Clearance. Neural Plast 2015; 2015:109106. [PMID: 26346563 PMCID: PMC4539499 DOI: 10.1155/2015/109106] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2015] [Accepted: 04/17/2015] [Indexed: 12/21/2022] Open
Abstract
Recent evidence has shown that astrocytes play essential roles in synaptic transmission and plasticity. Nevertheless, how neuronal activity alters astroglial functional properties and whether such properties also display specific forms of plasticity still remain elusive. Here, we review research findings supporting this aspect of astrocytes, focusing on their roles in the clearance of extracellular potassium and glutamate, two neuroactive substances promptly released during excitatory synaptic transmission. Their subsequent removal, which is primarily carried out by glial potassium channels and glutamate transporters, is essential for proper functioning of the brain. Similar to neurons, different forms of short- and long-term plasticity in astroglial uptake have been reported. In addition, we also present novel findings showing robust potentiation of astrocytic inward currents in response to repetitive stimulations at mild frequencies, as low as 0.75 Hz, in acute hippocampal slices. Interestingly, neurotransmission was hardly affected at this frequency range, suggesting that astrocytes may be more sensitive to low frequency stimulation and may exhibit stronger plasticity than neurons to prevent hyperexcitability. Taken together, these important findings strongly indicate that astrocytes display both short- and long-term plasticity in their clearance of excess neuroactive substances from the extracellular space, thereby regulating neuronal activity and brain homeostasis.
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17
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Sun L, Gao J, Zhao M, Cui J, Li Y, Yang X, Jing X, Wu Z. A novel cognitive impairment mechanism that astrocytic p-connexin 43 promotes neuronic autophagy via activation of P2X7R and down-regulation of GLT-1 expression in the hippocampus following traumatic brain injury in rats. Behav Brain Res 2015; 291:315-324. [PMID: 26031379 DOI: 10.1016/j.bbr.2015.05.049] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2015] [Accepted: 05/27/2015] [Indexed: 11/29/2022]
Abstract
Connexin 43 (Cx43) is one of the major gap junction proteins in astrocytes. Our previous studies reported that astrocytic phosphorylated Cx43 (p-CX43) regulated neuronic autophagy levels in the rat hippocampus after traumatic brain injury (TBI). In this study, we explored the underlying molecular mechanism by which gap junctional intercellular communication influenced neuronic autophagy and therefore initiated cognitive and memory impairments after TBI. The gap junctional blocker carbenoxolone (CBX) or autophagy inhibitor 3-methyladenine (3-MA) reduced latencies, as compared to TBI rats. Similarly, CBX or 3-MA restored long-term potentiation (LTP), relative to TBI hippocampal slices. Immunoblotting analysis showed that the expression of autophagy-related gene Beclin-1 in the hippocampus post-TBI were decreased in response to treatment with CBX, the P2X7 receptor (P2X7R) antagonist Oxidized ATP (OxATP) or ceftriaxone (Cef) which increased the expression and activity of the glutamate transporter (GLT-1) in the central nervous system (CNS). Moreover, CBX or OxATP pretreatment increased GLT-1 level in the rat hippocampus after TBI. However, CBX pretreatment suppressed P2X7R expression whereas maintained P2X7 level post-TBI. Confocal images revealed that p-CX43, P2X7 and GLT-1 strongly colocalized with glial fibrillary acidic protein (GFAP). Taken together, these results implied that Cx43, might induce neuronic autophagy by activation of P2X7R and reduce the expression of GLT-1 in the hippocampus, promoting TBI-induced cognitive deficits repair. Therefore, control of this communication may be serve as therapeutic strategies for intervention against TBI.
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Affiliation(s)
- Liqian Sun
- Department of Interventional Neuroradiology, Beijing Neurosurgical Institute and Beijing Tiantan Hospital, Capital Medical University, Beijing 100050, China
| | - Junling Gao
- Department of Histology and Embryology, School of Basic Medical Science, North China University Science And Technology, Tangshan 063000, Hebei, China
| | - Manman Zhao
- Department of Histology and Embryology, School of Basic Medical Science, North China University Science And Technology, Tangshan 063000, Hebei, China
| | - Jianzhong Cui
- Department of Neurosurgery, Tangshan Gongren Hospital, Tangshan 063000, Hebei, China
| | - Youxiang Li
- Department of Interventional Neuroradiology, Beijing Neurosurgical Institute and Beijing Tiantan Hospital, Capital Medical University, Beijing 100050, China
| | - Xinjian Yang
- Department of Interventional Neuroradiology, Beijing Neurosurgical Institute and Beijing Tiantan Hospital, Capital Medical University, Beijing 100050, China
| | - Xiaobin Jing
- Department of Ophthalmology, Tangshan Ophthalmology Hospital, Tangshan 063000, Hebei, China
| | - Zhongxue Wu
- Department of Interventional Neuroradiology, Beijing Neurosurgical Institute and Beijing Tiantan Hospital, Capital Medical University, Beijing 100050, China.
