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Freitas GA, Niswender CM. GRM7 gene mutations and consequences for neurodevelopment. Pharmacol Biochem Behav 2023; 225:173546. [PMID: 37003303 PMCID: PMC10192299 DOI: 10.1016/j.pbb.2023.173546] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/24/2023] [Revised: 03/22/2023] [Accepted: 03/28/2023] [Indexed: 04/03/2023]
Abstract
The metabotropic glutamate receptor 7 (mGlu7), encoded by the GRM7 gene in humans, is a presynaptic, G protein-coupled glutamate receptor that is essential for modulating neurotransmission. Mutations in or reduced expression of GRM7 have been identified in different genetic neurodevelopmental disorders (NDDs), and rare biallelic missense variants have been proposed to underlie a subset of NDDs. Clinical GRM7 variants have been associated with a range of symptoms consistent with neurodevelopmental molecular features, including hypomyelination, brain atrophy and defects in axon outgrowth. Here, we review the newest findings regarding the cellular and molecular defects caused by GRM7 variants in NDD patients.
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Affiliation(s)
- Geanne A Freitas
- Department of Pharmacology and Warren Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, TN 37212, United States of America
| | - Colleen M Niswender
- Department of Pharmacology and Warren Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, TN 37212, United States of America; Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, TN 37212, United States of America; Vanderbilt Brain Institute, Vanderbilt University, Nashville, TN 37212, United States of America; Vanderbilt Kennedy Center, Vanderbilt University Medical Center, Nashville, TN 37232, United States of America.
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2
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Perez-Gianmarco L, Kurt B, Kukley M. Technical approaches and challenges to study AMPA receptors in oligodendrocyte lineage cells: Past, present, and future. Glia 2023; 71:819-847. [PMID: 36453615 DOI: 10.1002/glia.24305] [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: 06/02/2022] [Revised: 11/05/2022] [Accepted: 11/10/2022] [Indexed: 12/03/2022]
Abstract
Receptors for α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPARs) are ligand-gated ionotropic receptors for glutamate that is a major excitatory neurotransmitter in the central nervous system. AMPARs are located at postsynaptic sites of neuronal synapses where they mediate fast synaptic signaling and synaptic plasticity. Remarkably, AMPARs are also expressed by glial cells. Their expression by the oligodendrocyte (OL) lineage cells is of special interest because AMPARs mediate fast synaptic communication between neurons and oligodendrocyte progenitor cells (OPCs), modulate proliferation and differentiation of OPCs, and may also be involved in regulation of myelination. On the other hand, during pathological conditions, AMPARs may mediate damage of the OL lineage cells. In the present review, we focus on the technical approaches that have been used to study AMPARs in the OL lineage cells, and discuss future perspectives of AMPAR research in these glial cells.
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Affiliation(s)
- Lucila Perez-Gianmarco
- Laboratory of Neuronal and Glial Physiology, Achucarro Basque Center for Neuroscience, Leioa, Spain.,Department of Neurosciences, University of the Basque Country (UPV/EHU), Leioa, Spain
| | - Begüm Kurt
- Laboratory of Neuronal and Glial Physiology, Achucarro Basque Center for Neuroscience, Leioa, Spain.,Department of Neurosciences, University of the Basque Country (UPV/EHU), Leioa, Spain
| | - Maria Kukley
- Laboratory of Neuronal and Glial Physiology, Achucarro Basque Center for Neuroscience, Leioa, Spain.,Ikerbasque - Basque Foundation for Science, Bilbao, Spain
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3
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Kurki SN, Uvarov P, Pospelov AS, Trontti K, Hübner AK, Srinivasan R, Watanabe M, Hovatta I, Hübner CA, Kaila K, Virtanen MA. Expression patterns of NKCC1 in neurons and non-neuronal cells during cortico-hippocampal development. Cereb Cortex 2022; 33:5906-5923. [PMID: 36573432 PMCID: PMC10183754 DOI: 10.1093/cercor/bhac470] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2022] [Revised: 11/05/2022] [Accepted: 11/06/2022] [Indexed: 12/28/2022] Open
Abstract
Abstract
The Na-K-2Cl cotransporter NKCC1 is widely expressed in cells within and outside the brain. However, our understanding of its roles in brain functions throughout development, as well as in neuropsychiatric and neurological disorders, has been severely hindered by the lack of reliable data on its developmental and (sub)cellular expression patterns. We provide here the first properly controlled analysis of NKCC1 protein expression in various cell types of the mouse brain using custom-made antibodies and an NKCC1 knock-out validated immunohistochemical procedure, with parallel data based on advanced mRNA approaches. NKCC1 protein and mRNA are expressed at remarkably high levels in oligodendrocytes. In immature neurons, NKCC1 protein was located in the somata, whereas in adult neurons, only NKCC1 mRNA could be clearly detected. NKCC1 immunoreactivity is also seen in microglia, astrocytes, developing pericytes, and in progenitor cells of the dentate gyrus. Finally, a differential expression of NKCC1 splice variants was observed, with NKCC1a predominating in non-neuronal cells and NKCC1b in neurons. Taken together, our data provide a cellular basis for understanding NKCC1 functions in the brain and enable the identification of major limitations and promises in the development of neuron-targeting NKCC1-blockers.
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Affiliation(s)
- Samu N Kurki
- University of Helsinki Molecular and Integrative Biosciences, , 00014 Helsinki , Finland
- Helsinki Institute of Life Science, University of Helsinki Neuroscience Center, , 00014 Helsinki , Finland
| | - Pavel Uvarov
- University of Helsinki Molecular and Integrative Biosciences, , 00014 Helsinki , Finland
- Helsinki Institute of Life Science, University of Helsinki Neuroscience Center, , 00014 Helsinki , Finland
| | - Alexey S Pospelov
- University of Helsinki Molecular and Integrative Biosciences, , 00014 Helsinki , Finland
- Helsinki Institute of Life Science, University of Helsinki Neuroscience Center, , 00014 Helsinki , Finland
| | - Kalevi Trontti
- Helsinki Institute of Life Science, University of Helsinki Neuroscience Center, , 00014 Helsinki , Finland
- University of Helsinki SleepWell Research Program, Faculty of Medicine, , 00014 Helsinki , Finland
- University of Helsinki Department of Psychology and Logopedics, , 00014 Helsinki , Finland
| | - Antje K Hübner
- Jena University Hospital, Friedrich Schiller Universität Institute of Human Genetics, , 07747 Jena , Germany
| | - Rakenduvadhana Srinivasan
- University of Helsinki Molecular and Integrative Biosciences, , 00014 Helsinki , Finland
- Helsinki Institute of Life Science, University of Helsinki Neuroscience Center, , 00014 Helsinki , Finland
| | - Masahiko Watanabe
- Hokkaido University Department of Anatomy, Faculty of Medicine, , Sapporo 060–8638 , Japan
| | - Iiris Hovatta
- Helsinki Institute of Life Science, University of Helsinki Neuroscience Center, , 00014 Helsinki , Finland
- University of Helsinki SleepWell Research Program, Faculty of Medicine, , 00014 Helsinki , Finland
- University of Helsinki Department of Psychology and Logopedics, , 00014 Helsinki , Finland
| | - Christian A Hübner
- Jena University Hospital, Friedrich Schiller Universität Institute of Human Genetics, , 07747 Jena , Germany
| | - Kai Kaila
- University of Helsinki Molecular and Integrative Biosciences, , 00014 Helsinki , Finland
- Helsinki Institute of Life Science, University of Helsinki Neuroscience Center, , 00014 Helsinki , Finland
| | - Mari A Virtanen
- University of Helsinki Molecular and Integrative Biosciences, , 00014 Helsinki , Finland
- Helsinki Institute of Life Science, University of Helsinki Neuroscience Center, , 00014 Helsinki , Finland
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Bai X, Kirchhoff F, Scheller A. Oligodendroglial GABAergic Signaling: More Than Inhibition! Neurosci Bull 2021; 37:1039-1050. [PMID: 33928492 PMCID: PMC8275815 DOI: 10.1007/s12264-021-00693-w] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2020] [Accepted: 11/22/2020] [Indexed: 12/12/2022] Open
Abstract
GABA is the main inhibitory neurotransmitter in the CNS acting at two distinct types of receptor: ligand-gated ionotropic GABAA receptors and G protein-coupled metabotropic GABAB receptors, thus mediating fast and slow inhibition of excitability at central synapses. GABAergic signal transmission has been intensively studied in neurons in contrast to oligodendrocytes and their precursors (OPCs), although the latter express both types of GABA receptor. Recent studies focusing on interneuron myelination and interneuron-OPC synapses have shed light on the importance of GABA signaling in the oligodendrocyte lineage. In this review, we start with a short summary on GABA itself and neuronal GABAergic signaling. Then, we elaborate on the physiological role of GABA receptors within the oligodendrocyte lineage and conclude with a description of these receptors as putative targets in treatments of CNS diseases.
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Affiliation(s)
- Xianshu Bai
- Molecular Physiology, Center for Integrative Physiology and Molecular Medicine (CIPMM), University of Saarland, 66421, Homburg, Germany
| | - Frank Kirchhoff
- Molecular Physiology, Center for Integrative Physiology and Molecular Medicine (CIPMM), University of Saarland, 66421, Homburg, Germany.
| | - Anja Scheller
- Molecular Physiology, Center for Integrative Physiology and Molecular Medicine (CIPMM), University of Saarland, 66421, Homburg, Germany
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5
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Kamen Y, Pivonkova H, Evans KA, Káradóttir RT. A Matter of State: Diversity in Oligodendrocyte Lineage Cells. Neuroscientist 2021; 28:144-162. [PMID: 33567971 DOI: 10.1177/1073858420987208] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Oligodendrocyte precursor cells (OPCs) give rise to oligodendrocytes which myelinate axons in the central nervous system. Although classically thought to be a homogeneous population, OPCs are reported to have different developmental origins and display regional and temporal diversity in their transcriptome, response to growth factors, and physiological properties. Similarly, evidence is accumulating that myelinating oligodendrocytes display transcriptional heterogeneity. Analyzing this reported heterogeneity suggests that OPCs, and perhaps also myelinating oligodendrocytes, may exist in different functional cell states. Here, we review the evidence indicating that OPCs and oligodendrocytes are diverse, and we discuss the implications of functional OPC states for myelination in the adult brain and for myelin repair.
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Affiliation(s)
- Yasmine Kamen
- Wellcome-Medical Research Council Cambridge Stem Cell Institute & Department of Veterinary Medicine, University of Cambridge, Cambridge, UK
| | - Helena Pivonkova
- Wellcome-Medical Research Council Cambridge Stem Cell Institute & Department of Veterinary Medicine, University of Cambridge, Cambridge, UK
| | - Kimberley A Evans
- Wellcome-Medical Research Council Cambridge Stem Cell Institute & Department of Veterinary Medicine, University of Cambridge, Cambridge, UK
| | - Ragnhildur T Káradóttir
- Wellcome-Medical Research Council Cambridge Stem Cell Institute & Department of Veterinary Medicine, University of Cambridge, Cambridge, UK.,Department of Physiology, BioMedical Center, Faculty of Medicine, University of Iceland, Reykjavik, Iceland
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6
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Serrano-Regal MP, Bayón-Cordero L, Ordaz RP, Garay E, Limon A, Arellano RO, Matute C, Sánchez-Gómez MV. Expression and Function of GABA Receptors in Myelinating Cells. Front Cell Neurosci 2020; 14:256. [PMID: 32973453 PMCID: PMC7472887 DOI: 10.3389/fncel.2020.00256] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2020] [Accepted: 07/24/2020] [Indexed: 01/14/2023] Open
Abstract
Myelin facilitates the fast transmission of nerve impulses and provides metabolic support to axons. Differentiation of oligodendrocyte progenitor cells (OPCs) and Schwann cell (SC) precursors is critical for myelination during development and myelin repair in demyelinating disorders. Myelination is tightly controlled by neuron-glia communication and requires the participation of a wide repertoire of signals, including neurotransmitters such as glutamate, ATP, adenosine, or γ-aminobutyric acid (GABA). GABA is the main inhibitory neurotransmitter in the central nervous system (CNS) and it is also present in the peripheral nervous system (PNS). The composition and function of GABA receptors (GABARs) are well studied in neurons, while their nature and role in glial cells are still incipient. Recent studies demonstrate that GABA-mediated signaling mechanisms play relevant roles in OPC and SC precursor development and function, and stand out the implication of GABARs in oligodendrocyte (OL) and SC maturation and myelination. In this review, we highlight the evidence supporting the novel role of GABA with an emphasis on the molecular identity of the receptors expressed in these glial cells and the possible signaling pathways involved in their actions. GABAergic signaling in myelinating cells may have potential implications for developing novel reparative therapies in demyelinating diseases.
