1
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Untiet V, Verkhratsky A. How astrocytic chloride modulates brain states. Bioessays 2024; 46:e2400004. [PMID: 38615322 DOI: 10.1002/bies.202400004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2024] [Revised: 04/03/2024] [Accepted: 04/04/2024] [Indexed: 04/16/2024]
Abstract
The way the central nervous system (CNS) responds to diverse stimuli is contingent upon the specific brain state of the individual, including sleep and wakefulness. Despite the wealth of readout parameters and data delineating the brain states, the primary mechanisms are yet to be identified. Here we highlight the role of astrocytes, with a specific emphasis on chloride (Cl-) homeostasis as a modulator of brain states. Neuronal activity is regulated by the concentration of ions that determine excitability. Astrocytes, as the CNS homeostatic cells, are recognised for their proficiency in maintaining dynamic homeostasis of ions, known as ionostasis. Nevertheless, the contribution of astrocyte-driven ionostasis to the genesis of brain states or their response to sleep-inducing pharmacological agents has been overlooked. Our objective is to underscore the significance of astrocytic Cl- homeostasis, elucidating how it may underlie the modulation of brain states. We endeavour to contribute to a comprehensive understanding of the interplay between astrocytes and brain states.
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Affiliation(s)
- Verena Untiet
- Division of Glial Disease and Therapeutics, Center for Translational Neuromedicine, University of Copenhagen, Copenhagen, Denmark
| | - Alexei Verkhratsky
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK
- Achucarro Centre for Neuroscience, IKERBASQUE, Basque Foundation for Science, Bilbao, Spain
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2
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Medina AM, Hagenauer MH, Krolewski DM, Hughes E, Forrester LCT, Walsh DM, Waselus M, Richardson E, Turner CA, Sequeira PA, Cartagena PM, Thompson RC, Vawter MP, Bunney BG, Myers RM, Barchas JD, Lee FS, Schatzberg AF, Bunney WE, Akil H, Watson SJ. Neurotransmission-related gene expression in the frontal pole is altered in subjects with bipolar disorder and schizophrenia. Transl Psychiatry 2023; 13:118. [PMID: 37031222 PMCID: PMC10082811 DOI: 10.1038/s41398-023-02418-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/26/2022] [Revised: 03/22/2023] [Accepted: 03/27/2023] [Indexed: 04/10/2023] Open
Abstract
The frontal pole (Brodmann area 10, BA10) is the largest cytoarchitectonic region of the human cortex, performing complex integrative functions. BA10 undergoes intensive adolescent grey matter pruning prior to the age of onset for bipolar disorder (BP) and schizophrenia (SCHIZ), and its dysfunction is likely to underly aspects of their shared symptomology. In this study, we investigated the role of BA10 neurotransmission-related gene expression in BP and SCHIZ. We performed qPCR to measure the expression of 115 neurotransmission-related targets in control, BP, and SCHIZ postmortem samples (n = 72). We chose this method for its high sensitivity to detect low-level expression. We then strengthened our findings by performing a meta-analysis of publicly released BA10 microarray data (n = 101) and identified sources of convergence with our qPCR results. To improve interpretation, we leveraged the unusually large database of clinical metadata accompanying our samples to explore the relationship between BA10 gene expression, therapeutics, substances of abuse, and symptom profiles, and validated these findings with publicly available datasets. Using these convergent sources of evidence, we identified 20 neurotransmission-related genes that were differentially expressed in BP and SCHIZ in BA10. These results included a large diagnosis-related decrease in two important therapeutic targets with low levels of expression, HTR2B and DRD4, as well as other findings related to dopaminergic, GABAergic and astrocytic function. We also observed that therapeutics may produce a differential expression that opposes diagnosis effects. In contrast, substances of abuse showed similar effects on BA10 gene expression as BP and SCHIZ, potentially amplifying diagnosis-related dysregulation.
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Affiliation(s)
- Adriana M Medina
- Michigan Neuroscience Institute, University of Michigan, Ann Arbor, MI, USA
| | | | - David M Krolewski
- Michigan Neuroscience Institute, University of Michigan, Ann Arbor, MI, USA
| | - Evan Hughes
- Michigan Neuroscience Institute, University of Michigan, Ann Arbor, MI, USA
| | | | | | - Maria Waselus
- Michigan Neuroscience Institute, University of Michigan, Ann Arbor, MI, USA
| | - Evelyn Richardson
- Michigan Neuroscience Institute, University of Michigan, Ann Arbor, MI, USA
| | - Cortney A Turner
- Michigan Neuroscience Institute, University of Michigan, Ann Arbor, MI, USA
| | | | | | - Robert C Thompson
- Michigan Neuroscience Institute, University of Michigan, Ann Arbor, MI, USA
| | | | | | - Richard M Myers
- HudsonAlpha Institute for Biotechnology, Huntsville, AL, USA
| | | | | | | | | | - Huda Akil
- Michigan Neuroscience Institute, University of Michigan, Ann Arbor, MI, USA
| | - Stanley J Watson
- Michigan Neuroscience Institute, University of Michigan, Ann Arbor, MI, USA
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3
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Untiet V, Beinlich FRM, Kusk P, Kang N, Ladrón-de-Guevara A, Song W, Kjaerby C, Andersen M, Hauglund N, Bojarowska Z, Sigurdsson B, Deng S, Hirase H, Petersen NC, Verkhratsky A, Nedergaard M. Astrocytic chloride is brain state dependent and modulates inhibitory neurotransmission in mice. Nat Commun 2023; 14:1871. [PMID: 37015909 PMCID: PMC10073105 DOI: 10.1038/s41467-023-37433-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2022] [Accepted: 03/15/2023] [Indexed: 04/06/2023] Open
Abstract
Information transfer within neuronal circuits depends on the balance and recurrent activity of excitatory and inhibitory neurotransmission. Chloride (Cl-) is the major central nervous system (CNS) anion mediating inhibitory neurotransmission. Astrocytes are key homoeostatic glial cells populating the CNS, although the role of these cells in regulating excitatory-inhibitory balance remains unexplored. Here we show that astrocytes act as a dynamic Cl- reservoir regulating Cl- homoeostasis in the CNS. We found that intracellular chloride concentration ([Cl-]i) in astrocytes is high and stable during sleep. In awake mice astrocytic [Cl-]i is lower and exhibits large fluctuation in response to both sensory input and motor activity. Optogenetic manipulation of astrocytic [Cl-]i directly modulates neuronal activity during locomotion or whisker stimulation. Astrocytes thus serve as a dynamic source of extracellular Cl- available for GABAergic transmission in awake mice, which represents a mechanism for modulation of the inhibitory tone during sustained neuronal activity.
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Affiliation(s)
- Verena Untiet
- Division of Glial Disease and Therapeutics, Center for Translational Neuromedicine, University of Copenhagen, 2200, Copenhagen, Denmark.
| | - Felix R M Beinlich
- Division of Glial Disease and Therapeutics, Center for Translational Neuromedicine, University of Copenhagen, 2200, Copenhagen, Denmark
| | - Peter Kusk
- Division of Glial Disease and Therapeutics, Center for Translational Neuromedicine, University of Copenhagen, 2200, Copenhagen, Denmark
| | - Ning Kang
- Division of Glial Disease and Therapeutics, Center for Translational Neuromedicine, Department of Neurosurgery, University of Rochester Medical Center, Rochester, NY, 14642, USA
| | - Antonio Ladrón-de-Guevara
- Division of Glial Disease and Therapeutics, Center for Translational Neuromedicine, Department of Neurosurgery, University of Rochester Medical Center, Rochester, NY, 14642, USA
- Department of Biomedical Engineering, University of Rochester, Rochester, NY, 14627, USA
| | - Wei Song
- Division of Glial Disease and Therapeutics, Center for Translational Neuromedicine, Department of Neurosurgery, University of Rochester Medical Center, Rochester, NY, 14642, USA
| | - Celia Kjaerby
- Division of Glial Disease and Therapeutics, Center for Translational Neuromedicine, University of Copenhagen, 2200, Copenhagen, Denmark
| | - Mie Andersen
- Division of Glial Disease and Therapeutics, Center for Translational Neuromedicine, University of Copenhagen, 2200, Copenhagen, Denmark
| | - Natalie Hauglund
- Division of Glial Disease and Therapeutics, Center for Translational Neuromedicine, University of Copenhagen, 2200, Copenhagen, Denmark
| | - Zuzanna Bojarowska
- Division of Glial Disease and Therapeutics, Center for Translational Neuromedicine, University of Copenhagen, 2200, Copenhagen, Denmark
| | - Björn Sigurdsson
- Division of Glial Disease and Therapeutics, Center for Translational Neuromedicine, University of Copenhagen, 2200, Copenhagen, Denmark
| | - Saiyue Deng
- Department of Neurology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, P.R. China
| | - Hajime Hirase
- Division of Glial Disease and Therapeutics, Center for Translational Neuromedicine, University of Copenhagen, 2200, Copenhagen, Denmark
| | - Nicolas C Petersen
- Division of Glial Disease and Therapeutics, Center for Translational Neuromedicine, University of Copenhagen, 2200, Copenhagen, Denmark
| | - Alexei Verkhratsky
- Division of Glial Disease and Therapeutics, Center for Translational Neuromedicine, University of Copenhagen, 2200, Copenhagen, Denmark.
- Faculty of Biology, Medicine and Health, The University of Manchester, Oxford Rd, Manchester, M13 9PL, UK.
- Achucarro Centre for Neuroscience, IKERBASQUE, Basque Foundation for Science, Plaza Euskadi 5, 48009, Bilbao, Spain.
| | - Maiken Nedergaard
- Division of Glial Disease and Therapeutics, Center for Translational Neuromedicine, University of Copenhagen, 2200, Copenhagen, Denmark.
- Division of Glial Disease and Therapeutics, Center for Translational Neuromedicine, Department of Neurosurgery, University of Rochester Medical Center, Rochester, NY, 14642, USA.
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4
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Giantomasi L, Ribeiro JF, Barca-Mayo O, Malerba M, Miele E, De Pietri Tonelli D, Berdondini L. Astrocytes actively support long-range molecular clock synchronization of segregated neuronal populations. Sci Rep 2023; 13:4815. [PMID: 36964220 PMCID: PMC10038999 DOI: 10.1038/s41598-023-31966-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Accepted: 03/20/2023] [Indexed: 03/26/2023] Open
Abstract
In mammals, the suprachiasmatic nucleus of the hypothalamus is the master circadian pacemaker that synchronizes the clocks in the central nervous system and periphery, thus orchestrating rhythms throughout the body. However, little is known about how so many cellular clocks within and across brain circuits can be effectively synchronized. In this work, we investigated the implication of two possible pathways: (i) astrocytes-mediated synchronization and (ii) neuronal paracrine factors-mediated synchronization. By taking advantage of a lab-on-a-chip microfluidic device developed in our laboratory, here we report that both pathways are involved. We found the paracrine factors-mediated synchronization of molecular clocks is diffusion-limited and, in our device, effective only in case of a short distance between neuronal populations. Interestingly, interconnecting astrocytes define an active signaling channel that can synchronize molecular clocks of neuronal populations also at longer distances. At mechanism level, we found that astrocytes-mediated synchronization involves both GABA and glutamate, while neuronal paracrine factors-mediated synchronization occurs through GABA signaling. These findings identify a previously unknown role of astrocytes as active cells that might distribute long-range signals to synchronize the brain clocks, thus further strengthening the importance of reciprocal interactions between glial and neuronal cells in the context of circadian circuitry.
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Affiliation(s)
- Lidia Giantomasi
- Microtechnology for Neuroelectronics, Fondazione Istituto Italiano Di Tecnologia (IIT), 16163, Genova, Italy
| | - João F Ribeiro
- Microtechnology for Neuroelectronics, Fondazione Istituto Italiano Di Tecnologia (IIT), 16163, Genova, Italy
| | - Olga Barca-Mayo
- Neurobiology of miRNA, Fondazione Istituto Italiano Di Tecnologia (IIT), 16163, Genova, Italy
- Circadian and Glial Biology Lab, Physiology Department, Molecular Medicine, and Chronic Diseases Research Centre (CiMUS), University of Santiago de Compostela, Santiago de Compostela, Spain
| | - Mario Malerba
- Microtechnology for Neuroelectronics, Fondazione Istituto Italiano Di Tecnologia (IIT), 16163, Genova, Italy
- Centre de Nanosciences et de Nanotechnologies (C2N), CNRS UMR 9001, Université Paris-Saclay, 91120, Palaiseau, France
| | - Ermanno Miele
- Microtechnology for Neuroelectronics, Fondazione Istituto Italiano Di Tecnologia (IIT), 16163, Genova, Italy
- NanoPhotonics Centre, Cavendish Laboratory, Department of Physics, University of Cambridge, Cambridge, UK
| | | | - Luca Berdondini
- Microtechnology for Neuroelectronics, Fondazione Istituto Italiano Di Tecnologia (IIT), 16163, Genova, Italy.