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Cheung G, Chever O, Rouach N. Connexons and pannexons: newcomers in neurophysiology. Front Cell Neurosci 2014; 8:348. [PMID: 25408635 PMCID: PMC4219455 DOI: 10.3389/fncel.2014.00348] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2014] [Accepted: 10/06/2014] [Indexed: 11/14/2022] Open
Abstract
Connexin hemichannels are single membrane channels which have been traditionally thought to work in pairs to form gap junction channels across two opposing cells. In astrocytes, gap junction channels allow direct intercellular communication and greatly facilitate the transmission of signals. Recently, there has been growing evidence demonstrating that connexin hemichannels, as well as pannexin channels, on their own are open in various conditions. They allow bidirectional flow of ions and signaling molecules and act as release sites for transmitters like ATP and glutamate into the extracellular space. While much attention has focused on the function of connexin hemichannels and pannexons during pathological situations like epilepsy, inflammation, neurodegeneration or ischemia, their potential roles in physiology is often ignored. In order to fully understand the dynamic properties and roles of connexin hemichannels and pannexons in the brain, it is essential to decipher whether they also have some physiological functions and contribute to normal cerebral processes. Here, we present recent studies in the CNS suggesting emerging physiological functions of connexin hemichannels and pannexons in normal neuronal activity and behavior. We also discuss how these pioneer studies pave the way for future research to extend the physiological relevance of connexons and pannexons, and some fundamental issues yet to be addressed.
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Affiliation(s)
- Giselle Cheung
- Neuroglial Interactions in Cerebral Physiopathology, Center for Interdisciplinary Research in Biology, Collège de France, CNRS UMR 7241, INSERM U1050, Labex Memolife, PSL Research University Paris, France
| | - Oana Chever
- Neuroglial Interactions in Cerebral Physiopathology, Center for Interdisciplinary Research in Biology, Collège de France, CNRS UMR 7241, INSERM U1050, Labex Memolife, PSL Research University Paris, France
| | - Nathalie Rouach
- Neuroglial Interactions in Cerebral Physiopathology, Center for Interdisciplinary Research in Biology, Collège de France, CNRS UMR 7241, INSERM U1050, Labex Memolife, PSL Research University Paris, France
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19
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Miguel-Hidalgo JJ, Wilson BA, Hussain S, Meshram A, Rajkowska G, Stockmeier CA. Reduced connexin 43 immunolabeling in the orbitofrontal cortex in alcohol dependence and depression. J Psychiatr Res 2014; 55:101-9. [PMID: 24774648 PMCID: PMC4078739 DOI: 10.1016/j.jpsychires.2014.04.007] [Citation(s) in RCA: 82] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/24/2014] [Revised: 03/18/2014] [Accepted: 04/04/2014] [Indexed: 11/28/2022]
Abstract
Reduced density of glial cells and low levels of some astrocyte proteins have been described in the orbitofrontal cortex (OFC) in depression and alcoholism, two disorders often comorbid. These regressive changes may also involve the communication between astrocytes via gap junctions and hemichannels, which play important regulatory roles in neurotransmission. We determined levels and morphological immunostaining parameters of connexin 43 (Cx43), the main protein subunit of astrocyte gap junctions/hemichannels, in the OFC of subjects with depression, alcoholism or comorbid depression/alcoholism as compared to non-psychiatric subjects. Postmortem brain samples from 23 subjects with major depressive disorder (MDD), 16 with alcohol dependence, 13 with comorbid MDD and alcohol dependence, and 20 psychiatrically-normal comparison subjects were processed for western blots to determine Cx43 levels. Area fraction of Cx43 immunoreactivity, and density and average size of immunoreactive puncta were measured in histological sections. There was a significant, larger than 60 percent decrease in Cx43 level in the three psychiatric groups as compared to controls. Area fraction of immunoreactivity and immunoreactive punctum size were reduced in all psychiatric groups, but Cx43-immunoreactive puncta density was reduced only in alcohol-dependent subjects. Among psychiatric subjects, no difference in Cx43 levels or immunostaining was found between suicides and non-suicides. The present data suggest that dysfunction of the OFC is accompanied by reduction in the levels of gap junction protein Cx43 in depression and alcoholism, and reduction in density of Cx43 immunoreactive puncta only in alcoholism, pointing to altered gap junction or hemichannel-based communication in the pathophysiology of those disorders.
