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Bonvento G, Oliet SHR, Panatier A. Glycolysis-derived L-serine levels versus PHGDH expression in Alzheimer's disease. Cell Metab 2022; 34:654-655. [PMID: 35508106 DOI: 10.1016/j.cmet.2022.04.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Revised: 03/22/2022] [Accepted: 04/06/2022] [Indexed: 11/17/2022]
Abstract
Recent work from Bonvento and colleagues indicated that synaptic and memory deficits in early Alzheimer's disease (AD) are related to a shortage in L-serine production in astrocytes. Here, the authors, responding to correspondence from Chen and colleagues, discuss how this deficiency does not necessarily require a decrease in PHGDH expression and conclude that the primary event leading to lower serine production is more likely related to altered glycolytic flux in early AD than to PHGDH expression.
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Affiliation(s)
- Gilles Bonvento
- Université Paris-Saclay, CEA, CNRS, MIRCen, Laboratoire des Maladies Neurodégénératives, Fontenay-aux-Roses, France.
| | - Stéphane H R Oliet
- Université de Bordeaux, INSERM, Neurocentre Magendie, U1215, Bordeaux, France
| | - Aude Panatier
- Université de Bordeaux, INSERM, Neurocentre Magendie, U1215, Bordeaux, France
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2
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Abstract
Astrocytes are sensitive to ongoing neuronal/network activities and, accordingly, regulate neuronal functions (synaptic transmission, synaptic plasticity, behavior, etc.) by the context-dependent release of several gliotransmitters (e.g., glutamate, glycine, D-serine, ATP). To sense diverse input, astrocytes express a plethora of G-protein coupled receptors, which couple, via Gi/o and Gq, to the intracellular Ca2+ release channel IP3-receptor (IP3R). Indeed, manipulating astrocytic IP3R-Ca2+ signaling is highly consequential at the network and behavioral level: Depleting IP3R subtype 2 (IP3R2) results in reduced GPCR-Ca2+ signaling and impaired synaptic plasticity; enhancing IP3R-Ca2+ signaling affects cognitive functions such as learning and memory, sleep, and mood. However, as a result of discrepancies in the literature, the role of GPCR-IP3R-Ca2+ signaling, especially under physiological conditions, remains inconclusive. One primary reason for this could be that IP3R2 has been used to represent all astrocytic IP3Rs, including IP3R1 and IP3R3. Indeed, IP3R1 and IP3R3 are unique Ca2+ channels in their own right; they have unique biophysical properties, often display distinct distribution, and are differentially regulated. As a result, they mediate different physiological roles to IP3R2. Thus, these additional channels promise to enrich the diversity of spatiotemporal Ca2+ dynamics and provide unique opportunities for integrating neuronal input and modulating astrocyte–neuron communication. The current review weighs evidence supporting the existence of multiple astrocytic-IP3R isoforms, summarizes distinct sub-type specific properties that shape spatiotemporal Ca2+ dynamics. We also discuss existing experimental tools and future refinements to better recapitulate the endogenous activities of each IP3R isoform.
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Affiliation(s)
- Mark W Sherwood
- University of Bordeaux, INSERM, Neurocentre Magendie, U1215, Bordeaux, France
| | - Misa Arizono
- University of Bordeaux, CNRS, Interdisciplinary Institute for Neuroscience, IINS, UMR 5297, Bordeaux, France
| | - Aude Panatier
- University of Bordeaux, INSERM, Neurocentre Magendie, U1215, Bordeaux, France
| | - Katsuhiko Mikoshiba
- ShanghaiTech University, Shanghai, China.,Faculty of Science, Toho University, Funabashi, Japan.,RIKEN CLST, Kobe, Japan
| | - Stéphane H R Oliet
- University of Bordeaux, INSERM, Neurocentre Magendie, U1215, Bordeaux, France
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3
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Sherwood MW, Oliet SHR, Panatier A. NMDARs, Coincidence Detectors of Astrocytic and Neuronal Activities. Int J Mol Sci 2021; 22:7258. [PMID: 34298875 PMCID: PMC8307462 DOI: 10.3390/ijms22147258] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Revised: 06/30/2021] [Accepted: 06/30/2021] [Indexed: 12/18/2022] Open
Abstract
Synaptic plasticity is an extensively studied cellular correlate of learning and memory in which NMDARs play a starring role. One of the most interesting features of NMDARs is their ability to act as a co-incident detector. It is unique amongst neurotransmitter receptors in this respect. Co-incident detection is possible because the opening of NMDARs requires membrane depolarisation and the binding of glutamate. Opening of NMDARs also requires a co-agonist. Although the dynamic regulation of glutamate and membrane depolarization have been well studied in coincident detection, the role of the co-agonist site is unexplored. It turns out that non-neuronal glial cells, astrocytes, regulate co-agonist availability, giving them the ability to influence synaptic plasticity. The unique morphology and spatial arrangement of astrocytes at the synaptic level affords them the capacity to sample and integrate information originating from unrelated synapses, regardless of any pre-synaptic and post-synaptic commonality. As astrocytes are classically considered slow responders, their influence at the synapse is widely recognized as modulatory. The aim herein is to reconsider the potential of astrocytes to participate directly in ongoing synaptic NMDAR activity and co-incident detection.
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Affiliation(s)
- Mark W. Sherwood
- University of Bordeaux, INSERM, Neurocentre Magendie, U1215, F-3300 Bordeaux, France;
| | | | - Aude Panatier
- University of Bordeaux, INSERM, Neurocentre Magendie, U1215, F-3300 Bordeaux, France;
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4
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Escartin C, Galea E, Lakatos A, O'Callaghan JP, Petzold GC, Serrano-Pozo A, Steinhäuser C, Volterra A, Carmignoto G, Agarwal A, Allen NJ, Araque A, Barbeito L, Barzilai A, Bergles DE, Bonvento G, Butt AM, Chen WT, Cohen-Salmon M, Cunningham C, Deneen B, De Strooper B, Díaz-Castro B, Farina C, Freeman M, Gallo V, Goldman JE, Goldman SA, Götz M, Gutiérrez A, Haydon PG, Heiland DH, Hol EM, Holt MG, Iino M, Kastanenka KV, Kettenmann H, Khakh BS, Koizumi S, Lee CJ, Liddelow SA, MacVicar BA, Magistretti P, Messing A, Mishra A, Molofsky AV, Murai KK, Norris CM, Okada S, Oliet SHR, Oliveira JF, Panatier A, Parpura V, Pekna M, Pekny M, Pellerin L, Perea G, Pérez-Nievas BG, Pfrieger FW, Poskanzer KE, Quintana FJ, Ransohoff RM, Riquelme-Perez M, Robel S, Rose CR, Rothstein JD, Rouach N, Rowitch DH, Semyanov A, Sirko S, Sontheimer H, Swanson RA, Vitorica J, Wanner IB, Wood LB, Wu J, Zheng B, Zimmer ER, Zorec R, Sofroniew MV, Verkhratsky A. Reactive astrocyte nomenclature, definitions, and future directions. Nat Neurosci 2021; 24:312-325. [PMID: 33589835 PMCID: PMC8007081 DOI: 10.1038/s41593-020-00783-4] [Citation(s) in RCA: 937] [Impact Index Per Article: 312.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2020] [Accepted: 12/16/2020] [Indexed: 12/18/2022]
Abstract
Reactive astrocytes are astrocytes undergoing morphological, molecular, and functional remodeling in response to injury, disease, or infection of the CNS. Although this remodeling was first described over a century ago, uncertainties and controversies remain regarding the contribution of reactive astrocytes to CNS diseases, repair, and aging. It is also unclear whether fixed categories of reactive astrocytes exist and, if so, how to identify them. We point out the shortcomings of binary divisions of reactive astrocytes into good-vs-bad, neurotoxic-vs-neuroprotective or A1-vs-A2. We advocate, instead, that research on reactive astrocytes include assessment of multiple molecular and functional parameters-preferably in vivo-plus multivariate statistics and determination of impact on pathological hallmarks in relevant models. These guidelines may spur the discovery of astrocyte-based biomarkers as well as astrocyte-targeting therapies that abrogate detrimental actions of reactive astrocytes, potentiate their neuro- and glioprotective actions, and restore or augment their homeostatic, modulatory, and defensive functions.
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Affiliation(s)
- Carole Escartin
- Université Paris-Saclay, CEA, CNRS, MIRCen, Laboratoire des Maladies Neurodégénératives, Fontenay-aux-Roses, France.
| | - Elena Galea
- Institut de Neurociències and Departament de Bioquímica i Biologia Molecular, Unitat de Bioquímica de Medicina, Universitat Autònoma de Barcelona, Barcelona, Spain.
- ICREA, Barcelona, Spain.
| | - András Lakatos
- John van Geest Centre for Brain Repair and Division of Stem Cell Neurobiology, Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK
- Wellcome Trust-MRC Cambridge Stem Cell Institute, Cambridge Biomedical Campus, Cambridge, UK
| | - James P O'Callaghan
- Health Effects Laboratory Division, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, Morgantown, West Virginia, USA
| | - Gabor C Petzold
- German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany
- Division of Vascular Neurology, Department of Neurology, University Hospital Bonn, Bonn, Germany
| | - Alberto Serrano-Pozo
- Alzheimer Research Unit, Department of Neurology, Massachusetts General Hospital, Charlestown, Massachusetts, USA
- Harvard Medical School, Boston, Massachusetts, USA
| | - Christian Steinhäuser
- Institute of Cellular Neurosciences, Medical Faculty, University of Bonn, Bonn, Germany
| | - Andrea Volterra
- Department of Fundamental Neuroscience, University of Lausanne, Lausanne, Switzerland
| | - Giorgio Carmignoto
- Neuroscience Institute, Italian National Research Council (CNR), Padua, Italy
- Department of Biomedical Sciences, University of Padua, Padua, Italy
| | - Amit Agarwal
- The Chica and Heinz Schaller Research Group, Institute for Anatomy and Cell Biology, Heidelberg University, Heidelberg, Germany
| | - Nicola J Allen
- Salk Institute for Biological Studies, Molecular Neurobiology Laboratory, La Jolla, California, USA
| | - Alfonso Araque
- Department of Neuroscience, University of Minnesota, Minneapolis, Minnesota, USA
| | | | - Ari Barzilai
- Department of Neurobiology, George S. Wise, Faculty of Life Sciences and Sagol School of Neuroscience, Tel Aviv University, Ramat Aviv Tel Aviv, Israel
| | - Dwight E Bergles
- The Solomon H. Snyder Department of Neuroscience, Kavli Neuroscience Discovery Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Gilles Bonvento
- Université Paris-Saclay, CEA, CNRS, MIRCen, Laboratoire des Maladies Neurodégénératives, Fontenay-aux-Roses, France
| | - Arthur M Butt
- School of Pharmacy and Biomedical Science, University of Portsmouth, Portsmouth, UK
| | - Wei-Ting Chen
- Center for Brain and Disease Research, VIB and University of Leuven, Leuven, Belgium
| | - Martine Cohen-Salmon
- 'Physiology and Physiopathology of the Gliovascular Unit' Research Group, Center for Interdisciplinary Research in Biology (CIRB), College de France, Unité Mixte de Recherche 7241 CNRS, Unité1050 INSERM, PSL Research University, Paris, France
| | - Colm Cunningham
- Trinity Biomedical Sciences Institute & Trinity College Institute of Neuroscience, School of Biochemistry & Immunology, Trinity College Dublin, Dublin, Republic of Ireland
| | - Benjamin Deneen
- Center for Cell and Gene Therapy, Department of Neurosurgery, Baylor College of Medicine, Houston, Texas, USA
| | - Bart De Strooper
- Center for Brain and Disease Research, VIB and University of Leuven, Leuven, Belgium
- UK Dementia Research Institute at the University College London, London, UK
| | - Blanca Díaz-Castro
- UK Dementia Research Institute at the University of Edinburgh, Centre for Discovery Brain Sciences, Edinburgh, UK
| | - Cinthia Farina
- Institute of Experimental Neurology (INSpe) and Division of Neuroscience, San Raffaele Scientific Institute, Milan, Italy
| | | | - Vittorio Gallo
- Center for Neuroscience Research, Children's National Research Institute, Children's National Hospital, Washington DC, USA
| | - James E Goldman
- Department of Pathology & Cell Biology, Columbia University, New York, New York, USA
| | - Steven A Goldman
- University of Rochester Medical Center, Rochester, New York, USA
- Center for Translational Neuromedicine, University of Copenhagen Faculty of Health and Medical Science and Rigshospitalet, Kobenhavn N, Denmark
| | - Magdalena Götz
- Physiological Genomics, Biomedical Center, Ludwig-Maximilians-Universitaet & Institute of Stem Cell Research, Helmholtz Center Munich, Munich, Germany
- Synergy, Excellence Cluster of Systems Neurology, Biomedical Center, Munich, Germany
| | - Antonia Gutiérrez
- Dpto. Biología Celular, Genética y Fisiología, Instituto de Investigación Biomédica de Málaga-IBIMA, Facultad de Ciencias, Universidad de Málaga, Málaga, Spain
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain
| | - Philip G Haydon
- Department of Neuroscience, Tufts University School of Medicine, Boston, Massachusetts, USA
| | - Dieter H Heiland
- Microenvironment and Immunology Research Laboratory, Medical Center, Faculty of Medicine, University of Freiburg, Freiburg, Germany
- Department of Neurosurgery, Medical Center, University of Freiburg, Faculty of Medicine, Freiburg, Germany
| | - Elly M Hol
- Department of Translational Neuroscience, University Medical Center Utrecht Brain Center, Utrecht University, Utrecht, The Netherlands
| | - Matthew G Holt
- Laboratory of Glia Biology, VIB-KU Leuven Center for Brain and Disease Research, Leuven, Belgium
| | - Masamitsu Iino
- Division of Cellular and Molecular Pharmacology, Nihon University School of Medicine, Tokyo, Japan
| | - Ksenia V Kastanenka
- Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts, USA
| | - Helmut Kettenmann
- Cellular Neurosciences, Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany
| | - Baljit S Khakh
- Department of Physiology, David Geffen School of Medicine at UCLA, Los Angeles, California, USA
| | - Schuichi Koizumi
- Department of Neuropharmacology, Interdisciplinary Graduate School of Medicine, University of Yamanashi, Yamanashi, Japan
| | - C Justin Lee
- Center for Cognition and Sociality, Institute for Basic Science 55, Expo-ro, Yuseong-gu, Daejeon, Korea
| | - Shane A Liddelow