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5
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Sanchez GM, Incedal TC, Prada J, O'Callaghan P, Dyachok O, Echeverry S, Dumral Ö, Nguyen PM, Xie B, Barg S, Kreuger J, Dandekar T, Idevall-Hagren O. The β-cell primary cilium is an autonomous Ca2+ compartment for paracrine GABA signaling. J Cell Biol 2023; 222:213674. [PMID: 36350286 DOI: 10.1083/jcb.202108101] [Citation(s) in RCA: 14] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Revised: 04/11/2022] [Accepted: 10/12/2022] [Indexed: 11/11/2022] Open
Abstract
The primary cilium is an organelle present in most adult mammalian cells that is considered as an antenna for sensing the local microenvironment. Here, we use intact mouse pancreatic islets of Langerhans to investigate signaling properties of the primary cilium in insulin-secreting β-cells. We find that GABAB1 receptors are strongly enriched at the base of the cilium, but are mobilized to more distal locations upon agonist binding. Using cilia-targeted Ca2+ indicators, we find that activation of GABAB1 receptors induces selective Ca2+ influx into primary cilia through a mechanism that requires voltage-dependent Ca2+ channel activation. Islet β-cells utilize cytosolic Ca2+ increases as the main trigger for insulin secretion, yet we find that increases in cytosolic Ca2+ fail to propagate into the cilium, and that this isolation is largely due to enhanced Ca2+ extrusion in the cilium. Our work reveals local GABA action on primary cilia that involves Ca2+ influx and depends on restricted Ca2+ diffusion between the cilium and cytosol.
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Affiliation(s)
| | | | - Juan Prada
- Department of Bioinformatics, University of Würzburg, Würzburg, Germany
| | - Paul O'Callaghan
- Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden
| | - Oleg Dyachok
- Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden
| | | | - Özge Dumral
- Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden
| | - Phuoc My Nguyen
- Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden
| | - Beichen Xie
- Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden
| | - Sebastian Barg
- Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden
| | - Johan Kreuger
- Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden
| | - Thomas Dandekar
- Department of Bioinformatics, University of Würzburg, Würzburg, Germany
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6
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Jiménez-Dinamarca I, Reyes-Lizana R, Lemunao-Inostroza Y, Cárdenas K, Castro-Lazo R, Peña F, Lucero CM, Prieto-Villalobos J, Retamal MA, Orellana JA, Stehberg J. GABAergic Regulation of Astroglial Gliotransmission through Cx43 Hemichannels. Int J Mol Sci 2022; 23:13625. [PMID: 36362410 PMCID: PMC9656947 DOI: 10.3390/ijms232113625] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2022] [Revised: 09/30/2022] [Accepted: 10/09/2022] [Indexed: 02/12/2024] Open
Abstract
Gamma-Aminobutyric acid (GABA) is the primary inhibitory neurotransmitter in the brain. It is produced by interneurons and recycled by astrocytes. In neurons, GABA activates the influx of Cl- via the GABAA receptor or efflux or K+ via the GABAB receptor, inducing hyperpolarization and synaptic inhibition. In astrocytes, the activation of both GABAA and GABAB receptors induces an increase in intracellular Ca2+ and the release of glutamate and ATP. Connexin 43 (Cx43) hemichannels are among the main Ca2+-dependent cellular mechanisms for the astroglial release of glutamate and ATP. However, no study has evaluated the effect of GABA on astroglial Cx43 hemichannel activity and Cx43 hemichannel-mediated gliotransmission. Here we assessed the effects of GABA on Cx43 hemichannel activity in DI NCT1 rat astrocytes and hippocampal brain slices. We found that GABA induces a Ca2+-dependent increase in Cx43 hemichannel activity in astrocytes mediated by the GABAA receptor, as it was blunted by the GABAA receptor antagonist bicuculline but unaffected by GABAB receptor antagonist CGP55845. Moreover, GABA induced the Cx43 hemichannel-dependent release of glutamate and ATP, which was also prevented by bicuculline, but unaffected by CGP. Gliotransmission in response to GABA was also unaffected by pannexin 1 channel blockade. These results are discussed in terms of the possible role of astroglial Cx43 hemichannel-mediated glutamate and ATP release in regulating the excitatory/inhibitory balance in the brain and their possible contribution to psychiatric disorders.
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Affiliation(s)
- Ivanka Jiménez-Dinamarca
- Laboratorio de Neurobiología, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad Andres Bello, Santiago 8370186, Chile
| | - Rachel Reyes-Lizana
- Laboratorio de Neurobiología, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad Andres Bello, Santiago 8370186, Chile
| | - Yordan Lemunao-Inostroza
- Laboratorio de Neurobiología, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad Andres Bello, Santiago 8370186, Chile
| | - Kevin Cárdenas
- Laboratorio de Neurobiología, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad Andres Bello, Santiago 8370186, Chile
| | - Raimundo Castro-Lazo
- Laboratorio de Neurobiología, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad Andres Bello, Santiago 8370186, Chile
| | - Francisca Peña
- Laboratorio de Neurobiología, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad Andres Bello, Santiago 8370186, Chile
- Centro de Fisiología Celular e Integrativa, Facultad de Medicina, Universidad del Desarrollo–Clínica Alemana, Santiago 7780272, Chile
| | - Claudia M. Lucero
- Departamento de Neurología, Escuela de Medicina and Centro Interdisciplinario de Neurociencias, Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago 8330024, Chile
| | - Juan Prieto-Villalobos
- Departamento de Neurología, Escuela de Medicina and Centro Interdisciplinario de Neurociencias, Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago 8330024, Chile
| | - Mauricio Antonio Retamal
- Centro de Fisiología Celular e Integrativa, Facultad de Medicina, Universidad del Desarrollo–Clínica Alemana, Santiago 7780272, Chile
| | - Juan Andrés Orellana
- Departamento de Neurología, Escuela de Medicina and Centro Interdisciplinario de Neurociencias, Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago 8330024, Chile
| | - Jimmy Stehberg
- Laboratorio de Neurobiología, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad Andres Bello, Santiago 8370186, Chile
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7
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Liu J, Feng X, Wang Y, Xia X, Zheng JC. Astrocytes: GABAceptive and GABAergic Cells in the Brain. Front Cell Neurosci 2022; 16:892497. [PMID: 35755777 PMCID: PMC9231434 DOI: 10.3389/fncel.2022.892497] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2022] [Accepted: 05/17/2022] [Indexed: 12/14/2022] Open
Abstract
Astrocytes, the most numerous glial cells in the brain, play an important role in preserving normal neural functions and mediating the pathogenesis of neurological disorders. Recent studies have shown that astrocytes are GABAceptive and GABAergic astrocytes express GABAA receptors, GABAB receptors, and GABA transporter proteins to capture and internalize GABA. GABAceptive astrocytes thus influence both inhibitory and excitatory neurotransmission by controlling the levels of extracellular GABA. Furthermore, astrocytes synthesize and release GABA to directly regulate brain functions. In this review, we highlight recent research progresses that support astrocytes as GABAceptive and GABAergic cells. We also summarize the roles of GABAceptive and GABAergic astrocytes that serve as an inhibitory node in the intercellular communication in the brain. Besides, we discuss future directions for further expanding our knowledge on the GABAceptive and GABAergic astrocyte signaling.
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Affiliation(s)
- Jianhui Liu
- Department of Anesthesiology, Tongji Hospital affiliated to Tongji University School of Medicine, Shanghai, China
| | - Xuanran Feng
- Department of Anesthesiology, Tongji Hospital affiliated to Tongji University School of Medicine, Shanghai, China
| | - Yi Wang
- Translational Research Center, Shanghai Yangzhi Rehabilitation Hospital affiliated to Tongji University School of Medicine, Shanghai, China
| | - Xiaohuan Xia
- Department of Anesthesiology, Tongji Hospital affiliated to Tongji University School of Medicine, Shanghai, China.,Center for Translational Neurodegeneration and Regenerative Therapy, Tongji Hospital affiliated to Tongji University School of Medicine, Shanghai, China.,Shanghai Frontiers Science Center of Nanocatalytic Medicine, Shanghai, China.,Translational Research Institute of Brain and Brain-Like Intelligence, Shanghai Fourth People's Hospital affiliated to Tongji University School of Medicine, Shanghai, China
| | - Jialin C Zheng
- Department of Anesthesiology, Tongji Hospital affiliated to Tongji University School of Medicine, Shanghai, China.,Center for Translational Neurodegeneration and Regenerative Therapy, Tongji Hospital affiliated to Tongji University School of Medicine, Shanghai, China.,Shanghai Frontiers Science Center of Nanocatalytic Medicine, Shanghai, China.,Translational Research Institute of Brain and Brain-Like Intelligence, Shanghai Fourth People's Hospital affiliated to Tongji University School of Medicine, Shanghai, China.,Collaborative Innovation Center for Brain Science, Tongji University, Shanghai, China
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8
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Verkhratsky A, Parpura V, Li B, Scuderi C. Astrocytes: The Housekeepers and Guardians of the CNS. ADVANCES IN NEUROBIOLOGY 2021; 26:21-53. [PMID: 34888829 DOI: 10.1007/978-3-030-77375-5_2] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Astroglia are a diverse group of cells in the central nervous system. They are of the ectodermal, neuroepithelial origin and vary in morphology and function, yet, they can be collectively defined as cells having principle function to maintain homeostasis of the central nervous system at all levels of organisation, including homeostasis of ions, pH and neurotransmitters; supplying neurones with metabolic substrates; supporting oligodendrocytes and axons; regulating synaptogenesis, neurogenesis, and formation and maintenance of the blood-brain barrier; contributing to operation of the glymphatic system; and regulation of systemic homeostasis being central chemosensors for oxygen, CO2 and Na+. Their basic physiological features show a lack of electrical excitability (inapt to produce action potentials), but display instead a rather active excitability based on variations in cytosolic concentrations of Ca2+ and Na+. It is expression of neurotransmitter receptors, pumps and transporters at their plasmalemma, along with transports on the endoplasmic reticulum and mitochondria that exquisitely regulate the cytosolic levels of these ions, the fluctuation of which underlies most, if not all, astroglial homeostatic functions.
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Affiliation(s)
- Alexei Verkhratsky
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK.
- Achucarro Center for Neuroscience, IKERBASQUE, Basque Foundation for Science, Bilbao, Spain.
| | - Vladimir Parpura
- Department of Neurobiology, The University of Alabama at Birmingham, Birmingham, AL, USA
| | - Baoman Li
- Department of Forensic Analytical Toxicology, School of Forensic Medicine, China Medical University, Shenyang, China
| | - Caterina Scuderi
- Department of Physiology and Pharmacology "Vittorio Erspamer", SAPIENZA University of Rome, Rome, Italy
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9
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Honoré E, Khlaifia A, Bosson A, Lacaille JC. Hippocampal Somatostatin Interneurons, Long-Term Synaptic Plasticity and Memory. Front Neural Circuits 2021; 15:687558. [PMID: 34149368 PMCID: PMC8206813 DOI: 10.3389/fncir.2021.687558] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Accepted: 04/30/2021] [Indexed: 12/13/2022] Open
Abstract
A distinctive feature of the hippocampal structure is the diversity of inhibitory interneurons. These complex inhibitory interconnections largely contribute to the tight modulation of hippocampal circuitry, as well as to the formation and coordination of neuronal assemblies underlying learning and memory. Inhibitory interneurons provide more than a simple transitory inhibition of hippocampal principal cells (PCs). The synaptic plasticity of inhibitory neurons provides long-lasting changes in the hippocampal network and is a key component of memory formation. The dendrite targeting interneurons expressing the peptide somatostatin (SOM) are particularly interesting in this regard because they display unique long-lasting synaptic changes leading to metaplastic regulation of hippocampal networks. In this article, we examine the actions of the neuropeptide SOM on hippocampal cells, synaptic plasticity, learning, and memory. We address the different subtypes of hippocampal SOM interneurons. We describe the long-term synaptic plasticity that takes place at the excitatory synapses of SOM interneurons, its singular induction and expression mechanisms, as well as the consequences of these changes on the hippocampal network, learning, and memory. We also review evidence that astrocytes provide cell-specific dynamic regulation of inhibition of PC dendrites by SOM interneurons. Finally, we cover how, in mouse models of Alzheimer’s disease (AD), dysfunction of plasticity of SOM interneuron excitatory synapses may also contribute to cognitive impairments in brain disorders.