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Affiliation(s)
- José Javier Miguel-Hidalgo
- Department of Psychiatry and Human Behavior, University of Mississippi Medical Center, 2500 N. State Street, Jackson, MS 39216-4505, USA.
| | - Barbara A. Wilson
- Psychiatry and Human Behavior, University of Mississippi Medical Center, Jackson, MS
| | - Syed Hussain
- Psychiatry and Human Behavior, University of Mississippi Medical Center, Jackson, MS
| | - Ashish Meshram
- Psychiatry and Human Behavior, University of Mississippi Medical Center, Jackson, MS
| | - Grazyna Rajkowska
- Psychiatry and Human Behavior, University of Mississippi Medical Center, Jackson, MS
| | - Craig A. Stockmeier
- Psychiatry and Human Behavior, University of Mississippi Medical Center, Jackson, MS,Psychiatry, Case Western Reserve University, Cleveland, OH
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Pannasch U, Rouach N. Emerging role for astroglial networks in information processing: from synapse to behavior. Trends Neurosci 2013; 36:405-17. [PMID: 23659852 DOI: 10.1016/j.tins.2013.04.004] [Citation(s) in RCA: 179] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2012] [Revised: 04/01/2013] [Accepted: 04/01/2013] [Indexed: 01/05/2023]
Abstract
Astrocytes contribute to neurotransmission through a variety of mechanisms ranging from synapse isolation to active signaling. Astroglial involvement in neurophysiology has been mostly investigated at the single-cell level. However, a unique feature of astrocytes is their high level of intercellular connectivity mediated by connexins, the proteins forming gap junction (GJ) channels. These astroglial GJ circuits enable the rapid intercellular exchange of ions, metabolites, and neuroactive substances. Recent findings have suggested that, despite their extensity, astroglial networks are also selective, preferential as well as plastic, and can regulate synapses, neuronal circuits, and behavior. The present review critically discusses the impact of astroglial networks on normal and pathological neuronal information processing as well as the underlying mechanisms.
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Affiliation(s)
- Ulrike Pannasch
- Neuroglial Interactions in Cerebral Physiopathology, Center for Interdisciplinary Research in Biology, Centre Nationale de la Recherche Scientifique (CNRS) Unité Mixte de Recherche 7241, Institut National de la Santé et de la Recherche Médicale (INSERM) Unité 1050, Collège de France, 75005 Paris, France
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21
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Kang HK, Kim OB, Min SK, Jung SY, Jang DH, Kwon TK, Min BM, Yeo IS. The effect of the DLTIDDSYWYRI motif of the human laminin α2 chain on implant osseointegration. Biomaterials 2013; 34:4027-4037. [PMID: 23465831 DOI: 10.1016/j.biomaterials.2013.02.023] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2012] [Accepted: 02/11/2013] [Indexed: 10/27/2022]
Abstract
Considerable effort has been directed towards replacing lost teeth using tissue-engineering methods such as titanium implants. A number of studies have tried to modify bioinert titanium surfaces by coating them with functionally bioactive molecules for faster and stronger osseointegration than pure titanium surfaces. Recently, peptides have been recognized as valuable scientific tools in the field of tissue-engineering. The DLTIDDSYWYRI motif of the human laminin-2 α2 chain has been previously reported to promote the attachment of various cell types; however, the in vivo effects of the DLTIDDSYWYRI motif on new bone formation have not yet been studied. To examine whether a laminin-2-derived peptide can promote osseointegration by accelerating new bone formation in vivo, we applied titanium implants coated with the DLTIDDSYWYRI motif in a rabbit tibia model. The application of the DLTIDDSYWYRI motif-treated implant to tibia wounds enhanced collagen deposition and alkaline phosphatase expression. It significantly promoted implant osseointegration compared with treatment with scrambled peptide-treated implants by increasing the bone-to-implant contact ratio and bone area. These findings support the hypothesis that the DLTIDDSYWYRI motif acts as an effective osseointegration accelerator by enhancing new bone formation.
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Affiliation(s)
- Hyun Ki Kang
- Department of Oral Biochemistry and Program in Cancer and Developmental Biology, Dental Research Institute, Seoul National University School of Dentistry, 28 Yeonkun-Dong, Chongno-Ku, Seoul 110-749, Republic of Korea.
| | - O Bok Kim
- Department of Oral Biochemistry and Program in Cancer and Developmental Biology, Dental Research Institute, Seoul National University School of Dentistry, 28 Yeonkun-Dong, Chongno-Ku, Seoul 110-749, Republic of Korea.
| | - Seung-Ki Min
- Department of Oral and Maxillofacial Surgery, Seoul National University School of Dentistry, 28 Yeonkun-Dong, Chongno-Ku, Seoul 110-749, Republic of Korea.