- Neuroscience Institute, Department of Neuroscience and Physiology, Department of Ophthalmology, NYU School of Medicine, New York, USA
| | - Brian A MacVicar
- Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, British Columbia, Canada
| | - Pierre Magistretti
- Division of Biological and Environmental Sciences and Engineering, King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia
- Centre de Neurosciences Psychiatriques, University of Lausanne and CHUV, Site de Cery, Prilly-Lausanne, Lausanne, Switzerland
| | - Albee Messing
- Waisman Center and School of Veterinary Medicine, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Anusha Mishra
- Department of Neurology Jungers Center for Neurosciences Research and Knight Cardiovascular Institute, Oregon Health & Science University, Portland, Oregon, USA
| | - Anna V Molofsky
- Departments of Psychiatry/Weill Institute for Neuroscience University of California, San Francisco, California, USA
| | - Keith K Murai
- Centre for Research in Neuroscience, Department of Neurology & Neurosurgery, Brain Repair and Integrative Neuroscience Program, Research Institute of the McGill University Health Centre, Montreal, Quebec, Canada
| | - Christopher M Norris
- Sanders-Brown Center on Aging, University of Kentucky College of Medicine, Lexington, Kentucky, USA
| | - Seiji Okada
- Department of Immunobiology and Neuroscience, Medical Institute of Bioregulation, Kyushu University, Fukuoka, Japan
| | - Stéphane H R Oliet
- Université de Bordeaux, Inserm, Neurocentre Magendie, U1215, Bordeaux, France
| | - João F Oliveira
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Braga, Portugal
- ICVS/3B's -PT Government Associate Laboratory, Braga/Guimarães, Portugal
- IPCA-EST-2Ai, Polytechnic Institute of Cávado and Ave, Applied Artificial Intelligence Laboratory, Campus of IPCA, Barcelos, Portugal
| | - Aude Panatier
- Université de Bordeaux, Inserm, Neurocentre Magendie, U1215, Bordeaux, France
| | - Vladimir Parpura
- Department of Neurobiology, The University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Marcela Pekna
- Laboratory of Regenerative Neuroimmunology, Center for Brain Repair, Department of Clinical Neuroscience, Institute of Neuroscience and Physiology, Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
| | - Milos Pekny
- Laboratory of Astrocyte Biology and CNS Regeneration, Center for Brain Repair, Department of Clinical Neuroscience, Institute of Neuroscience and Physiology, Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
| | - Luc Pellerin
- INSERM U1082, Université de Poitiers, Poitiers, France
| | - Gertrudis Perea
- Department of Functional and Systems Neurobiology, Cajal Institute, CSIC, Madrid, Spain
| | - Beatriz G Pérez-Nievas
- Department of Basic and Clinical Neuroscience, Maurice Wohl Clinical Neuroscience Institute, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK
| | - Frank W Pfrieger
- Centre National de la Recherche Scientifique, Université de Strasbourg, Institut des Neurosciences Cellulaires et Intégratives, Strasbourg, France
| | - Kira E Poskanzer
- Department of Biochemistry & Biophysics, Kavli Institute for Fundamental Neuroscience, University of California, San Francisco, California, USA
| | - Francisco J Quintana
- Ann Romney Center for Neurologic Diseases, Brigham and Women's Hospital, Harvard Medical School. Associate Member, The Broad Institute, Boston, Massachusetts, USA
| | | | - Miriam Riquelme-Perez
- Université Paris-Saclay, CEA, CNRS, MIRCen, Laboratoire des Maladies Neurodégénératives, Fontenay-aux-Roses, France
| | - Stefanie Robel
- Fralin Biomedical Research Institute at Virginia Tech Carilion, School of Neuroscience Virginia Tech, Riverside Circle, Roanoke, Virginia, USA
| | - Christine R Rose
- Institute of Neurobiology, Heinrich Heine University, Düsseldorf, Germany
| | - Jeffrey D Rothstein
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Nathalie Rouach
- Neuroglial Interactions in Cerebral Physiology and Pathologies, Center for Interdisciplinary Research in Biology, Collège de France, CNRS UMR 7241, INSERM U1050, Labex Memolife, PSL Research University Paris, Paris, France
| | - David H Rowitch
- Wellcome Trust-MRC Cambridge Stem Cell Institute, Cambridge Biomedical Campus, Cambridge, UK
| | - Alexey Semyanov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Moscow, Russia
- Sechenov First Moscow State Medical University, Moscow, Russia
| | - Swetlana Sirko
- Physiological Genomics, Biomedical Center, LMU Munich, Munich, Germany
- Institute for Stem Cell Research, Helmholtz Zentrum Munich, Neuherberg, Germany
| | - Harald Sontheimer
- Virginia Tech School of Neuroscience and Center for Glial Biology in Health, Disease and Cancer, Virginia Tech at the Fralin Biomedical Research Institute, Roanoke, Virginia, USA
| | - Raymond A Swanson
- Dept. of Neurology, University of California San Francisco and San Francisco Veterans Affairs Health Care System, San Francisco, California, USA
| | - Javier Vitorica
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain
- Dept. Bioquímica y Biología Molecular, Instituto de Biomedicina de Sevilla, Universidad de Sevilla, Hospital Virgen del Rocío/CSIC, Sevilla, Spain
| | - Ina-Beate Wanner
- Semel Institute for Neuroscience & Human Behavior, IDDRC, David Geffen School of Medicine, UCLA, Los Angeles, California, USA
| | - Levi B Wood
- George W. Woodruff School of Mechanical Engineering, Wallace H. Coulter Department of Biomedical Engineering at Georgia Tech and Emory, and Parker H. Petit Institute for Bioengineering & Bioscience, Georgia Institute of Technology, Atlanta, Georgia, USA
| | - Jiaqian Wu
- The Vivian L. Smith Department of Neurosurgery, Center for Stem Cell and Regenerative Medicine, MD Anderson Cancer Center UTHealth Graduate School of Biomedical Sciences, McGovern Medical School, UTHealth, University of Texas Health Science Center at Houston, Houston, TX, USA
| | - Binhai Zheng
- Department of Neurosciences, UC San Diego School of Medicine, La Jolla; VA San Diego Research Service, San Diego, CA, USA
| | - Eduardo R Zimmer
- Department of Pharmacology, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
| | - Robert Zorec
- Laboratory of Neuroendocrinology, Molecular Cell Physiology, Institute of Pathophysiology, University of Ljubljana, Faculty of Medicine, Ljubljana, Slovenia
- Celica Biomedical, 1000, Ljubljana, Slovenia
| | - Michael V Sofroniew
- Department of Neurobiology, David Geffen School of Medicine, University of California, Los Angeles, California, USA.
| | - Alexei Verkhratsky
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK.
- Achúcarro Basque Center for Neuroscience, IKERBASQUE, Basque Foundation for Science, Bilbao, Spain.
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5
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Cunnane SC, Trushina E, Morland C, Prigione A, Casadesus G, Andrews ZB, Beal MF, Bergersen LH, Brinton RD, de la Monte S, Eckert A, Harvey J, Jeggo R, Jhamandas JH, Kann O, la Cour CM, Martin WF, Mithieux G, Moreira PI, Murphy MP, Nave KA, Nuriel T, Oliet SHR, Saudou F, Mattson MP, Swerdlow RH, Millan MJ. Brain energy rescue: an emerging therapeutic concept for neurodegenerative disorders of ageing. Nat Rev Drug Discov 2020; 19:609-633. [PMID: 32709961 PMCID: PMC7948516 DOI: 10.1038/s41573-020-0072-x] [Citation(s) in RCA: 383] [Impact Index Per Article: 95.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/03/2020] [Indexed: 12/11/2022]
Abstract
The brain requires a continuous supply of energy in the form of ATP, most of which is produced from glucose by oxidative phosphorylation in mitochondria, complemented by aerobic glycolysis in the cytoplasm. When glucose levels are limited, ketone bodies generated in the liver and lactate derived from exercising skeletal muscle can also become important energy substrates for the brain. In neurodegenerative disorders of ageing, brain glucose metabolism deteriorates in a progressive, region-specific and disease-specific manner - a problem that is best characterized in Alzheimer disease, where it begins presymptomatically. This Review discusses the status and prospects of therapeutic strategies for countering neurodegenerative disorders of ageing by improving, preserving or rescuing brain energetics. The approaches described include restoring oxidative phosphorylation and glycolysis, increasing insulin sensitivity, correcting mitochondrial dysfunction, ketone-based interventions, acting via hormones that modulate cerebral energetics, RNA therapeutics and complementary multimodal lifestyle changes.
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Affiliation(s)
- Stephen C Cunnane
- Department of Medicine, Université de Sherbrooke, Sherbrooke, QC, Canada.
- Research Center on Aging, Sherbrooke, QC, Canada.
| | | | - Cecilie Morland
- Department of Pharmaceutical Biosciences, Institute of Pharmacy, University of Oslo, Oslo, Norway
| | - Alessandro Prigione
- Department of General Pediatrics, Neonatology, and Pediatric Cardiology, University of Dusseldorf, Dusseldorf, Germany
| | - Gemma Casadesus
- Department of Biological Sciences, Kent State University, Kent, OH, USA
| | - Zane B Andrews
- Monash Biomedicine Discovery Institute, Monash University, Clayton, VIC, Australia
- Department of Physiology, Monash University, Clayton, VIC, Australia
| | - M Flint Beal
- Department of Neurology, Weill Cornell Medicine, New York, NY, USA
| | - Linda H Bergersen
- Department of Anatomy, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
| | | | | | | | - Jenni Harvey
- Ninewells Hospital, University of Dundee, Dundee, UK
- Medical School, University of Dundee, Dundee, UK
| | - Ross Jeggo
- Centre for Therapeutic Innovation in Neuropsychiatry, Institut de Recherche Servier, Croissy sur Seine, France
| | - Jack H Jhamandas
- Department of Medicine, University of Albeta, Edmonton, AB, Canada
- Neuroscience and Mental Health Institute, University of Albeta, Edmonton, AB, Canada
| | - Oliver Kann
- Institute of Physiology and Pathophysiology, University of Heidelberg, Heidelberg, Germany
| | - Clothide Mannoury la Cour
- Centre for Therapeutic Innovation in Neuropsychiatry, Institut de Recherche Servier, Croissy sur Seine, France
| | - William F Martin
- Institute of Molecular Evolution, University of Dusseldorf, Dusseldorf, Germany
| | | | - Paula I Moreira
- CNC Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal
- Faculty of Medicine, University of Coimbra, Coimbra, Portugal
| | - Michael P Murphy
- MRC Mitochondrial Biology Unit, University of Cambridge, Cambridge, UK
| | - Klaus-Armin Nave
- Department of Biosciences, University of Heidelberg, Heidelberg, Germany
| | - Tal Nuriel
- Columbia University Medical Center, New York, NY, USA
| | - Stéphane H R Oliet
- Neurocentre Magendie, INSERM U1215, Bordeaux, France
- Université de Bordeaux, Bordeaux, France
| | - Frédéric Saudou
- University of Grenoble Alpes, Grenoble, France
- INSERM U1216, CHU Grenoble Alpes, Grenoble Institute Neurosciences, Grenoble, France
| | - Mark P Mattson
- Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | | | - Mark J Millan
- Centre for Therapeutic Innovation in Neuropsychiatry, Institut de Recherche Servier, Croissy sur Seine, France.
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6
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Ciappelloni S, Bouchet D, Dubourdieu N, Boué-Grabot E, Kellermayer B, Manso C, Marignier R, Oliet SHR, Tourdias T, Groc L. Aquaporin-4 Surface Trafficking Regulates Astrocytic Process Motility and Synaptic Activity in Health and Autoimmune Disease. Cell Rep 2020; 27:3860-3872.e4. [PMID: 31242419 DOI: 10.1016/j.celrep.2019.05.097] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2018] [Revised: 03/08/2019] [Accepted: 05/23/2019] [Indexed: 01/21/2023] Open
Abstract
Astrocytes constantly adapt their ramified morphology in order to support brain cell assemblies. Such plasticity is partly mediated by ion and water fluxes, which rely on the water channel aquaporin-4 (AQP4). The mechanism by which this channel locally contributes to process dynamics has remained elusive. Using a combination of single-molecule and calcium imaging approaches, we here investigated in hippocampal astrocytes the dynamic distribution of the AQP4 isoforms M1 and M23. Surface AQP4-M1 formed small aggregates that contrast with the large AQP4-M23 clusters that are enriched near glutamatergic synapses. Strikingly, stabilizing surface AQP4-M23 tuned the motility of astrocyte processes and favors glutamate synapse activity. Furthermore, human autoantibodies directed against AQP4 from neuromyelitis optica (NMO) patients impaired AQP4-M23 dynamic distribution and, consequently, astrocyte process and synaptic activity. Collectively, it emerges that the membrane dynamics of AQP4 isoform regulate brain cell assemblies in health and autoimmune brain disease targeting AQP4.
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Affiliation(s)
- Silvia Ciappelloni
- Interdisciplinary Institute for NeuroSciences, CNRS UMR 5297, 33077 Bordeaux, France; Université de Bordeaux, 33077 Bordeaux, France; INSERM U1215, Neurocentre Magendie, 33077 Bordeaux, France
| | - Delphine Bouchet
- Interdisciplinary Institute for NeuroSciences, CNRS UMR 5297, 33077 Bordeaux, France; Université de Bordeaux, 33077 Bordeaux, France
| | - Nadège Dubourdieu
- Université de Bordeaux, 33077 Bordeaux, France; INSERM U1215, Neurocentre Magendie, 33077 Bordeaux, France
| | - Eric Boué-Grabot
- Université de Bordeaux, 33077 Bordeaux, France; CNRS, Institut des Maladies Neurodégénératives, UMR 5293, 33000 Bordeaux, France
| | - Blanka Kellermayer
- Interdisciplinary Institute for NeuroSciences, CNRS UMR 5297, 33077 Bordeaux, France; Université de Bordeaux, 33077 Bordeaux, France
| | - Constance Manso
- Interdisciplinary Institute for NeuroSciences, CNRS UMR 5297, 33077 Bordeaux, France; Université de Bordeaux, 33077 Bordeaux, France
| | - Romain Marignier
- INSERM U1028, CNRS UMR 5292, Center for Research in Neuroscience of Lyon, Lyon, France
| | - Stéphane H R Oliet
- Université de Bordeaux, 33077 Bordeaux, France; INSERM U1215, Neurocentre Magendie, 33077 Bordeaux, France
| | - Thomas Tourdias
- Université de Bordeaux, 33077 Bordeaux, France; INSERM U1215, Neurocentre Magendie, 33077 Bordeaux, France
| | - Laurent Groc
- Interdisciplinary Institute for NeuroSciences, CNRS UMR 5297, 33077 Bordeaux, France; Université de Bordeaux, 33077 Bordeaux, France.