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Affiliation(s)
- Mari Paz Serrano-Regal
- Laboratory of Neurobiology, Achucarro Basque Center for Neuroscience, Leioa, Spain
- Department of Neurosciences, University of the Basque Country (UPV/EHU), Leioa, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas (CIBERNED), Leioa, Spain
| | - Laura Bayón-Cordero
- Laboratory of Neurobiology, Achucarro Basque Center for Neuroscience, Leioa, Spain
- Department of Neurosciences, University of the Basque Country (UPV/EHU), Leioa, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas (CIBERNED), Leioa, Spain
| | - Rainald Pablo Ordaz
- Laboratorio de Neurofisiología Celular, Instituto de Neurobiología, Universidad Nacional Autónoma de México, Juriquilla, Mexico
| | - Edith Garay
- Laboratorio de Neurofisiología Celular, Instituto de Neurobiología, Universidad Nacional Autónoma de México, Juriquilla, Mexico
| | - Agenor Limon
- Department of Neurology, Mitchell Center for Neurodegenerative Diseases, University of Texas Medical Branch, Galveston, TX, United States
| | - Rogelio O. Arellano
- Laboratorio de Neurofisiología Celular, Instituto de Neurobiología, Universidad Nacional Autónoma de México, Juriquilla, Mexico
| | - Carlos Matute
- Laboratory of Neurobiology, Achucarro Basque Center for Neuroscience, Leioa, Spain
- Department of Neurosciences, University of the Basque Country (UPV/EHU), Leioa, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas (CIBERNED), Leioa, Spain
| | - María Victoria Sánchez-Gómez
- Laboratory of Neurobiology, Achucarro Basque Center for Neuroscience, Leioa, Spain
- Department of Neurosciences, University of the Basque Country (UPV/EHU), Leioa, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas (CIBERNED), Leioa, Spain
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Labrada-Moncada FE, Martínez-Torres A, Reyes-Haro D. GABA A Receptors are Selectively Expressed in NG2 Glia of the Cerebellar White Matter. Neuroscience 2020; 433:132-143. [PMID: 32171821 DOI: 10.1016/j.neuroscience.2020.03.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2019] [Revised: 02/22/2020] [Accepted: 03/03/2020] [Indexed: 12/20/2022]
Abstract
The cerebellum is involved in the coordination of movement. Its cellular composition is dominated by GABAergic neuronal types, and glial cells are known to express functional receptors. GABAergic signaling regulates cell proliferation, differentiation, and migration during neurodevelopment. However, little is known about the functional expression of GABA receptors in the cerebellar white matter (WM). Thus, the aim of this study was to test whether glial cells express functional GABA receptors during postnatal development (P7-P9) of cerebellar WM. Immunofluorescence showed that half of the astrocytes express GAD67, suggesting that glial cells synthesize GABA. Calcium imaging in cerebellar slices revealed that GABA and the GABAA agonist muscimol evoked calcium transients in sulforhodamine B negative cells, whereas the GABAB agonist baclofen failed to evoke responses in cerebellar WM. Whole-cell patch-clamp recordings of GFAP+ cells showed dye coupling and a passive current-voltage relation typical of astrocytes. Surprisingly, these cells did not respond to muscimol. Two additional populations were identified as GFAP- cells. The first population showed dye coupling, slow decaying inward and outward currents with no voltage dependence, and did not respond to GABAA agonists. The second population showed an outward-rectifying current-voltage relationship and responded to muscimol, but dye coupling was absent. These cells received synaptic input and were NG2+, but evoked calcium waves failed to modulate the frequency of spontaneous postsynaptic currents (sPSCs) or signaling into NG2 glia. We conclude that GABAA receptor-mediated signaling is selective for NG2 glia in the WM of the cerebellum.
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Affiliation(s)
- Francisco Emmanuel Labrada-Moncada
- Departamento Neurobiología Celular y Molecular, Instituto de Neurobiología, Universidad Nacional Autónoma de México, Campus Juriquilla, Boulevard Juriquilla 3001, Juriquilla, Querétaro CP76230, Mexico
| | - Ataúlfo Martínez-Torres
- Departamento Neurobiología Celular y Molecular, Instituto de Neurobiología, Universidad Nacional Autónoma de México, Campus Juriquilla, Boulevard Juriquilla 3001, Juriquilla, Querétaro CP76230, Mexico
| | - Daniel Reyes-Haro
- Departamento Neurobiología Celular y Molecular, Instituto de Neurobiología, Universidad Nacional Autónoma de México, Campus Juriquilla, Boulevard Juriquilla 3001, Juriquilla, Querétaro CP76230, Mexico.
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Serrano-Regal MP, Luengas-Escuza I, Bayón-Cordero L, Ibarra-Aizpurua N, Alberdi E, Pérez-Samartín A, Matute C, Sánchez-Gómez MV. Oligodendrocyte Differentiation and Myelination Is Potentiated via GABA B Receptor Activation. Neuroscience 2019; 439:163-180. [PMID: 31349008 DOI: 10.1016/j.neuroscience.2019.07.014] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2019] [Revised: 07/02/2019] [Accepted: 07/03/2019] [Indexed: 02/07/2023]
Abstract
Differentiation of oligodendrocyte precursor cells (OPCs) into mature oligodendrocytes (OLs) is a key event for axonal myelination in the central nervous system (CNS). Several growth factors and neurotransmitters like GABA are postulated as important regulators of that process, and different protein kinases may also participate in OL differentiation and myelination. However, the molecular mechanisms underlying the regulation of myelination by neurotransmitters are only partially known. In the present study, we provide evidence showing that GABA receptors (GABARs) play an important role in OL differentiation. First, we observed that OPCs and OLs synthesize GABA and expressed GABAR and transporters, both in vitro and in vivo and, in contrast to GABAARs, the subunits GABAB1R and GABAB2R are expressed in OLs over time. Then, we found that exogenous GABA increases the number of myelin segments and MBP expression in DRG-OPC cocultures, indicating that GABA regulates myelination when OLs are in contact with axons. Notably, in purified rat OPC cultures, chronic treatment with GABA and baclofen, specific GABABR agonist, accelerates OPC differentiation by enhancing the processes branching and myelin protein expression, effects that are reverted in presence of GABABR specific antagonist CGP55845. Exposure of OPCs to baclofen promotes the Src-phosphorylation, and the baclofen-induced maturation is attenuated in presence of the Src-family kinases inhibitor PP2. None of these effects are mediated by the GABAAR agonist muscimol. Together, these results highlight the relevance of the GABAergic system in OL differentiation, and indicate that this functional role is mediated through GABABR involving the participation of Src-family kinases. This article is part of a Special Issue entitled: Honoring Ricardo Miledi - outstanding neuroscientist of XX-XXI centuries.
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Affiliation(s)
- Mari Paz Serrano-Regal
- Deparment of Neurosciences, University of the Basque Country (UPV/EHU), Leioa, Spain; Achucarro Basque Center for Neuroscience, Leioa, Spain; Centro de Investigación en Red de Enfermedades Neurodegenerativas (CIBERNED), Leioa, Spain
| | - Irene Luengas-Escuza
- Deparment of Neurosciences, University of the Basque Country (UPV/EHU), Leioa, Spain
| | - Laura Bayón-Cordero
- Deparment of Neurosciences, University of the Basque Country (UPV/EHU), Leioa, Spain
| | - Naroa Ibarra-Aizpurua
- Deparment of Neurosciences, University of the Basque Country (UPV/EHU), Leioa, Spain
| | - Elena Alberdi
- Deparment of Neurosciences, University of the Basque Country (UPV/EHU), Leioa, Spain; Achucarro Basque Center for Neuroscience, Leioa, Spain; Centro de Investigación en Red de Enfermedades Neurodegenerativas (CIBERNED), Leioa, Spain
| | - Alberto Pérez-Samartín
- Deparment of Neurosciences, University of the Basque Country (UPV/EHU), Leioa, Spain; Achucarro Basque Center for Neuroscience, Leioa, Spain; Centro de Investigación en Red de Enfermedades Neurodegenerativas (CIBERNED), Leioa, Spain
| | - Carlos Matute
- Deparment of Neurosciences, University of the Basque Country (UPV/EHU), Leioa, Spain; Achucarro Basque Center for Neuroscience, Leioa, Spain; Centro de Investigación en Red de Enfermedades Neurodegenerativas (CIBERNED), Leioa, Spain.
| | - María Victoria Sánchez-Gómez
- Deparment of Neurosciences, University of the Basque Country (UPV/EHU), Leioa, Spain; Achucarro Basque Center for Neuroscience, Leioa, Spain; Centro de Investigación en Red de Enfermedades Neurodegenerativas (CIBERNED), Leioa, Spain.
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9
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Mouihate A, Kalakh S. Ganaxolone enhances microglial clearance activity and promotes remyelination in focal demyelination in the corpus callosum of ovariectomized rats. CNS Neurosci Ther 2019; 26:240-250. [PMID: 31332963 PMCID: PMC6978248 DOI: 10.1111/cns.13195] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2018] [Revised: 06/24/2019] [Accepted: 06/27/2019] [Indexed: 12/01/2022] Open
Abstract
Aim Experimental studies have shown that the progesterone metabolite, allopregnanolone, is endowed with promyelinating effects. The mechanisms underlying these promyelinating effects are not well understood. Therefore, we explored the impact of allopregnanolone's synthetic analogue, ganaxolone, on remyelination and microglial activation following focal demyelination in the corpus callosum of ovariectomized rats. Methods Ovariectomized adult Sprague Dawley rats received a stereotaxic injection of 2 µL of 1% lysolecithin solution in the corpus callosum followed by daily injections of either ganaxolone (intraperitoneal injection [i.p.], 2.5 mg/kg) or vehicle. The demyelination lesion was assessed 3 and 7 days postdemyelination insult using Luxol fast blue staining and transmission electron microscopy. The expression levels of myelin proteins (MBP, MAG, MOG, CNPase) were explored using Western blot. The inflammatory response and clearance of damaged myelin were evaluated using immunofluorescent staining (Iba1, dMBP, GFAP) and multiplex enzyme‐linked immunosorbent assay (IL‐1β, TNF‐α, IL‐4, IL‐10, IL‐6). Results Systemic administration of ganaxolone promoted remyelination of lysolecithin‐induced demyelination, upregulated the expression of major myelin proteins, and enhanced microglial clearance of damaged myelin. Astrocytosis, as well as locally produced pro‐ and antiinflammatory cytokines, was not affected by ganaxolone treatment. Conclusion Ganaxolone promotes remyelination in response to focal demyelination of the corpus callosum of ovariectomized rats. This effect is, at least in part, mediated by enhancing microglial clearance of myelin debris, which creates a conducive environment for a successful remyelination process.