| | - Sung Youn Jung
- Department of Oral Biochemistry and Program in Cancer and Developmental Biology, Dental Research Institute, Seoul National University School of Dentistry, 28 Yeonkun-Dong, Chongno-Ku, Seoul 110-749, Republic of Korea.
| | - Da Hyun Jang
- Department of Oral Biochemistry and Program in Cancer and Developmental Biology, Dental Research Institute, Seoul National University School of Dentistry, 28 Yeonkun-Dong, Chongno-Ku, Seoul 110-749, Republic of Korea.
| | - Taek-Ka Kwon
- Department of Dentistry, St. Vincent Hospital, Catholic University of Korea, Ji-Dong, Paldal-Ku, Suwon 442-723, Republic of Korea.
| | - Byung-Moo Min
- Department of Oral Biochemistry and Program in Cancer and Developmental Biology, Dental Research Institute, Seoul National University School of Dentistry, 28 Yeonkun-Dong, Chongno-Ku, Seoul 110-749, Republic of Korea.
| | - In-Sung Yeo
- Department of Prosthodontics and Dental Research Institute, Seoul National University School of Dentistry, 28 Yeonkun-Dong, Chongno-Ku, Seoul 110-749, Republic of Korea.
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22
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Li Y, Zhou Y, Danbolt NC. The rates of postmortem proteolysis of glutamate transporters differ dramatically between cells and between transporter subtypes. J Histochem Cytochem 2012; 60:811-21. [PMID: 22859703 DOI: 10.1369/0022155412458589] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Glutamate transporters (GLT-1, GLAST, EAAC1) limit the actions of excitatory amino acids. Because a disturbed transporter operation can cause or aggravate neurological diseases, transporters are of considerable neuropathological interest. Human samples, however, are seldom obtained fresh. Here, we used mice brains to study how fast glutamate transporters are degraded after death. Immunoblots showed that terminal GLT-1 epitopes (within residues 1-26 and 518-573) had mostly disappeared after 24 hr. GLAST termini (1-25 and 522-543) degraded slightly slower. In contrast, epitopes within central parts of GLT-1 (493-508) and the EAAC1 C-terminus (510-523) were readily detectable after 72 hr. The decline in immunoreactivity of the GLT-1 and GLAST termini was also seen in tissue sections, but proteolysis did not happen synchronously in all cells. At 24 hr, scattered cells remained strongly immunopositive, while the majority of cells were completely immunonegative. GLAST and GLT-1 co-localized in neocortical tissue, but at 12 hr, many GLAST-positive cells had lost the GLT-1 termini. The uneven disappearance of labeling was not observed with the antibodies to GLT-1 residues 493-508. The immunoreactivity to this epitope correlated better with the reported glutamate uptake activity. Thus, postmortem delay may affect epitopes differently, possibly causing erroneous conclusions about relative expression levels.
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Affiliation(s)
- Yuchuan Li
- Department 3 E.N.T., 1st Affiliated Hospital of Zhengzhou University, Zhengzhou, China
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23
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Unger T, Bette S, Zhang J, Theis M, Engele J. Connexin-deficiency affects expression levels of glial glutamate transporters within the cerebrum. Neurosci Lett 2011; 506:12-6. [PMID: 22037505 DOI: 10.1016/j.neulet.2011.10.032] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2010] [Revised: 10/12/2011] [Accepted: 10/16/2011] [Indexed: 11/17/2022]
Abstract
The glial glutamate transporter subtypes, GLT-1/EAAT-2 and GLAST/EAAT-1 clear the bulk of extracellular glutamate and are severely dysregulated in various acute and chronic brain diseases. Despite the previous identification of several extracellular factors modulating glial glutamate transporter expression, our knowledge of the regulatory network controlling glial glutamate transport in health and disease still remains incomplete. In studies with cultured cortical astrocytes, we previously obtained evidence that glial glutamate transporter expression is also affected by gap junctions/connexins. To assess whether gap junctions would likewise control the in vivo expression of glial glutamate transporters, we have now assessed their expression levels in brains of conditional Cx43 knockout mice, total Cx30 knockouts, as well as Cx43/Cx30 double knockouts. We found that either knocking out Cx30, Cx43, or both increases GLT-1/EAAT-2 protein levels in the cerebral cortex to a similar extent. By contrast, GLAST/EAAT-1 protein levels maximally increased in cerebral cortices of Cx30/Cx43 double knockouts, implying that gap junctions differentially affect the expression of GLT-1/EAAT-2 and GLAST/EAAT-1. Quantitative PCR analysis further revealed that increases in glial glutamate transporter expression are brought about by transcriptional and translational/posttranslational processes. Moreover, GLT-1/EAAT-2- and GLAST/EAAT-1 protein levels remained unchanged in the hippocampi of Cx43/Cx30 double knockouts when compared to Cx43fl/fl controls, indicating brain region-specific effects of gap junctions on glial glutamate transport. Since astrocytic gap junction coupling is affected in various forms of brain injuries, our findings point to gap junctions/connexins as important regulators of glial glutamate turnover in the diseased cerebral cortex.