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Affiliation(s)
- Eve Honoré
- Department of Neurosciences, Centre for Interdisciplinary Research on Brain and Learning, Research Group on the Central Nervous System, Université de Montréal, Montreal, QC, Canada
| | - Abdessattar Khlaifia
- Department of Neurosciences, Centre for Interdisciplinary Research on Brain and Learning, Research Group on the Central Nervous System, Université de Montréal, Montreal, QC, Canada
| | - Anthony Bosson
- Department of Neurosciences, Centre for Interdisciplinary Research on Brain and Learning, Research Group on the Central Nervous System, Université de Montréal, Montreal, QC, Canada
| | - Jean-Claude Lacaille
- Department of Neurosciences, Centre for Interdisciplinary Research on Brain and Learning, Research Group on the Central Nervous System, Université de Montréal, Montreal, QC, Canada
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10
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Perez C, Felix L, Durry S, Rose CR, Ullah G. On the origin of ultraslow spontaneous Na + fluctuations in neurons of the neonatal forebrain. J Neurophysiol 2021; 125:408-425. [PMID: 33236936 PMCID: PMC7948148 DOI: 10.1152/jn.00373.2020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Revised: 11/19/2020] [Accepted: 11/19/2020] [Indexed: 11/22/2022] Open
Abstract
Spontaneous neuronal and astrocytic activity in the neonate forebrain is believed to drive the maturation of individual cells and their integration into complex brain-region-specific networks. The previously reported forms include bursts of electrical activity and oscillations in intracellular Ca2+ concentration. Here, we use ratiometric Na+ imaging to demonstrate spontaneous fluctuations in the intracellular Na+ concentration of CA1 pyramidal neurons and astrocytes in tissue slices obtained from the hippocampus of mice at postnatal days 2-4 (P2-4). These occur at very low frequency (∼2/h), can last minutes with amplitudes up to several millimolar, and mostly disappear after the first postnatal week. To further investigate their mechanisms, we model a network consisting of pyramidal neurons and interneurons. Experimentally observed Na+ fluctuations are mimicked when GABAergic inhibition in the simulated network is made depolarizing. Both our experiments and computational model show that blocking voltage-gated Na+ channels or GABAergic signaling significantly diminish the neuronal Na+ fluctuations. On the other hand, blocking a variety of other ion channels, receptors, or transporters including glutamatergic pathways does not have significant effects. Our model also shows that the amplitude and duration of Na+ fluctuations decrease as we increase the strength of glial K+ uptake. Furthermore, neurons with smaller somatic volumes exhibit fluctuations with higher frequency and amplitude. As opposed to this, larger extracellular to intracellular volume ratio observed in neonatal brain exerts a dampening effect. Finally, our model predicts that these periods of spontaneous Na+ influx leave neonatal neuronal networks more vulnerable to seizure-like states when compared with mature brain.NEW & NOTEWORTHY Spontaneous activity in the neonate forebrain plays a key role in cell maturation and brain development. We report spontaneous, ultraslow, asynchronous fluctuations in the intracellular Na+ concentration of neurons and astrocytes. We show that this activity is not correlated with the previously reported synchronous neuronal population bursting or Ca2+ oscillations, both of which occur at much faster timescales. Furthermore, extracellular K+ concentration remains nearly constant. The spontaneous Na+ fluctuations disappear after the first postnatal week.
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Affiliation(s)
- Carlos Perez
- Department of Physics, University of South Florida, Tampa, Florida
| | - Lisa Felix
- Faculty of Mathematics and Natural Sciences, Institute of Neurobiology, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Simone Durry
- Faculty of Mathematics and Natural Sciences, Institute of Neurobiology, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Christine R Rose
- Faculty of Mathematics and Natural Sciences, Institute of Neurobiology, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Ghanim Ullah
- Department of Physics, University of South Florida, Tampa, Florida
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11
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Abstract
In the twentieth century, neuropsychiatric disorders have been perceived solely from a neurone-centric point of view, which considers neurones as the key cellular elements of pathological processes. This dogma has been challenged thanks to the better comprehension of the brain functioning, which, even if far from being complete, has revealed the complexity of interactions that exist between neurones and neuroglia. Glial cells represent a highly heterogeneous population of cells of neural (astroglia and oligodendroglia) and non-neural (microglia) origin populating the central nervous system. The variety of glia reflects the innumerable functions that glial cells perform to support functions of the nervous system. Aberrant execution of glial functions contributes to the development of neuropsychiatric pathologies. Arguably, all types of glial cells are implicated in the neuropathology; however, astrocytes have received particular attention in recent years because of their pleiotropic functions that make them decisive in maintaining cerebral homeostasis. This chapter describes the multiple roles of astrocytes in the healthy central nervous system and discusses the diversity of astroglial responses in neuropsychiatric disorders suggesting that targeting astrocytes may represent an effective therapeutic strategy.
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Affiliation(s)
- Caterina Scuderi
- Department of Physiology and Pharmacology "Vittorio Erspamer", SAPIENZA University of Rome, Rome, Italy.
| | - Alexei Verkhratsky
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK
- Achucarro Center for Neuroscience, IKERBASQUE, Basque Foundation for Science, Bilbao, Spain
| | - Vladimir Parpura
- Department of Neurobiology, The University of Alabama at Birmingham, Birmingham, AL, USA
| | - Baoman Li
- Department of Forensic Analytical Toxicology, School of Forensic Medicine, China Medical University, Shenyang, China
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12
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Caudal LC, Gobbo D, Scheller A, Kirchhoff F. The Paradox of Astroglial Ca 2 + Signals at the Interface of Excitation and Inhibition. Front Cell Neurosci 2020; 14:609947. [PMID: 33324169 PMCID: PMC7726216 DOI: 10.3389/fncel.2020.609947] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Accepted: 11/03/2020] [Indexed: 12/15/2022] Open
Abstract
Astroglial networks constitute a non-neuronal communication system in the brain and are acknowledged modulators of synaptic plasticity. A sophisticated set of transmitter receptors in combination with distinct secretion mechanisms enables astrocytes to sense and modulate synaptic transmission. This integrative function evolved around intracellular Ca2+ signals, by and large considered as the main indicator of astrocyte activity. Regular brain physiology meticulously relies on the constant reciprocity of excitation and inhibition (E/I). Astrocytes are metabolically, physically, and functionally associated to the E/I convergence. Metabolically, astrocytes provide glutamine, the precursor of both major neurotransmitters governing E/I in the central nervous system (CNS): glutamate and γ-aminobutyric acid (GABA). Perisynaptic astroglial processes are structurally and functionally associated with the respective circuits throughout the CNS. Astonishingly, in astrocytes, glutamatergic as well as GABAergic inputs elicit similar rises in intracellular Ca2+ that in turn can trigger the release of glutamate and GABA as well. Paradoxically, as gliotransmitters, these two molecules can thus strengthen, weaken or even reverse the input signal. Therefore, the net impact on neuronal network function is often convoluted and cannot be simply predicted by the nature of the stimulus itself. In this review, we highlight the ambiguity of astrocytes on discriminating and affecting synaptic activity in physiological and pathological state. Indeed, aberrant astroglial Ca2+ signaling is a key aspect of pathological conditions exhibiting compromised network excitability, such as epilepsy. Here, we gather recent evidence on the complexity of astroglial Ca2+ signals in health and disease, challenging the traditional, neuro-centric concept of segregating E/I, in favor of a non-binary, mutually dependent perspective on glutamatergic and GABAergic transmission.
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Affiliation(s)
- Laura C Caudal
- Department of Molecular Physiology, Center for Integrative Physiology and Molecular Medicine, University of Saarland, Homburg, Germany
| | - Davide Gobbo
- Department of Molecular Physiology, Center for Integrative Physiology and Molecular Medicine, University of Saarland, Homburg, Germany
| | - Anja Scheller
- Department of Molecular Physiology, Center for Integrative Physiology and Molecular Medicine, University of Saarland, Homburg, Germany
| | - Frank Kirchhoff
- Department of Molecular Physiology, Center for Integrative Physiology and Molecular Medicine, University of Saarland, Homburg, Germany
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13
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Felix L, Stephan J, Rose CR. Astrocytes of the early postnatal brain. Eur J Neurosci 2020; 54:5649-5672. [PMID: 32406559 DOI: 10.1111/ejn.14780] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2020] [Revised: 04/30/2020] [Accepted: 05/06/2020] [Indexed: 12/21/2022]
Abstract
In the rodent forebrain, the majority of astrocytes are generated during the early postnatal phase. Following differentiation, astrocytes undergo maturation which accompanies the development of the neuronal network. Neonate astrocytes exhibit a distinct morphology and domain size which differs to their mature counterparts. Moreover, many of the plasma membrane proteins prototypical for fully developed astrocytes are only expressed at low levels at neonatal stages. These include connexins and Kir4.1, which define the low membrane resistance and highly negative membrane potential of mature astrocytes. Newborn astrocytes moreover express only low amounts of GLT-1, a glutamate transporter critical later in development. Furthermore, they show specific differences in the properties and spatio-temporal pattern of intracellular calcium signals, resulting from differences in their repertoire of receptors and signalling pathways. Therefore, roles fulfilled by mature astrocytes, including ion and transmitter homeostasis, are underdeveloped in the young brain. Similarly, astrocytic ion signalling in response to neuronal activity, a process central to neuron-glia interaction, differs between the neonate and mature brain. This review describes the unique functional properties of astrocytes in the first weeks after birth and compares them to later stages of development. We conclude that with an immature neuronal network and wider extracellular space, astrocytic support might not be as demanding and critical compared to the mature brain. The delayed differentiation and maturation of astrocytes in the first postnatal weeks might thus reflect a reduced need for active, energy-consuming regulation of the extracellular space and a less tight control of glial feedback onto synaptic transmission.
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Affiliation(s)
- Lisa Felix
- Institute of Neurobiology, Faculty of Mathematics and Natural Sciences, Heinrich Heine University Duesseldorf, Duesseldorf, Germany
| | - Jonathan Stephan
- Institute of Neurobiology, Faculty of Mathematics and Natural Sciences, Heinrich Heine University Duesseldorf, Duesseldorf, Germany
| | - Christine R Rose
- Institute of Neurobiology, Faculty of Mathematics and Natural Sciences, Heinrich Heine University Duesseldorf, Duesseldorf, Germany
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14
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Tonon MC, Vaudry H, Chuquet J, Guillebaud F, Fan J, Masmoudi-Kouki O, Vaudry D, Lanfray D, Morin F, Prevot V, Papadopoulos V, Troadec JD, Leprince J. Endozepines and their receptors: Structure, functions and pathophysiological significance. Pharmacol Ther 2020; 208:107386. [DOI: 10.1016/j.pharmthera.2019.06.008] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2019] [Accepted: 06/20/2019] [Indexed: 02/06/2023]
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15
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Zou RX, Gu X, Ding JJ, Wang T, Bi N, Niu K, Ge M, Chen XT, Wang HL. Pb exposure induces an imbalance of excitatory and inhibitory synaptic transmission in cultured rat hippocampal neurons. Toxicol In Vitro 2019; 63:104742. [PMID: 31785328 DOI: 10.1016/j.tiv.2019.104742] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Revised: 11/12/2019] [Accepted: 11/24/2019] [Indexed: 12/16/2022]
Abstract
An appropriate balance of excitatory and inhibitory synapse maintains the network stability of the central nervous system. Our recent work showed lead (Pb) exposure can inhibit synaptic transmission in cultured hippocampal neurons. However, it is not clear whether Pb exposure disrupt the balance of excitatory and inhibitory synaptic transmission. Here, primary cultured hippocampal neurons from Sprague-Dawley (SD) rats were exposed to Pb (0.2 μM, 1 μM, 5 μM, respectively) from Days in Vitro (DIV) 7 to DIV 12 for 5 days and the excitatory and inhibitory synaptic transmission was examined. Patch clamp recording results showed that distinct from exposures of 0.2 μM and 5 μM, 1 μM Pb exposure significantly increased the mIPSC frequency and decreased the mEPSC frequency, leading to a uniform inhibitory outcome. Further, the number of inhibitory presynaptic puncta was significantly increased after 1 μM Pb exposure, while the number of excitatory presynaptic terminals was decreased. In addition 1 μM Pb increased the glutamic acid decarboxylase (GAD65) expression and the surface GABAA receptor (GABAAR) clusters. This shift might potentiate the synthesis of GABA and enhance the surface distribution of postsynaptic GABAAR clusters in hippocampus neurons. Together, these data showed that Pb exposure disrupted the balance of excitatory and inhibitory synaptic transmission via abnormal GABAergic neurotransmission.