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Affiliation(s)
- Abdeslam Mouihate
- Department of Physiology, Faculty of Medicine, Kuwait University, Safat, Kuwait
| | - Samah Kalakh
- Department of Physiology, Faculty of Medicine, Kuwait University, Safat, Kuwait
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10
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Tsata V, Kroehne V, Reinhardt S, El-Armouche A, Brand M, Wagner M, Reimer MM. Electrophysiological Properties of Adult Zebrafish Oligodendrocyte Progenitor Cells. Front Cell Neurosci 2019; 13:102. [PMID: 31031593 PMCID: PMC6473327 DOI: 10.3389/fncel.2019.00102] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2018] [Accepted: 02/28/2019] [Indexed: 11/13/2022] Open
Abstract
Low remyelination efficiency after spinal cord injury (SCI) is a major restraint to successful axonal and functional regeneration in mammals. In contrast, adult zebrafish can: (i) regenerate oligodendrocytes and myelin sheaths within 2 weeks post lesion; (ii) re-grow axonal projections across the lesion site and (iii) recover locomotor function within 6 weeks after spinal cord transection. However, little is known about the intrinsic properties of oligodendrocyte progenitor cells (OPCs), the remyelinating cells of the central nervous system (CNS). Here, we demonstrate that purified OPCs from the adult zebrafish spinal cord are electrically active. They functionally express voltage-gated K+ and Na+ channels, glutamate receptors and exhibit depolarizing, tetrodotoxin (TTX)-sensitive spikes, as previously seen in rodent and human OPCs. Furthermore, we show that the percentage of zebrafish OPCs exhibiting depolarizing spikes and Nav-mediated currents is lower as compared to rodent white matter OPCs, where these membrane characteristics have been shown to underlie OPC injury susceptibility. These findings imply that adult zebrafish OPCs resemble electrical properties found in mammals and represent a relevant cell type towards understanding the biology of the primary cells targeted in remyelination therapies for non-regenerative species. The in vitro platform introduced in this study could be used in the future to: (i) elucidate how membrane characteristics of zebrafish OPCs change upon injury and (ii) identify potential signaling components underlying OPC injury recognition.
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Affiliation(s)
- Vasiliki Tsata
- Center for Regenerative Therapies TU Dresden (CRTD) and Center for Molecular and Cellular Bioengineering (CMCB), Technische Universitaet, Dresden, Germany
| | - Volker Kroehne
- Center for Regenerative Therapies TU Dresden (CRTD) and Center for Molecular and Cellular Bioengineering (CMCB), Technische Universitaet, Dresden, Germany
| | - Susanne Reinhardt
- Dresden Genome Center, Center for Regenerative Therapies TU Dresden (CRTD), Center for Molecular and Cellular Bioengineering (CMCB), Technische Universitaet Dresden, Dresden, Germany
| | - Ali El-Armouche
- Department of Pharmacology and Toxicology, Technische Universitaet Dresden, Dresden, Germany
| | - Michael Brand
- Center for Regenerative Therapies TU Dresden (CRTD) and Center for Molecular and Cellular Bioengineering (CMCB), Technische Universitaet, Dresden, Germany
| | - Michael Wagner
- Department of Pharmacology and Toxicology, Technische Universitaet Dresden, Dresden, Germany.,Department of Rhythmology, Heart Center Dresden, Technische Universitaet Dresden, Dresden, Germany
| | - Michell M Reimer
- Center for Regenerative Therapies TU Dresden (CRTD) and Center for Molecular and Cellular Bioengineering (CMCB), Technische Universitaet, Dresden, Germany
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11
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Habermacher C, Angulo MC, Benamer N. Glutamate versus GABA in neuron-oligodendroglia communication. Glia 2019; 67:2092-2106. [PMID: 30957306 DOI: 10.1002/glia.23618] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2019] [Revised: 02/28/2019] [Accepted: 03/19/2019] [Indexed: 12/20/2022]
Abstract
In the central nervous system (CNS), myelin sheaths around axons are formed by glial cells named oligodendrocytes (OLs). In turn, OLs are generated by oligodendrocyte precursor cells (OPCs) during postnatal development and in adults, according to a process that depends on the proliferation and differentiation of these progenitors. The maturation of OL lineage cells as well as myelination by OLs are complex and highly regulated processes in the CNS. OPCs and OLs express an array of receptors for neurotransmitters, in particular for the two main CNS neurotransmitters glutamate and GABA, and are therefore endowed with the capacity to respond to neuronal activity. Initial studies in cell cultures demonstrated that both glutamate and GABA signaling mechanisms play important roles in OL lineage cell development and function. However, much remains to be learned about the communication of glutamatergic and GABAergic neurons with oligodendroglia in vivo. This review focuses on recent major advances in our understanding of the neuron-oligodendroglia communication mediated by glutamate and GABA in the CNS, and highlights the present controversies in the field. We discuss the expression, activation modes and potential roles of synaptic and extrasynaptic receptors along OL lineage progression. We review the properties of OPC synaptic connectivity with presynaptic glutamatergic and GABAergic neurons in the brain and consider the implication of glutamate and GABA signaling in activity-driven adaptive myelination.
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Affiliation(s)
- Chloé Habermacher
- Institute of Psychiatry and Neuroscience of Paris (IPNP), INSERM U1266, Paris, France.,Université Paris Descartes, Paris, France
| | - María C Angulo
- Institute of Psychiatry and Neuroscience of Paris (IPNP), INSERM U1266, Paris, France.,Université Paris Descartes, Paris, France
| | - Najate Benamer
- Institute of Psychiatry and Neuroscience of Paris (IPNP), INSERM U1266, Paris, France.,Université Paris Descartes, Paris, France
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Region- and Cell Type-Specific Facilitation of Synaptic Function at Destination Synapses Induced by Oligodendrocyte Depolarization. J Neurosci 2019; 39:4036-4050. [PMID: 30862665 DOI: 10.1523/jneurosci.1619-18.2019] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2018] [Revised: 03/01/2019] [Accepted: 03/06/2019] [Indexed: 11/21/2022] Open
Abstract
The axonal conduction of action potentials affects the absolute time it takes to transmit nerve impulses as well as temporal summation at destination synapses. At the physiological level, oligodendrocyte depolarization facilitates axonal conduction along myelinated fibers in the hippocampus; however, the functional significance of this facilitation is largely unknown. In this study, we examined the physiology of the facilitation of axonal conduction by investigating the changes in synaptic responses at destination synapses using male and female mice in which channelrhodopsin-2 expression was restricted to oligodendrocytes. The subiculum, one of the projection areas of the examined axons at the alveus of the hippocampus, is divided into three regions (proximal, mid, and distal) and contains two types of principal neurons: regular firing and bursting pyramidal cells. We found a significant increase in excitatory synaptic responses following optogenetic oligodendrocyte depolarization in bursting neurons at two of the three regions, but not in regular firing neurons at any region. The long-term potentiation (LTP) induced by theta burst stimulation at the synapses showing a significant increase was also enhanced after oligodendrocyte depolarization. Conversely, the reduction of oligodendrocyte depolarization during theta burst stimulation, which was achieved by photostimulation of archaerhodopsin-T expressed selectively on oligodendrocytes, reduced the magnitude of LTP. These results show that oligodendrocyte depolarization contributes to the fine control of synaptic activity between the axons they myelinate and targets subicular cells in a region- and cell type-specific manner, and suggest that oligodendrocyte depolarization during conditioning of stimuli is involved in the induction of LTP.SIGNIFICANCE STATEMENT All activity in the nervous system depends on the propagation of action potentials. Changes in the axonal conduction of action potentials influence the timing of synaptic transmission and information processing in neural circuits. At the physiological level, oligodendrocyte depolarization facilitates axonal conduction along myelinated fibers. In this study, we investigated the functional significance of the facilitation of axonal conduction induced by physiological oligodendrocyte depolarization. Using optogenetics and electrophysiological recordings, we demonstrated that oligodendrocyte depolarization in mice expressing channelrhodopsin-2 on oligodendrocytes increased excitatory synaptic responses and enhanced the induction of long-term potentiation at destination synapses in a region- and cell type-specific manner. This facilitation may have a hitherto unappreciated influence on the transfer of information between regions in the nervous system.
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13
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Chorghay Z, Káradóttir RT, Ruthazer ES. White Matter Plasticity Keeps the Brain in Tune: Axons Conduct While Glia Wrap. Front Cell Neurosci 2018; 12:428. [PMID: 30519159 PMCID: PMC6251003 DOI: 10.3389/fncel.2018.00428] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2018] [Accepted: 10/30/2018] [Indexed: 12/28/2022] Open
Abstract
Precise timing of neuronal inputs is crucial for brain circuit function and development, where it contributes critically to experience-dependent plasticity. Myelination therefore provides an important adaptation mechanism for vertebrate circuits. Despite its importance to circuit activity, the interplay between neuronal activity and myelination has yet to be fully elucidated. In recent years, significant attention has been devoted to uncovering and explaining the phenomenon of white matter (WM) plasticity. Here, we summarize some of the critical evidence for modulation of the WM by neuronal activity, ranging from human diffusion tensor imaging (DTI) studies to experiments in animal models. These experiments reveal activity-dependent changes in the differentiation and proliferation of the oligodendrocyte lineage, and in the critical properties of the myelin sheaths. We discuss the implications of such changes for synaptic function and plasticity, and present the underlying mechanisms of neuron–glia communication, with a focus on glutamatergic signaling and the axomyelinic synapse. Finally, we examine evidence that myelin plasticity may be subject to critical periods. Taken together, the present review aims to provide insights into myelination in the context of brain circuit formation and function, emphasizing the bidirectional interplay between neurons and myelinating glial cells to better inform future investigations of nervous system plasticity.
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Affiliation(s)
- Zahraa Chorghay
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, QC, Canada
| | - Ragnhildur Thóra Káradóttir
- Department of Veterinary Medicine, Wellcome Trust - Medical Research Council Stem Cell Institute, University of Cambridge, Cambridge, United Kingdom
| | - Edward S Ruthazer
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, QC, Canada
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14
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Astrocyte Sodium Signalling and Panglial Spread of Sodium Signals in Brain White Matter. Neurochem Res 2017; 42:2505-2518. [PMID: 28214986 DOI: 10.1007/s11064-017-2197-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2016] [Revised: 01/19/2017] [Accepted: 01/28/2017] [Indexed: 10/20/2022]
Abstract
In brain grey matter, excitatory synaptic transmission activates glutamate uptake into astrocytes, inducing sodium signals which propagate into neighboring astrocytes through gap junctions. These sodium signals have been suggested to serve an important role in neuro-metabolic coupling. So far, it is unknown if astrocytes in white matter-that is in brain regions devoid of synapses-are also able to undergo such intra- and intercellular sodium signalling. In the present study, we have addressed this question by performing quantitative sodium imaging in acute tissue slices of mouse corpus callosum. Focal application of glutamate induced sodium transients in SR101-positive astrocytes. These were largely unaltered in the presence of ionotropic glutamate receptors blockers, but strongly dampened upon pharmacological inhibition of glutamate uptake. Sodium signals induced in individual astrocytes readily spread into neighboring SR101-positive cells with peak amplitudes decaying monoexponentially with distance from the stimulated cell. In addition, spread of sodium was largely unaltered during pharmacological inhibition of purinergic and glutamate receptors, indicating gap junction-mediated, passive diffusion of sodium between astrocytes. Using cell-type-specific, transgenic reporter mice, we found that sodium signals also propagated, albeit less effectively, from astrocytes to neighboring oligodendrocytes and NG2 cells. Again, panglial spread was unaltered with purinergic and glutamate receptors blocked. Taken together, our results demonstrate that activation of sodium-dependent glutamate transporters induces sodium signals in white matter astrocytes, which spread within the astrocyte syncytium. In addition, we found a panglial passage of sodium signals from astrocytes to NG2 cells and oligodendrocytes, indicating functional coupling between these macroglial cells in white matter.
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15
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Neurosteroid Allopregnanolone Suppresses Median Nerve Injury–induced Mechanical Hypersensitivity and Glial Extracellular Signal–regulated Kinase Activation through γ-Aminobutyric Acid Type A Receptor Modulation in the Rat Cuneate Nucleus. Anesthesiology 2016; 125:1202-1218. [DOI: 10.1097/aln.0000000000001360] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Abstract
Background
Mechanisms underlying neuropathic pain relief by the neurosteroid allopregnanolone remain uncertain. We investigated if allopregnanolone attenuates glial extracellular signal-regulated kinase (ERK) activation in the cuneate nucleus (CN) concomitant with neuropathic pain relief in median nerve chronic constriction injury (CCI) model rats.