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Affiliation(s)
- Tina Unger
- Institute of Anatomy, University of Leipzig, Medical Faculty, Liebigstr. 13, 04103 Leipzig, Germany
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24
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Altered expression of glutamate signaling, growth factor, and glia genes in the locus coeruleus of patients with major depression. Mol Psychiatry 2011; 16:634-46. [PMID: 20386568 PMCID: PMC2927798 DOI: 10.1038/mp.2010.44] [Citation(s) in RCA: 252] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Several studies have proposed that brain glutamate signaling abnormalities and glial pathology have a role in the etiology of major depressive disorder (MDD). These conclusions were primarily drawn from post-mortem studies in which forebrain brain regions were examined. The locus coeruleus (LC) is the primary source of extensive noradrenergic innervation of the forebrain and as such exerts a powerful regulatory role over cognitive and affective functions, which are dysregulated in MDD. Furthermore, altered noradrenergic neurotransmission is associated with depressive symptoms and is thought to have a role in the pathophysiology of MDD. In the present study we used laser-capture microdissection (LCM) to selectively harvest LC tissue from post-mortem brains of MDD patients, patients with bipolar disorder (BPD) and from psychiatrically normal subjects. Using microarray technology we examined global patterns of gene expression. Differential mRNA expression of select candidate genes was then interrogated using quantitative real-time PCR (qPCR) and in situ hybridization (ISH). Our findings reveal multiple signaling pathway alterations in the LC of MDD but not BPD subjects. These include glutamate signaling genes, SLC1A2, SLC1A3 and GLUL, growth factor genes FGFR3 and TrkB, and several genes exclusively expressed in astroglia. Our data extend previous findings of altered glutamate, astroglial and growth factor functions in MDD for the first time to the brainstem. These findings indicate that such alterations: (1) are unique to MDD and distinguishable from BPD, and (2) affect multiple brain regions, suggesting a whole-brain dysregulation of such functions.
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25
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Neuroinflammation leads to region-dependent alterations in astrocyte gap junction communication and hemichannel activity. J Neurosci 2011; 31:414-25. [PMID: 21228152 DOI: 10.1523/jneurosci.5247-10.2011] [Citation(s) in RCA: 124] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Inflammation attenuates gap junction (GJ) communication in cultured astrocytes. Here we used a well-characterized model of experimental brain abscess as a tool to query effects of the CNS inflammatory milieu on astrocyte GJ communication and electrophysiological properties. Whole-cell patch-clamp recordings were performed on green fluorescent protein (GFP)-positive astrocytes in acute brain slices from glial fibrillary acidic protein-GFP mice at 3 or 7 d after Staphylococcus aureus infection in the striatum. Astrocyte GJ communication was significantly attenuated in regions immediately surrounding the abscess margins and progressively increased to levels typical of uninfected brain with increasing distance from the abscess proper. Conversely, astrocytes bordering the abscess demonstrated hemichannel activity as evident by enhanced ethidium bromide (EtBr) uptake that could be blocked by several pharmacological inhibitors, including the connexin 43 (Cx43) mimetic peptide Gap26, carbenoxolone, the pannexin1 (Panx1) mimetic peptide (10)Panx1, and probenecid. However, hemichannel opening was transient with astrocytic EtBr uptake observed near the abscess at day 3 but not day 7 after infection. The region-dependent pattern of hemichannel activity at day 3 directly correlated with increases in Cx43, Cx30, Panx1, and glutamate transporter expression (glial L-glutamate transporter and L-glutamate/L-aspartate transporter) along the abscess margins. Changes in astrocyte resting membrane potential and input conductance correlated with the observed changes in GJ communication and hemichannel activity. Collectively, these findings indicate that astrocyte coupling and electrical properties are most dramatically affected near the primary inflammatory site and reveal an opposing relationship between the open states of GJ channels versus hemichannels during acute infection. This relationship may extend to other CNS diseases typified with an inflammatory component.