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Affiliation(s)
- Rong-Xin Zou
- Engineering Research Center of Bio-process, Ministry of Education, Hefei University of Technology, 193 Tunxi Road, Hefei, Anhui 230009, PR China; School of Food Science and Engineering, Hefei University of Technology, Hefei, Anhui 230009, PR China
| | - Xiaozhen Gu
- School of Food Science and Engineering, Hefei University of Technology, Hefei, Anhui 230009, PR China
| | - Jin-Jun Ding
- School of Food Science and Engineering, Hefei University of Technology, Hefei, Anhui 230009, PR China
| | - Tiandong Wang
- School of Food Science and Engineering, Hefei University of Technology, Hefei, Anhui 230009, PR China
| | - Nanxi Bi
- School of Food Science and Engineering, Hefei University of Technology, Hefei, Anhui 230009, PR China
| | - Kang Niu
- School of Food Science and Engineering, Hefei University of Technology, Hefei, Anhui 230009, PR China
| | - Mengmeng Ge
- School of Food Science and Engineering, Hefei University of Technology, Hefei, Anhui 230009, PR China
| | - Xiang-Tao Chen
- School of Pharmacy, Anhui Medical University, Hefei, Anhui 230031, PR China.
| | - Hui-Li Wang
- Engineering Research Center of Bio-process, Ministry of Education, Hefei University of Technology, 193 Tunxi Road, Hefei, Anhui 230009, PR China; School of Food Science and Engineering, Hefei University of Technology, Hefei, Anhui 230009, PR China.
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16
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Verkhratsky A, Parpura V, Vardjan N, Zorec R. Physiology of Astroglia. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1175:45-91. [PMID: 31583584 DOI: 10.1007/978-981-13-9913-8_3] [Citation(s) in RCA: 56] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Astrocytes are principal cells responsible for maintaining the brain homeostasis. Additionally, these glial cells are also involved in homocellular (astrocyte-astrocyte) and heterocellular (astrocyte-other cell types) signalling and metabolism. These astroglial functions require an expression of the assortment of molecules, be that transporters or pumps, to maintain ion concentration gradients across the plasmalemma and the membrane of the endoplasmic reticulum. Astrocytes sense and balance their neurochemical environment via variety of transmitter receptors and transporters. As they are electrically non-excitable, astrocytes display intracellular calcium and sodium fluctuations, which are not only used for operative signalling but can also affect metabolism. In this chapter we discuss the molecules that achieve ionic gradients and underlie astrocyte signalling.
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Affiliation(s)
- Alexei Verkhratsky
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, M13 9PT, UK. .,Faculty of Health and Medical Sciences, Center for Basic and Translational Neuroscience, University of Copenhagen, 2200, Copenhagen, Denmark. .,Achucarro Center for Neuroscience, IKERBASQUE, Basque Foundation for Science, 48011, Bilbao, Spain.
| | - Vladimir Parpura
- Department of Neurobiology, The University of Alabama at Birmingham, Birmingham, AL, USA
| | - Nina Vardjan
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Faculty of Medicine, Institute of Pathophysiology, University of Ljubljana, Ljubljana, Slovenia.,Celica Biomedical, Ljubljana, Slovenia
| | - Robert Zorec
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Faculty of Medicine, Institute of Pathophysiology, University of Ljubljana, Ljubljana, Slovenia.,Celica Biomedical, Ljubljana, Slovenia
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17
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Diverse Actions of Astrocytes in GABAergic Signaling. Int J Mol Sci 2019; 20:ijms20122964. [PMID: 31216630 PMCID: PMC6628243 DOI: 10.3390/ijms20122964] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2019] [Revised: 06/10/2019] [Accepted: 06/14/2019] [Indexed: 01/06/2023] Open
Abstract
An imbalance of excitatory and inhibitory neurotransmission leading to over excitation plays a crucial role in generating seizures, while enhancing GABAergic mechanisms are critical in terminating seizures. In recent years, it has been reported in many studies that astrocytes are deeply involved in synaptic transmission. Astrocytes form a critical component of the “tripartite” synapses by wrapping around the pre- and post-synaptic elements. From this location, astrocytes are known to greatly influence the dynamics of ions and transmitters in the synaptic cleft. Despite recent extensive research on excitatory tripartite synapses, inhibitory tripartite synapses have received less attention, even though they influence inhibitory synaptic transmission by affecting chloride and GABA concentration dynamics. In this review, we will discuss the diverse actions of astrocytic chloride and GABA homeostasis at GABAergic tripartite synapses. We will then consider the pathophysiological impacts of disturbed GABA homeostasis at the tripartite synapse.
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18
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Mederos S, Perea G. GABAergic-astrocyte signaling: A refinement of inhibitory brain networks. Glia 2019; 67:1842-1851. [PMID: 31145508 PMCID: PMC6772151 DOI: 10.1002/glia.23644] [Citation(s) in RCA: 69] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2018] [Revised: 05/16/2019] [Accepted: 05/20/2019] [Indexed: 12/13/2022]
Abstract
Interneurons play a critical role in precise control of network operation. Indeed, higher brain capabilities such as working memory, cognitive flexibility, attention, or social interaction rely on the action of GABAergic interneurons. Evidence from excitatory neurons and synapses has revealed astrocytes as integral elements of synaptic transmission. However, GABAergic interneurons can also engage astrocyte signaling; therefore, it is tempting to speculate about different scenarios where, based on particular interneuron cell type, GABAergic‐astrocyte interplay would be involved in diverse outcomes of brain function. In this review, we will highlight current data supporting the existence of dynamic GABAergic‐astrocyte communication and its impact on the inhibitory‐regulated brain responses, bringing new perspectives on the ways astrocytes might contribute to efficient neuronal coding.
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Affiliation(s)
- Sara Mederos
- Department of Functional and Systems Neurobiology, Instituto Cajal, CSIC, Madrid, Spain
| | - Gertrudis Perea
- Department of Functional and Systems Neurobiology, Instituto Cajal, CSIC, Madrid, Spain
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19
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Woo DH, Bae JY, Nam MH, An H, Ju YH, Won J, Choi JH, Hwang EM, Han KS, Bae YC, Lee CJ. Activation of Astrocytic μ-opioid Receptor Elicits Fast Glutamate Release Through TREK-1-Containing K2P Channel in Hippocampal Astrocytes. Front Cell Neurosci 2018; 12:319. [PMID: 30319359 PMCID: PMC6170663 DOI: 10.3389/fncel.2018.00319] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2018] [Accepted: 09/03/2018] [Indexed: 11/13/2022] Open
Abstract
Recently, μ-opioid receptor (MOR), one of the well-known Gi-protein coupled receptors (Gi-GPCR), was reported to be highly expressed in the hippocampal astrocytes. However, the role of astrocytic MOR has not been investigated. Here we report that activation of astrocytic MOR by [D-Ala2,N-MePhe4,Gly-ol]-enkephalin (DAMGO), a selective MOR agonist, causes a fast glutamate release using sniffer patch technique. We also found that the DAMGO-induced glutamate release was not observed in the astrocytes from MOR-deficient mice and MOR-short hairpin RNA (shRNA)-expressed astrocytes. In addition, the glutamate release was significantly reduced by gene silencing of the TREK-1-containing two-pore potassium (K2P) channel, which mediates passive conductance in astrocytes. Our findings were consistent with the previous study demonstrating that activation of Gi-GPCR such as cannabinoid receptor CB1 and adenosine receptor A1 causes a glutamate release through TREK-1-containing K2P channel from hippocampal astrocytes. We also demonstrated that MOR and TREK-1 are significantly co-localized in the hippocampal astrocytes. Furthermore, we found that both MOR and TREK-1-containing K2P channels are localized in the same subcellular compartments, soma and processes, of astrocytes. Our study raises a novel possibility that astrocytic MOR may participate in several physiological and pathological actions of opioids, including analgesia and addiction, through astrocytically released glutamate and its signaling pathway.
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Affiliation(s)
- Dong Ho Woo
- Center for Neural Science and Center for Functional Connectomics, Korea Institute of Science and Technology (KIST), Seoul, South Korea.,Animal Model Research Center, Korea Institute of Toxicology, Korea Research Institute of Chemical Technology, Daejeon, South Korea
| | - Jin Young Bae
- Department of Anatomy and Neurobiology, School of Dentistry, Kyungpook National University, Daegu, South Korea
| | - Min-Ho Nam
- Center for Neural Science and Center for Functional Connectomics, Korea Institute of Science and Technology (KIST), Seoul, South Korea.,Department of Science in Korean Medicine, Graduate School, Kyung Hee University, Seoul, South Korea
| | - Heeyoung An
- Center for Neural Science and Center for Functional Connectomics, Korea Institute of Science and Technology (KIST), Seoul, South Korea.,KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul, South Korea
| | - Yeon Ha Ju
- Center for Neural Science and Center for Functional Connectomics, Korea Institute of Science and Technology (KIST), Seoul, South Korea.,Division of Bio-Medical Science & Technology, Korea Institute of Science and Technology (KIST) School, Korea University of Science and Technology, Seoul, South Korea
| | - Joungha Won
- Center for Neural Science and Center for Functional Connectomics, Korea Institute of Science and Technology (KIST), Seoul, South Korea.,Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, South Korea
| | - Jae Hyouk Choi
- Center for Neural Science and Center for Functional Connectomics, Korea Institute of Science and Technology (KIST), Seoul, South Korea.,Division of Bio-Medical Science & Technology, Korea Institute of Science and Technology (KIST) School, Korea University of Science and Technology, Seoul, South Korea
| | - Eun Mi Hwang
- Center for Neural Science and Center for Functional Connectomics, Korea Institute of Science and Technology (KIST), Seoul, South Korea.,Division of Bio-Medical Science & Technology, Korea Institute of Science and Technology (KIST) School, Korea University of Science and Technology, Seoul, South Korea
| | - Kyung-Seok Han
- Center for Neural Science and Center for Functional Connectomics, Korea Institute of Science and Technology (KIST), Seoul, South Korea.,Division of Bio-Medical Science & Technology, Korea Institute of Science and Technology (KIST) School, Korea University of Science and Technology, Seoul, South Korea
| | - Yong Chul Bae
- Department of Anatomy and Neurobiology, School of Dentistry, Kyungpook National University, Daegu, South Korea
| | - C Justin Lee
- Center for Neural Science and Center for Functional Connectomics, Korea Institute of Science and Technology (KIST), Seoul, South Korea.,KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul, South Korea.,Division of Bio-Medical Science & Technology, Korea Institute of Science and Technology (KIST) School, Korea University of Science and Technology, Seoul, South Korea
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20
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Lia A, Zonta M, Requie LM, Carmignoto G. Dynamic interactions between GABAergic and astrocytic networks. Neurosci Lett 2018; 689:14-20. [PMID: 29908949 DOI: 10.1016/j.neulet.2018.06.026] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2018] [Revised: 06/12/2018] [Accepted: 06/13/2018] [Indexed: 10/28/2022]
Abstract
Brain network activity derives from the concerted action of different cell populations. Together with interneurons, astrocytes play fundamental roles in shaping the inhibition in brain circuitries and modulating neuronal transmission. In this review, we summarize past and recent findings that reveal in neural networks the importance of the interaction between GABAergic signaling and astrocytes and discuss its physiological and pathological relevance.
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Affiliation(s)
- Annamaria Lia
- University of Padua, Department of Biomedical Sciences, Padua, Italy; CNR, Neuroscience Institute, Padua, Italy
| | - Micaela Zonta
- University of Padua, Department of Biomedical Sciences, Padua, Italy; CNR, Neuroscience Institute, Padua, Italy.
| | - Linda Maria Requie
- University of Padua, Department of Biomedical Sciences, Padua, Italy; CNR, Neuroscience Institute, Padua, Italy
| | - Giorgio Carmignoto
- University of Padua, Department of Biomedical Sciences, Padua, Italy; CNR, Neuroscience Institute, Padua, Italy
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21
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Abstract
Astrocytes are neural cells of ectodermal, neuroepithelial origin that provide for homeostasis and defense of the central nervous system (CNS). Astrocytes are highly heterogeneous in morphological appearance; they express a multitude of receptors, channels, and membrane transporters. This complement underlies their remarkable adaptive plasticity that defines the functional maintenance of the CNS in development and aging. Astrocytes are tightly integrated into neural networks and act within the context of neural tissue; astrocytes control homeostasis of the CNS at all levels of organization from molecular to the whole organ.