Methods
We examined the time course and cellular localization of phosphorylated ERK (p-ERK) in CN after CCI. We subsequently employed microinjection of a mitogen-activated protein kinase kinase (ERK kinase) inhibitor, PD98059, to clarify the role of ERK phosphorylation in neuropathic pain development. Furthermore, we explored the effects of allopregnanolone (by mouth), intra-CN microinjection of γ-aminobutyric acid type A receptor antagonist (bicuculline) or γ-aminobutyric acid type B receptor antagonist (phaclofen) plus allopregnanolone, and allopregnanolone synthesis inhibitor (medroxyprogesterone; subcutaneous) on ERK activation and CCI-induced behavioral hypersensitivity.
Results
At 7 days post-CCI, p-ERK levels in ipsilateral CN were significantly increased and reached a peak. PD98059 microinjection into the CN 1 day after CCI dose-dependently attenuated injury-induced behavioral hypersensitivity (withdrawal threshold [mean ± SD], 7.4 ± 1.1, 8.7 ± 1.0, and 10.3 ± 0.8 g for 2.0, 2.5, and 3.0 mM PD98059, respectively, at 7 days post-CCI; n = 6 for each dose). Double immunofluorescence showed that p-ERK was localized to both astrocytes and microglia. Allopregnanolone significantly diminished CN p-ERK levels, glial activation, proinflammatory cytokines, and behavioral hypersensitivity after CCI. Bicuculline, but not phaclofen, blocked all effects of allopregnanolone. Medroxyprogesterone treatment reduced endogenous CN allopregnanolone and exacerbated nerve injury-induced neuropathic pain.
Conclusions
Median nerve injury-induced CN glial ERK activation modulated the development of behavioral hypersensitivity. Allopregnanolone attenuated glial ERK activation and neuropathic pain via γ-aminobutyric acid type A receptors. Reduced endogenous CN allopregnanolone after medroxyprogesterone administration rendered rats more susceptible to CCI-induced neuropathy.
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16
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Baraban M, Mensch S, Lyons DA. Adaptive myelination from fish to man. Brain Res 2016; 1641:149-161. [PMID: 26498877 PMCID: PMC4907128 DOI: 10.1016/j.brainres.2015.10.026] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2015] [Revised: 10/13/2015] [Accepted: 10/14/2015] [Indexed: 01/06/2023]
Abstract
Myelinated axons with nodes of Ranvier are an evolutionary elaboration common to essentially all jawed vertebrates. Myelin made by Schwann cells in our peripheral nervous system and oligodendrocytes in our central nervous system has been long known to facilitate rapid energy efficient nerve impulse propagation. However, it is now also clear, particularly in the central nervous system, that myelin is not a simple static insulator but that it is dynamically regulated throughout development and life. New myelin sheaths can be made by newly differentiating oligodendrocytes, and mature myelin sheaths can be stimulated to grow again in the adult. Furthermore, numerous studies in models from fish to man indicate that neuronal activity can affect distinct stages of oligodendrocyte development and the process of myelination itself. This begs questions as to how these effects of activity are mediated at a cellular and molecular level and whether activity-driven adaptive myelination is a feature common to all myelinated axons, or indeed all oligodendrocytes, or is specific to cells or circuits with particular functions. Here we review the recent literature on this topic, elaborate on the key outstanding questions in the field, and look forward to future studies that incorporate investigations in systems from fish to man that will provide further insight into this fundamental aspect of nervous system plasticity. This article is part of a Special Issue entitled SI: Myelin Evolution.
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Affiliation(s)
- Marion Baraban
- Centre for Neuroregeneration, University of Edinburgh, 49 Little France Crescent, Edinburgh EH16 4SB, UK
| | - Sigrid Mensch
- Centre for Neuroregeneration, University of Edinburgh, 49 Little France Crescent, Edinburgh EH16 4SB, UK
| | - David A Lyons
- Centre for Neuroregeneration, University of Edinburgh, 49 Little France Crescent, Edinburgh EH16 4SB, UK.
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17
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Arellano RO, Sánchez-Gómez MV, Alberdi E, Canedo-Antelo M, Chara JC, Palomino A, Pérez-Samartín A, Matute C. Axon-to-Glia Interaction Regulates GABAA Receptor Expression in Oligodendrocytes. Mol Pharmacol 2015; 89:63-74. [PMID: 26538574 DOI: 10.1124/mol.115.100594] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2015] [Accepted: 11/03/2015] [Indexed: 01/02/2023] Open
Abstract
Myelination requires oligodendrocyte-neuron communication, and both neurotransmitters and contact interactions are essential for this process. Oligodendrocytes are endowed with neurotransmitter receptors whose expression levels and properties may change during myelination. However, only scant information is available about the extent and timing of these changes or how they are regulated by oligodendrocyte-neuron interactions. Here, we used electrophysiology to study the expression of ionotropic GABA, glutamate, and ATP receptors in oligodendrocytes derived from the optic nerve and forebrain cultured either alone or in the presence of dorsal root ganglion neurons. We observed that oligodendrocytes from both regions responded to these transmitters at 1 day in culture. After the first day in culture, however, GABA sensitivity diminished drastically to less than 10%, while that of glutamate and ATP remained constant. In contrast, the GABA response amplitude was sustained and remained stable in oligodendrocytes cocultured with dorsal root ganglion neurons. Immunochemistry and pharmacological properties of the responses indicated that they were mediated by distinctive GABAA receptors and that in coculture with neurons, the oligodendrocytes bearing the receptors were those in direct contact with axons. These results reveal that GABAA receptor regulation in oligodendrocytes is driven by axonal cues and that GABA signaling may play a role in myelination and/or during axon-glia recognition.
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Affiliation(s)
- Rogelio O Arellano
- Achucarro Basque Center for Neuroscience, Centro de Investigación Biomédica en Red en Enfermedades Neurodegenerativas, and Departamento de Neurociencias, Universidad del País Vasco, Leioa, Spain (R.O.A., M.V.S.-G., E.A., M.C.-A., J.C.C., A.P., A.P.-S., C.M.); and Instituto de Neurobiología, Laboratorio de Neurofisiología Celular, Universidad Nacional Autónoma de México, Juriquilla, Querétaro, México (R.O.A.)
| | - María Victoria Sánchez-Gómez
- Achucarro Basque Center for Neuroscience, Centro de Investigación Biomédica en Red en Enfermedades Neurodegenerativas, and Departamento de Neurociencias, Universidad del País Vasco, Leioa, Spain (R.O.A., M.V.S.-G., E.A., M.C.-A., J.C.C., A.P., A.P.-S., C.M.); and Instituto de Neurobiología, Laboratorio de Neurofisiología Celular, Universidad Nacional Autónoma de México, Juriquilla, Querétaro, México (R.O.A.)
| | - Elena Alberdi
- Achucarro Basque Center for Neuroscience, Centro de Investigación Biomédica en Red en Enfermedades Neurodegenerativas, and Departamento de Neurociencias, Universidad del País Vasco, Leioa, Spain (R.O.A., M.V.S.-G., E.A., M.C.-A., J.C.C., A.P., A.P.-S., C.M.); and Instituto de Neurobiología, Laboratorio de Neurofisiología Celular, Universidad Nacional Autónoma de México, Juriquilla, Querétaro, México (R.O.A.)
| | - Manuel Canedo-Antelo
- Achucarro Basque Center for Neuroscience, Centro de Investigación Biomédica en Red en Enfermedades Neurodegenerativas, and Departamento de Neurociencias, Universidad del País Vasco, Leioa, Spain (R.O.A., M.V.S.-G., E.A., M.C.-A., J.C.C., A.P., A.P.-S., C.M.); and Instituto de Neurobiología, Laboratorio de Neurofisiología Celular, Universidad Nacional Autónoma de México, Juriquilla, Querétaro, México (R.O.A.)
| | - Juan Carlos Chara
- Achucarro Basque Center for Neuroscience, Centro de Investigación Biomédica en Red en Enfermedades Neurodegenerativas, and Departamento de Neurociencias, Universidad del País Vasco, Leioa, Spain (R.O.A., M.V.S.-G., E.A., M.C.-A., J.C.C., A.P., A.P.-S., C.M.); and Instituto de Neurobiología, Laboratorio de Neurofisiología Celular, Universidad Nacional Autónoma de México, Juriquilla, Querétaro, México (R.O.A.)
| | - Aitor Palomino
- Achucarro Basque Center for Neuroscience, Centro de Investigación Biomédica en Red en Enfermedades Neurodegenerativas, and Departamento de Neurociencias, Universidad del País Vasco, Leioa, Spain (R.O.A., M.V.S.-G., E.A., M.C.-A., J.C.C., A.P., A.P.-S., C.M.); and Instituto de Neurobiología, Laboratorio de Neurofisiología Celular, Universidad Nacional Autónoma de México, Juriquilla, Querétaro, México (R.O.A.)
| | - Alberto Pérez-Samartín
- Achucarro Basque Center for Neuroscience, Centro de Investigación Biomédica en Red en Enfermedades Neurodegenerativas, and Departamento de Neurociencias, Universidad del País Vasco, Leioa, Spain (R.O.A., M.V.S.-G., E.A., M.C.-A., J.C.C., A.P., A.P.-S., C.M.); and Instituto de Neurobiología, Laboratorio de Neurofisiología Celular, Universidad Nacional Autónoma de México, Juriquilla, Querétaro, México (R.O.A.)
| | - Carlos Matute
- Achucarro Basque Center for Neuroscience, Centro de Investigación Biomédica en Red en Enfermedades Neurodegenerativas, and Departamento de Neurociencias, Universidad del País Vasco, Leioa, Spain (R.O.A., M.V.S.-G., E.A., M.C.-A., J.C.C., A.P., A.P.-S., C.M.); and Instituto de Neurobiología, Laboratorio de Neurofisiología Celular, Universidad Nacional Autónoma de México, Juriquilla, Querétaro, México (R.O.A.)
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18
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Larson VA, Zhang Y, Bergles DE. Electrophysiological properties of NG2(+) cells: Matching physiological studies with gene expression profiles. Brain Res 2015; 1638:138-160. [PMID: 26385417 DOI: 10.1016/j.brainres.2015.09.010] [Citation(s) in RCA: 68] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2015] [Revised: 08/31/2015] [Accepted: 09/08/2015] [Indexed: 01/11/2023]
Abstract
NG2(+) glial cells are a dynamic population of non-neuronal cells that give rise to myelinating oligodendrocytes in the central nervous system. These cells express numerous ion channels and neurotransmitter receptors, which endow them with a complex electrophysiological profile that is unique among glial cells. Despite extensive analysis of the electrophysiological properties of these cells, relatively little was known about the molecular identity of the channels and receptors that they express. The generation of new RNA-Seq datasets for NG2(+) cells has provided the means to explore how distinct genes contribute to the physiological properties of these progenitors. In this review, we systematically compare the results obtained through RNA-Seq transcriptional analysis of purified NG2(+) cells to previous physiological and molecular studies of these cells to define the complement of ion channels and neurotransmitter receptors expressed by NG2(+) cells in the mammalian brain and discuss the potential significance of the unique physiological properties of these cells. This article is part of a Special Issue entitled SI:NG2-glia(Invited only).