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26
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Bao F, Chen M, Zhang Y, Zhao Z. Hypoalgesia in mice lacking aquaporin-4 water channels. Brain Res Bull 2010; 83:298-303. [DOI: 10.1016/j.brainresbull.2010.08.015] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2010] [Revised: 08/14/2010] [Accepted: 08/27/2010] [Indexed: 11/24/2022]
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27
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Giaume C. Astroglial Wiring is Adding Complexity to Neuroglial Networking. FRONTIERS IN NEUROENERGETICS 2010; 2. [PMID: 20922057 PMCID: PMC2948443 DOI: 10.3389/fnene.2010.00129] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/03/2010] [Accepted: 08/23/2010] [Indexed: 01/05/2023]
Abstract
Astrocytes are organized as networks of communicating cells due to their high expression level of connexins, the molecular constituents of gap junction channels. Based on their permeability properties for ions and small signaling molecules such astroglial wiring interferes with neuronal activity and survival. In this paper, I identify and discuss which future technical and conceptual progress or advances should be achieved in order to better understand how neuroglial networking contributes to brain functions and dysfunctions.
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28
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Min SK, Lee SC, Hong SD, Chung CP, Park WH, Min BM. The effect of a laminin-5-derived peptide coated onto chitin microfibers on re-epithelialization in early-stage wound healing. Biomaterials 2010; 31:4725-30. [PMID: 20303583 DOI: 10.1016/j.biomaterials.2010.02.045] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2010] [Accepted: 02/17/2010] [Indexed: 10/19/2022]
Abstract
Considerable effort has been directed towards regenerating defective tissues using tissue-engineering methods. Recently, peptides have been recognized as a valuable scientific tool in the field of tissue-engineering. The PPFLMLLKGSTR motif of the human laminin-5 alpha3 chain has been previously reported to promote keratinocyte survival; however, the in vivo effects of the PPFLMLLKGSTR motif have not yet been studied. These studies raised the hypothesis that a laminin-5-derived peptide can promote wound healing by accelerating re-epithelialization in vivo. To examine this hypothesis, we applied chitin microfibrous matrices coated with the PPFLMLLKGSTR motif in both rat and rabbit full-thickness cutaneous wound models. Compared with vehicle-treated and peptide-treated cutaneous wounds, the application significantly promoted early-stage wound healing by accelerating re-epithelialization, notably reduced inflammatory cell infiltration, and prominently enhanced fibroblast proliferation. These findings support our hypothesis that the PPFLMLLKGSTR motif acts as a very effective wound healing accelerator by enhancing re-epithelialization.
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Affiliation(s)
- Seung-Ki Min
- Department of Oral and Maxillofacial Surgery, Seoul National University School of Dentistry, Seoul 110-749, Republic of Korea.
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29
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New concepts regarding cerebral vasospasm: glial-centric mechanisms. Can J Anaesth 2010; 57:479-89. [PMID: 20131107 DOI: 10.1007/s12630-010-9271-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2009] [Accepted: 01/12/2010] [Indexed: 10/19/2022] Open
Abstract
PURPOSE Poor outcome in patients with cerebral vasospasm following subarachnoid hemorrhage remains a serious clinical problem. The current management with focus on the cerebrovascular constriction accounts for the use of "triple-H" therapy (hypertension, hypervolemia, and hemodilution) to enhance cerebral blood flow through constricted vessels. Recent work suggests that spreading depression (a stereotypical response of cerebral cortical tissue to noxious stimuli with subsequent oligemic blood flow) occurs in patients with cerebral vasospasm. A narrative review was conducted to examine the relationship between spreading depression and subarachnoid hemorrhage and to identify the anesthetic effects on the propagation of spreading depression. PRINCIPAL FINDINGS Following review of the literature, an underlying mechanism is advanced that cerebral vasospasm is not primarily a problem of the cerebral vasculature but a consequence of glial cell dysfunction following spreading depression - a glial-centric cause for vasospasm. Such a mechanism for vasospasm becomes manifest when spreading depression waves transition to peri-infarct depolarization waves - with protracted ischemic blood flow in compromised tissue. The extracellular microenvironment with high potassium and low nitric oxide tension can account for conducting vessel narrowing. CONCLUSIONS The implication for clinical management is discussed supposing glial cell dysfunction is an underlying mechanism responsible for the vascular spasm.
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30
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Sun XL, Hu G. ATP-sensitive potassium channels: A promising target for protecting neurovascular unit function in stroke. Clin Exp Pharmacol Physiol 2010; 37:243-52. [DOI: 10.1111/j.1440-1681.2009.05190.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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31
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Giaume C, Theis M. Pharmacological and genetic approaches to study connexin-mediated channels in glial cells of the central nervous system. ACTA ACUST UNITED AC 2009; 63:160-76. [PMID: 19963007 DOI: 10.1016/j.brainresrev.2009.11.005] [Citation(s) in RCA: 104] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2009] [Revised: 11/18/2009] [Accepted: 11/19/2009] [Indexed: 11/18/2022]
Abstract
This review gives an overview of connexin expression in glial cells of the central nervous system, the different modes of connexin action, including gap junctional channels and hemichannels, as well as the available methodologies to measure their activity. We summarize the strengths and limitations of current pharmacological and genetic approaches to interfere with connexin channel functions. We outline new avenues not only to study specific mechanisms by which connexins exert these functions but also to selectively investigate well-defined coupling compartments among glial networks.