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7
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Arizono M, Inavalli VVGK, Panatier A, Pfeiffer T, Angibaud J, Levet F, Veer MJTT, Stobart J, Bellocchio L, Mikoshiba K, Marsicano G, Weber B, Oliet SHR, Nägerl UV. Author Correction: Structural basis of astrocytic Ca 2+ signals at tripartite synapses. Nat Commun 2020; 11:2541. [PMID: 32424204 PMCID: PMC7235234 DOI: 10.1038/s41467-020-16453-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Affiliation(s)
- Misa Arizono
- Interdisciplinary Institute for Neuroscience, University of Bordeaux, Bordeaux, France.,Interdisciplinary Institute for Neuroscience, CNRS UMR 5297, Bordeaux, France
| | - V V G Krishna Inavalli
- Interdisciplinary Institute for Neuroscience, University of Bordeaux, Bordeaux, France.,Interdisciplinary Institute for Neuroscience, CNRS UMR 5297, Bordeaux, France
| | - Aude Panatier
- Interdisciplinary Institute for Neuroscience, University of Bordeaux, Bordeaux, France.,NeuroCentre Magendie, Inserm U1215, Bordeaux, France
| | - Thomas Pfeiffer
- Interdisciplinary Institute for Neuroscience, University of Bordeaux, Bordeaux, France.,Interdisciplinary Institute for Neuroscience, CNRS UMR 5297, Bordeaux, France
| | - Julie Angibaud
- Interdisciplinary Institute for Neuroscience, University of Bordeaux, Bordeaux, France.,Interdisciplinary Institute for Neuroscience, CNRS UMR 5297, Bordeaux, France
| | - Florian Levet
- Interdisciplinary Institute for Neuroscience, University of Bordeaux, Bordeaux, France.,Interdisciplinary Institute for Neuroscience, CNRS UMR 5297, Bordeaux, France.,Bordeaux Imaging Center, University of Bordeaux, Bordeaux, France.,Bordeaux Imaging Center, CNRS UMS 3420, Bordeaux, France.,Bordeaux Imaging Center, INSERM US04, Bordeaux, France
| | - Mirelle J T Ter Veer
- Interdisciplinary Institute for Neuroscience, University of Bordeaux, Bordeaux, France.,Interdisciplinary Institute for Neuroscience, CNRS UMR 5297, Bordeaux, France
| | - Jillian Stobart
- University of Zurich, Institute of Pharmacology & Toxicology, Zürich, Switzerland
| | - Luigi Bellocchio
- Interdisciplinary Institute for Neuroscience, University of Bordeaux, Bordeaux, France.,NeuroCentre Magendie, Inserm U1215, Bordeaux, France
| | | | - Giovanni Marsicano
- Interdisciplinary Institute for Neuroscience, University of Bordeaux, Bordeaux, France.,NeuroCentre Magendie, Inserm U1215, Bordeaux, France
| | - Bruno Weber
- University of Zurich, Institute of Pharmacology & Toxicology, Zürich, Switzerland
| | - Stéphane H R Oliet
- Interdisciplinary Institute for Neuroscience, University of Bordeaux, Bordeaux, France.,NeuroCentre Magendie, Inserm U1215, Bordeaux, France
| | - U Valentin Nägerl
- Interdisciplinary Institute for Neuroscience, University of Bordeaux, Bordeaux, France. .,Interdisciplinary Institute for Neuroscience, CNRS UMR 5297, Bordeaux, France.
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8
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Blaszczyk L, Maître M, Lesté-Lasserre T, Clark S, Cota D, Oliet SHR, Fénelon VS. Sequential alteration of microglia and astrocytes in the rat thalamus following spinal nerve ligation. J Neuroinflammation 2018; 15:349. [PMID: 30572902 PMCID: PMC6302506 DOI: 10.1186/s12974-018-1378-z] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Accepted: 11/26/2018] [Indexed: 12/28/2022] Open
Abstract
Background Spinal reactive astrocytes and microglia are known to participate to the initiation and maintenance of neuropathic pain. However, whether reactive astrocytes and microglia in thalamic nuclei that process sensory-discriminative aspects of pain play a role in pain behavior remains poorly investigated. Therefore, the present study evaluated whether the presence of reactive glia (hypertrophy, increased number and upregulation of glial markers) in the ventral posterolateral thalamic nucleus (VPL) correlates with pain symptoms, 14 and 28 days after unilateral L5/L6 spinal nerve ligation (SNL) in rats. Methods Mechanical allodynia and hyperalgesia (von Frey filament stimulation) as well as ambulatory pain (dynamic weight bearing apparatus) were assessed. Levels of nine glial transcripts were determined by quantitative real-time PCR on laser microdissected thalamic nuclei, and levels of proteins were assessed by Western blot. We also studied by immunohistofluorescence the expression of glial markers that label processes (GFAP for astrocytes and iba-1 for microglia) and cell body (S100β for astrocytes and iba-1 for microglia) and quantified the immunostained surface and the number of astrocytes and microglia (conventional counts and optical dissector method of stereological counting). Results Differential, time-dependent responses were observed concerning microglia and astrocytes. Specifically, at day 14, iba-1 immunostained area and number of iba-1 immunopositive cells were decreased in the VPL of SNL as compared to naïve rats. By contrast, at day 28, GFAP-immunostained area was increased in the VPL of SNL as compared to naïve rats while number of GFAP/S100β immunopositive cells remained unchanged. Using quantitative real-time PCR of laser microdissected VPL, we found a sequential increase in mRNA expression of cathepsin S (day 14), fractalkine (day 28), and fractalkine receptor (day 14), three well-known markers of microglial reactivity. Using Western blot, we confirmed an increase in protein expression of fractalkine receptor at day 14. Conclusions Our results demonstrate a sequential alteration of microglia and astrocytes in the thalamus of animals with lesioned peripheral nerves. Furthermore, our data report unprecedented concomitant molecular signs of microglial activation and morphological signs of microglial decline in the thalamus of these animals.
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Affiliation(s)
- Lucie Blaszczyk
- Bordeaux University, Bordeaux, France.,Neurocentre Magendie, INSERM U1215, Bordeaux, France
| | - Marlène Maître
- Bordeaux University, Bordeaux, France.,Neurocentre Magendie, INSERM U1215, Bordeaux, France
| | - Thierry Lesté-Lasserre
- Bordeaux University, Bordeaux, France.,Neurocentre Magendie, INSERM U1215, Bordeaux, France
| | - Samantha Clark
- Bordeaux University, Bordeaux, France.,Neurocentre Magendie, INSERM U1215, Bordeaux, France
| | - Daniela Cota
- Bordeaux University, Bordeaux, France.,Neurocentre Magendie, INSERM U1215, Bordeaux, France
| | - Stéphane H R Oliet
- Bordeaux University, Bordeaux, France.,Neurocentre Magendie, INSERM U1215, Bordeaux, France
| | - Valérie S Fénelon
- Bordeaux University, Bordeaux, France. .,Neurocentre Magendie, INSERM U1215, Bordeaux, France.
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9
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Ceyzériat K, Ben Haim L, Denizot A, Pommier D, Matos M, Guillemaud O, Palomares MA, Abjean L, Petit F, Gipchtein P, Gaillard MC, Guillermier M, Bernier S, Gaudin M, Aurégan G, Joséphine C, Déchamps N, Veran J, Langlais V, Cambon K, Bemelmans AP, Baijer J, Bonvento G, Dhenain M, Deleuze JF, Oliet SHR, Brouillet E, Hantraye P, Carrillo-de Sauvage MA, Olaso R, Panatier A, Escartin C. Modulation of astrocyte reactivity improves functional deficits in mouse models of Alzheimer's disease. Acta Neuropathol Commun 2018; 6:104. [PMID: 30322407 PMCID: PMC6190663 DOI: 10.1186/s40478-018-0606-1] [Citation(s) in RCA: 112] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2018] [Accepted: 09/24/2018] [Indexed: 11/26/2022] Open
Abstract
Astrocyte reactivity and neuroinflammation are hallmarks of CNS pathological conditions such as Alzheimer’s disease. However, the specific role of reactive astrocytes is still debated. This controversy may stem from the fact that most strategies used to modulate astrocyte reactivity and explore its contribution to disease outcomes have only limited specificity. Moreover, reactive astrocytes are now emerging as heterogeneous cells and all types of astrocyte reactivity may not be controlled efficiently by such strategies. Here, we used cell type-specific approaches in vivo and identified the JAK2-STAT3 pathway, as necessary and sufficient for the induction and maintenance of astrocyte reactivity. Modulation of this cascade by viral gene transfer in mouse astrocytes efficiently controlled several morphological and molecular features of reactivity. Inhibition of this pathway in mouse models of Alzheimer’s disease improved three key pathological hallmarks by reducing amyloid deposition, improving spatial learning and restoring synaptic deficits. In conclusion, the JAK2-STAT3 cascade operates as a master regulator of astrocyte reactivity in vivo. Its inhibition offers new therapeutic opportunities for Alzheimer’s disease.
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10
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Hilal ML, Moreau MM, Racca C, Pinheiro VL, Piguel NH, Santoni MJ, Dos Santos Carvalho S, Blanc JM, Abada YSK, Peyroutou R, Medina C, Doat H, Papouin T, Vuillard L, Borg JP, Rachel R, Panatier A, Montcouquiol M, Oliet SHR, Sans N. Activity-Dependent Neuroplasticity Induced by an Enriched Environment Reverses Cognitive Deficits in Scribble Deficient Mouse. Cereb Cortex 2018; 27:5635-5651. [PMID: 28968740 DOI: 10.1093/cercor/bhw333] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2016] [Indexed: 12/31/2022] Open
Abstract
Planar cell polarity (PCP) signaling is well known to play a critical role during prenatal brain development; whether it plays specific roles at postnatal stages remains rather unknown. Here, we investigated the role of a key PCP-associated gene scrib in CA1 hippocampal structure and function at postnatal stages. We found that Scrib is required for learning and memory consolidation in the Morris water maze as well as synaptic maturation and NMDAR-dependent bidirectional plasticity. Furthermore, we unveiled a direct molecular interaction between Scrib and PP1/PP2A phosphatases whose levels were decreased in postsynaptic density of conditional knock-out mice. Remarkably, exposure to enriched environment (EE) preserved memory formation in CaMK-Scrib-/- mice by recovering synaptic plasticity and maturation. Thus, Scrib is required for synaptic function involved in memory formation and EE has beneficiary therapeutic effects. Our results demonstrate a distinct new role for a PCP-associated protein, beyond embryonic development, in cognitive functions during adulthood.
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Affiliation(s)
- Muna L Hilal
- INSERM, Neurocentre Magendie, Unité U1215, F-33000 Bordeaux, France.,University of Bordeaux, Neurocentre Magendie, U1215, F-33000 Bordeaux, France
| | - Maité M Moreau
- INSERM, Neurocentre Magendie, Unité U1215, F-33000 Bordeaux, France.,University of Bordeaux, Neurocentre Magendie, U1215, F-33000 Bordeaux, France
| | - Claudia Racca
- Institute of Neuroscience, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Vera L Pinheiro
- INSERM, Neurocentre Magendie, Unité U1215, F-33000 Bordeaux, France.,University of Bordeaux, Neurocentre Magendie, U1215, F-33000 Bordeaux, France
| | - Nicolas H Piguel
- INSERM, Neurocentre Magendie, Unité U1215, F-33000 Bordeaux, France.,University of Bordeaux, Neurocentre Magendie, U1215, F-33000 Bordeaux, France
| | - Marie-Josée Santoni
- CRCM, INSERM U1068, F-13009 Marseille, France.,CRCM, CNRS UMR7258, F-13009 Marseille, France.,Institut Paoli-Calmettes, F-13009 Marseille, France.,Aix-Marseille Université, F-13007 Marseille, France
| | - Steve Dos Santos Carvalho
- INSERM, Neurocentre Magendie, Unité U1215, F-33000 Bordeaux, France.,University of Bordeaux, Neurocentre Magendie, U1215, F-33000 Bordeaux, France
| | - Jean-Michel Blanc
- INSERM, Neurocentre Magendie, Unité U1215, F-33000 Bordeaux, France.,BioXtal Structural Biology Unit, Campus de Luminy, F-13288 Marseille, France.,University of Bordeaux, Plateforme de Biochimie et de Biophysique des protéines, FR Bordeaux Neurocampus, F-33000 Bordeaux, France
| | - Yah-Se K Abada
- INSERM, Neurocentre Magendie, Unité U1215, F-33000 Bordeaux, France.,University of Bordeaux, Neurocentre Magendie, U1215, F-33000 Bordeaux, France
| | - Ronan Peyroutou
- INSERM, Neurocentre Magendie, Unité U1215, F-33000 Bordeaux, France.,University of Bordeaux, Neurocentre Magendie, U1215, F-33000 Bordeaux, France
| | - Chantal Medina
- INSERM, Neurocentre Magendie, Unité U1215, F-33000 Bordeaux, France.,University of Bordeaux, Neurocentre Magendie, U1215, F-33000 Bordeaux, France
| | - Hélène Doat
- INSERM, Neurocentre Magendie, Unité U1215, F-33000 Bordeaux, France.,University of Bordeaux, Neurocentre Magendie, U1215, F-33000 Bordeaux, France
| | - Thomas Papouin
- INSERM, Neurocentre Magendie, Unité U1215, F-33000 Bordeaux, France.,University of Bordeaux, Neurocentre Magendie, U1215, F-33000 Bordeaux, France
| | - Laurent Vuillard
- BioXtal Structural Biology Unit, Campus de Luminy, F-13288 Marseille, France
| | - Jean-Paul Borg
- CRCM, INSERM U1068, F-13009 Marseille, France.,CRCM, CNRS UMR7258, F-13009 Marseille, France.,Institut Paoli-Calmettes, F-13009 Marseille, France.,Aix-Marseille Université, F-13007 Marseille, France
| | - Rivka Rachel
- Mouse Cancer Genetics Program, National Cancer Institute-Frederick, Frederick, Maryland 21702, USA
| | - Aude Panatier
- INSERM, Neurocentre Magendie, Unité U1215, F-33000 Bordeaux, France.,University of Bordeaux, Neurocentre Magendie, U1215, F-33000 Bordeaux, France
| | - Mireille Montcouquiol
- INSERM, Neurocentre Magendie, Unité U1215, F-33000 Bordeaux, France.,University of Bordeaux, Neurocentre Magendie, U1215, F-33000 Bordeaux, France
| | - Stéphane H R Oliet
- INSERM, Neurocentre Magendie, Unité U1215, F-33000 Bordeaux, France.,University of Bordeaux, Neurocentre Magendie, U1215, F-33000 Bordeaux, France
| | - Nathalie Sans
- INSERM, Neurocentre Magendie, Unité U1215, F-33000 Bordeaux, France.,University of Bordeaux, Neurocentre Magendie, U1215, F-33000 Bordeaux, France
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11
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Robin LM, Oliveira da Cruz JF, Langlais VC, Martin-Fernandez M, Metna-Laurent M, Busquets-Garcia A, Bellocchio L, Soria-Gomez E, Papouin T, Varilh M, Sherwood MW, Belluomo I, Balcells G, Matias I, Bosier B, Drago F, Van Eeckhaut A, Smolders I, Georges F, Araque A, Panatier A, Oliet SHR, Marsicano G. Astroglial CB 1 Receptors Determine Synaptic D-Serine Availability to Enable Recognition Memory. Neuron 2018; 98:935-944.e5. [PMID: 29779943 DOI: 10.1016/j.neuron.2018.04.034] [Citation(s) in RCA: 143] [Impact Index Per Article: 23.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2017] [Revised: 03/20/2018] [Accepted: 04/24/2018] [Indexed: 12/22/2022]
Abstract
Bidirectional communication between neurons and astrocytes shapes synaptic plasticity and behavior. D-serine is a necessary co-agonist of synaptic N-methyl-D-aspartate receptors (NMDARs), but the physiological factors regulating its impact on memory processes are scantly known. We show that astroglial CB1 receptors are key determinants of object recognition memory by determining the availability of D-serine at hippocampal synapses. Mutant mice lacking CB1 receptors from astroglial cells (GFAP-CB1-KO) displayed impaired object recognition memory and decreased in vivo and in vitro long-term potentiation (LTP) at CA3-CA1 hippocampal synapses. Activation of CB1 receptors increased intracellular astroglial Ca2+ levels and extracellular levels of D-serine in hippocampal slices. Accordingly, GFAP-CB1-KO displayed lower occupancy of the co-agonist binding site of synaptic hippocampal NMDARs. Finally, elevation of D-serine levels fully rescued LTP and memory impairments of GFAP-CB1-KO mice. These data reveal a novel mechanism of in vivo astroglial control of memory and synaptic plasticity via the D-serine-dependent control of NMDARs.