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Affiliation(s)
- Alexei Verkhratsky
- The University of Manchester , Manchester , United Kingdom ; Achúcarro Basque Center for Neuroscience, IKERBASQUE, Basque Foundation for Science , Bilbao , Spain ; Department of Neuroscience, University of the Basque Country UPV/EHU and CIBERNED, Leioa, Spain ; Center for Basic and Translational Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark ; and Center for Translational Neuromedicine, University of Rochester Medical Center , Rochester, New York
| | - Maiken Nedergaard
- The University of Manchester , Manchester , United Kingdom ; Achúcarro Basque Center for Neuroscience, IKERBASQUE, Basque Foundation for Science , Bilbao , Spain ; Department of Neuroscience, University of the Basque Country UPV/EHU and CIBERNED, Leioa, Spain ; Center for Basic and Translational Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark ; and Center for Translational Neuromedicine, University of Rochester Medical Center , Rochester, New York
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22
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Verkhratsky A, Nedergaard M. Physiology of Astroglia. Physiol Rev 2018; 98:239-389. [PMID: 29351512 PMCID: PMC6050349 DOI: 10.1152/physrev.00042.2016] [Citation(s) in RCA: 951] [Impact Index Per Article: 158.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Revised: 03/22/2017] [Accepted: 04/27/2017] [Indexed: 02/07/2023] Open
Abstract
Astrocytes are neural cells of ectodermal, neuroepithelial origin that provide for homeostasis and defense of the central nervous system (CNS). Astrocytes are highly heterogeneous in morphological appearance; they express a multitude of receptors, channels, and membrane transporters. This complement underlies their remarkable adaptive plasticity that defines the functional maintenance of the CNS in development and aging. Astrocytes are tightly integrated into neural networks and act within the context of neural tissue; astrocytes control homeostasis of the CNS at all levels of organization from molecular to the whole organ.
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Affiliation(s)
- Alexei Verkhratsky
- The University of Manchester , Manchester , United Kingdom ; Achúcarro Basque Center for Neuroscience, IKERBASQUE, Basque Foundation for Science , Bilbao , Spain ; Department of Neuroscience, University of the Basque Country UPV/EHU and CIBERNED, Leioa, Spain ; Center for Basic and Translational Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark ; and Center for Translational Neuromedicine, University of Rochester Medical Center , Rochester, New York
| | - Maiken Nedergaard
- The University of Manchester , Manchester , United Kingdom ; Achúcarro Basque Center for Neuroscience, IKERBASQUE, Basque Foundation for Science , Bilbao , Spain ; Department of Neuroscience, University of the Basque Country UPV/EHU and CIBERNED, Leioa, Spain ; Center for Basic and Translational Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark ; and Center for Translational Neuromedicine, University of Rochester Medical Center , Rochester, New York
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23
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Aburawi S, Al-Tubuly R, Alghzewi E, Gorash Z. Effects of calcium channel blockers on antidepressant action of Alprazolam and Imipramine. Libyan J Med 2016. [DOI: 10.3402/ljm.v2i4.4727] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- S.M. Aburawi
- Dept of Pharmacology and Clinical Pharmacy, Faculty of Pharmacy, El-Fateh University, Libya
| | - R.A. Al-Tubuly
- Dept of Pharmacology and Clinical Pharmacy, Faculty of Pharmacy, El-Fateh University, Libya
| | - E.A. Alghzewi
- Dept of Pharmacology and Clinical Pharmacy, Faculty of Pharmacy, El-Fateh University, Libya
| | - Z.M. Gorash
- Dept of Pharmacology and Clinical Pharmacy, Faculty of Pharmacy, El-Fateh University, Libya
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24
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GABAergic Regulation of Adult Hippocampal Neurogenesis. Mol Neurobiol 2016; 54:5497-5510. [DOI: 10.1007/s12035-016-0072-3] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2016] [Accepted: 08/18/2016] [Indexed: 01/17/2023]
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25
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Rózsa M, Baka J, Bordé S, Rózsa B, Katona G, Tamás G. Unitary GABAergic volume transmission from individual interneurons to astrocytes in the cerebral cortex. Brain Struct Funct 2015; 222:651-659. [PMID: 26683686 DOI: 10.1007/s00429-015-1166-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2015] [Accepted: 11/27/2015] [Indexed: 01/06/2023]
Abstract
Communication between individual GABAergic cells and their target neurons is mediated by synapses and, in the case of neurogliaform cells (NGFCs), by unitary volume transmission. Effects of non-synaptic volume transmission might involve non-neuronal targets, and astrocytes not receiving GABAergic synapses but expressing GABA receptors are suitable for evaluating this hypothesis. Testing several cortical interneuron types in slices of the rat cerebral cortex, we show selective unitary transmission from NGFCs to astrocytes with an early, GABAA receptor and GABA transporter-mediated component and a late component that results from the activation of GABA transporters and neuronal GABAB receptors. We could not detect Ca2+ influx in astrocytes associated with unitary GABAergic responses. Our experiments identify a presynaptic cell-type-specific, GABA-mediated communication pathway from individual neurons to astrocytes, assigning a role for unitary volume transmission in the control of ionic and neurotransmitter homeostasis.
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Affiliation(s)
- Márton Rózsa
- MTA-SZTE Research Group for Cortical Microcircuits, Department of Anatomy, Physiology and Neuroscience, University of Szeged, Közép fasor 52, Szeged, 6726, Hungary
| | - Judith Baka
- MTA-SZTE Research Group for Cortical Microcircuits, Department of Anatomy, Physiology and Neuroscience, University of Szeged, Közép fasor 52, Szeged, 6726, Hungary
| | - Sándor Bordé
- MTA-SZTE Research Group for Cortical Microcircuits, Department of Anatomy, Physiology and Neuroscience, University of Szeged, Közép fasor 52, Szeged, 6726, Hungary
| | - Balázs Rózsa
- Two-Photon Imaging Center, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, 1083, Hungary
| | - Gergely Katona
- Two-Photon Imaging Center, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, 1083, Hungary
| | - Gábor Tamás
- MTA-SZTE Research Group for Cortical Microcircuits, Department of Anatomy, Physiology and Neuroscience, University of Szeged, Közép fasor 52, Szeged, 6726, Hungary.
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Losi G, Mariotti L, Carmignoto G. GABAergic interneuron to astrocyte signalling: a neglected form of cell communication in the brain. Philos Trans R Soc Lond B Biol Sci 2015; 369:20130609. [PMID: 25225102 DOI: 10.1098/rstb.2013.0609] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
GABAergic interneurons represent a minority of all cortical neurons and yet they efficiently control neural network activities in all brain areas. In parallel, glial cell astrocytes exert a broad control of brain tissue homeostasis and metabolism, modulate synaptic transmission and contribute to brain information processing in a dynamic interaction with neurons that is finely regulated in time and space. As most studies have focused on glutamatergic neurons and excitatory transmission, our knowledge of functional interactions between GABAergic interneurons and astrocytes is largely defective. Here, we critically discuss the currently available literature that hints at a potential relevance of this specific signalling in brain function. Astrocytes can respond to GABA through different mechanisms that include GABA receptors and transporters. GABA-activated astrocytes can, in turn, modulate local neuronal activity by releasing gliotransmitters including glutamate and ATP. In addition, astrocyte activation by different signals can modulate GABAergic neurotransmission. Full clarification of the reciprocal signalling between different GABAergic interneurons and astrocytes will improve our understanding of brain network complexity and has the potential to unveil novel therapeutic strategies for brain disorders.
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Affiliation(s)
- Gabriele Losi
- Department of Biomedical Science, Consiglio Nazionale delle Ricerche, Neuroscience Institute and University of Padova, Padova, Italy
| | - Letizia Mariotti
- Department of Biomedical Science, Consiglio Nazionale delle Ricerche, Neuroscience Institute and University of Padova, Padova, Italy
| | - Giorgio Carmignoto
- Department of Biomedical Science, Consiglio Nazionale delle Ricerche, Neuroscience Institute and University of Padova, Padova, Italy
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Mariotti L, Losi G, Sessolo M, Marcon I, Carmignoto G. The inhibitory neurotransmitter GABA evokes long-lasting Ca(2+) oscillations in cortical astrocytes. Glia 2015; 64:363-73. [PMID: 26496414 PMCID: PMC5057345 DOI: 10.1002/glia.22933] [Citation(s) in RCA: 84] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2015] [Accepted: 09/28/2015] [Indexed: 12/31/2022]
Abstract
Studies over the last decade provided evidence that in a dynamic interaction with neurons glial cell astrocytes contribut to fundamental phenomena in the brain. Most of the knowledge on this derives, however, from studies monitoring the astrocyte Ca2+ response to glutamate. Whether astrocytes can similarly respond to other neurotransmitters, including the inhibitory neurotransmitter GABA, is relatively unexplored. By using confocal and two photon laser‐scanning microscopy the astrocyte response to GABA in the mouse somatosensory and temporal cortex was studied. In slices from developing (P15‐20) and adult (P30‐60) mice, it was found that in a subpopulation of astrocytes GABA evoked somatic Ca2+ oscillations. This response was mediated by GABAB receptors and involved both Gi/o protein and inositol 1,4,5‐trisphosphate (IP3) signalling pathways. In vivo experiments from young adult mice, revealed that also cortical astrocytes in the living brain exibit GABAB receptor‐mediated Ca2+ elevations. At all astrocytic processes tested, local GABA or Baclofen brief applications induced long‐lasting Ca2+ oscillations, suggesting that all astrocytes have the potential to respond to GABA. Finally, in patch‐clamp recordings it was found that Ca2+ oscillations induced by Baclofen evoked astrocytic glutamate release and slow inward currents (SICs) in pyramidal cells from wild type but not IP3R2−/− mice, in which astrocytic GABAB receptor‐mediated Ca2+ elevations are impaired. These data suggest that cortical astrocytes in the mouse brain can sense the activity of GABAergic interneurons and through their specific recruitment contribut to the distinct role played on the cortical network by the different subsets of GABAergic interneurons. GLIA 2016;64:363–373
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Affiliation(s)
- Letizia Mariotti
- Neuroscience Institute, National Research Council (CNR) and Department of Biomedical Sciences, University of Padova, via U.Bassi 58/B, Padova, 35121, Italy
| | - Gabriele Losi
- Neuroscience Institute, National Research Council (CNR) and Department of Biomedical Sciences, University of Padova, via U.Bassi 58/B, Padova, 35121, Italy
| | - Michele Sessolo
- Neuroscience Institute, National Research Council (CNR) and Department of Biomedical Sciences, University of Padova, via U.Bassi 58/B, Padova, 35121, Italy
| | - Iacopo Marcon
- Neuroscience Institute, National Research Council (CNR) and Department of Biomedical Sciences, University of Padova, via U.Bassi 58/B, Padova, 35121, Italy
| | - Giorgio Carmignoto
- Neuroscience Institute, National Research Council (CNR) and Department of Biomedical Sciences, University of Padova, via U.Bassi 58/B, Padova, 35121, Italy
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Liu Z, Chopp M. Astrocytes, therapeutic targets for neuroprotection and neurorestoration in ischemic stroke. Prog Neurobiol 2015; 144:103-20. [PMID: 26455456 DOI: 10.1016/j.pneurobio.2015.09.008] [Citation(s) in RCA: 401] [Impact Index Per Article: 44.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2015] [Revised: 08/06/2015] [Accepted: 09/05/2015] [Indexed: 01/04/2023]
Abstract
Astrocytes are the most abundant cell type within the central nervous system. They play essential roles in maintaining normal brain function, as they are a critical structural and functional part of the tripartite synapses and the neurovascular unit, and communicate with neurons, oligodendrocytes and endothelial cells. After an ischemic stroke, astrocytes perform multiple functions both detrimental and beneficial, for neuronal survival during the acute phase. Aspects of the astrocytic inflammatory response to stroke may aggravate the ischemic lesion, but astrocytes also provide benefit for neuroprotection, by limiting lesion extension via anti-excitotoxicity effects and releasing neurotrophins. Similarly, during the late recovery phase after stroke, the glial scar may obstruct axonal regeneration and subsequently reduce the functional outcome; however, astrocytes also contribute to angiogenesis, neurogenesis, synaptogenesis, and axonal remodeling, and thereby promote neurological recovery. Thus, the pivotal involvement of astrocytes in normal brain function and responses to an ischemic lesion designates them as excellent therapeutic targets to improve functional outcome following stroke. In this review, we will focus on functions of astrocytes and astrocyte-mediated events during stroke and recovery. We will provide an overview of approaches on how to reduce the detrimental effects and amplify the beneficial effects of astrocytes on neuroprotection and on neurorestoration post stroke, which may lead to novel and clinically relevant therapies for stroke.
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Affiliation(s)
- Zhongwu Liu
- Department of Neurology, Henry Ford Hospital, Detroit, MI, USA.
| | - Michael Chopp
- Department of Neurology, Henry Ford Hospital, Detroit, MI, USA; Department of Physics, Oakland University, Rochester, MI, USA
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Terunuma M, Haydon PG, Pangalos MN, Moss SJ. Purinergic receptor activation facilitates astrocytic GABAB receptor calcium signalling. Neuropharmacology 2014; 88:74-81. [PMID: 25261019 DOI: 10.1016/j.neuropharm.2014.09.015] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2014] [Revised: 09/04/2014] [Accepted: 09/06/2014] [Indexed: 12/11/2022]
Abstract
Gamma-aminobutyric acid B receptors (GABABRs) are heterodimeric G-protein coupled receptors, which mediate slow synaptic inhibition in the brain. Emerging evidence suggests astrocytes also express GABABRs, although their physiological significance remains unknown. To begin addressing this issue, we have used imaging and biochemical analysis to examine the role GABABRs play in regulating astrocytic Ca(2+) signalling. Using live imaging of cultured cortical astrocytes loaded with calcium indicator Fluo-4/AM, we found that astrocytic GABABRs are able to induce astrocytic calcium transients only if they are pre-activated by P2 purinoceptors (P2YRs). The GABABR-mediated calcium transients were attenuated by the removal of extracellular calcium. Furthermore, P2YRs enhance the phosphorylation of astrocytic GABABR R2 subunits on both serine 783 (S783) and serine 892 (S892), two phosphorylation sites that are well known to regulate the activity and the cell surface stability of GABABRs. Collectively these results suggest that P2YR mediated signalling is an important determinant of GABABR activity and phosphorylation in astrocytes.