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32
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Hewett JA. Determinants of regional and local diversity within the astroglial lineage of the normal central nervous system. J Neurochem 2009; 110:1717-36. [PMID: 19627442 DOI: 10.1111/j.1471-4159.2009.06288.x] [Citation(s) in RCA: 78] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Astrocytes are a major component of the resident non-neuronal glial cell population of the CNS. They are ubiquitously distributed throughout the brain and spinal cord, where they were initially thought to function in both structural and homeostatic capacities, providing the framework and environment in which neurons performed their parenchymal duties. However, this stroma-like view of astrocytes is no longer satisfactory. Mounting evidence particularly within the last decade indicates that astrocytes do not simply support neuronal activity but directly contribute to it. Congruent with this evolving view of astrocyte function in information processing is the emergent notion that these glial cells are not a homogeneous population of cells. Thus, astrocytes in various anatomically distinct regions of the normal CNS possess unique phenotypic characteristics that may directly influence the particular neuronal activities that define these regions. Remarkably, regional populations of astrocytes appear to exhibit local heterogeneity as well. Many phenotypic traits of the astrocyte lineage are responsive to local environmental cues (i.e., are adaptable), suggesting that plasticity contributes to this diversity. However, compelling evidence suggests that astrocytes arise from multiple distinct progenitor pools in the developing CNS, raising the intriguing possibility that some astrocyte heterogeneity may result from intrinsic differences between these progenitors. The purpose of this review is to explore the evidence for and mechanistic determinants of regional and local astrocyte diversity.
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Affiliation(s)
- James A Hewett
- Department of Neuroscience, University of Connecticut Health Center, Farmington, Connecticut, USA.
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Wright CS, van Steensel MAM, Hodgins MB, Martin PEM. Connexin mimetic peptides improve cell migration rates of human epidermal keratinocytes and dermal fibroblasts in vitro. Wound Repair Regen 2009; 17:240-9. [PMID: 19320893 DOI: 10.1111/j.1524-475x.2009.00471.x] [Citation(s) in RCA: 88] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Nonhealing cutaneous wounds, a major cause of morbidity and mortality, are difficult to treat. Recent studies suggest that significant increases in skin wound-healing rates occur by altering gap junction intercellular communication (GJIC). As migration of keratinocytes and fibroblasts is an important feature of wound healing, this study investigated whether migration rates in cultured normal human epidermal keratinocytes and dermal fibroblasts could be altered by modulating GJIC via connexin mimetic peptides. First, HeLa cells stably transfected with connexin43 (Cx43), Cx40, or Cx26 were used as a model to determine connexin specificity and the doses of connexin mimetic peptides required to attenuate GJIC. Gap26 and Gap26M inhibited GJIC dose dependently and were nonconnexin specific, whereas Gap27 was Cx43-selective. Skin keratinocytes and fibroblasts expressed a variety of connexins, with Cx43 predominating. Cx43 protein expression was reduced at leading edges 3 hours after scraping confluent monolayers, resolving at 24 hours. Gap26M and Gap27 significantly increased migration rates across scrapes in keratinocytes and fibroblasts by blocking gap junction functionality. GJIC inhibition can thus directly influence keratinocyte and fibroblast migration. Furthermore, our results support the therapeutic potential of connexin mimetic peptides to aid wound closure, and provide a simple approach to screening new agents.