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Affiliation(s)
- Valerie A Larson
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Ye Zhang
- Department of Neurobiology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Dwight E Bergles
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
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19
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Sahel A, Ortiz FC, Kerninon C, Maldonado PP, Angulo MC, Nait-Oumesmar B. Alteration of synaptic connectivity of oligodendrocyte precursor cells following demyelination. Front Cell Neurosci 2015; 9:77. [PMID: 25852473 PMCID: PMC4362325 DOI: 10.3389/fncel.2015.00077] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2014] [Accepted: 02/21/2014] [Indexed: 11/13/2022] Open
Abstract
Oligodendrocyte precursor cells (OPCs) are a major source of remyelinating oligodendrocytes in demyelinating diseases such as Multiple Sclerosis (MS). While OPCs are innervated by unmyelinated axons in the normal brain, the fate of such synaptic contacts after demyelination is still unclear. By combining electrophysiology and immunostainings in different transgenic mice expressing fluorescent reporters, we studied the synaptic innervation of OPCs in the model of lysolecithin (LPC)-induced demyelination of corpus callosum. Synaptic innervation of reactivated OPCs in the lesion was revealed by the presence of AMPA receptor-mediated synaptic currents, VGluT1+ axon-OPC contacts in 3D confocal reconstructions and synaptic junctions observed by electron microscopy. Moreover, 3D confocal reconstructions of VGluT1 and NG2 immunolabeling showed the existence of glutamatergic axon-OPC contacts in post-mortem MS lesions. Interestingly, patch-clamp recordings in LPC-induced lesions demonstrated a drastic decrease in spontaneous synaptic activity of OPCs early after demyelination that was not caused by an impaired conduction of compound action potentials. A reduction in synaptic connectivity was confirmed by the lack of VGluT1+ axon-OPC contacts in virtually all rapidly proliferating OPCs stained with EdU (50-ethynyl-20-deoxyuridine). At the end of the massive proliferation phase in lesions, the proportion of innervated OPCs rapidly recovers, although the frequency of spontaneous synaptic currents did not reach control levels. In conclusion, our results demonstrate that newly-generated OPCs do not receive synaptic inputs during their active proliferation after demyelination, but gain synapses during the remyelination process. Hence, glutamatergic synaptic inputs may contribute to inhibit OPC proliferation and might have a physiopathological relevance in demyelinating disorders.
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Affiliation(s)
- Aurélia Sahel
- INSERM U1127, Institut du Cerveau et de la Moelle Epinière Paris, France ; Université Paris 6, Sorbonne Paris Cité, UMR-S1127 Paris, France ; Centre National de la Recherche Scientifique UMR 7225 Paris, France
| | - Fernando C Ortiz
- INSERM U1128 Paris, France ; Université Paris Descartes, Sorbonne Paris Cité Paris, France
| | - Christophe Kerninon
- INSERM U1127, Institut du Cerveau et de la Moelle Epinière Paris, France ; Université Paris 6, Sorbonne Paris Cité, UMR-S1127 Paris, France ; Centre National de la Recherche Scientifique UMR 7225 Paris, France
| | - Paloma P Maldonado
- INSERM U1128 Paris, France ; Université Paris Descartes, Sorbonne Paris Cité Paris, France
| | - María Cecilia Angulo
- INSERM U1128 Paris, France ; Université Paris Descartes, Sorbonne Paris Cité Paris, France
| | - Brahim Nait-Oumesmar
- INSERM U1127, Institut du Cerveau et de la Moelle Epinière Paris, France ; Université Paris 6, Sorbonne Paris Cité, UMR-S1127 Paris, France ; Centre National de la Recherche Scientifique UMR 7225 Paris, France
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20
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Hirrlinger J, Nave KA. Adapting brain metabolism to myelination and long-range signal transduction. Glia 2014; 62:1749-61. [DOI: 10.1002/glia.22737] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2013] [Revised: 07/23/2014] [Accepted: 07/23/2014] [Indexed: 12/24/2022]
Affiliation(s)
- Johannes Hirrlinger
- Department of Neurogenetics; Max-Planck-Institute for Experimental Medicine; Göttingen Germany
- Carl-Ludwig-Institute for Physiology, Faculty of Medicine, University of Leipzig; Leipzig Germany
| | - Klaus-Armin Nave
- Department of Neurogenetics; Max-Planck-Institute for Experimental Medicine; Göttingen Germany
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21
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Yamazaki Y, Fujiwara H, Kaneko K, Hozumi Y, Xu M, Ikenaka K, Fujii S, Tanaka KF. Short- and long-term functional plasticity of white matter induced by oligodendrocyte depolarization in the hippocampus. Glia 2014; 62:1299-312. [PMID: 24756966 DOI: 10.1002/glia.22681] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2013] [Revised: 04/07/2014] [Accepted: 04/10/2014] [Indexed: 11/06/2022]
Abstract
Plastic changes in white matter have received considerable attention in relation to normal cognitive function and learning. Oligodendrocytes and myelin, which constitute the white matter in the central nervous system, can respond to neuronal activity with prolonged depolarization of membrane potential and/or an increase in the intracellular Ca(2+) concentration. Depolarization of oligodendrocytes increases the conduction velocity of an action potential along axons myelinated by the depolarized oligodendrocytes, indicating that white matter shows functional plasticity, as well as structural plasticity. However, the properties and mechanism of oligodendrocyte depolarization-induced functional plastic changes in white matter are largely unknown. Here, we investigated the functional plasticity of white matter in the hippocampus using mice with oligodendrocytes expressing channelrhodopsin-2. Using extracellular recordings of compound action potentials at the alveus of the hippocampus, we demonstrated that light-evoked depolarization of oligodendrocytes induced early- and late-onset facilitation of axonal conduction that was dependent on the magnitude of oligodendrocyte depolarization; the former lasted for approximately 10 min, whereas the latter continued for up to 3 h. Using whole-cell recordings from CA1 pyramidal cells and recordings of antidromic action potentials, we found that the early-onset short-lasting component included the synchronization of action potentials. Moreover, pharmacological analysis demonstrated that the activation of Ba(2+) -sensitive K(+) channels was involved in early- and late-onset facilitation, whereas 4-aminopyridine-sensitive K(+) channels were only involved in the early-onset component. These results demonstrate that oligodendrocyte depolarization induces short- and long-term functional plastic changes in the white matter of the hippocampus and plays active roles in brain functions.
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Affiliation(s)
- Yoshihiko Yamazaki
- Department of Physiology, Yamagata University School of Medicine, Yamagata, Japan
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22
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Butt AM, Fern RF, Matute C. Neurotransmitter signaling in white matter. Glia 2014; 62:1762-79. [PMID: 24753049 DOI: 10.1002/glia.22674] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2013] [Revised: 03/04/2014] [Accepted: 03/31/2014] [Indexed: 12/16/2022]
Abstract
White matter (WM) tracts are bundles of myelinated axons that provide for rapid communication throughout the CNS and integration in grey matter (GM). The main cells in myelinated tracts are oligodendrocytes and astrocytes, with small populations of microglia and oligodendrocyte precursor cells. The prominence of neurotransmitter signaling in WM, which largely exclude neuronal cell bodies, indicates it must have physiological functions other than neuron-to-neuron communication. A surprising aspect is the diversity of neurotransmitter signaling in WM, with evidence for glutamatergic, purinergic (ATP and adenosine), GABAergic, glycinergic, adrenergic, cholinergic, dopaminergic and serotonergic signaling, acting via a wide range of ionotropic and metabotropic receptors. Both axons and glia are potential sources of neurotransmitters and may express the respective receptors. The physiological functions of neurotransmitter signaling in WM are subject to debate, but glutamate and ATP-mediated signaling have been shown to evoke Ca(2+) signals in glia and modulate axonal conduction. Experimental findings support a model of neurotransmitters being released from axons during action potential propagation acting on glial receptors to regulate the homeostatic functions of astrocytes and myelination by oligodendrocytes. Astrocytes also release neurotransmitters, which act on axonal receptors to strengthen action potential propagation, maintaining signaling along potentially long axon tracts. The co-existence of multiple neurotransmitters in WM tracts suggests they may have diverse functions that are important for information processing. Furthermore, the neurotransmitter signaling phenomena described in WM most likely apply to myelinated axons of the cerebral cortex and GM areas, where they are doubtless important for higher cognitive function.
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Affiliation(s)
- Arthur M Butt
- Institute of Biomedical and Biomolecular Sciences, School of Pharmacy and Biomedical Sciences, University of Portsmouth, United Kingdom
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Song M, Yu SP. Ionic regulation of cell volume changes and cell death after ischemic stroke. Transl Stroke Res 2013; 5:17-27. [PMID: 24323733 DOI: 10.1007/s12975-013-0314-x] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2013] [Revised: 10/16/2013] [Accepted: 11/19/2013] [Indexed: 12/20/2022]
Abstract
Stroke is a leading cause of human death and disability in the USA and around the world. Shortly after the cerebral ischemia, cell swelling is the earliest morphological change in injured neuronal, glial, and endothelial cells. Cytotoxic swelling directly results from increased Na(+) (with H2O) and Ca(2+) influx into cells via ionic mechanisms evoked by membrane depolarization and a number of harmful factors such as glutamate accumulation and the production of oxygen reactive species. During the sub-acute and chronic phases after ischemia, injured cells may show a phenotype of cell shrinkage due to complex processes involving membrane receptors/channels and programmed cell death signals. This review will introduce some progress in the understanding of the regulation of pathological cell volume changes and the involved receptors and channels, including NMDA and AMPA receptors, acid-sensing ion channels, hemichannels, transient receptor potential channels, and KCNQ channels. Moreover, accumulating evidence supports a key role of energy deficiency and dysfunction of Na(+)/K(+)-ATPase in ischemia-induced cell volume changes and cell death. Specifically, the Na(+) pump failure is a prerequisite for disruption of ionic homeostasis including a pro-apoptotic disruption of the K(+) homeostasis. Finally, we will introduce the concept of hybrid cell death as a result of the Na(+) pump failure in cultured cells and the ischemic brain. The goal of this review is to outline recent understanding of the ionic mechanism of ischemic cytotoxicity and suggest innovative ideas for future translational research.
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Affiliation(s)
- Mingke Song
- Department of Anesthesiology, Emory University School of Medicine, 101 Woodruff Circle, WMB Building Suite 620, Atlanta, GA, 30322, USA
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Xiao L, Hu C, Yang W, Guo D, Li C, Shen W, Liu X, Aijun H, Dan W, He C. NMDA receptor couples Rac1-GEF Tiam1 to direct oligodendrocyte precursor cell migration. Glia 2013; 61:2078-99. [PMID: 24123220 DOI: 10.1002/glia.22578] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2013] [Revised: 08/02/2013] [Accepted: 08/26/2013] [Indexed: 12/13/2022]
Affiliation(s)
- Lin Xiao
- Institute of Neuroscience and Key Laboratory of Molecular Neurobiology of Ministry of Education; Neuroscience Center of Changzheng Hospital, Second Military Medical University; Shanghai People's Republic of China
| | - Chun Hu
- Institute of Neuroscience and Key Laboratory of Molecular Neurobiology of Ministry of Education; Neuroscience Center of Changzheng Hospital, Second Military Medical University; Shanghai People's Republic of China
| | - Wenjing Yang
- Institute of Neuroscience and Key Laboratory of Molecular Neurobiology of Ministry of Education; Neuroscience Center of Changzheng Hospital, Second Military Medical University; Shanghai People's Republic of China
| | - Dazhi Guo
- Institute of Neuroscience and Key Laboratory of Molecular Neurobiology of Ministry of Education; Neuroscience Center of Changzheng Hospital, Second Military Medical University; Shanghai People's Republic of China
| | - Cui Li
- Institute of Neuroscience and Key Laboratory of Molecular Neurobiology of Ministry of Education; Neuroscience Center of Changzheng Hospital, Second Military Medical University; Shanghai People's Republic of China
| | - Weiran Shen
- Institute of Neuroscience and Key Laboratory of Molecular Neurobiology of Ministry of Education; Neuroscience Center of Changzheng Hospital, Second Military Medical University; Shanghai People's Republic of China
| | - Xiuyun Liu
- Institute of Neuroscience and Key Laboratory of Molecular Neurobiology of Ministry of Education; Neuroscience Center of Changzheng Hospital, Second Military Medical University; Shanghai People's Republic of China
| | - Huang Aijun
- Institute of Neuroscience and Key Laboratory of Molecular Neurobiology of Ministry of Education; Neuroscience Center of Changzheng Hospital, Second Military Medical University; Shanghai People's Republic of China
| | - Wang Dan
- Institute of Neuroscience and Key Laboratory of Molecular Neurobiology of Ministry of Education; Neuroscience Center of Changzheng Hospital, Second Military Medical University; Shanghai People's Republic of China
| | - Cheng He
- Institute of Neuroscience and Key Laboratory of Molecular Neurobiology of Ministry of Education; Neuroscience Center of Changzheng Hospital, Second Military Medical University; Shanghai People's Republic of China
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Li C, Xiao L, Liu X, Yang W, Shen W, Hu C, Yang G, He C. A functional role of NMDA receptor in regulating the differentiation of oligodendrocyte precursor cells and remyelination. Glia 2013; 61:732-49. [PMID: 23440860 DOI: 10.1002/glia.22469] [Citation(s) in RCA: 99] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2012] [Accepted: 12/27/2012] [Indexed: 11/12/2022]
Abstract
Differentiation of oligodendrocyte precursor cells (OPCs) is the most important event for the myelination of central nervous system (CNS) axons during development and remyelination in demyelinating diseases, while the underlying molecular mechanisms remain largely unknown. Here we show that NMDA receptor (NMDAR) is a functional regulator of OPCs differentiation and remyelination. First, GluN1, GluN2A, and GluN2B subunits are expressed in oligodendrocyte lineage cells (OLs) in vitro and in vivo by immunostaining and Western blot analysis. Second, in a purified rat OPC culture system, NMDARs specially mediate OPCs differentiation by enhancing myelin proteins expression and the processes branching at the immature to mature oligodendrocyte transition analyzed by a serial of developmental stage-specific antigens. Moreover, pharmacological NMDAR antagonists or specific knockdown of GluN1 by RNA interference in OPCs prevents the differentiation induced by NMDA. NMDA can activate the mammalian target of rapamycin (mTOR) signal in OPCs and the pro-differentiation effect of NMDA is obstructed by the mTOR inhibitor rapamycin, suggesting NMDAR exerts its effect through mTOR-dependent mechanism. Furthermore, NMDA increases numbers of myelin segments in DRG-OPC cocultures. Finally, NMDAR specific antagonist MK801 delays remyelination in the cuprizone model examined by LFB-PAS, immunofluorescence and electron microscopy. This effect appears to result from inhibiting OPCs differentiation as more NG2(+) OPCs but less GST-π(+) mature oligodendrocytes are observed. Together, these results indicate that NMDAR plays a critical role in the regulation of OPCs differentiation in vitro and remyelination in cuprizone model which may provide potential target for the treatment of demyelination disease.