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Affiliation(s)
- Laurie M Robin
- INSERM U1215, NeuroCentre Magendie, 33077 Bordeaux, France; University of Bordeaux, 33077 Bordeaux, France
| | - José F Oliveira da Cruz
- INSERM U1215, NeuroCentre Magendie, 33077 Bordeaux, France; University of Bordeaux, 33077 Bordeaux, France; Department of Biomedical and Biotechnological Sciences, Section of Pharmacology, University of Catania, 95123 Catania, Italy
| | - Valentin C Langlais
- INSERM U1215, NeuroCentre Magendie, 33077 Bordeaux, France; University of Bordeaux, 33077 Bordeaux, France
| | | | - Mathilde Metna-Laurent
- INSERM U1215, NeuroCentre Magendie, 33077 Bordeaux, France; University of Bordeaux, 33077 Bordeaux, France; Aelis Farma, 33077 Bordeaux, France
| | - Arnau Busquets-Garcia
- INSERM U1215, NeuroCentre Magendie, 33077 Bordeaux, France; University of Bordeaux, 33077 Bordeaux, France
| | - Luigi Bellocchio
- INSERM U1215, NeuroCentre Magendie, 33077 Bordeaux, France; University of Bordeaux, 33077 Bordeaux, France
| | - Edgar Soria-Gomez
- INSERM U1215, NeuroCentre Magendie, 33077 Bordeaux, France; University of Bordeaux, 33077 Bordeaux, France; Department of Neurosciences, University of the Basque Country UPV/EHU, 48940 Leioa, Spain; IKERBASQUE, Basque Foundation for Science, 48013 Bilbao, Spain
| | - Thomas Papouin
- INSERM U1215, NeuroCentre Magendie, 33077 Bordeaux, France; University of Bordeaux, 33077 Bordeaux, France
| | - Marjorie Varilh
- INSERM U1215, NeuroCentre Magendie, 33077 Bordeaux, France; University of Bordeaux, 33077 Bordeaux, France
| | - Mark W Sherwood
- INSERM U1215, NeuroCentre Magendie, 33077 Bordeaux, France; University of Bordeaux, 33077 Bordeaux, France
| | - Ilaria Belluomo
- INSERM U1215, NeuroCentre Magendie, 33077 Bordeaux, France; University of Bordeaux, 33077 Bordeaux, France
| | - Georgina Balcells
- INSERM U1215, NeuroCentre Magendie, 33077 Bordeaux, France; University of Bordeaux, 33077 Bordeaux, France
| | - Isabelle Matias
- INSERM U1215, NeuroCentre Magendie, 33077 Bordeaux, France; University of Bordeaux, 33077 Bordeaux, France
| | - Barbara Bosier
- INSERM U1215, NeuroCentre Magendie, 33077 Bordeaux, France; University of Bordeaux, 33077 Bordeaux, France
| | - Filippo Drago
- Department of Biomedical and Biotechnological Sciences, Section of Pharmacology, University of Catania, 95123 Catania, Italy
| | - Ann Van Eeckhaut
- Vrije Universiteit Brussel, Department of Pharmaceutical Chemistry, Drug Analysis and Drug Information (FASC), Research group Experimental Pharmacology, Center for Neurosciences (C4N), Laarbeeklaan 103, 1090 Brussels, Belgium
| | - Ilse Smolders
- Vrije Universiteit Brussel, Department of Pharmaceutical Chemistry, Drug Analysis and Drug Information (FASC), Research group Experimental Pharmacology, Center for Neurosciences (C4N), Laarbeeklaan 103, 1090 Brussels, Belgium
| | - Francois Georges
- University of Bordeaux, 33077 Bordeaux, France; Centre National de la Recherche Scientifique, Neurodegenerative Diseases Institute, UMR 5293, 33076 Bordeaux, France
| | - Alfonso Araque
- Department of Neuroscience, University of Minnesota, Minneapolis, MN 55455, USA
| | - Aude Panatier
- INSERM U1215, NeuroCentre Magendie, 33077 Bordeaux, France; University of Bordeaux, 33077 Bordeaux, France
| | - Stéphane H R Oliet
- INSERM U1215, NeuroCentre Magendie, 33077 Bordeaux, France; University of Bordeaux, 33077 Bordeaux, France
| | - Giovanni Marsicano
- INSERM U1215, NeuroCentre Magendie, 33077 Bordeaux, France; University of Bordeaux, 33077 Bordeaux, France.
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12
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Murphy-Royal C, Dupuis J, Groc L, Oliet SHR. Astroglial glutamate transporters in the brain: Regulating neurotransmitter homeostasis and synaptic transmission. J Neurosci Res 2017; 95:2140-2151. [PMID: 28150867 DOI: 10.1002/jnr.24029] [Citation(s) in RCA: 104] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Revised: 12/20/2016] [Accepted: 01/02/2017] [Indexed: 12/29/2022]
Abstract
Astrocytes, the major glial cell type in the central nervous system (CNS), are critical for brain function and have been implicated in various disorders of the central nervous system. These cells are involved in a wide range of cerebral processes including brain metabolism, control of central blood flow, ionic homeostasis, fine-tuning synaptic transmission, and neurotransmitter clearance. Such varied roles can be efficiently carried out due to the intimate interactions astrocytes maintain with neurons, the vasculature, as well as with other glial cells. Arguably, one of the most important functions of astrocytes in the brain is their control of neurotransmitter clearance. This is particularly true for glutamate whose timecourse in the synaptic cleft needs to be controlled tightly under physiological conditions to maintain point-to-point excitatory transmission, thereby limiting spillover and activation of more receptors. Most importantly, accumulation of glutamate in the extracellular space can trigger excessive activation of glutamatergic receptors and lead to excitotoxicity, a trademark of many neurodegenerative diseases. It is thus of utmost importance for both physiological and pathophysiological reasons to understand the processes that control glutamate time course within the synaptic cleft and regulate its concentrations in the extracellular space. © 2017 Wiley Periodicals, Inc.
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Affiliation(s)
- Ciaran Murphy-Royal
- Neurocentre Magendie, Inserm U1215, Bordeaux, France.,Université de Bordeaux, Bordeaux, France
| | - Julien Dupuis
- Université de Bordeaux, Bordeaux, France.,Interdisciplinary Institute for Neuroscience, CNRS UMR 5297, Bordeaux, France
| | - Laurent Groc
- Université de Bordeaux, Bordeaux, France.,Interdisciplinary Institute for Neuroscience, CNRS UMR 5297, Bordeaux, France
| | - Stéphane H R Oliet
- Neurocentre Magendie, Inserm U1215, Bordeaux, France.,Université de Bordeaux, Bordeaux, France
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13
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Abstract
N-methyl D-aspartate receptors (NMDARs) exist in different forms owing to multiple combinations of subunits that can assemble into a functional receptor. In addition, they are located not only at synapses but also at extrasynaptic sites. There has been intense speculation over the past decade about whether specific NMDAR subtypes and/or locations are responsible for inducing synaptic plasticity and excitotoxicity. Here, we review the latest findings on the organization, subunit composition and endogenous control of NMDARs at extrasynaptic sites and consider their putative functions. Because astrocytes are capable of controlling NMDARs through the release of gliotransmitters, we also discuss the role of the glial environment in regulating the activity of these receptors.
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Affiliation(s)
- Thomas Papouin
- Neuroscience Department, Tufts University School of Medicine, Boston, MA 02111, USA
| | - Stéphane H R Oliet
- Neurocentre Magendie, Inserm U862, Bordeaux, France Université de Bordeaux, Bordeaux, France
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14
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Lefèvre Y, Amadio A, Vincent P, Descheemaeker A, Oliet SHR, Dallel R, Voisin DL. Neuropathic pain depends upon D-serine co-activation of spinal NMDA receptors in rats. Neurosci Lett 2015; 603:42-7. [PMID: 26182881 DOI: 10.1016/j.neulet.2015.07.010] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2015] [Revised: 06/20/2015] [Accepted: 07/05/2015] [Indexed: 12/30/2022]
Abstract
Activation of N-methyl-d-aspartate (NMDA) receptors is critical for hypersensitivity in chronic neuropathic pain. Since astroglia can regulate NMDA receptor activation by releasing the NMDA receptor co-agonist d-serine, we investigated the role of NMDA receptor and d-serine in neuropathic chronic pain. Male Wistar rats underwent right L5-L6 spinal nerve ligation or sham surgery and were tested for mechanical allodynia and hyperalgesia after 14 days. Acute intrathecal administration of the NMDA receptor antagonist d-AP5 as well as chronic administration of the glia metabolism inhibitor fluoroacetate significantly reduced mechanical allodynia in neuropathic rats. The effect of fluoroacetate was reversed by acutely administered intrathecal d-serine. Degrading d-serine using acute intrathecal administration of d-aminoacid oxidase also reduced pain symptoms. Immunocytochemistry showed that about 70% of serine racemase, the synthesizing enzyme of d-serine, was expressed in astrocyte processes in the superficial laminae of L5 dorsal horn. Serine racemase expression was upregulated in astrocyte processes in neuropathic rats compared to sham rats. These results show that neuropathic pain depends upon glial d-serine that co-activates spinal NMDA receptors.
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Affiliation(s)
- Yan Lefèvre
- Neurocentre Magendie, Inserm U862, F-33000 Bordeaux, France; Univ. Bordeaux, F-33000 Bordeaux, France
| | - Aurélie Amadio
- Neurocentre Magendie, Inserm U862, F-33000 Bordeaux, France; Univ. Bordeaux, F-33000 Bordeaux, France
| | - Peggy Vincent
- Neurocentre Magendie, Inserm U862, F-33000 Bordeaux, France; Univ. Bordeaux, F-33000 Bordeaux, France
| | - Amélie Descheemaeker
- Clermont Université, Université d'Auvergne, NEURO-DOL, BP 10448, F-63000 Clermont-Ferrand, Inserm, U1107, F-63001 Clermont-Ferrand, France
| | - Stéphane H R Oliet
- Neurocentre Magendie, Inserm U862, F-33000 Bordeaux, France; Univ. Bordeaux, F-33000 Bordeaux, France
| | - Radhouane Dallel
- Clermont Université, Université d'Auvergne, NEURO-DOL, BP 10448, F-63000 Clermont-Ferrand, Inserm, U1107, F-63001 Clermont-Ferrand, France
| | - Daniel L Voisin
- Neurocentre Magendie, Inserm U862, F-33000 Bordeaux, France; Univ. Bordeaux, F-33000 Bordeaux, France.
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15
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Carney KE, Milanese M, van Nierop P, Li KW, Oliet SHR, Smit AB, Bonanno G, Verheijen MHG. Proteomic analysis of gliosomes from mouse brain: identification and investigation of glial membrane proteins. J Proteome Res 2014; 13:5918-27. [PMID: 25308431 DOI: 10.1021/pr500829z] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Astrocytes are being increasingly recognized as crucial contributors to neuronal function at synapses, axons, and somas. Reliable methods that can provide insight into astrocyte proteins at the neuron-astrocyte functional interface are highly desirable. Here, we conducted a mass spectrometry analysis of Percoll gradient-isolated gliosomes, a viable preparation of glial subcellular particles often used to study mechanisms of astrocytic transmitter uptake and release and their regulation. Gliosomes were compared with synaptosomes, a preparation containing the neurotransmitter release machinery, and, accordingly, synaptosomes were enriched for proteins involved in synaptic vesicle-mediated transport. Interestingly, gliosome preparations were found to be enriched for different classes of known astrocyte proteins, such as VAMP3 (involved in astrocyte exocytosis), Ezrin (perisynaptic astrocyte cytoskeletal protein), and Basigin (astrocyte membrane glycoprotein), as well as for G-protein-mediated signaling proteins. Mass spectrometry data are available via ProteomeXchange with the identifier PXD001375. Together, these data provide the first detailed description of the gliosome proteome and show that gliosomes can be a useful preparation to study glial membrane proteins and associated processes.