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Affiliation(s)
- Miho Terunuma
- Department of Cell Physiology and Pharmacology, College of Medicine, Biological Sciences and Psychology, University of Leicester, University Road, Leicester LE1 9HN, UK.
| | - Philip G Haydon
- Department of Neuroscience, Tufts University School of Medicine, Boston, MA 02111, USA
| | - Menelas N Pangalos
- Innovative Medicines, AstraZeneca, Mereside, Alderley Park, Cheshire SK10 4TG, UK
| | - Stephen J Moss
- Department of Neuroscience, Tufts University School of Medicine, Boston, MA 02111, USA; Department of Neuroscience, Physiology & Pharmacology, University College London, Gower Street, London WC1E 6BT, UK.
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Abstract
Astrocytes have been found to play important roles in physiology being fundamental for ionic homeostasis and glutamate clearance from the synaptic cleft by their plasma membrane glutamate transporters. Astrocytes are electrically non-excitable, but they exhibit Ca(2+) signaling, which now has been demonstrated to serve as an indirect mediator of neuron-glia bidirectional interactions through gliotransmission via tripartite synapses and to modulate synaptic function and plasticity. Spontaneous astrocytic Ca(2+) signaling was observed in vivo. Intercellular Ca(2+) waves in astrocytes can be evoked by a variety of stimulations. Astrocytes are critically involved in many pathological conditions including ischemic stroke. For example, it is well known that astrocytes become reactive and form glial scar after stroke. In animal models of some brain disorders, astrocytes have been shown to exhibit enhanced Ca(2+) excitability featured as regenerative intercellular Ca(2+) waves. This chapter briefly summarizes astrocytic Ca(2+) signaling pathways under normal conditions and in experimental in vitro and in vivo ischemic models. It discusses the possible mechanisms and therapeutic implication underlying the enhanced astrocytic Ca(2+) excitability in stroke.
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Affiliation(s)
- Shinghua Ding
- Dalton Cardiovascular Research Center, Department of Bioengineering, University of Missouri-Columbia, 134 Research Park Drive, Columbia, MO, 65211, USA,
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Cheng ZY, Wang XP, Schmid KL, Han XG. GABAB1 and GABAB2 receptor subunits co-expressed in cultured human RPE cells regulate intracellular Ca2+ via Gi/o-protein and phospholipase C pathways. Neuroscience 2014; 280:254-61. [PMID: 25241062 DOI: 10.1016/j.neuroscience.2014.09.021] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2014] [Revised: 09/10/2014] [Accepted: 09/10/2014] [Indexed: 11/26/2022]
Abstract
GABAB receptors associate with Gi/o-proteins that regulate voltage-gated Ca(2+) channels and thus the intracellular Ca(2+) concentration ([Ca(2+)]i), there is also reported cross-regulation of phospholipase C. These associations have been studied extensively in the brain and also shown to occur in non-neural cells (e.g. human airway smooth muscle). More recently GABAB receptors have been observed in chick retinal pigment epithelium (RPE). The aims were to investigate whether the GABAB receptor subunits, GABAB1 and GABAB2, are co-expressed in cultured human RPE cells, and then determine if the GABAB receptor similarly regulates the [Ca(2+)]i of RPE cells and if phospholipase C is involved. Human RPE cells were cultured from five donor eye cups. Evidence for GABAB1 and GABAB2 mRNAs and proteins in the RPE cell cultures was investigated using real time polymerase chain reaction, western blots and immunofluorescence. The effects of the GABAB receptor agonist baclofen, antagonist CGP46381, a Gi/o-protein inhibitor pertussis toxin, and the phospholipase C inhibitor U73122 on [Ca(2+)]i in cultured human RPE were demonstrated using Fluo-3. Both GABAB1 and GABAB2 mRNA and protein were identified in cell cultures of human RPE; antibody staining was co-localized to the cell membrane and cytoplasm. One-hundred micromolars of baclofen caused a transient increase in the [Ca(2+)]i of RPE cells regardless of whether Ca(2+) was added to the buffer. Baclofen-induced increases in the [Ca(2+)]i were attenuated by pre-treatment with CGP46381, pertussis toxin, and U73122. GABAB1 and GABAB2 are co-expressed in cell cultures of human RPE. GABAB receptors in RPE regulate the [Ca(2+)]i via a Gi/o-protein and phospholipase C pathway.
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Affiliation(s)
- Z-Y Cheng
- Department of Ophthalmology, Qilu Hospital, Shandong University, Jinan, Shandong 250012, China.
| | - X-P Wang
- The Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education and Chinese Ministry of Health, Qilu Hospital, Shandong University, Jinan, Shandong 250012, China
| | - K L Schmid
- School of Optometry and Vision Science, Faculty of Health, and Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, QLD 4059, Australia
| | - X-G Han
- Department of Ophthalmology, The Second Hospital, Jinan, Shandong 250001, China
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32
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Shim J, Mukherjee T, Mondal BC, Liu T, Young GC, Wijewarnasuriya DP, Banerjee U. Olfactory control of blood progenitor maintenance. Cell 2014; 155:1141-53. [PMID: 24267893 DOI: 10.1016/j.cell.2013.10.032] [Citation(s) in RCA: 87] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2013] [Revised: 08/28/2013] [Accepted: 10/07/2013] [Indexed: 12/25/2022]
Abstract
Drosophila hematopoietic progenitor maintenance involves both near neighbor and systemic interactions. This study shows that olfactory receptor neurons (ORNs) function upstream of a small set of neurosecretory cells that express GABA. Upon olfactory stimulation, GABA from these neurosecretory cells is secreted into the circulating hemolymph and binds to metabotropic GABAB receptors expressed on blood progenitors within the hematopoietic organ, the lymph gland. The resulting GABA signal causes high cytosolic Ca(2+), which is necessary and sufficient for progenitor maintenance. Thus, the activation of an odorant receptor is essential for blood progenitor maintenance, and consequently, larvae raised on minimal odor environments fail to sustain a pool of hematopoietic progenitors. This study links sensory perception and the effects of its deprivation on the integrity of the hematopoietic and innate immune systems in Drosophila. PAPERCLIP:
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Affiliation(s)
- Jiwon Shim
- Department of Molecular, Cell, and Developmental Biology, University of California, Los Angeles, Los Angeles, CA 90095, USA; Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, University of California, Los Angeles, Los Angeles, CA 90095, USA
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Abstract
Astrocytes are the predominant glial cell type in the CNS. Although astrocytes are electrically nonexcitable, their excitability is manifested by their Ca2+ signaling, which serves as a mediator of neuron-glia bidirectional interactions via tripartite synapses. Studies from in vivo two-photon imaging indicate that in healthy animals, the properties of spontaneous astrocytic Ca2+ signaling are affected by animal species, age, wakefulness and the location of astrocytes in the brain. Intercellular Ca2+ waves in astrocytes can be evoked by a variety of stimulations. In animal models of some brain disorders, astrocytes can exhibit enhanced Ca2+ excitability featured as regenerative intercellular Ca2+ waves. This review first briefly summarizes the astrocytic Ca2+ signaling pathway and the procedure of in vivo two-photon Ca2+ imaging of astrocytes. It subsequently summarizes in vivo astrocytic Ca2+ signaling in health and brain disorders from experimental studies of animal models, and discusses the possible mechanisms and therapeutic implications underlying the enhanced Ca2+ excitability in astrocytes in brain disorders. Finally, this review summarizes molecular genetic approaches used to selectively manipulate astrocyte function in vivo and their applications to study the role of astrocytes in synaptic plasticity and brain disorders.
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Affiliation(s)
- Shinghua Ding
- Dalton Cardiovascular Research Center, Department of Biological Engineering, University of Missouri, Columbia, MO 65211, USA
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Gellerich FN, Gizatullina Z, Gainutdinov T, Muth K, Seppet E, Orynbayeva Z, Vielhaber S. The control of brain mitochondrial energization by cytosolic calcium: the mitochondrial gas pedal. IUBMB Life 2013; 65:180-90. [PMID: 23401251 DOI: 10.1002/iub.1131] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2012] [Accepted: 12/08/2012] [Indexed: 11/05/2022]
Abstract
This review focuses on problems of the intracellular regulation of mitochondrial function in the brain via the (i) supply of mitochondria with ADP by means of ADP shuttles and channels and (ii) the Ca(2+) control of mitochondrial substrate supply. The permeability of the mitochondrial outer membrane for adenine nucleotides is low. Therefore rate dependent concentration gradients exist between the mitochondrial intermembrane space and the cytosol. The existence of dynamic ADP gradients is an important precondition for the functioning of ADP shuttles, for example CrP-shuttle. Cr at mM concentrations instead of ADP diffuses from the cytosol through the porin pores into the intermembrane space. The CrP-shuttle isoenzymes work in different directions which requires different metabolite concentrations mainly caused by dynamic ADP compartmentation. The ADP shuttle mechanisms alone cannot explain the load dependent changes in mitochondrial energization, and a complete model of mitochondrial regulation have to account the Ca(2+) -dependent substrate supply too. According to the old paradigmatic view, Ca(2+) (cyt) taken up by the mitochondrial Ca(2+) uniporter activates dehydrogenases within the matrix. However, recently it was found that Ca(2+) (cyt) at low nM concentrations exclusively activates the state 3 respiration via aralar, the mitochondrial glutamate/aspartate carrier. At higher Ca(2+) (cyt) (> 500 nM), brain mitochondria take up Ca(2+) for activation of substrate oxidation rates. Since brain mitochondrial pyruvate oxidation is only slightly influenced by Ca(2+) (cyt) , it was proposed that the cytosolic formation of pyruvate from its precursors is tightly controlled by the Ca(2+) dependent malate/aspartate shuttle. At low (50-100 nM) Ca(2+) (cyt) the pyruvate formation is suppressed, providing a substrate limitation control in neurons. This so called "gas pedal" mechanism explains why the energy metabolism of neurons in the nucleus suprachiasmaticus could be down-regulated at night but activated at day as a basis for the circadian changes in Ca(2+) (cyt) . It also could explain the energetic disadvantages caused by altered Ca(2+) (cyt) at mitochondrial diseases and neurodegeneration.
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Affiliation(s)
- Frank Norbert Gellerich
- Leibniz Institute for Neurobiology Magdeburg, Department of Behavioral Neurology, 39118 Magdeburg, Germany.
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Parpura V, Verkhratsky A. Astroglial amino acid-based transmitter receptors. Amino Acids 2013; 44:1151-8. [DOI: 10.1007/s00726-013-1458-4] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2012] [Accepted: 01/02/2013] [Indexed: 10/27/2022]
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Gérard F, Hansson E. Inflammatory activation enhances NMDA-triggered Ca2+ signalling and IL-1β secretion in primary cultures of rat astrocytes. Brain Res 2012; 1473:1-8. [PMID: 22836011 DOI: 10.1016/j.brainres.2012.07.032] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2011] [Revised: 03/13/2012] [Accepted: 07/17/2012] [Indexed: 10/28/2022]
Abstract
The aim of the present study was to measure the effects of NMDA receptor antagonists on rat astroglial-enriched primary cultures after incubation with lipopolysaccharide (LPS), with a view to explaining the role of NMDA receptors in the inflammatory activation of astrocytes. First, the presence of NMDA receptor subunits was confirmed at the protein level by immunocytochemical methods. The presence of functional NMDA receptors containing GluN2B subunits was then established by ratiometric fluorescent Ca(2+) imaging which revealed transient NMDA-triggered Ca(2+) responses. These responses could be blocked by the competitive antagonist 2-amino-5-phosphonopentoate (APV) and the non-competitive GluN2B subunit-selective antagonist ifenprodil. The NMDA-evoked Ca(2+) transients were dependent on Ca(2+) release from intracellular stores via interaction with InsP3-sensitive receptors as they were blocked by thapsigargin or xestospongin C. Following 24h incubation with LPS, astroglial inflammatory activation increased IL-1β secretion and NMDA-triggered Ca(2+) transients. The addition of APV or ifenprodil inhibited these enhanced responses, suggesting that LPS exposure stimulates IL-1β release from astrocytes through a mechanism that requires NMDA receptor stimulation.