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Affiliation(s)
- Cui Li
- Institute of Neuroscience and MOE Key Laboratory of Molecular Neurobiology, Neuroscience Research Center of Changzheng Hospital, Second Military Medical University, Shanghai, 200433, China
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Mcferrin MB, Sontheimer H. A role for ion channels in glioma cell invasion. NEURON GLIA BIOLOGY 2012; 2:39-49. [PMID: 16520829 PMCID: PMC1389710 DOI: 10.1017/s17440925x06000044] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Grants] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Many cells, including neuronal and glial progenitor cells, stem cells and microglial cells, have the capacity to move through the extracellular spaces of the developing and mature brain. This is particularly pronounced in astrocyte-derived tumors, gliomas, which diffusely infiltrate the normal brain. Although a significant body of literature exists regarding signals that are involved in the guidance of cells and their processes, little attention has been paid to cell-shape and cell-volume changes of migratory cells. However, extracellular spaces in the brain are very narrow and represent a major obstacle that requires cells to dynamically regulate their volume. Recent studies in glioma cells show that this involves the secretion of Cl(-) and K(+) with water. Pharmacological inhibition of Cl(-) channels impairs their ability to migrate and limits tumor progression in experimental tumor models. One Cl(-)-channel inhibitor, chlorotoxin, is currently in Phase II clinical trials to treat malignant glioma. This article reviews our current knowledge of cell-volume changes and the role of ion channels during the migration of glioma cells. It also discusses evidence that supports the importance of channel-mediated cell-volume changes in the migration of immature neurons and progenitor cells during development. New unpublished data is presented, which demonstrates that Cl(-) and K(+) channels involved in cell shrinkage localize to lipid-raft domains on the invadipodia of glioma cells and that their presence might be regulated by trafficking of these proteins in and out of lipid rafts.
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Affiliation(s)
| | - Harald Sontheimer
- Correspondence should be addressed to: Harald Sontheimer, Ph.D. Department of Neurobiology, The University of Alabama at Birmingham 1119 6th Ave S. CIRC 545 USA phone: +1 205 975 5805 fax: +1 205 975 5518
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Cesetti T, Ciccolini F, Li Y. GABA Not Only a Neurotransmitter: Osmotic Regulation by GABA(A)R Signaling. Front Cell Neurosci 2012; 6:3. [PMID: 22319472 PMCID: PMC3268181 DOI: 10.3389/fncel.2012.00003] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2011] [Accepted: 01/10/2012] [Indexed: 12/05/2022] Open
Abstract
Mature macroglia and almost all neural progenitor types express γ-aminobutyric (GABA) A receptors (GABAARs), whose activation by ambient or synaptic GABA, leads to influx or efflux of chloride (Cl−) depending on its electro-chemical gradient (ECl). Since the flux of Cl− is indissolubly associated to that of osmotically obliged water, GABAARs regulate water movements by modulating ion gradients. In addition, since water movements also occur through specialized water channels and transporters, GABAAR signaling could affect the movement of water by regulating the function of the channels and transporters involved, thereby affecting not only the direction of the water fluxes but also their dynamics. We will here review recent observations indicating that in neural cells GABAAR-mediated osmotic regulation affects the cellular volume thereby activating multiple intracellular signaling mechanisms important for cell proliferation, maturation, and survival. In addition, we will discuss evidence that the osmotic regulation exerted by GABA may contribute to brain water homeostasis in physiological and in pathological conditions causing brain edema, in which the GABAergic transmission is often altered.
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Affiliation(s)
- Tiziana Cesetti
- Department of Physiology and Pathophysiology, Interdisciplinary Center for Neurosciences, University of Heidelberg Heidelberg, Germany
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Rosas-Arellano A, Machuca-Parra AI, Reyes-Haro D, Miledi R, Martínez-Torres A. Expression of GABAρ receptors in the neostriatum: localization in aspiny, medium spiny neurons and GFAP-positive cells. J Neurochem 2012; 122:900-10. [PMID: 22168837 DOI: 10.1111/j.1471-4159.2011.07621.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
GABAergic transmission in the neostriatum plays a central role in motor coordination, in which a plethora of GABA-A receptor subunits combine to modulate neural inhibition. GABAρ receptors were originally described in the mammalian retina. These receptors possess special electrophysiological and pharmacological properties, forming a characteristic class of ionotropic receptors. In previous studies, we suggested that GABAρ receptors are expressed in the neostriatum, and in this report we show that they are indeed present in all the calretinin-positive interneurons of the neostriatum. In addition, they are located in calbindin-positive interneurons and projection neurons that express the dopamine D(2) receptor. GABAρ receptors were also located in 30% of the glial fibrillary acidic protein-positive cells, and may therefore also contribute to gliotransmission. Quantitative reverse transcription-PCR suggested that the mRNAs of this receptor do not express as much as in the retina, and that GABAρ2 is more abundant than GABAρ1. Electrophysiological recordings in brain slices provided evidence of neurons expressing a cis-4-aminocrotonic acid-activated, 1,2,5,6-tetrahydropyridine-4-yl methylphosphinic acid-sensitive ionotropic GABA receptor, indicating the presence of functional GABAρ receptors in the neostriatum. Finally, electron-microscopy and immunogold located the receptors mainly in perisynaptic as well as in extrasynaptic sites. All these observations reinforce the importance of GABAρ receptors in the neostriatum and contribute to the diversity of inhibitory regulation in this area.
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Affiliation(s)
- Abraham Rosas-Arellano
- Departamento de Neurobiología Celular y Molecular, Universidad Nacional Autónoma de México, Instituto de Neurobiología, Campus Juriquilla, Querétaro, Mexico
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Martínez-Delgado G, Estrada-Mondragón A, Miledi R, Martínez-Torres A. An Update on GABAρ Receptors. Curr Neuropharmacol 2011; 8:422-33. [PMID: 21629448 PMCID: PMC3080597 DOI: 10.2174/157015910793358141] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2009] [Revised: 04/08/2010] [Accepted: 06/21/2010] [Indexed: 01/29/2023] Open
Abstract
The present review discusses the functional and molecular diversity of GABAρ receptors. These receptors were originally described in the mammalian retina, and their functional role in the visual pathway has been recently elucidated; however new studies on their distribution in the brain and spinal cord have revealed that they are more spread than originally thought, and thus it will be important to determine their physiological contribution to the GABAergic transmission in other areas of the central nervous system. In addition, molecular modeling has revealed peculiar traits of these receptors that have impacted on the interpretations of the latest pharmacolgical and biophysical findings. Finally, sequencing of several vertebrate genomes has permitted a comparative analysis of the organization of the GABAρ genes.
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Affiliation(s)
- Gustavo Martínez-Delgado
- Instituto de Neurbiología, Departamento de Neurobiología Celular y Molecular, Laboratorio D15, Campus UNAM Juriquilla. Querétaro 76230, México
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31
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Fröhlich N, Nagy B, Hovhannisyan A, Kukley M. Fate of neuron-glia synapses during proliferation and differentiation of NG2 cells. J Anat 2011; 219:18-32. [PMID: 21592101 PMCID: PMC3130157 DOI: 10.1111/j.1469-7580.2011.01392.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/11/2011] [Indexed: 11/30/2022] Open
Abstract
Progenitor cells expressing proteoglycan NG2 (also known as oligodendrocyte precursor cells or polydendrocytes) are widespread in the grey and white matter of the CNS; they comprise 8-9% of the total cell population in adult white matter, and 2-3% of total cells in adult grey matter. NG2 cells have a complex stellate morphology, with highly branched processes that may extend more than 100 μm around the cell body. NG2 cells express a complex set of voltage-gated channels, AMPA/kainate and/or γ-aminobutyric acid (GABA)(A) receptors, and receive glutamatergic and/or GABAergic synaptic input from neurons. In every region of the brain NG2 cells are found as proliferative cells, and the fraction of actively cycling NG2 cells is quite high in young as well as in adult animals. During development NG2 cells either differentiate into myelinating oligodendrocytes (and possibly also few astrocytes and neurons) or persist in the brain parenchyma as NG2 cells. This review highlights new findings related to the morphological and electrophysiological changes of NG2 cells, and the fate of synaptic input between neurons and NG2 cells during proliferation and differentiation of these cells in the neonatal and adult nervous system of rodents.
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Affiliation(s)
- Nicole Fröhlich
- Group of Neuron–Glia Interactions, Werner Reichardt Centre for Integrative Neuroscience, University of TübingenTübingen, Germany
| | - Bálint Nagy
- Group of Neuron–Glia Interactions, Werner Reichardt Centre for Integrative Neuroscience, University of TübingenTübingen, Germany
| | - Anahit Hovhannisyan
- Group of Neuron–Glia Interactions, Werner Reichardt Centre for Integrative Neuroscience, University of TübingenTübingen, Germany
- Group of Retinal Circuits and Optogenetics, Werner Reichardt Centre for Integrative Neuroscience, University of TübingenTübingen, Germany
| | - Maria Kukley
- Group of Neuron–Glia Interactions, Werner Reichardt Centre for Integrative Neuroscience, University of TübingenTübingen, Germany
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Vélez-Fort M, Audinat E, Angulo MC. Central Role of GABA in Neuron–Glia Interactions. Neuroscientist 2011; 18:237-50. [PMID: 21609943 DOI: 10.1177/1073858411403317] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The major types of glial cells—astrocytes, microglia, and cells of the oligodendroglial lineage—are known to express functional metabotropic and ionotropic GABA receptors. Neuronal signaling mechanisms allowing for the activation of these receptors in glia are probably as complex as those described among neurons and involve synaptic and extrasynaptic transmission modes. In addition, astrocytes can signal back to neurons by releasing GABA, probably through unconventional nonvesicular mechanisms. The decryption of the roles played by GABAergic signaling in neuron–glia interactions is only beginning, but it has been suggested that activation of glial cells by GABA influences important functions of the brain such as neuronal activity, differentiation, myelination, and neuroprotection. This review discusses the cellular mechanisms allowing the major types of glial cells to sense and transmit GABAergic signals and gives an overview of potential roles of this signaling pathway in developing and mature brains.