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Affiliation(s)
- Karen E Carney
- Department of Molecular & Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Neuroscience Campus Amsterdam, VU University Amsterdam , 1081 HV Amsterdam, The Netherlands
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16
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Charron G, Doudnikoff E, Canron MH, Li Q, Véga C, Marais S, Baufreton J, Vital A, Oliet SHR, Bezard E. Astrocytosis in parkinsonism: considering tripartite striatal synapses in physiopathology? Front Aging Neurosci 2014; 6:258. [PMID: 25309435 PMCID: PMC4174038 DOI: 10.3389/fnagi.2014.00258] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2014] [Accepted: 09/10/2014] [Indexed: 01/30/2023] Open
Abstract
The current concept of basal ganglia organization and function in physiological and pathophysiological conditions excludes the most numerous cells in the brain, i.e., the astrocytes, present with a ratio of 10:1 neuron. Their role in neurodegenerative condition such as Parkinson's disease (PD) remains to be elucidated. Before embarking into physiological investigations of the yet-to-be-identified "tripartite" synapses in the basal ganglia in general and the striatum in particular, we therefore characterized anatomically the PD-related modifications in astrocytic morphology, the changes in astrocytic network connections and the consequences on the spatial relationship between astrocytic processes and asymmetric synapses in normal and PD-like conditions in experimental and human PD. Our results unravel a dramatic regulation of striatal astrocytosis supporting the hypothesis of a key role in (dys) regulating corticostriatal transmission. Astrocytes and their various properties might thus represent a therapeutic target in PD.
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Affiliation(s)
- Giselle Charron
- Institut des Maladies Neurodégénératives, Université de Bordeaux, UMR 5293 Bordeaux, France ; CNRS, Institut des Maladies Neurodégénératives, UMR 5293 Bordeaux, France
| | - Evelyne Doudnikoff
- Institut des Maladies Neurodégénératives, Université de Bordeaux, UMR 5293 Bordeaux, France ; CNRS, Institut des Maladies Neurodégénératives, UMR 5293 Bordeaux, France
| | - Marie-Helene Canron
- Institut des Maladies Neurodégénératives, Université de Bordeaux, UMR 5293 Bordeaux, France ; CNRS, Institut des Maladies Neurodégénératives, UMR 5293 Bordeaux, France
| | - Qin Li
- Institute of Laboratory Animal Sciences, Chinese Academy of Medical Science and Peking Union Medical College Beijing, China
| | - Céline Véga
- CNRS, Institut des Maladies Neurodégénératives, UMR 5293 Bordeaux, France ; UFR Sciences de la Vie, University Pierre et Marie Curie (UPMC) Paris, France
| | - Sebastien Marais
- Bordeaux Imaging Center, UMS 3420, Université de Bordeaux Bordeaux, France ; CNRS, Bordeaux Imaging Center, UMS 3420 Bordeaux, France ; INSERM, Bordeaux Imaging Center, US 004 Bordeaux, France
| | - Jérôme Baufreton
- Institut des Maladies Neurodégénératives, Université de Bordeaux, UMR 5293 Bordeaux, France ; CNRS, Institut des Maladies Neurodégénératives, UMR 5293 Bordeaux, France
| | - Anne Vital
- Institut des Maladies Neurodégénératives, Université de Bordeaux, UMR 5293 Bordeaux, France ; CNRS, Institut des Maladies Neurodégénératives, UMR 5293 Bordeaux, France
| | - Stéphane H R Oliet
- Neurocentre Magendie, U862, Institut National de la Santé et de la Recherche Médicale Bordeaux, France
| | - Erwan Bezard
- Institut des Maladies Neurodégénératives, Université de Bordeaux, UMR 5293 Bordeaux, France ; CNRS, Institut des Maladies Neurodégénératives, UMR 5293 Bordeaux, France ; Institute of Laboratory Animal Sciences, Chinese Academy of Medical Science and Peking Union Medical College Beijing, China
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17
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Abstract
The identification of the presence of active signaling between astrocytes and neurons in a process termed gliotransmission has caused a paradigm shift in our thinking about brain function. However, we are still in the early days of the conceptualization of how astrocytes influence synapses, neurons, networks, and ultimately behavior. In this Perspective, our goal is to identify emerging principles governing gliotransmission and consider the specific properties of this process that endow the astrocyte with unique functions in brain signal integration. We develop and present hypotheses aimed at reconciling confounding reports and define open questions to provide a conceptual framework for future studies. We propose that astrocytes mainly signal through high-affinity slowly desensitizing receptors to modulate neurons and perform integration in spatiotemporal domains complementary to those of neurons.
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Affiliation(s)
- Alfonso Araque
- Instituto Cajal, Consejo Superior de Investigaciones Científicas, 28002 Madrid, Spain; Department of Neuroscience, University of Minnesota, Minneapolis, MN 55455, USA
| | - Giorgio Carmignoto
- Istituto di Neuroscienze, Consiglio Nazionale delle Ricerche and Dipartimento Scienze Biomediche, Università di Padova, 35121 Padova, Italy.
| | - Philip G Haydon
- Department of Neuroscience, Tufts University School of Medicine, Boston, MA 02111, USA
| | - Stéphane H R Oliet
- Inserm U862, Neurocentre Magendie, 33077 Bordeaux, France; Université de Bordeaux, 33077 Bordeaux, France
| | - Richard Robitaille
- Département de Neurosciences, Université de Montréal, Montréal, QC H3C 3J7, Canada; Groupe de Recherche sur le Système Nerveux Central, Université de Montréal, Montréal, QC H3C 3J7, Canada
| | - Andrea Volterra
- Département de Neurosciences Fondamentales (DNF), Faculté de Biologie et de Médecine, Université de Lausanne, 1005 Lausanne, Switzerland
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18
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Dine J, Ducourneau VRR, Fénelon VS, Fossat P, Amadio A, Eder M, Israel JM, Oliet SHR, Voisin DL. Extracellular signal-regulated kinase phosphorylation in forebrain neurones contributes to osmoregulatory mechanisms. J Physiol 2014; 592:1637-54. [PMID: 24492838 DOI: 10.1113/jphysiol.2013.261008] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Vasopressin secretion from the magnocellular neurosecretory cells (MNCs) is crucial for body fluid homeostasis. Osmotic regulation of MNC activity involves the concerted modulation of intrinsic mechanosensitive ion channels, taurine release from local astrocytes as well as excitatory inputs derived from osmosensitive forebrain regions. Extracellular signal-regulated protein kinases (ERK) are mitogen-activated protein kinases that transduce extracellular stimuli into intracellular post-translational and transcriptional responses, leading to changes in intrinsic neuronal properties and synaptic function. Here, we investigated whether ERK activation (i.e. phosphorylation) plays a role in the functioning of forebrain osmoregulatory networks. We found that within 10 min after intraperitoneal injections of hypertonic saline (3 m, 6 m) in rats, many phosphoERK-immunopositive neurones were observed in osmosensitive forebrain regions, including the MNC containing supraoptic nuclei. The intensity of ERK labelling was dose-dependent. Reciprocally, slow intragastric infusions of water that lower osmolality reduced basal ERK phosphorylation. In the supraoptic nucleus, ERK phosphorylation predominated in vasopressin neurones vs. oxytocin neurones and was absent from astrocytes. Western blot experiments confirmed that phosphoERK expression in the supraoptic nucleus was dose dependent. Intracerebroventricular administration of the ERK phosphorylation inhibitor U 0126 before a hyperosmotic challenge reduced the number of both phosphoERK-immunopositive neurones and Fos expressing neurones in osmosensitive forebrain regions. Blockade of ERK phosphorylation also reduced hypertonically induced depolarization and an increase in firing of the supraoptic MNCs recorded in vitro. It finally reduced hypertonically induced vasopressin release in the bloodstream. Altogether, these findings identify ERK phosphorylation as a new element contributing to the osmoregulatory mechanisms of vasopressin release.
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Affiliation(s)
- Julien Dine
- Inserm, U862, Neurocentre Magendie, Université de Bordeaux, 146 Rue Léo-Saignat, F-33077 Bordeaux, France.
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19
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Goudriaan A, Camargo N, Carney KE, Oliet SHR, Smit AB, Verheijen MHG. Novel cell separation method for molecular analysis of neuron-astrocyte co-cultures. Front Cell Neurosci 2014; 8:12. [PMID: 24523672 PMCID: PMC3906515 DOI: 10.3389/fncel.2014.00012] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2013] [Accepted: 01/08/2014] [Indexed: 11/15/2022] Open
Abstract
Over the last decade, the importance of astrocyte-neuron communication in neuronal development and synaptic plasticity has become increasingly clear. Since neuron-astrocyte interactions represent highly dynamic and reciprocal processes, we hypothesized that many astrocyte genes may be regulated as a consequence of their interactions with maturing neurons. In order to identify such neuron-responsive astrocyte genes in vitro, we sought to establish an expedited technique for separation of neurons from co-cultured astrocytes. Our newly established method makes use of cold jet, which exploits different adhesion characteristics of subpopulations of cells (Jirsova etal., 1997), and is rapid, performed under ice-cold conditions and avoids protease-mediated isolation of astrocytes or time-consuming centrifugation, yielding intact astrocyte mRNA with approximately 90% of neuronal RNA removed. Using this purification method, we executed genome-wide profiling in which RNA derived from astrocyte-only cultures was compared with astrocyte RNA derived from differentiating neuron-astrocyte co-cultures. Data analysis determined that many astrocytic mRNAs and biological processes are regulated by neuronal interaction. Our results validate the cold jet as an efficient method to separate astrocytes from neurons in co-culture, and reveals that neurons induce robust gene-expression changes in co-cultured astrocytes.
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Affiliation(s)
- Andrea Goudriaan
- Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Neuroscience Campus Amsterdam, VU University Amsterdam Amsterdam, Netherlands
| | - Nutabi Camargo
- Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Neuroscience Campus Amsterdam, VU University Amsterdam Amsterdam, Netherlands
| | - Karen E Carney
- Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Neuroscience Campus Amsterdam, VU University Amsterdam Amsterdam, Netherlands ; INSERM U862, Neurocentre Magendie Bordeaux, France ; Université de Bordeaux Bordeaux, France
| | - Stéphane H R Oliet
- INSERM U862, Neurocentre Magendie Bordeaux, France ; Université de Bordeaux Bordeaux, France
| | - August B Smit
- Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Neuroscience Campus Amsterdam, VU University Amsterdam Amsterdam, Netherlands
| | - Mark H G Verheijen
- Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Neuroscience Campus Amsterdam, VU University Amsterdam Amsterdam, Netherlands
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20
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Oliet SHR, Papouin T. [Importance of the location of NMDA glutamate receptors]. Med Sci (Paris) 2013; 29:260-2. [PMID: 23544379 DOI: 10.1051/medsci/2013293011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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21
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Papouin T, Ladépêche L, Ruel J, Sacchi S, Labasque M, Hanini M, Groc L, Pollegioni L, Mothet JP, Oliet SHR. Synaptic and extrasynaptic NMDA receptors are gated by different endogenous coagonists. Cell 2012; 150:633-46. [PMID: 22863013 DOI: 10.1016/j.cell.2012.06.029] [Citation(s) in RCA: 507] [Impact Index Per Article: 42.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2011] [Revised: 04/18/2012] [Accepted: 06/05/2012] [Indexed: 11/20/2022]
Abstract
N-methyl-d-aspartate receptors (NMDARs) are located in neuronal cell membranes at synaptic and extrasynaptic locations, where they are believed to mediate distinct physiological and pathological processes. Activation of NMDARs requires glutamate and a coagonist whose nature and impact on NMDAR physiology remain elusive. We report that synaptic and extrasynaptic NMDARs are gated by different endogenous coagonists, d-serine and glycine, respectively. The regionalized availability of the coagonists matches the preferential affinity of synaptic NMDARs for d-serine and extrasynaptic NMDARs for glycine. Furthermore, glycine and d-serine inhibit NMDAR surface trafficking in a subunit-dependent manner, which is likely to influence NMDARs subcellular location. Taking advantage of this coagonist segregation, we demonstrate that long-term potentiation and NMDA-induced neurotoxicity rely on synaptic NMDARs only. Conversely, long-term depression requires both synaptic and extrasynaptic receptors. Our observations provide key insights into the operating mode of NMDARs, emphasizing functional distinctions between synaptic and extrasynaptic NMDARs in brain physiology.
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Affiliation(s)
- Thomas Papouin
- INSERM U862, Neurocentre Magendie, 33077 Bordeaux, France
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22
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Abstract
Classically, glia have been regarded as non-excitable cells that provide nourishment and physical scaffolding for neurones. However, it is now generally accepted that glia are active participants in brain function that can modulate neuronal communication via several mechanisms. Investigations of anatomical plasticity in the magnocellular neuroendocrine system of the hypothalamic paraventricular and supraoptic nuclei led the way in the development of much of our understanding of glial regulation of neuronal activity. In this review, we provide an overview of glial regulation of magnocellular neurone activity from a historical perspective of the development of our knowledge of the morphological changes that are evident in the paraventricular and supraoptic nuclei. We also focus on recent data from the authors' laboratories presented at the 9th World Congress on Neurohypophysial Hormones that have contributed to our understanding of the multiple mechanisms by which glia modulate the activity of neurones, including: gliotransmitter modulation of synaptic transmission; trans-synaptic modulation by glial neurotransmitter transporter regulation of neurotransmitter spillover; and glial neurotransmitter transporter modulation of excitability by regulation of ambient neurotransmitter levels and their action on extrasynaptic receptors. The magnocellular neuroendocrine system secretes oxytocin and vasopressin from the posterior pituitary gland to control birth, lactation and body fluid balance, and we finally speculate as to whether glial regulation of individual magnocellular neurones might co-ordinate population activity to respond appropriately to altered physiological circumstances.