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Affiliation(s)
- Franck Gérard
- Department of Clinical Neuroscience and Rehabilitation, Institute of Neuroscience and Physiology, University of Gothenburg, Per Dubbsgatan 14, 1tr, Sahlgrenska Academy University, SE 413 45 Gothenburg, Sweden.
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Direct and glia-mediated effects of GABA on development of central olfactory neurons. ACTA ACUST UNITED AC 2012; 7:143-61. [PMID: 22874585 DOI: 10.1017/s1740925x12000075] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Previously studied for its role in processing olfactory information in the antennal lobe, GABA also may shape development of the olfactory pathway, acting either through or on glial cells. Early in development, the dendrites of GABAergic neurons extend to the glial border that surrounds the nascent olfactory lobe neuropil. These neuropil glia express both GABAA and GABAB receptors, about half of the glia in acute cultures responded to GABA with small outward currents, and about a third responded with small transient increases in intracellular calcium. The neuronal classes that express GABA in vivo, the local interneurons and a subset of projection neurons, also do so in culture. Exposure to GABA in culture increased the size and complexity of local interneurons, but had no effect on glial morphology. The presence of glia alone did not affect neuronal morphology, but in the presence of both glia and GABA, the growth-enhancing effects of GABA on cultured antennal lobe neurons were eliminated. Contact between the glial cells and the neurons was not necessary. Operating in vivo, these antagonistic effects, one direct and one glia mediated, could help to sculpt the densely branched, tufted arbors that are characteristic of neurons innervating olfactory glomeruli.
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38
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Yoon BE, Woo J, Lee CJ. Astrocytes as GABA-ergic and GABA-ceptive cells. Neurochem Res 2012; 37:2474-9. [PMID: 22700085 DOI: 10.1007/s11064-012-0808-z] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2012] [Revised: 05/21/2012] [Accepted: 05/23/2012] [Indexed: 10/28/2022]
Abstract
GABA (gamma-aminobutyric acid) is considered to be the major inhibitory neurotransmitter that is synthesized in and released from GABA-ergic neurons in the brain. However, recent studies have shown that not only neurons but astrocytes contain a considerable amount of GABA, which can be released and activate the receptors responsive to GABA. In addition, astrocytes are themselves responsive to GABA by expressing GABA receptors. These exciting new findings raise more questions about the origin of GABA, whether it is synthesized or taken up, and about the role of astrocytic GABA and GABA receptors. In this review, we propose several potential pathways for astrocytes to accumulate GABA and discuss the evidence for functional expression of GABA receptors in astrocytes.
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Affiliation(s)
- Bo-Eun Yoon
- WCI Center for Functional Connectomics, Korea Institute of Science and Technology (KIST), Seoul 136-791, Korea
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39
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Gassmann M, Bettler B. Regulation of neuronal GABA(B) receptor functions by subunit composition. Nat Rev Neurosci 2012; 13:380-94. [PMID: 22595784 DOI: 10.1038/nrn3249] [Citation(s) in RCA: 248] [Impact Index Per Article: 20.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
GABA(B) receptors (GABA(B)Rs) are G protein-coupled receptors for GABA, the main inhibitory neurotransmitter in the CNS. In the past 5 years, notable advances have been made in our understanding of the molecular composition of these receptors. GABA(B)Rs are now known to comprise principal and auxiliary subunits that influence receptor properties in distinct ways. The principal subunits regulate the surface expression and the axonal versus dendritic distribution of these receptors, whereas the auxiliary subunits determine agonist potency and the kinetics of the receptor response. This Review summarizes current knowledge on how the subunit composition of GABA(B)Rs affects the distribution of these receptors, neuronal processes and higher brain functions.
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Affiliation(s)
- Martin Gassmann
- Department of Biomedicine, Institute of Physiology, University of Basel, Klingelbergstr. 50-70, 4056 Basel, Switzerland.
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40
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Desrues L, Lefebvre T, Lecointre C, Schouft MT, Leprince J, Compère V, Morin F, Proust F, Gandolfo P, Tonon MC, Castel H. Down-regulation of GABA(A) receptor via promiscuity with the vasoactive peptide urotensin II receptor. Potential involvement in astrocyte plasticity. PLoS One 2012; 7:e36319. [PMID: 22563490 PMCID: PMC3341351 DOI: 10.1371/journal.pone.0036319] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2011] [Accepted: 04/02/2012] [Indexed: 02/07/2023] Open
Abstract
GABAA receptor (GABAAR) expression level is inversely correlated with the proliferation rate of astrocytes after stroke or during malignancy of astrocytoma, leading to the hypothesis that GABAAR expression/activation may work as a cell proliferation repressor. A number of vasoactive peptides exhibit the potential to modulate astrocyte proliferation, and the question whether these mechanisms may imply alteration in GABAAR-mediated functions and/or plasma membrane densities is open. The peptide urotensin II (UII) activates a G protein-coupled receptor named UT, and mediates potent vasoconstriction or vasodilation in mammalian vasculature. We have previously demonstrated that UII activates a PLC/PIPs/Ca2+ transduction pathway, via both Gq and Gi/o proteins and stimulates astrocyte proliferation in culture. It was also shown that UT/Gq/IP3 coupling is regulated by the GABAAR in rat cultured astrocytes. Here we report that UT and GABAAR are co-expressed in cerebellar glial cells from rat brain slices, in human native astrocytes and in glioma cell line, and that UII inhibited the GABAergic activity in rat cultured astrocytes. In CHO cell line co-expressing human UT and combinations of GABAAR subunits, UII markedly depressed the GABA current (β3γ2>α2β3γ2>α2β1γ2). This effect, characterized by a fast short-term inhibition followed by drastic and irreversible run-down, is not relayed by G proteins. The run-down partially involves Ca2+ and phosphorylation processes, requires dynamin, and results from GABAAR internalization. Thus, activation of the vasoactive G protein-coupled receptor UT triggers functional inhibition and endocytosis of GABAAR in CHO and human astrocytes, via its receptor C-terminus. This UII-induced disappearance of the repressor activity of GABAAR, may play a key role in the initiation of astrocyte proliferation.
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Affiliation(s)
- Laurence Desrues
- Inserm U982, Laboratory of Neuronal and Neuroendocrine Communication and Differentiation, Astrocyte and Vascular Niche, University of Rouen, Mont-Saint-Aignan, France
- Institute of Research and Biomedical Innovation (IRIB), Normandy University PRES, University of Rouen, Mont-Saint-Aignan, France
| | - Thomas Lefebvre
- Inserm U982, Laboratory of Neuronal and Neuroendocrine Communication and Differentiation, Astrocyte and Vascular Niche, University of Rouen, Mont-Saint-Aignan, France
- Institute of Research and Biomedical Innovation (IRIB), Normandy University PRES, University of Rouen, Mont-Saint-Aignan, France
| | - Céline Lecointre
- Inserm U982, Laboratory of Neuronal and Neuroendocrine Communication and Differentiation, Astrocyte and Vascular Niche, University of Rouen, Mont-Saint-Aignan, France
- Institute of Research and Biomedical Innovation (IRIB), Normandy University PRES, University of Rouen, Mont-Saint-Aignan, France
| | - Marie-Thérèse Schouft
- Inserm U982, Laboratory of Neuronal and Neuroendocrine Communication and Differentiation, Astrocyte and Vascular Niche, University of Rouen, Mont-Saint-Aignan, France
- Institute of Research and Biomedical Innovation (IRIB), Normandy University PRES, University of Rouen, Mont-Saint-Aignan, France
| | - Jérôme Leprince
- Inserm U982, Laboratory of Neuronal and Neuroendocrine Communication and Differentiation, Astrocyte and Vascular Niche, University of Rouen, Mont-Saint-Aignan, France
- Institute of Research and Biomedical Innovation (IRIB), Normandy University PRES, University of Rouen, Mont-Saint-Aignan, France
| | - Vincent Compère
- Inserm U982, Laboratory of Neuronal and Neuroendocrine Communication and Differentiation, Astrocyte and Vascular Niche, University of Rouen, Mont-Saint-Aignan, France
- Institute of Research and Biomedical Innovation (IRIB), Normandy University PRES, University of Rouen, Mont-Saint-Aignan, France
- Department of Anesthesiology and Critical Care, Rouen University Hospital, Rouen, France
| | - Fabrice Morin
- Inserm U982, Laboratory of Neuronal and Neuroendocrine Communication and Differentiation, Astrocyte and Vascular Niche, University of Rouen, Mont-Saint-Aignan, France
- Institute of Research and Biomedical Innovation (IRIB), Normandy University PRES, University of Rouen, Mont-Saint-Aignan, France
| | - François Proust
- Inserm U982, Laboratory of Neuronal and Neuroendocrine Communication and Differentiation, Astrocyte and Vascular Niche, University of Rouen, Mont-Saint-Aignan, France
- Institute of Research and Biomedical Innovation (IRIB), Normandy University PRES, University of Rouen, Mont-Saint-Aignan, France
- Department of Neurosurgery, Rouen University Hospital, Rouen, France
| | - Pierrick Gandolfo
- Inserm U982, Laboratory of Neuronal and Neuroendocrine Communication and Differentiation, Astrocyte and Vascular Niche, University of Rouen, Mont-Saint-Aignan, France
- Institute of Research and Biomedical Innovation (IRIB), Normandy University PRES, University of Rouen, Mont-Saint-Aignan, France
| | - Marie-Christine Tonon
- Inserm U982, Laboratory of Neuronal and Neuroendocrine Communication and Differentiation, Astrocyte and Vascular Niche, University of Rouen, Mont-Saint-Aignan, France
- Institute of Research and Biomedical Innovation (IRIB), Normandy University PRES, University of Rouen, Mont-Saint-Aignan, France
| | - Hélène Castel
- Inserm U982, Laboratory of Neuronal and Neuroendocrine Communication and Differentiation, Astrocyte and Vascular Niche, University of Rouen, Mont-Saint-Aignan, France
- Institute of Research and Biomedical Innovation (IRIB), Normandy University PRES, University of Rouen, Mont-Saint-Aignan, France
- * E-mail:
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Devor A, Boas DA, Einevoll GT, Buxton RB, Dale AM. Neuronal Basis of Non-Invasive Functional Imaging: From Microscopic Neurovascular Dynamics to BOLD fMRI. NEURAL METABOLISM IN VIVO 2012. [DOI: 10.1007/978-1-4614-1788-0_15] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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Pyramidal neurons are "neurogenic hubs" in the neurovascular coupling response to whisker stimulation. J Neurosci 2011; 31:9836-47. [PMID: 21734275 DOI: 10.1523/jneurosci.4943-10.2011] [Citation(s) in RCA: 122] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The whisker-to-barrel cortex is widely used to study neurovascular coupling, but the cellular basis that underlies the perfusion changes is still largely unknown. Here, we identified neurons recruited by whisker stimulation in the rat somatosensory cortex using double immunohistochemistry for c-Fos and markers of glutamatergic and GABAergic neurons, and investigated in vivo their contribution along with that of astrocytes in the evoked perfusion response. Whisker stimulation elicited cerebral blood flow (CBF) increases concomitantly with c-Fos upregulation in pyramidal cells that coexpressed cyclooxygenase-2 (COX-2) and GABA interneurons that coexpressed vasoactive intestinal polypeptide and/or choline acetyltransferase, but not somatostatin or parvalbumin. The evoked CBF response was decreased by blockade of NMDA (MK-801, -37%), group I metabotropic glutamate (MPEP+LY367385, -40%), and GABA-A (picrotoxin, -31%) receptors, but not by GABA-B, VIP, or muscarinic receptor antagonism. Picrotoxin decreased stimulus-induced somatosensory evoked potentials and CBF responses. Combined blockade of GABA-A and NMDA receptors yielded an additive decreasing effect (-61%) of the evoked CBF compared with each antagonist alone, demonstrating cooperation of both excitatory and inhibitory systems in the hyperemic response. Blockade of prostanoid synthesis by inhibiting COX-2 (indomethacin, NS-398), expressed by ∼40% of pyramidal cells but not by astrocytes, impaired the CBF response (-50%). The hyperemic response was also reduced (-40%) after inhibition of astroglial oxidative metabolism or epoxyeicosatrienoic acids synthesis. These results demonstrate that changes in pyramidal cell activity, sculpted by specific types of inhibitory GABA interneurons, drive the CBF response to whisker stimulation and, further, that metabolically active astrocytes are also required.