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Affiliation(s)
- Mateo Vélez-Fort
- Inserm U603, Paris, France
- CNRS UMR 8154, Paris, France
- Université Paris Descartes, Paris, France
- Division of Neurophysiology, The National Institute for Medical Research, Mill Hill, UK
| | - Etienne Audinat
- Inserm U603, Paris, France
- CNRS UMR 8154, Paris, France
- Université Paris Descartes, Paris, France
| | - María Cecilia Angulo
- Inserm U603, Paris, France
- CNRS UMR 8154, Paris, France
- Université Paris Descartes, Paris, France
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Faroni A, Magnaghi V. The neurosteroid allopregnanolone modulates specific functions in central and peripheral glial cells. Front Endocrinol (Lausanne) 2011; 2:103. [PMID: 22654838 PMCID: PMC3356145 DOI: 10.3389/fendo.2011.00103] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/30/2011] [Accepted: 12/05/2011] [Indexed: 12/15/2022] Open
Abstract
Since the first observations on the existence of "neurosteroids" in the 1980s, our understanding of the importance of these endogenous steroids in the control of the central and peripheral nervous system (PNS) has increased progressively. Although most of the observations were made in neuronal cells, equally important are the effects that neurosteroids exert on glial cells. Among the different classes of neurosteroids acting on glial cells, the progesterone 5α-3α metabolite, allopregnanolone, displays a particular mechanism of action involving primarily the modulation of classic GABA receptors. In this review, we focus our attention on allopregnanolone because its effects on the physiology of glial cells of the central and PNS are intriguing and could potentially lead to the development of new strategies for neuroprotection and/or regeneration of injured nervous tissues.
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Affiliation(s)
- Alessandro Faroni
- Blond McIndoe Laboratories, Regenerative Biomedicine, School of Medicine, The University of ManchesterManchester, UK
- Department of Endocrinology, Physiopathology, Applied Biology, University of MilanMilan, Italy
| | - Valerio Magnaghi
- Department of Endocrinology, Physiopathology, Applied Biology, University of MilanMilan, Italy
- *Correspondence: Valerio Magnaghi, Department of Endocrinology, Physiopathology, Applied Biology, University of Milan, Via G. Balzaretti 9, 20133 Milan, Italy. e-mail:
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Ionotropic receptors in neuronal-astroglial signalling: what is the role of "excitable" molecules in non-excitable cells. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2010; 1813:992-1002. [PMID: 20869992 DOI: 10.1016/j.bbamcr.2010.09.007] [Citation(s) in RCA: 88] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2010] [Revised: 09/13/2010] [Accepted: 09/16/2010] [Indexed: 01/02/2023]
Abstract
Astroglial cells were long considered to serve merely as the structural and metabolic supporting cast and scenery against which the shining neurones perform their illustrious duties. Relatively recent evidence, however, indicates that astrocytes are intimately involved in many of the brain's functions. Astrocytes possess a diverse assortment of ionotropic transmitter receptors, which enable these glial cells to respond to many of the same signals that act on neurones. Ionotropic receptors mediate neurone-driven signals to astroglial cells in various brain areas including neocortex, hippocampus and cerebellum. Activation of ionotropic receptors trigger rapid signalling events in astroglia; these events, represented by local Ca(2+) or Na(+) signals provide the mechanism for fast neuronal-glial signalling at the synaptic level. Since astrocytes can detect chemical transmitters that are released from neurones and can release their own extracellular signals, gliotransmitters, they are intricately involved in homocellular and heterocellular signalling mechanisms in the nervous system. This article is part of a Special Issue entitled: 11th European Symposium on Calcium.
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Kolodziejczyk K, Saab AS, Nave KA, Attwell D. Why do oligodendrocyte lineage cells express glutamate receptors? F1000 BIOLOGY REPORTS 2010; 2:57. [PMID: 21173873 PMCID: PMC2990618 DOI: 10.3410/b2-57] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The function of glutamate receptors on oligodendrocytes and their precursor cells is poorly understood, with their only clear action being to damage these cells in pathological conditions. Here we review recent studies of glutamate signalling to oligodendrocyte lineage cells, and explore what its physiological function may be.
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Affiliation(s)
- Karolina Kolodziejczyk
- Department of Neuroscience, Physiology and Pharmacology, University College LondonGower Street, London WC1E 6BTUK
| | - Aiman S Saab
- Abteilung Neurogenetik, Max-Planck-Institut für Experimentelle MedizinHermann-Rein-Strasse 3, 37075 GöttingenGermany
| | - Klaus-Armin Nave
- Abteilung Neurogenetik, Max-Planck-Institut für Experimentelle MedizinHermann-Rein-Strasse 3, 37075 GöttingenGermany
| | - David Attwell
- Department of Neuroscience, Physiology and Pharmacology, University College LondonGower Street, London WC1E 6BTUK
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36
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Magnaghi V. GABA and neuroactive steroid interactions in glia: new roles for old players? Curr Neuropharmacol 2010; 5:47-64. [PMID: 18615153 DOI: 10.2174/157015907780077132] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2006] [Revised: 04/24/2006] [Accepted: 07/27/2006] [Indexed: 02/06/2023] Open
Abstract
In recent years it has becoming clear that glial cells of the central and peripheral nervous system play a crucial role from the earliest stages of development throughout adult life. Glial cells are important for neuronal plasticity, axonal conduction and synaptic transmission. In this respect, glial cells are able to produce, uptake and metabolize many factors that are essential for neuronal physiology, including classic neurotransmitters and neuroactive steroids. In particular, neuroactive steroids, which are mainly synthesized by glial cells, are able to modulate some neurotransmitter receptors affecting both glia and neurons. Among the signaling systems that are specialized for neuron-glial communication, we can include neurotransmitter GABA.The main focus of this review is to illustrate the cross-talk between neurons and glial cells in terms of GABA neurotransmission and actions of neuroactive steroids. To this purpose, we will review the presence of the different GABA receptors in the glial cells of the central and peripheral nervous system. Then, we will discuss their modulation by some neuroactive steroids.
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Affiliation(s)
- Valerio Magnaghi
- Department of Endocrinology and Center of Excellence on Neurodegenerative Disease, University of Milan, Italy.
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Larionova NP, Reutov VP, Samosudova NV, Chailakhyan LM. Neuroglial chemical synapses in the cerebellum of adult frog. DOKLADY BIOLOGICAL SCIENCES : PROCEEDINGS OF THE ACADEMY OF SCIENCES OF THE USSR, BIOLOGICAL SCIENCES SECTIONS 2010; 432:171-175. [PMID: 20665146 DOI: 10.1134/s0012496610030026] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2009] [Indexed: 05/29/2023]
Affiliation(s)
- N P Larionova
- Kharkevich Institute for Information Transmission Problems, Russian Academy of Sciences, Moscow, 127994, Russia
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38
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Abstract
The mammalian CNS contains an abundant, widely distributed population of glial cells that serve as oligodendrocyte progenitors. It has been reported that these NG2-immunoreactive cells (NG2(+) cells) form synapses and generate action potentials, suggesting that neural-evoked excitation of these progenitors may regulate oligodendrogenesis. However, recent studies also suggest that NG2(+) cells are comprised of functionally distinct groups that differ in their ability to respond to neuronal activity, undergo differentiation, and experience injury following ischemia. To better define the physiological properties of NG2(+) cells, we used transgenic mice that allowed an unbiased sampling of this population and unambiguous identification of cells in discrete states of differentiation. Using acute brain slices prepared from developing and mature mice, we found that NG2(+) cells in diverse brain regions share a core set of physiological properties, including expression of voltage-gated Na(+) (NaV) channels and ionotropic glutamate receptors, and formation of synapses with glutamatergic neurons. Although small amplitude Na(+) spikes could be elicited in some NG2(+) cells during the first postnatal week, they were not capable of generating action potentials. Transition of these progenitors to the premyelinating stage was accompanied by the rapid removal of synaptic input, as well as downregulation of AMPA and NMDA receptors and NaV channels. Thus, prior reports of physiological heterogeneity among NG2(+) cells may reflect analysis of cells in later stages of maturation. These results suggest that NG2(+) cells are uniquely positioned within the oligodendrocyte lineage to monitor the firing patterns of surrounding neurons.
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Hoffmann A, Grimm C, Kraft R, Goldbaum O, Wrede A, Nolte C, Hanisch UK, Richter-Landsberg C, Brück W, Kettenmann H, Harteneck C. TRPM3 is expressed in sphingosine-responsive myelinating oligodendrocytes. J Neurochem 2010; 114:654-65. [PMID: 20163522 DOI: 10.1111/j.1471-4159.2010.06644.x] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Oligodendrocytes are the myelin-forming cells of the CNS and guarantee proper nerve conduction. Sphingosine, one major component of myelin, has recently been identified to activate TRPM3, a member of the melastatin-related subfamily of transient receptor potential (TRP) channels. TRPM3 has been demonstrated to be expressed in brain with unknown cellular distribution. Here, we show for the first time that TRPM3 is expressed in oligodendrocytes in vitro and in vivo. TRPM3 is present during oligodendrocyte differentiation. Immunohistochemistry of adult rat brain slices revealed staining of white matter areas, which co-localized with oligodendrocyte markers. Analysis of the developmental distribution revealed that, prior to myelination, TRPM3 channels are localized on neurons. On oligodendrocytes they are found after the onset of myelination. RT-PCR studies showed that the transcription of TRPM3 splice variants is also developmentally regulated in vitro. Ca(2+) imaging approaches revealed the presence of a sphingosine-induced Ca(2+) entry mechanism in oligodendrocytes - with a pharmacological profile similar to the profile published for heterologously expressed TRPM3. These findings indicate that TRPM3 participates as a Ca(2+)-permeable and sphingosine-activated channel in oligodendrocyte differentiation and CNS myelination.
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Affiliation(s)
- Anja Hoffmann
- Zelluläre Neurowissenschaften, Max-Delbrück-Centrum, Berlin, Germany
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40
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Constantinou S, Fern R. Conduction block and glial injury induced in developing central white matter by glycine, GABA, noradrenalin, or nicotine, studied in isolated neonatal rat optic nerve. Glia 2009; 57:1168-77. [DOI: 10.1002/glia.20839] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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41
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Yamazaki Y, Hozumi Y, Kaneko K, Fujii S, Goto K, Kato H. Oligodendrocytes: facilitating axonal conduction by more than myelination. Neuroscientist 2009; 16:11-8. [PMID: 19429890 DOI: 10.1177/1073858409334425] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Oligodendrocytes have received much attention in relation to neurological and psychiatric disorders. The involvement of oligodendrocytes and their myelin in normal brain functions has been suggested by many lines of evidence. The conduction velocity of action potentials along axons is dramatically increased by myelination, that is, the formation of a passive insulator. There is a growing understanding of the functional roles of ion channels and neurotransmitter receptors on oligodendrocytes, and the activity-dependent facilitative effect of oligodendrocytes on conduction velocity has been demonstrated. In this article, we summarize evidence for the ability of oligodendrocytes to monitor neuronal activity and for the facilitation of axonal conduction by oligodendrocytes by mechanisms other than myelination. We suggest the underlying mechanisms for this facilitation in relation to the morphological dynamics of myelinating processes and discuss the physiological roles of the facilitation in information processing.
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Affiliation(s)
- Yoshihiko Yamazaki
- Department of Neurophysiology, Yamagata University Schoolof Medicine, Yamagata, Japan.