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Affiliation(s)
- Jeffrey G. Tasker
- Neurobiology Division, Department of Cell and Molecular Biology, Tulane University, New Orleans, LA, USA
| | - Stéphane H. R. Oliet
- Institut National de la Santé et de la Recherche Médicale, Unité 862, Université de Bordeaux, Bordeaux, France
| | - Jaideep S. Bains
- Hotchkiss Brain Institute and Department of Physiology and Pharmacology, University of Calgary, Calgary, Alberta, Canada
| | - Colin H. Brown
- Centre for Neuroendocrinology and Department of Physiology, Otago School of Medical Sciences, University of Otago, Dunedin, New Zealand
| | - Javier E. Stern
- Department of Physiology, Georgia Health Sciences University, Augusta, GA, USA
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23
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Parpura V, Heneka MT, Montana V, Oliet SHR, Schousboe A, Haydon PG, Stout RF, Spray DC, Reichenbach A, Pannicke T, Pekny M, Pekna M, Zorec R, Verkhratsky A. Glial cells in (patho)physiology. J Neurochem 2012; 121:4-27. [PMID: 22251135 DOI: 10.1111/j.1471-4159.2012.07664.x] [Citation(s) in RCA: 398] [Impact Index Per Article: 33.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Neuroglial cells define brain homeostasis and mount defense against pathological insults. Astroglia regulate neurogenesis and development of brain circuits. In the adult brain, astrocytes enter into intimate dynamic relationship with neurons, especially at synaptic sites where they functionally form the tripartite synapse. At these sites, astrocytes regulate ion and neurotransmitter homeostasis, metabolically support neurons and monitor synaptic activity; one of the readouts of the latter manifests in astrocytic intracellular Ca(2+) signals. This form of astrocytic excitability can lead to release of chemical transmitters via Ca(2+) -dependent exocytosis. Once in the extracellular space, gliotransmitters can modulate synaptic plasticity and cause changes in behavior. Besides these physiological tasks, astrocytes are fundamental for progression and outcome of neurological diseases. In Alzheimer's disease, for example, astrocytes may contribute to the etiology of this disorder. Highly lethal glial-derived tumors use signaling trickery to coerce normal brain cells to assist tumor invasiveness. This review not only sheds new light on the brain operation in health and disease, but also points to many unknowns.
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Affiliation(s)
- Vladimir Parpura
- Department of Neurobiology, Center for Glial Biology in Medicine, Civitan International Research Center, Atomic Force Microscopy & Nanotechnology Laboratories, and Evelyn F. McKnight Brain Institute, University of Alabama, Birmingham, Alabama, USA.
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24
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Fossat P, Turpin FR, Sacchi S, Dulong J, Shi T, Rivet JM, Sweedler JV, Pollegioni L, Millan MJ, Oliet SHR, Mothet JP. Glial D-serine gates NMDA receptors at excitatory synapses in prefrontal cortex. ACTA ACUST UNITED AC 2011; 22:595-606. [PMID: 21690263 DOI: 10.1093/cercor/bhr130] [Citation(s) in RCA: 134] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
N-methyl-D-aspartate receptors (NMDARs) subserve numerous neurophysiological and neuropathological processes in the cerebral cortex. Their activation requires the binding of glutamate and also of a coagonist. Whereas glycine and D-serine (D-ser) are candidates for such a role at central synapses, the nature of the coagonist in cerebral cortex remains unknown. We first show that the glycine-binding site of NMDARs is not saturated in acute slices preparations of medial prefrontal cortex (mPFC). Using enzymes that selectively degrade either D-ser or glycine, we demonstrate that under the present conditions, D-ser is the principle endogenous coagonist of synaptic NMDARs at mature excitatory synapses in layers V/VI of mPFC where it is essential for long-term potentiation (LTP) induction. Furthermore, blocking the activity of glia with the metabolic inhibitor, fluoroacetate, impairs NMDAR-mediated synaptic transmission and prevents LTP induction by reducing the extracellular levels of D-serine. Such deficits can be restored by exogenous D-ser, indicating that the D-amino acid mainly originates from glia in the mPFC, as further confirmed by double-immunostaining studies for D-ser and anti-glial fibrillary acidic protein. Our findings suggest that D-ser modulates neuronal networks in the cerebral cortex by gating the activity of NMDARs and that altering its levels is relevant to the induction and potentially treatment of psychiatric and neurological disorders.
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Affiliation(s)
- Pascal Fossat
- Institut National de la Santé et de la Recherche Médicale U862, Neurocentre Magendie, 33077 Bordeaux, France
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25
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Massa F, Koehl M, Wiesner T, Grosjean N, Revest JM, Piazza PV, Abrous DN, Oliet SHR. Conditional reduction of adult neurogenesis impairs bidirectional hippocampal synaptic plasticity. Proc Natl Acad Sci U S A 2011; 108:6644-9. [PMID: 21464314 PMCID: PMC3081011 DOI: 10.1073/pnas.1016928108] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Adult neurogenesis is a process by which the brain produces new neurons once development has ceased. Adult hippocampal neurogenesis has been linked to the relational processing of spatial information, a role attributed to the contribution of newborn neurons to long-term potentiation (LTP). However, whether newborn neurons also influence long-term depression (LTD), and how synaptic transmission and plasticity are affected as they incorporate their network, remain to be determined. To address these issues, we took advantage of a genetic model in which a majority of adult-born neurons can be selectively ablated in the dentate gyrus (DG) and, most importantly, in which neurogenesis can be restored on demand. Using electrophysiological recordings, we show that selective reduction of adult-born neurons impairs synaptic transmission at medial perforant pathway synapses onto DG granule cells. Furthermore, LTP and LTD are largely compromised at these synapses, probably as a result of an increased induction threshold. Whereas the deficits in synaptic transmission and plasticity are completely rescued by restoring neurogenesis, these synapses regain their ability to express LTP much faster than their ability to express LTD. These results demonstrate that both LTP and LTD are influenced by adult neurogenesis. They also indicate that as newborn neurons integrate their network, the ability to express bidirectional synaptic plasticity is largely improved at these synapses. These findings establish that adult neurogenesis is an important process for synaptic transmission and bidirectional plasticity in the DG, accounting for its role in efficiently integrating novel incoming information and in forming new memories.
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Affiliation(s)
- Federico Massa
- Institut National de la Santé et de la Recherche Médicale U862, Neurocentre Magendie, Glia-Neuron Interactions Group, F33077 Bordeaux, France
- Université de Bordeaux, F33077 Bordeaux, France
| | - Muriel Koehl
- Université de Bordeaux, F33077 Bordeaux, France
- Institut National de la Santé et de la Recherche Médicale U862, Neurocentre Magendie, Neurogenesis and Pathophysiology Group, F33077 Bordeaux, France
| | - Theresa Wiesner
- Université de Bordeaux, F33077 Bordeaux, France
- Institut National de la Santé et de la Recherche Médicale U862, Neurocentre Magendie, Endocannabinoids and Neuroadaptation Group, F33077 Bordeaux, France; and
| | - Noelle Grosjean
- Université de Bordeaux, F33077 Bordeaux, France
- Institut National de la Santé et de la Recherche Médicale U862, Neurocentre Magendie, Neurogenesis and Pathophysiology Group, F33077 Bordeaux, France
| | - Jean-Michel Revest
- Université de Bordeaux, F33077 Bordeaux, France
- Institut National de la Santé et de la Recherche Médicale U862, Neurocentre Magendie, Pathophysiology of Addiction Group, F33077 Bordeaux, France
| | - Pier-Vincenzo Piazza
- Université de Bordeaux, F33077 Bordeaux, France
- Institut National de la Santé et de la Recherche Médicale U862, Neurocentre Magendie, Pathophysiology of Addiction Group, F33077 Bordeaux, France
| | - Djoher Nora Abrous
- Université de Bordeaux, F33077 Bordeaux, France
- Institut National de la Santé et de la Recherche Médicale U862, Neurocentre Magendie, Neurogenesis and Pathophysiology Group, F33077 Bordeaux, France
| | - Stéphane H. R. Oliet
- Institut National de la Santé et de la Recherche Médicale U862, Neurocentre Magendie, Glia-Neuron Interactions Group, F33077 Bordeaux, France
- Université de Bordeaux, F33077 Bordeaux, France
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26
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Abstract
The supraoptic nuclei of the hypothalamus display a remarkable anatomical plasticity during lactation, parturition and chronic dehydration, conditions associated with massive neurohypophysial hormone secretion. This structural remodeling is characterized by a pronounced reduction of the astrocytic coverage of oxytocin neurons, resulting in an increase in the number and extent of directly juxtaposed neuronal surfaces. Although the exact role played by such an anatomical remodeling in the physiology of the hypothalamo-neurohypophysial system is still unknown, several findings obtained over the last decade indicate that synaptic and extrasynaptic transmissions are impacted by these structural changes. We review these data and try to extrapolate how such changes at the cellular level might affect the overall activity of the system. One repercussion of the retraction of glial processes is the accumulation of glutamate in the extracellular space. This build-up of glutamate causes an increased activation of pre-synaptic metabotropic glutamate receptors, which are negatively coupled to neurotransmitter release, and a switch in the mode of action of pre-synaptic kainate receptors that control GABA release. Finally, the range of action of substances released from astrocytes and acting on adjacent magnocellular neurons is also affected during the anatomical remodeling. It thus appears that the structural plasticity of the hypothalamic magnocellular nuclei strongly affects neuron-glial interactions and, as a consequence, induces significant changes in synaptic and extrasynaptic transmission.
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Affiliation(s)
- Stéphane H R Oliet
- Inserm U862, Neurocentre Magendie, 146 rue Léo Saignat, 33077 Bordeaux, France.
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27
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Turpin FR, Potier B, Dulong JR, Sinet PM, Alliot J, Oliet SHR, Dutar P, Epelbaum J, Mothet JP, Billard JM. Reduced serine racemase expression contributes to age-related deficits in hippocampal cognitive function. Neurobiol Aging 2009; 32:1495-504. [PMID: 19800712 DOI: 10.1016/j.neurobiolaging.2009.09.001] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2009] [Revised: 08/25/2009] [Accepted: 09/06/2009] [Indexed: 12/18/2022]
Abstract
To gain insight into the contribution of d-serine to impaired cognitive aging, we compared the metabolic pathway and content of the amino acid as well as d-serine-dependent synaptic transmission and plasticity in the hippocampus of young and old rats of the Wistar and Lou/C/Jall strains. Wistar rats display cognitive impairments with aging that are not found in the latter strain, which is therefore considered a model of healthy aging. Both mRNA and protein levels of serine racemase, the d-serine synthesizing enzyme, were decreased in the hippocampus but not in the cerebral cortex or cerebellum of aged Wistar rats, whereas the expression of d-amino acid oxidase, which degrades the amino acid, was not affected. Consequently, hippocampal levels of endogenous d-serine were significantly lower. In contrast, serine racemase expression and d-serine levels were not altered in the hippocampus of aged Lou/C/Jall rats. Ex vivo electrophysiological recordings in hippocampal slices showed a marked reduction in N-methyl-d-aspartate-receptor (NMDA-R)-mediated synaptic potentials and theta-burst-induced long-term potentiation (LTP) in the CA1 area of aged Wistar rats, which were restored by exogenous d-serine. In contrast, NMDA-R activation, LTP induction and responses to d-serine were not altered in aged Lou/C/Jall rats. These results further strengthen the notion that the serine racemase-dependent pathway is a prime target of hippocampus-dependent cognitive deficits with aging. Understanding the processes that specifically affect serine racemase during aging could thus provide key insights into the treatment of memory deficits in the elderly.
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Affiliation(s)
- F R Turpin
- Centre de Psychiatrie et Neurosciences, INSERM, UMR 894, Université Paris Descartes, Faculté de Médecine René Descartes, Paris, F-75014, France.
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28
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Theodosis DT, Poulain DA, Oliet SHR. Activity-Dependent Structural and Functional Plasticity of Astrocyte-Neuron Interactions. Physiol Rev 2008; 88:983-1008. [DOI: 10.1152/physrev.00036.2007] [Citation(s) in RCA: 387] [Impact Index Per Article: 24.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Observations from different brain areas have established that the adult nervous system can undergo significant experience-related structural changes throughout life. Less familiar is the notion that morphological plasticity affects not only neurons but glial cells as well. Yet there is abundant evidence showing that astrocytes, the most numerous cells in the mammalian brain, are highly mobile. Under physiological conditions as different as reproduction, sensory stimulation, and learning, they display a remarkable structural plasticity, particularly conspicuous at the level of their lamellate distal processes that normally ensheath all portions of neurons. Distal astrocytic processes can undergo morphological changes in a matter of minutes, a remodeling that modifies the geometry and diffusion properties of the extracellular space and relationships with adjacent neuronal elements, especially synapses. Astrocytes respond to neuronal activity via ion channels, neurotransmitter receptors, and transporters on their processes; they transmit information via release of neuroactive substances. Where astrocytic processes are mobile then, astrocytic-neuronal interactions become highly dynamic, a plasticity that has important functional consequences since it modifies extracellular ionic homeostasis, neurotransmission, gliotransmission, and ultimately neuronal function at the cellular and system levels. Although a complete picture of intervening cellular mechanisms is lacking, some have been identified, notably certain permissive molecular factors common to systems capable of remodeling (cell surface and extracellular matrix adhesion molecules, cytoskeletal proteins) and molecules that appear specific to each system (neuropeptides, neurotransmitters, steroids, growth factors) that trigger or reverse the morphological changes.
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Oliet SHR, Mothet JP. Regulation of N-methyl-D-aspartate receptors by astrocytic D-serine. Neuroscience 2008; 158:275-83. [PMID: 18358625 DOI: 10.1016/j.neuroscience.2008.01.071] [Citation(s) in RCA: 98] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2007] [Revised: 01/28/2008] [Accepted: 01/28/2008] [Indexed: 10/22/2022]
Abstract
NMDA receptors (NMDARs) are key glutamatergic receptors in the CNS. Their permeability to Ca2+ and their voltage-dependent Mg2+ block make them essential for synaptic transmission, synaptic plasticity, rhythmogenesis, gene expression and excitotoxicity. One very peculiar property is that their activation requires the binding of both glutamate and a co-agonist like glycine or D-serine. There is a growing body of evidence indicating that D-serine, rather than glycine as originally thought, is the endogenous ligand for NMDARs in many brain structures. D-serine is synthesized mainly in glial cells and it is released upon activation of glutamate receptors. Its concentration in the synaptic cleft controls the number of NMDAR available for activation by glutamate. Consequently, the glial environment of neurons has a critical impact on the direction and magnitude of NMDAR-dependent synaptic plasticity.