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Vélez-Fort M, Audinat E, Angulo MC. Central Role of GABA in Neuron–Glia Interactions. Neuroscientist 2011; 18:237-50. [PMID: 21609943 DOI: 10.1177/1073858411403317] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The major types of glial cells—astrocytes, microglia, and cells of the oligodendroglial lineage—are known to express functional metabotropic and ionotropic GABA receptors. Neuronal signaling mechanisms allowing for the activation of these receptors in glia are probably as complex as those described among neurons and involve synaptic and extrasynaptic transmission modes. In addition, astrocytes can signal back to neurons by releasing GABA, probably through unconventional nonvesicular mechanisms. The decryption of the roles played by GABAergic signaling in neuron–glia interactions is only beginning, but it has been suggested that activation of glial cells by GABA influences important functions of the brain such as neuronal activity, differentiation, myelination, and neuroprotection. This review discusses the cellular mechanisms allowing the major types of glial cells to sense and transmit GABAergic signals and gives an overview of potential roles of this signaling pathway in developing and mature brains.
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Affiliation(s)
- Mateo Vélez-Fort
- Inserm U603, Paris, France
- CNRS UMR 8154, Paris, France
- Université Paris Descartes, Paris, France
- Division of Neurophysiology, The National Institute for Medical Research, Mill Hill, UK
| | - Etienne Audinat
- Inserm U603, Paris, France
- CNRS UMR 8154, Paris, France
- Université Paris Descartes, Paris, France
| | - María Cecilia Angulo
- Inserm U603, Paris, France
- CNRS UMR 8154, Paris, France
- Université Paris Descartes, Paris, France
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44
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Cauli B, Hamel E. Revisiting the role of neurons in neurovascular coupling. FRONTIERS IN NEUROENERGETICS 2010; 2:9. [PMID: 20616884 PMCID: PMC2899521 DOI: 10.3389/fnene.2010.00009] [Citation(s) in RCA: 178] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/18/2010] [Accepted: 05/26/2010] [Indexed: 11/13/2022]
Abstract
In this article, we will review molecular, anatomical, physiological and pharmacological data in an attempt to better understand how excitatory and inhibitory neurons recruited by distinct afferent inputs to the cerebral cortex contribute to the coupled hemodynamic response, and how astrocytes can act as intermediaries to these neuronal populations. We aim at providing the pros and cons to the following statements that, depending on the nature of the afferent input to the neocortex, (i) different neuronal or astroglial messengers, likely acting in sequence, mediate the hemodynamic changes, (ii) some recruited neurons release messengers that directly alter blood vessel tone, (iii) others act by modulating neuronal and astroglial activity, and (iv) astrocytes act as intermediaries for both excitatory and inhibitory neurotransmitters. We will stress that a given afferent signal activates a precise neuronal circuitry that determines the mediators of the hemodynamic response as well as the level of interaction with surrounding astrocytes.
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Affiliation(s)
- Bruno Cauli
- Laboratoire de Neurobiologie des Processus Adaptatifs, Université Pierre et Marie Curie Paris, France
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45
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Magnaghi V. GABA and neuroactive steroid interactions in glia: new roles for old players? Curr Neuropharmacol 2010; 5:47-64. [PMID: 18615153 DOI: 10.2174/157015907780077132] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2006] [Revised: 04/24/2006] [Accepted: 07/27/2006] [Indexed: 02/06/2023] Open
Abstract
In recent years it has becoming clear that glial cells of the central and peripheral nervous system play a crucial role from the earliest stages of development throughout adult life. Glial cells are important for neuronal plasticity, axonal conduction and synaptic transmission. In this respect, glial cells are able to produce, uptake and metabolize many factors that are essential for neuronal physiology, including classic neurotransmitters and neuroactive steroids. In particular, neuroactive steroids, which are mainly synthesized by glial cells, are able to modulate some neurotransmitter receptors affecting both glia and neurons. Among the signaling systems that are specialized for neuron-glial communication, we can include neurotransmitter GABA.The main focus of this review is to illustrate the cross-talk between neurons and glial cells in terms of GABA neurotransmission and actions of neuroactive steroids. To this purpose, we will review the presence of the different GABA receptors in the glial cells of the central and peripheral nervous system. Then, we will discuss their modulation by some neuroactive steroids.
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Affiliation(s)
- Valerio Magnaghi
- Department of Endocrinology and Center of Excellence on Neurodegenerative Disease, University of Milan, Italy.
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46
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Schwirtlich M, Emri Z, Antal K, Máté Z, Katarova Z, Szabó G. GABA
A
and GABA
B
receptors of distinct properties affect oppositely the proliferation of mouse embryonic stem cells through synergistic elevation of intracellular Ca
2+. FASEB J 2009; 24:1218-28. [DOI: 10.1096/fj.09-143586] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Marija Schwirtlich
- Laboratory of Molecular Biology and GeneticsInstitute of Experimental MedicineHungarian Academy of SciencesBudapest Hungary
| | - Zsuzsa Emri
- Department of NeurochemistryChemical Research CenterHungarian Academy of SciencesBudapest Hungary
| | - Károly Antal
- Department of NeurochemistryChemical Research CenterHungarian Academy of SciencesBudapest Hungary
| | - Zoltan Máté
- Laboratory of Molecular Biology and GeneticsInstitute of Experimental MedicineHungarian Academy of SciencesBudapest Hungary
| | - Zoya Katarova
- Laboratory of Molecular Biology and GeneticsInstitute of Experimental MedicineHungarian Academy of SciencesBudapest Hungary
| | - Gabor Szabó
- Laboratory of Molecular Biology and GeneticsInstitute of Experimental MedicineHungarian Academy of SciencesBudapest Hungary
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47
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Serrano A, Robitaille R, Lacaille JC. Differential NMDA-dependent activation of glial cells in mouse hippocampus. Glia 2009; 56:1648-63. [PMID: 18618659 DOI: 10.1002/glia.20717] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
In the hippocampus, the NMDA receptor is thought to be an important glutamate receptor involved in synaptic plasticity and in memory processes. Until recently, NMDA receptors have been considered solely as neuronal components, but some evidence suggests that glial cells in the hippocampus, and in particular astrocytes, also could be activated by NMDA applications. On the basis of their shape and electrophysiological properties (linear and rectified I/V curve), we describe two different populations of glial cells from GFAP-GFP transgenic mice that are activated differentially by NMDA. We found that linear glial cells were depolarized by NMDA that was not dependent on Ca2+ rise but partially involved a Ca2+ entry. Additionally, NMDA-induced depolarization of linear glial cells involved both a TTX-independent pathway likely through a direct activation, and a TTX-dependent pathway that required neuronal activity. The NMDA-induced depolarization in these cells was in part due to the activation of glutamate transporters and GABA B receptors. Furthermore, TTX-dependent NMDA-induced activation regulates the level of gap junction coupling between linear glial cells. In contrast, NMDA-induced depolarization in outward rectifying cells do not require a Ca2+ rise but are mediated directly by Ca2+ entry and are independent of glutamate transporters, GABA B and GABA A receptors. Our findings reveal that NMDA differentially activates hippocampal glial cells and the glial network through heterogeneous mechanisms in a cell-type specific manner.
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Affiliation(s)
- Alexandre Serrano
- Groupe de Recherche sur le Système Nerveux Central et Département de Physiologie, Université de Montréal, Succursale Centre-Ville, Montréal, Québec, Canada
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48
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Meier SD, Kafitz KW, Rose CR. Developmental profile and mechanisms of GABA-induced calcium signaling in hippocampal astrocytes. Glia 2008; 56:1127-37. [PMID: 18442094 DOI: 10.1002/glia.20684] [Citation(s) in RCA: 104] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
GABA (gamma-aminobutyric acid) is a transmitter with dual action. Whereas it excites neurons during the first week of postnatal development, it represents the major inhibitory transmitter in the mature brain. GABA also activates astrocytes by binding to ionotropic (GABA(A)) and metabotropic (GABA(B)) receptors. This results in glial calcium transients which can induce the release of gliotransmitters, rendering GABA an important mediator of neuron-glia interaction. Using whole-cell patch-clamp and ratiometric calcium imaging in hippocampal slices from rats at postnatal days 3-34, we have analyzed the developmental profile as well as the cellular mechanisms of calcium signals induced by GABA(A) and GABA(B) receptor activation in astrocytes. We found that GABA-evoked glial calcium transients are mediated by both GABA(A) and GABA(B) receptors. Throughout development, GABA(A)-receptor activation resulted in immediate calcium transients in the vast majority of astrocytes, most likely by influx of calcium through voltage-gated calcium channels. GABA(B) receptor activation, in contrast, resulted in delayed calcium transients, which were blocked following depletion of intracellular calcium stores and during persistent activation of heterotrimeric G-proteins. GABA(B) receptor-mediated calcium signals exhibited a clear developmental profile with less than 10% of astrocytes responding at P3 or P32-34, and about 60% of cells between P11 and P15. Our data thus indicate that GABA(B) receptor-mediated calcium transients are due to calcium release from intracellular stores following G-protein activation. Moreover, GABA(B) receptor-mediated calcium signaling in astrocytes preferentially occurs at a period during postnatal development when hippocampal networks are established.
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Affiliation(s)
- Silke D Meier
- Institute for Neurobiology, Heinrich-Heine-University of Duesseldorf, Universitaetsstrasse 1, Duesseldorf, Germany
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49
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Hansson E, Westerlund A, Björklund U, Olsson T. mu-Opioid agonists inhibit the enhanced intracellular Ca(2+) responses in inflammatory activated astrocytes co-cultured with brain endothelial cells. Neuroscience 2008; 155:1237-49. [PMID: 18692967 DOI: 10.1016/j.neuroscience.2008.04.027] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2008] [Revised: 04/11/2008] [Accepted: 04/11/2008] [Indexed: 01/16/2023]
Abstract
In order to imitate the in vivo situation with constituents from the blood-brain barrier, astrocytes from newborn rat cerebral cortex were co-cultured with adult rat brain microvascular endothelial cells. These astrocytes exhibited a morphologically differentiated appearance with long processes. 5-HT, synthetic mu-, delta- or kappa-opioid agonists, and the endogenous opioids endomorphin-1, beta-endorphin, and dynorphin induced higher Ca(2+) amplitudes and/or more Ca(2+) transients in these cells than in astrocytes in monoculture, as a sign of more developed signal transduction systems. Furthermore, stimulation of the co-cultured astrocytes with 5-HT generated a pronounced increase in intracellular Ca(2+) release in the presence of the inflammatory or pain mediating activators substance P, calcitonin gene-related peptide (CGRP), lipopolysaccharide (LPS), or leptin. These Ca(2+) responses were restored by opioids so that the delta- and kappa-opioid receptor agonists reduced the number of Ca(2+) transients elicited after incubation in substance P+CGRP or leptin, while the mu- and delta-opioid receptor agonists attenuated the Ca(2+) amplitudes elicited in the presence of LPS or leptin. In LPS treated co-cultured astrocytes the mu-opioid receptor antagonist naloxone attenuated not only the endomorphin-1, but also the 5-HT evoked Ca(2+) transients. These results suggest that opioids, especially mu-opioid agonists, play a role in the control of neuroinflammatory activity in astrocytes and that naloxone, in addition to its interaction with mu-opioid receptors, also may act through some binding site on astrocytes, other than the classical opioid receptor.
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Affiliation(s)
- E Hansson
- Department of Clinical Neuroscience and Rehabilitation, The Sahlgrenska Academy, University of Gothenburg, 413 45 Gothenburg, Sweden.
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50
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Abstract
Estradiol is the most potent and ubiquitous member of a class of steroid hormones called estrogens. Fetuses and newborns are exposed to estradiol derived from their mother, their own gonads, and synthesized locally in their brains. Receptors for estradiol are nuclear transcription factors that regulate gene expression but also have actions at the membrane, including activation of signal transduction pathways. The developing brain expresses high levels of receptors for estradiol. The actions of estradiol on developing brain are generally permanent and range from establishment of sex differences to pervasive trophic and neuroprotective effects. Cellular end points mediated by estradiol include the following: 1) apoptosis, with estradiol preventing it in some regions but promoting it in others; 2) synaptogenesis, again estradiol promotes in some regions and inhibits in others; and 3) morphometry of neurons and astrocytes. Estradiol also impacts cellular physiology by modulating calcium handling, immediate-early-gene expression, and kinase activity. The specific mechanisms of estradiol action permanently impacting the brain are regionally specific and often involve neuronal/glial cross-talk. The introduction of endocrine disrupting compounds into the environment that mimic or alter the actions of estradiol has generated considerable concern, and the developing brain is a particularly sensitive target. Prostaglandins, glutamate, GABA, granulin, and focal adhesion kinase are among the signaling molecules co-opted by estradiol to differentiate male from female brains, but much remains to be learned. Only by understanding completely the mechanisms and impact of estradiol action on the developing brain can we also understand when these processes go awry.
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Affiliation(s)
- Margaret M McCarthy
- Department of Physiology, University of Maryland Baltimore School of Medicine, Baltimore, Maryland 21201, USA.
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