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42
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Nishiyama A, Komitova M, Suzuki R, Zhu X. Polydendrocytes (NG2 cells): multifunctional cells with lineage plasticity. Nat Rev Neurosci 2009; 10:9-22. [DOI: 10.1038/nrn2495] [Citation(s) in RCA: 647] [Impact Index Per Article: 43.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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43
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Cheung G, Kann O, Kohsaka S, Făerber K, Kettenmann H. GABAergic activities enhance macrophage inflammatory protein-1alpha release from microglia (brain macrophages) in postnatal mouse brain. J Physiol 2008; 587:753-68. [PMID: 19047202 DOI: 10.1113/jphysiol.2008.163923] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Microglial cells (brain macrophages) invade the brain during embryonic and early postnatal development, migrate preferentially along fibre tracts to their final position and transform from an amoeboid to a ramified morphology. Signals by which the invading microglia communicate with other brain cells are largely unknown. Here, we studied amoeboid microglia in postnatal corpus callosum obtained from 6- to 8-day-old mice. These cells accumulated on the surface of acute brain slices. Whole-cell patch-clamp recordings revealed that the specific GABA(A) receptor agonist muscimol triggered a transient increase in conductance typical for inward rectifying potassium channels in microglia. This current increase was not mediated by microglial GABA(A) receptors since microglial cells removed from the slice surface no longer reacted and cultured microglia only responded when a brain slice was placed in their close vicinity. Muscimol triggered a transient increase in extracellular potassium concentration ([K(+)](o)) in brain slices and an experimental elevation of [K(+)](o) mimicked the muscimol response in microglial cells. Moreover, in adult brain slices, muscimol led only to a minute increase in [K(+)](o) and microglial cells failed to respond to muscimol. In turn, an increase in [K(+)](o) stimulated the release of chemokine macrophage inflammatory protein-1alpha (MIP1-alpha) from brain slices and from cultures of microglia but not astrocytes. Our observations indicate that invading microglia in early postnatal development sense GABAergic activities indirectly via sensing changes in [K(+)](o) which results in an increase in MIP1-alpha release.
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Affiliation(s)
- Giselle Cheung
- Cellular Neurosciences, Max-Delbrueck-Center for Molecular Medicine, Berlin, Germany
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44
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McTigue DM, Tripathi RB. The life, death, and replacement of oligodendrocytes in the adult CNS. J Neurochem 2008; 107:1-19. [PMID: 18643793 DOI: 10.1111/j.1471-4159.2008.05570.x] [Citation(s) in RCA: 329] [Impact Index Per Article: 20.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Oligodendrocytes (OLs) are mature glial cells that myelinate axons in the brain and spinal cord. As such, they are integral to functional and efficient neuronal signaling. The embryonic lineage and postnatal development of OLs have been well-studied and many features of the process have been described, including the origin, migration, proliferation, and differentiation of precursor cells. Less clear is the extent to which OLs and damaged/dysfunctional myelin are replaced following injury to the adult CNS. OLs and their precursors are very vulnerable to conditions common to CNS injury and disease sites, such as inflammation, oxidative stress, and elevated glutamate levels leading to excitotoxicity. Thus, these cells become dysfunctional or die in multiple pathologies, including Alzheimer's disease, spinal cord injury, Parkinson's disease, ischemia, and hypoxia. However, studies of certain conditions to date have detected spontaneous OL replacement. This review will summarize current information on adult OL progenitors, mechanisms that contribute to OL death, the consequences of their loss and the pathological conditions in which spontaneous oligodendrogenesis from endogenous precursors has been observed in the adult CNS.
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Affiliation(s)
- Dana M McTigue
- Department of Neuroscience and Center for Brain and Spinal Cord Repair, The Ohio State University, Columbus, Ohio, USA.
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45
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Glutamatergic signaling in the brain's white matter. Neuroscience 2008; 158:266-74. [PMID: 18314276 DOI: 10.1016/j.neuroscience.2008.01.015] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2007] [Accepted: 01/05/2008] [Indexed: 11/22/2022]
Abstract
Glutamatergic signaling has been exceptionally well characterized in the brain's gray matter, where it underlies fast information processing, learning and memory, and also generates the neuronal damage that occurs in pathological conditions such as stroke. The role of glutamatergic signaling in the white matter, an area until recently thought to be devoid of synapses, is less well understood. Here we review what is known, and highlight what is not known, of glutamatergic signaling in the white matter. We focus on how glutamate is released, the location and properties of the receptors it acts on, the interacting molecules that may regulate trafficking or signaling of the receptors, the possible functional roles of glutamate in the white matter, and its pathological effects including the possibility of treating white matter disorders with glutamate receptor blockers.
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46
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Dronne MA, Grenier E, Dumont T, Hommel M, Boissel JP. Role of astrocytes in grey matter during stroke: a modelling approach. Brain Res 2006; 1138:231-42. [PMID: 17274959 DOI: 10.1016/j.brainres.2006.12.062] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2006] [Revised: 12/17/2006] [Accepted: 12/20/2006] [Indexed: 11/24/2022]
Abstract
The astrocytic response to stroke is extremely complex and incompletely understood. On the one hand, astrocytes are known to be neuroprotective when extracellular glutamate or potassium is slightly increased. But, on the other hand, they are considered to contribute to the extracellular glutamate increase during severe ischaemia. A mathematical model is used to reproduce the dynamics of the membrane potentials, intracellular and extracellular concentrations and volumes of neurons and astrocytes during ischaemia in order to study the role of astrocytes in grey matter during the first hour of a stroke. Under conditions of mild ischaemia, astrocytes are observed to take up glutamate via the glutamate transporter, and potassium via the Na/K/Cl cotransporter, which limits glutamate and potassium increase in the extracellular space. On the contrary, under conditions of severe ischaemia, astrocytes appear to be unable to maintain potassium homeostasis. Moreover, they are shown to contribute to the excitotoxicity process by expelling glutamate out of the cells via the reversed glutamate transporter. A detailed understanding of astrocytic function and influence on neuron survival during stroke is necessary to improve the neuroprotective strategies for stroke patients.
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Affiliation(s)
- Marie-Aimée Dronne
- UMR 5558, Université Lyon1, CNRS, Institut de Médecine Théorique, Lyon, France.
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47
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Káradóttir R, Attwell D. Neurotransmitter receptors in the life and death of oligodendrocytes. Neuroscience 2006; 145:1426-38. [PMID: 17049173 PMCID: PMC2173944 DOI: 10.1016/j.neuroscience.2006.08.070] [Citation(s) in RCA: 158] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2006] [Revised: 07/20/2006] [Accepted: 08/18/2006] [Indexed: 10/25/2022]
Abstract
Oligodendrocytes are crucial to the function of the mammalian brain: they increase the action potential conduction speed for a given axon diameter and thus facilitate the rapid flow of information between different brain areas. The proliferation and differentiation of developing oligodendrocytes, and their myelination of axons, are partly controlled by neurotransmitters. In addition, in models of conditions like stroke, periventricular leukomalacia leading to cerebral palsy, spinal cord injury and multiple sclerosis, oligodendrocytes are damaged by glutamate and, contrary to dogma, it has recently been discovered that this damage is mediated in part by N-methyl-D-aspartate receptors. Mutations in oligodendrocyte neurotransmitter receptors or their interacting proteins may cause defects in CNS function. Here we review the roles of neurotransmitter receptors in the normal function, and malfunction in pathological conditions, of oligodendrocytes.
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Affiliation(s)
- R Káradóttir
- Department of Physiology, University College London, Gower Street, London WC1E 6BT, UK.
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48
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Magnaghi V, Ballabio M, Consoli A, Lambert JJ, Roglio I, Melcangi RC. GABA receptor-mediated effects in the peripheral nervous system: A cross-interaction with neuroactive steroids. J Mol Neurosci 2006; 28:89-102. [PMID: 16632878 DOI: 10.1385/jmn:28:1:89] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2005] [Revised: 11/30/1999] [Accepted: 08/18/2005] [Indexed: 12/18/2022]
Abstract
Gamma-aminobutyric acid (GABA), the major inhibitory neurotransmitter in the adult mammalian central nervous system (CNS), exerts its action via an interaction with specific receptors (e.g., GABAA and GABAB). These receptors are expressed not only in neurons but also on glial cells of the CNS, which might represent a target for the allosteric action of neuroactive steroids. Herein, we have demonstrated first that in the peripheral nervous system (PNS), the sciatic nerve and myelin-producing Schwann cells express both GABAA and GABAB receptors. Specific ligands, muscimol and baclofen, respectively, control Schwann-cell proliferation and expression of some specific myelin proteins (i.e., glycoprotein P0 and peripheral myelin protein 22 [PMP22]). Moreover, the progesterone (P) metabolite allopregnanolone, acting via the GABAA receptor, can influence PMP22 synthesis. In addition, we demonstrate that P, dihydroprogesterone, and allopregnanolone influence the expression of GABAB subunits in Schwann cells. The results suggest, at least in the myelinating cells of the PNS, a cross-interaction within the GABAergic receptor system, via GABAA and GABAB receptors and neuroactive steroids.
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Affiliation(s)
- Valerio Magnaghi
- Department of Endocrinology and Center of Excellence on Neurodegenerative Diseases, University of Milan, 20133 Milan, Italy.
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49
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Verkhratsky A. Patching the glia reveals the functional organisation of the brain. Pflugers Arch 2006; 453:411-20. [PMID: 16775706 DOI: 10.1007/s00424-006-0099-9] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2006] [Accepted: 04/28/2006] [Indexed: 10/24/2022]
Abstract
The neuroglia was initially conceived by Rudolf Virchow as a non-cellular connective tissue holding neurones together. In 1894, Carl Ludwig Schleich proposed a hypothesis of fully integrated and interconnected neuronal-glial circuits as a substrate for brain function. This hypothesis received direct experimental support only hundred years later, after several physiological techniques, and most notably the patch-clamp method, were applied to glial cells. These experiments have demonstrated the existence of active and bi-directional neuronal-glial communications, integrating neuronal networks and glial syncytium into one functional circuit. The data accumulated during last 15 years prompt rethinking of the neuronal doctrine towards more inclusive concept, which regards both neurones and glia as equally responsible for information processing in the brain.
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Affiliation(s)
- Alexei Verkhratsky
- Faculty of Life Sciences, The University of Manchester, 1.124 Stopford Building, Oxford Road, Manchester, M13 9PT, UK.
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50
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Káradóttir R, Cavelier P, Bergersen LH, Attwell D. NMDA receptors are expressed in oligodendrocytes and activated in ischaemia. Nature 2006; 438:1162-6. [PMID: 16372011 PMCID: PMC1416283 DOI: 10.1038/nature04302] [Citation(s) in RCA: 555] [Impact Index Per Article: 30.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2005] [Accepted: 10/10/2005] [Indexed: 11/09/2022]
Abstract
Glutamate-mediated damage to oligodendrocytes contributes to mental or physical impairment in periventricular leukomalacia (pre- or perinatal white matter injury leading to cerebral palsy), spinal cord injury, multiple sclerosis and stroke. Unlike neurons, white matter oligodendrocytes reportedly lack NMDA (N-methyl-d-aspartate) receptors. It is believed that glutamate damages oligodendrocytes, especially their precursor cells, by acting on calcium-permeable AMPA (alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid)/kainate receptors alone or by reversing cystine-glutamate exchange and depriving cells of antioxidant protection. Here we show that precursor, immature and mature oligodendrocytes in the white matter of the cerebellum and corpus callosum exhibit NMDA-evoked currents, mediated by receptors that are blocked only weakly by Mg2+ and that may contain NR1, NR2C and NR3 NMDA receptor subunits. NMDA receptors are present in the myelinating processes of oligodendrocytes, where the small intracellular space could lead to a large rise in intracellular ion concentration in response to NMDA receptor activation. Simulating ischaemia led to development of an inward current in oligodendrocytes, which was partly mediated by NMDA receptors. These results point to NMDA receptors of unusual subunit composition as a potential therapeutic target for preventing white matter damage in a variety of diseases.
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Affiliation(s)
| | | | | | - David Attwell
- Send correspondence to: David Attwell, Dept. Physiology, University College London, Gower St., London, WC1E 6BT, England, Tel: (+44)-20-7679-7342; Fax: (+44)-20-7383-7005; E-mail
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