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Affiliation(s)
- S H R Oliet
- Neurocentre Magendie, INSERM U862, 146 rue Léo Saignat, 33077 Bordeaux, France.
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Abstract
The adult hypothalamo-neurohypophysial system undergoes a striking activity-dependent morphological remodelling that modifies the glial enwrapping of its magnocellular neurons. Although the functional consequences of such remodelling remain hypothetical, recent evidence has provided new insights into the repercussions of glial environment modifications on the physiology of magnocellular neurosecretory cells at the synaptic level. These studies have revealed that the reduced astrocytic coverage of magnocellular neurons occurring in the SON affects various functions in which astrocytes play key roles. These functions include uptake of neurotransmitters such as glutamate, restricting diffusion of neuroactive substances within the extracellular space and release of informative molecules known as gliotransmitters that act on neighbouring neurons to modulate synaptic transmission and excitability. Overall, our observations indicate that the neuron-glial anatomical reorganization leads to modifications of glutamatergic transmission that might be important for the physiology of the hypothalamo-neurohypophysial system.
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Affiliation(s)
- Stéphane H R Oliet
- Neuroscience Research Center, Inserm U862, Bordeaux, France; Université Victor Segalen Bordeaux 2, Bordeaux, France
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Abstract
Synaptic plasticity underlies higher brain functions such as learning and memory. At glutamatergic synapses in the vertebrate central nervous system, plasticity usually requires changes in the number of postsynaptic AMPA receptors. Recently, several studies have revealed that glial cells play an important role in regulating postsynaptic AMPA receptor density. This is accomplished through the release of gliotransmitters such as D-serine, ATP and TNF-alpha. More specifically, the availability of D-serine, the endogenous co-agonist of N-methyl-D-aspartate receptors in many brain areas, governs the induction of long-term potentiation and long-term depression. Meanwhile, ATP and TNF-alpha trigger long-lasting increases in synaptic strength at glutamatergic hypothalamic and hippocampal inputs, respectively, through mechanisms that promote AMPA receptor insertion in the absence of coincident presynaptic and postsynaptic activity. These data clearly demonstrate a vital role for glia in plasticity and argue that their contributions to brain function extend well beyond their outdated role as cellular 'glue'.
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Affiliation(s)
- Jaideep S Bains
- Department of Physiology & Biophysics, Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada
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Oliet SHR, Baimoukhametova DV, Piet R, Bains JS. Retrograde regulation of GABA transmission by the tonic release of oxytocin and endocannabinoids governs postsynaptic firing. J Neurosci 2007; 27:1325-33. [PMID: 17287507 PMCID: PMC6673587 DOI: 10.1523/jneurosci.2676-06.2007] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The probability of neurotransmitter release at the nerve terminal is an important determinant of synaptic efficacy. At some central synapses, the postsynaptic, or target, neuron determines neurotransmitter release probability (P(r)) at the presynaptic terminal. The mechanisms responsible for this target-cell dependent control of P(r) have not been elucidated. Using whole-cell patch-clamp recordings from magnocellular neurosecretory cells in the paraventricular and supraoptic nuclei of the hypothalamus, we demonstrate that inhibitory, GABA synapses specifically onto oxytocin (OT)-producing neurosecretory cells exhibit a low P(r) that is relatively uniform at multiple synapses onto the same cell. This low P(r) results from a two-step process that requires the tonic release of OT from the postsynaptic cell. The ambient extracellular levels of neuropeptide are sufficient to activate postsynaptic OT receptors and trigger the Ca2+-dependent production of endocannabinoids, which act in a retrograde manner at presynaptic cannabinoid CB1 receptors to decrease GABA release. The functional consequence of this tonic inhibition of GABA release is that all inhibitory inputs facilitate uniformly when activated at high rates of activity. This causes inhibition in the postsynaptic cell that is sufficiently powerful to disrupt firing. Blockade of CB1 receptors increases P(r) at these synapses, resulting in a rapid depression of IPSCs at high rates of activity, thereby eliminating the ability of afferent inputs to inhibit postsynaptic firing. By playing a deterministic role in GABA release at the afferent nerve terminal, the postsynaptic OT neuron effectively filters synaptic signals and thereby modulates its own activity patterns.
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Affiliation(s)
- Stéphane H. R. Oliet
- Institut National de la Santé et de la Recherche Médicale, Unité 862, Université Victor Segalen Bordeaux 2, Bordeaux 33077, France, and
| | - Dinara V. Baimoukhametova
- Department of Biophysics and Physiology, The Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada T2N 4N1
| | - Richard Piet
- Institut National de la Santé et de la Recherche Médicale, Unité 862, Université Victor Segalen Bordeaux 2, Bordeaux 33077, France, and
| | - Jaideep S. Bains
- Department of Biophysics and Physiology, The Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada T2N 4N1
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Panatier A, Theodosis DT, Mothet JP, Touquet B, Pollegioni L, Poulain DA, Oliet SHR. Glia-Derived d-Serine Controls NMDA Receptor Activity and Synaptic Memory. Cell 2006; 125:775-84. [PMID: 16713567 DOI: 10.1016/j.cell.2006.02.051] [Citation(s) in RCA: 643] [Impact Index Per Article: 35.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2005] [Revised: 01/03/2006] [Accepted: 02/28/2006] [Indexed: 02/05/2023]
Abstract
The NMDA receptor is a key player in excitatory transmission and synaptic plasticity in the central nervous system. Its activation requires the binding of both glutamate and a co-agonist like D-serine to its glycine site. As D-serine is released exclusively by astrocytes, we studied the physiological impact of the glial environment on NMDA receptor-dependent activity and plasticity. To this end, we took advantage of the changing astrocytic ensheathing of neurons occurring in the supraoptic nucleus during lactation. We provide direct evidence that in this hypothalamic structure the endogenous co-agonist of NMDA receptors is D-serine and not glycine. Consequently, the degree of astrocytic coverage of neurons governs the level of glycine site occupancy on the NMDA receptor, thereby affecting their availability for activation and thus the activity dependence of long-term synaptic changes. Such a contribution of astrocytes to synaptic metaplasticity fuels the emerging concept that astrocytes are dynamic partners of brain signaling.
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Abstract
Activity-dependent long-term synaptic changes were investigated at glutamatergic synapses in the supraoptic nucleus (SON) of the rat hypothalamus. In acute hypothalamic slices, high frequency stimulation (HFS) of afferent fibres caused long-term potentiation (LTP) of the amplitude of AMPA receptor-mediated excitatory postsynaptic currents (EPSCs) recorded with the whole-cell patch-clamp technique. LTP was also obtained in response to membrane depolarization paired with mild afferent stimulation. On the other hand, stimulating the inputs at 5 Hz for 3 min at resting membrane potential caused long-term depression (LTD) of excitatory transmission in the SON. These forms of synaptic plasticity required the activation of NMDA receptors since they were abolished in the presence of D-AP5 or ifenprodil, two selective blockers of these receptors. Analysis of paired-pulse facilitation and trial-to-trial variability indicated that LTP and LTD were not associated with changes in the probability of transmitter release, thereby suggesting that the locus of expression of these phenomena was postsynaptic. Using sharp microelectrode recordings in a hypothalamic explant preparation, we found that HFS also generates LTP at functionally defined glutamatergic synapses formed between the organum vasculosum lamina terminalis and SON neurons. Taken together, our findings indicate that glutamatergic synapses in the SON exhibit activity-dependent long-term synaptic changes similar to those prevailing in other brain areas. Such forms of plasticity could play an important role in the context of physiological responses, like dehydration or lactation, where the activity of presynaptic glutamatergic neurons is strongly increased.
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Theodosis DT, Koksma JJ, Trailin A, Langle SL, Piet R, Lodder JC, Timmerman J, Mansvelder H, Poulain DA, Oliet SHR, Brussaard AB. Oxytocin and estrogen promote rapid formation of functional GABA synapses in the adult supraoptic nucleus. Mol Cell Neurosci 2006; 31:785-94. [PMID: 16488155 DOI: 10.1016/j.mcn.2006.01.006] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2005] [Revised: 12/14/2005] [Accepted: 01/11/2006] [Indexed: 11/26/2022] Open
Abstract
We here investigated inhibitory synapse turnover in the adult brain using the hypothalamic supraoptic nucleus where new synapses form during different physiological conditions, in particular on oxytocin neurons largely controlled by GABAergic inputs and locally released oxytocin. Patch clamp recordings and ultrastructural analysis of the nucleus in acute slices from late gestating rats showed that oxytocin and estrogen promoted rapid formation of inhibitory synapses. Thus, after 2-h exposure to a combination of oxytocin and 17-beta estradiol, the frequency of miniature inhibitory postsynaptic currents was significantly enhanced. Since their amplitude and presynaptic GABA release probability were unmodified, this indicated an increased number of synapses. Electron microscopy confirmed increased densities of symmetric, putative GABAergic synapses within 2-h exposure to the peptide or steroid, effects which were reversible and oxytocin receptor mediated. Our observations thus offer direct evidence that hypothalamic GABAergic microcircuitries can undergo rapid and functional remodeling under changing neuroendocrine conditions.
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Affiliation(s)
- Dionysia T Theodosis
- Inserm, U 378, Bordeaux F33077 France; University Victor Segalen, Bordeaux F33077, France.
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Abstract
Since the late 80s, it is recognized that functional activation of N-methyl D-aspartate receptors (NMDARs) requires the binding of both glutamate and glycine. However, the surprising discovery that the wrong isomer of serine, D-serine, is present in mammals has profoundly challenged this dogmatic model of NMDARs activation. Indeed, there are accumulating evidence indicating that D-serine is the endogenous ligand for the glycine modulatory binding site in many brain areas. D-Serine is synthesized in glial cells by serine racemase (SR) and released upon activation of glutamate receptors. Here, we will provide an overview of recent findings on the molecular and cellular mechanisms involved in the synthesis and release of this gliotransmitter. We will also emphasize the function of this novel messenger in regulating synaptic excitatory transmission and plasticity in different brain areas. Because it fulfils all criteria for a gliotransmitter, D-serine regulatory action on glutamatergic transmission further illustrates the emerging concept of the "tripartite synapse".
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Affiliation(s)
- Stéphane H R Oliet
- INSERM U378 and Université Victor Segalen Bordeaux 2, 146 rue Léo Saignat, 33077 Bordeaux, France
| | - Jean-Pierre Mothet
- INSERM U378 and Université Victor Segalen Bordeaux 2, 146 rue Léo Saignat, 33077 Bordeaux, France
- Institut de Neurobiologie Alfred Fessard, Laboratoire de Neurobiologie Cellulaire et Moléculaire, CNRS UPR9040, 1 avenue de la Terrasse, 91198 Gif-sur-Yvette, France
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Oliet SHR, Panatier A, Piet R. Functional neuronal-glial anatomical remodelling in the hypothalamus. Novartis Found Symp 2006; 276:238-48; discussion 248-52, 275-81. [PMID: 16805434] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
The supraoptic nucleus (SON) of the hypothalamus undergoes a striking anatomical remodelling under conditions of intense stimulations like chronic dehydration, parturition and lactation. This morphological plasticity modifies the astrocytic coverage of magnocellular neurons and their synaptic afferent inputs. These changes occur within a few hours and are completely reversible upon the cessation of the stimulation. By comparing synaptic transmission and diffusion properties before and during this neuroglial remodelling, we have been able to show that the astrocytic environment of neurons contributes to the regulation of synaptic and extrasynaptic transmission. It appears that the presence of fine astrocytic processes enveloping synapses and neuronal elements ensures two important functions. First, they control the level of activation of presynaptic metabotropic glutamate autoreceptors located on glutamatergic terminals, thereby regulating synaptic strength at excitatory synapses. Second, they constitute a physical barrier to diffusion, limiting spatially and temporally spill-over of neurotransmitters and, as a consequence, extrasynaptic transmission, a process essential for intercellular communication. Using the neuroglial anatomical remodelling of the SON as an experimental model has brought new insights into the role of glial cells in the regulation of synaptic transmission and signal processing in the brain.
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Abstract
The supraoptic nucleus receives an abundant gamma-aminobutyric acid (GABA)ergic input which is inhibited by activation of various presynaptic metabotropic receptors. We here analysed the subtypes of voltage-gated Ca2+ channels intervening in the control of transmitter release at these synapses. To address this issue, we tested various specific inhibitors of Ca2+ channels on evoked inhibitory postsynaptic currents (IPSCs). Blocking N- and P-type voltage-gated Ca2+ channels with 1 micromomega-conotoxin-GVIA and 20 nmomega-agatoxin-IVA, respectively, dramatically reduced IPSC amplitude. Q- and L-type Ca2+ channels also contributed to GABAergic transmission, although to a lesser extent, as revealed by applications of 200 nmomega-agatoxin-IVA and of the dihydropyridines nifedipine (10 microm) and nimodipine (10 microm). Evoked IPSCs were insensitive to SNX-482 (300 nm), a blocker of some R-type Ca2+ channels. Analysis of selective blockade by the various antagonists suggested that multiple types of Ca2+ channels synergistically interact to trigger exocytosis at some individual GABA release sites. We next investigated whether inhibition of GABA release in response to the activation of metabotropic glutamate, GABA and adenosine receptors involved the modulation of these presynaptic Ca2+ channels. This was not the case, as the inhibitory actions of selective agonists of these receptors were unaffected by the presence of the different Ca2+ channel antagonists. This finding suggests that these metabotropic receptors modulate GABAergic transmission through a different mechanism, downstream of Ca2+ entry in the terminals, or upstream through the activation of K+ channels.