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Affiliation(s)
- Catherine S Wright
- Department of Biological and Biomedical Sciences, Glasgow Caledonian University, UK
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Orellana JA, Sáez PJ, Shoji KF, Schalper KA, Palacios-Prado N, Velarde V, Giaume C, Bennett MVL, Sáez JC. Modulation of brain hemichannels and gap junction channels by pro-inflammatory agents and their possible role in neurodegeneration. Antioxid Redox Signal 2009; 11:369-99. [PMID: 18816186 PMCID: PMC2713807 DOI: 10.1089/ars.2008.2130] [Citation(s) in RCA: 156] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
In normal brain, neurons, astrocytes, and oligodendrocytes, the most abundant and active cells express pannexins and connexins, protein subunits of two families forming membrane channels. Most available evidence indicates that in mammals endogenously expressed pannexins form only hemichannels and connexins form both gap junction channels and hemichannels. Whereas gap junction channels connect the cytoplasm of contacting cells and coordinate electric and metabolic activity, hemichannels communicate the intra- and extracellular compartments and serve as a diffusional pathway for ions and small molecules. A subthreshold stimulation by acute pathological threatening conditions (e.g., global ischemia subthreshold for cell death) enhances neuronal Cx36 and glial Cx43 hemichannel activity, favoring ATP release and generation of preconditioning. If the stimulus is sufficiently deleterious, microglia become overactivated and release bioactive molecules that increase the activity of hemichannels and reduce gap junctional communication in astroglial networks, depriving neurons of astrocytic protective functions, and further reducing neuronal viability. Continuous glial activation triggered by low levels of anomalous proteins expressed in several neurodegenerative diseases induce glial hemichannel and gap junction channel disorders similar to those of acute inflammatory responses triggered by ischemia or infectious diseases. These changes are likely to occur in diverse cell types of the CNS and contribute to neurodegeneration during inflammatory process.
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Affiliation(s)
- Juan A Orellana
- Departamento de Ciencias Fisiológicas, Pontificia Universidad Católica de Chile, Santiago, Chile.
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Endothelin-1 reverses the histone deacetylase inhibitor-induced increase in glial glutamate transporter transcription without affecting histone acetylation levels. Neurochem Int 2009; 55:22-7. [DOI: 10.1016/j.neuint.2008.12.020] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2008] [Revised: 12/19/2008] [Accepted: 12/22/2008] [Indexed: 12/21/2022]
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Tanaka M, Yamaguchi K, Tatsukawa T, Theis M, Willecke K, Itohara S. Connexin43 and bergmann glial gap junctions in cerebellar function. Front Neurosci 2008; 2:225-33. [PMID: 19225596 PMCID: PMC2622757 DOI: 10.3389/neuro.01.038.2008] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2008] [Accepted: 11/10/2008] [Indexed: 11/13/2022] Open
Abstract
Connexin43 (Cx43), a major component of astrocytic gap junctions, is abundantly expressed in Bergmann glial cells (BGCs) in the cerebellum, but the function of Cx43 in BGCs is largely unknown. BGCs are specialized astrocytes closely associated with Purkinje cells. Here, we review our recent studies of the role of Cx43 in gap junctional coupling between BGCs and in cerebellar function. We generated Cx43 conditional knockout mice with an S100b-Cre transgenic line (Cx43fl/fl:S100b-Cre), in which there was a significant postnatal loss of Cx43 in BGCs and cerebellar astrocytes. Gap junctional coupling between BGCs measured by dye coupling was virtually abolished in Cx43fl/fl:S100b-Cre mice. Electrophysiologic and behavioral analyses suggested that Cx43-mediated gap junctions and Cx43 hemichannels in BGCs are not necessary for the neuron-glia interactions required for cerebellum-dependent motor coordination and motor learning. These findings raise questions regarding the regional differences in the impact of the loss of Cx43 in the brain.
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Haghikia A, Ladage K, Hinkerohe D, Vollmar P, Heupel K, Dermietzel R, Faustmann PM. Implications of antiinflammatory properties of the anticonvulsant drug levetiracetam in astrocytes. J Neurosci Res 2008; 86:1781-8. [PMID: 18335543 DOI: 10.1002/jnr.21639] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
There is accumulating evidence that epileptic activity is accompanied by inflammatory processes. In the present study, we evaluated the effect of levetiracetam (Keppra), an anticonvulsant drug with decisive antiepileptic features, with regard to its putative antiinflammatory potential. We previously established an in vitro cell culture model to mimic inflammatory conditions: Primary astrocytic cultures of newborn rats were cocultured with 30% (M30) microglial cells. Alternatively, cocultures containing 5% microglia (M5) were incubated with the proinflammatory mediator, the cytokine interleukin-1beta (IL-1beta), and lipopolysaccharide (LPS), a potent bacterial activator of the immune system. For the M30 cocultures, we observed reduced expression of connexin 43 (Cx43), the predominant gap junction protein. Impaired functional dye coupling and depolarized membrane resting potential (MRP) were monitored in M30 cocultures as well as in M5 cocultures treated with IL-1beta and LPS. We could show that the Cx43 expression, the coupling property, and the membrane resting potential on which we focused our inflammatory coculture model were normalized to noninflammatory level under treatment with levetiracetam (Keppra). Cumulatively, our results provide evidence for antiinflammatory properties of levetiracetam in seizure treatment.
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Affiliation(s)
- Aiden Haghikia
- Department of Neurology, St. Josef-Hospital Bochum, Ruhr-University Bochum, Bochum, Germany.
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