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Theodosis DT, Piet R, Poulain DA, Oliet SHR. Neuronal, glial and synaptic remodeling in the adult hypothalamus: functional consequences and role of cell surface and extracellular matrix adhesion molecules. Neurochem Int 2004; 45:491-501. [PMID: 15186915 DOI: 10.1016/j.neuint.2003.11.003] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/10/2003] [Indexed: 10/26/2022]
Abstract
The adult hypothalamo-neurohypophysial system (HNS) undergoes activity-dependent morphological plasticity which modifies astrocytic coverage of its oxytocinergic neurons and their synaptic inputs. Thus, during physiological conditions that enhance central and peripheral release of oxytocin (OT), adjacent somata and dendrites of OT neurons become extensively juxtaposed, without intervening astrocytic processes and receive an increased number of synapses. The morphological changes occur within a few hours and are reversible with termination of stimulation. The reduced astrocytic coverage has direct functional consequences since it modifies extracellular ionic homeostasis, synaptic transmission, and the size and geometry of the extracellular space. It also contributes indirectly to neuronal function by permitting formation of synapses on neuronal surfaces freed of astrocytic processes. Overall, such remodeling is expected to potentiate activated neuronal firing, especially in clusters of tightly packed neurons, an anatomical arrangement characterizing OT neurons. This plasticity connotes dynamic cell interactions that must bring into play cell surface and extracellular matrix adhesive proteins like those intervening in developing neuronal systems undergoing neuronal-glial and synaptogenic transformations. It is worth noting, therefore, that adult HNS neurons and glia continue to express such molecules, including polysialic acid (PSA)-enriched neural cell adhesion molecule (PSA-NCAM) and the glycoprotein, tenascin-C. PSA is a large, complex sugar on the extracellular domain of NCAM considered a negative regulator of adhesion; it occurs in large amounts on the surfaces of HNS neurons and astrocytes. Tenascin-C, on the other hand, possesses adhesive and repulsive properties; it is secreted by HNS astrocytes and occurs in extracellular spaces and on cell surfaces after interaction with appropriate ligands. These molecules have been considered permissive factors for morphological plasticity. However, because of their localization and inherent properties, they may also serve to modulate the extracellular environment and in consequence, synaptic and volume transmission in a system in which the extracellular compartment is constantly being modified.
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Affiliation(s)
- Dionysia T Theodosis
- INSERM U378 Neurobiologie Morphofonctionelle, Univeristé Victor Segalen, 1 Rue Camille Saint-Saëns, F33077 Bordeaux Cedex, France.
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Panatier A, Poulain DA, Oliet SHR. Regulation of transmitter release by high-affinity group III mGluRs in the supraoptic nucleus of the rat hypothalamus. Neuropharmacology 2004; 47:333-41. [PMID: 15275822 DOI: 10.1016/j.neuropharm.2004.05.003] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2004] [Revised: 04/14/2004] [Accepted: 05/07/2004] [Indexed: 11/21/2022]
Abstract
We analyzed the subtypes of group III metabotropic glutamate receptors (mGluRs) modulating inhibitory and excitatory transmission in the rat supraoptic nucleus. Bath application of the agonist l-AP4 at 200 microM, a concentration that activates all group III mGluR subtypes, inhibited the frequency but not the amplitude of miniature inhibitory and excitatory postsynaptic currents, indicating a presynaptic site of action. l-AP4 at low concentrations (10 microM), as well as ACPT-1 (50 microM), a specific mGluR III agonist, inhibited transmission at GABAergic and glutamatergic synapses to the same extent as 200 microM l-AP4. Because the potency of l-AP4 and ACPT-1 is much higher on mGluR4 and mGluR8 than on mGluR7, these results are consistent with the presence of high-affinity group III mGluRs regulating transmitter release in this nucleus. In agreement with these findings, DCPG (30 microM), a selective mGluR8 agonist, induced a significant depression of inhibitory and excitatory synaptic currents. Group III mGluRs such as mGluR8, because of their high affinity for glutamate, are particularly well suited to detect small changes in the concentration of this excitatory amino acid in the extracellular space. Their presence, therefore, may favor the negative feedback control exerted by glutamate on its own release as well as the intersynaptic crosstalk mediated by glutamate spillover on adjacent synapses.
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Affiliation(s)
- Aude Panatier
- Inserm U378, Institut François Magendie, Université Victor Segalen, 1, rue Camille Saint Saëns, 33077 Bordeaux Cedex, France
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Piet R, Poulain DA, Oliet SHR. Contribution of astrocytes to synaptic transmission in the rat supraoptic nucleus. Neurochem Int 2004; 45:251-7. [PMID: 15145540 DOI: 10.1016/j.neuint.2003.07.005] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2003] [Revised: 07/21/2003] [Accepted: 07/21/2003] [Indexed: 12/29/2022]
Abstract
Astrocytes, besides supporting metabolic and scaffolding functions, play a prominent role in the modulation of neuronal communication. In particular, they are responsible for clearing synaptically-released glutamate via highly specific transporters located on their plasma membrane. Since glutamate is the main excitatory neurotransmitter in the central nervous system (CNS), astrocytes are likely to play a central role in the regulation of synaptic processing and overall cellular excitability. We recently investigated the influence of astrocytes on glutamatergic and GABAergic transmission in the rat supraoptic nucleus (SON) of the hypothalamus. This nucleus is part of the hypothalamus-neurohypophysial system (HNS), which constitutes a conspicuous example of activity-dependent neuroglial plasticity, in which certains physiological conditions, such as parturition, lactation, and dehydration are accompanied by a structural remodeling of the neurones, their synaptic inputs and their surrounding glia. The use of pharmacological inhibitors of glutamate transporters on this model, in which a physiological change in the astrocyte environment occurs, has brought new insights on the contribution of astrocytes to both excitatory and inhibitory neurotransmissions. The astrocytic environment of neurons appears to control glutamate uptake and diffusion in the extracellular space. This has direct repercussions on the tonic level of activation of presynaptic glutamate receptors and, as a consequence, on the release of neurotransmitter. This short review summarizes data obtained so far, which clearly support the view that astrocytes are indeed a third partner in synaptic transmission, and which show that the supraoptic nucleus represents a remarkable model to study dynamic physiological interactions between astrocytes and neurons.
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Affiliation(s)
- Richard Piet
- Inserm U.378, Institut François Magendie, Université Victor Segalen Bordeaux 2, 33077 Bordeaux, France
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Abstract
The adult hypothalamic-neurohypophysial system undergoes activity-dependent morphological plasticity that modifies the astrocytic enwrapping of its magnocellular neurones. For a long time, the functional consequences of such changes have remained hypothetical. Modifications in the glial environment of neurones are expected to have important physiological repercussions in view of the various functions played by astrocytes in the central nervous system. In particular, glial cells are essential for uptake of neurotransmitters, including glutamate, and for physically and functionally restricting diffusion of neuroactive substances within the extracellular space. Recent studies performed in the supraoptic nucleus of lactating and chronically dehydrated animals, in conditions where astrocytic coverage of neurones is reduced, have revealed a significant impairment of glutamate clearance. The resulting accumulation of the excitatory amino acid in the extracellular space around glutamatergic inputs causes an enhanced activation of presynaptic metabotropic glutamate receptors that inhibit transmitter release. In the supraoptic nucleus of lactating rats, neuroglial remodelling is accompanied by modification of the geometry, size and diffusion properties of the extracellular space. The latter observations suggest that, in the activated supraoptic nucleus, the range of action and the concentration of released neuroactive substances may be significantly enhanced. Overall, our observations indicate that the glial environment of supraoptic neurones influences synaptic glutamatergic transmission, as well as extrasynaptic forms of communication.
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Affiliation(s)
- S H R Oliet
- Inserm U378, Institut François Magendie, Université Victor Segalen, Bordeaux, France.
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Piet R, Vargová L, Syková E, Poulain DA, Oliet SHR. Physiological contribution of the astrocytic environment of neurons to intersynaptic crosstalk. Proc Natl Acad Sci U S A 2004; 101:2151-5. [PMID: 14766975 PMCID: PMC357067 DOI: 10.1073/pnas.0308408100] [Citation(s) in RCA: 207] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2003] [Indexed: 11/18/2022] Open
Abstract
Interactions between separate synaptic inputs converging on the same target appear to contribute to the fine-tuning of information processing in the central nervous system. Intersynaptic crosstalk is made possible by transmitter spillover from the synaptic cleft and its diffusion over a distance to neighboring synapses. This is the case for glutamate, which inhibits gamma-aminobutyric acid (GABA)ergic transmission in several brain regions through the activation of presynaptic receptors. Such heterosynaptic modulation depends on factors that influence diffusion in the extracellular space (ECS). Because glial cells represent a physical barrier to diffusion and, in addition, are essential for glutamate uptake, we investigated the physiological contribution of the astrocytic environment of neurons to glutamate-mediated intersynaptic communication in the brain. Here we show that the reduced astrocytic coverage of magnocellular neurons occurring in the supraoptic nucleus of lactating rats facilitates diffusion in the ECS, as revealed by tortuosity and volume fraction measurements. Under these conditions, glutamate spillover, monitored through metabotropic glutamate receptor-mediated depression of GABAergic transmission, is greatly enhanced. Conversely, impeding diffusion with dextran largely prevents crosstalk between glutamatergic and GABAergic afferent inputs. Astrocytes, therefore, by hindering diffusion in the ECS, regulate intersynaptic communication between neighboring synapses and, probably, overall volume transmission in the brain.
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Affiliation(s)
- Richard Piet
- Institut National de la Santé et de la Recherche Médicale Unité 378, Institut François Magendie, Université Victor Segalen Bordeaux 2, 33077 Bordeaux, France
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Abstract
Astrocytes clear synaptically released glutamate from the extracellular space through high-affinity transporters present on their plasma membrane. By controlling the extracellular level of the main excitatory transmitter in the central nervous system, astrocytes thus contribute prominently to the regulation of overall cellular excitability and synaptic information processing. We recently investigated the influence of the glial environment on glutamatergic and GABAergic neurotransmission in the supraoptic nucleus of the rat hypothalamus under physiological conditions such as lactation that significantly reduce astrocytic coverage of its neurons. By performing electrophysiological analyses on this unique model of dynamic neuronal-glial interactions, we have been able to show that the fine astrocytic processes normally enwrapping synapses serve two important functions. First, they govern the level of activation of presynaptic metabotropic glutamate receptors on glutamatergic terminals, thereby regulating synaptic efficacy at excitatory synapses. Second, they act as a physical and functional barrier to diffusion in the extracellular space, limiting spillover of glutamate and other neuroactive substances and therefore contributing to the regulation of heterosynaptic transmission and intercellular communication.
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Affiliation(s)
- Stéphane H R Oliet
- INSERM U378, Institut François Magendie, Université Victor Segalen Bordeaux 2, Bordeaux, France
| | - Richard Piet
- INSERM U378, Institut François Magendie, Université Victor Segalen Bordeaux 2, Bordeaux, France
| | - Dominique A Poulain
- INSERM U378, Institut François Magendie, Université Victor Segalen Bordeaux 2, Bordeaux, France
| | - Dionysia T Theodosis
- INSERM U378, Institut François Magendie, Université Victor Segalen Bordeaux 2, Bordeaux, France
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Abstract
The presence of group III metabotropic glutamate receptors on GABAergic terminals in the supraoptic nucleus suggests that the level of glutamate in the extracellular space may regulate synaptic strength at inhibitory synapses. To test this hypothesis we examined the consequences of increasing ambient glutamate on GABA-mediated synaptic activity in supraoptic neurons. The concentration of the excitatory amino acid in the extracellular space was increased pharmacologically by blocking glutamate transporters. Inhibition of the astrocyte-specific GLT-1 glutamate transporter led to a reversible decrease in evoked inhibitory postsynaptic current amplitude. This modulation had a presynaptic origin as revealed by analysis of paired-pulse ratio and miniature inhibitory currents. Furthermore, blocking group III metabotropic glutamate receptors with the specific antagonist MAP4 prevented the depression of GABAergic transmission induced by glutamate transporter blockade. Thus, presynaptic metabotropic glutamate receptors located on inhibitory terminals in the supraoptic nucleus appear to sense changes in ambient glutamate and modify GABA release accordingly. However, it seems that such changes need to reach a certain magnitude because the discrete deficit in glutamate clearance which occurs in the supraoptic nucleus of lactating rats is not sufficient to modulate GABA-mediated transmission. These results suggest that ambient glutamate contributes to the modulation of synaptic efficacy not only at glutamatergic synapses but also at inhibitory GABAergic synapses.
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Affiliation(s)
- Richard Piet
- INSERM U378, Institut François Magendie, 1, rue Camille St-Saëns, 33077 Bordeaux Cedex, France
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Abstract
One of the functions of astroglial cells in the central nervous system is to clear synaptically-released glutamate from the extracellular space. This is performed thanks to specific transporters of the excitatory amino acid expressed on their surface. The way by which astrocytic glutamate uptake contributes to synaptic transmission has been investigated via numerous experimental approaches but has never been addressed under conditions where neuroglial interactions are physiologically modified. Recently, we took advantage of the neuroglial plastic properties of the hypothalamo-neurohypophysial system to examine the consequences of a physiological reduction in the astrocytic coverage of neurons on glutamatergic synaptic transmission. This experimental model has brought some insights on the physiological interactions between glial cells and neurons at the level of the synapse. In particular, it has revealed that the degree of glial coverage of neurons influences glutamate concentration at the vicinity of excitatory synapses and, as a consequence, affects the level of activation of presynaptic glutamate receptors. Astrocytes, therefore, appear to contribute to the regulation of neuronal excitability by modulating synaptic efficacy at glutamatergic nerve terminals.
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Affiliation(s)
- Richard Piet
- INSERM U.378 and Université Victor Segalen, 1, rue Camille Saint Saëns, 33077 Bordeaux cedex, France
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47
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Abstract
The supraoptic and paraventricular nuclei of the hypothalamus undergo reversible anatomical changes under conditions of intense neurohypophysial hormone secretion, such as lactation, parturition and chronic dehydration. This morphological remodelling includes a reduction in astrocytic coverage of neurones resulting in an increase in the number and extent of directly juxtaposed somatic and dendritic surfaces. There is a growing body of evidence indicating that such anatomical plasticity is of functional significance. Astrocytic-dependent clearance of electrolytes and neurotransmitters from the extracellular space appears to be altered under conditions where glial coverage of magnocellular neurones is reduced. Glutamate, for example, has been found to accumulate in the extracellular space in the supraoptic nucleus of lactating animals and cause a modulation of synaptic efficacy. On the other hand, the range of action of substances released from astrocytes and acting on adjacent magnocellular neurones is expected to be limited during such anatomical remodelling. It thus appears that the structural plasticity of the magnocellular nuclei does affect neuroglial interactions, inducing significant changes in signal transmission and processing.
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Affiliation(s)
- S H R Oliet
- Inserm U378 and Université Victor Segalen, Bordeaux, France.
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