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Ali DN, Ali HM, Lopez MR, Kang S, Choi DS. Astrocytic GABAergic Regulation in Alcohol Use and Major Depressive Disorders. Cells 2024; 13:318. [PMID: 38391931 PMCID: PMC10887002 DOI: 10.3390/cells13040318] [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: 11/30/2023] [Revised: 01/26/2024] [Accepted: 02/06/2024] [Indexed: 02/24/2024] Open
Abstract
Gamma-aminobutyric acid (GABA) is the major inhibitory neurotransmitter in the central nervous system (CNS). Most GABAergic neurons synthesize GABA from glutamate and release it in the synaptic cleft in the CNS. However, astrocytes can also synthesize and release GABA, activating GABA receptors in the neighboring neurons in physiological and pathological conditions. As the primary homeostatic glial cells in the brain, astrocytes play a crucial role in regulating GABA homeostasis and synaptic neurotransmission. Accumulating evidence demonstrates that astrocytic GABA dysregulation is implicated in psychiatric disorders, including alcohol use disorder (AUD) and major depressive disorder (MDD), the most prevalent co-occurring psychiatric disorders. Several current medications and emerging pharmacological agents targeting GABA levels are in clinical trials for treating AUD and MDD. This review offers a concise summary of the role of astrocytic GABA regulation in AUD and MDD. We also provide an overview of the current understanding and areas of debate regarding the mechanisms by which astrocytes regulate GABA in the CNS and their potential significance in the molecular basis of AUD and MDD, paving the way toward future research directions and potential therapeutic target areas within this field.
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Affiliation(s)
- Dina N. Ali
- Department of Molecular Pharmacology and Experimental Therapeutics, Rochester, MN 55905, USA; (D.N.A.); (H.M.A.); (M.R.L.); (S.K.)
| | - Hossam M. Ali
- Department of Molecular Pharmacology and Experimental Therapeutics, Rochester, MN 55905, USA; (D.N.A.); (H.M.A.); (M.R.L.); (S.K.)
| | - Matthew R. Lopez
- Department of Molecular Pharmacology and Experimental Therapeutics, Rochester, MN 55905, USA; (D.N.A.); (H.M.A.); (M.R.L.); (S.K.)
| | - Shinwoo Kang
- Department of Molecular Pharmacology and Experimental Therapeutics, Rochester, MN 55905, USA; (D.N.A.); (H.M.A.); (M.R.L.); (S.K.)
| | - Doo-Sup Choi
- Department of Molecular Pharmacology and Experimental Therapeutics, Rochester, MN 55905, USA; (D.N.A.); (H.M.A.); (M.R.L.); (S.K.)
- Neuroscience Program, Rochester, MN 55905, USA
- Department of Psychiatry and Psychology, Mayo Clinic College of Medicine and Science, Rochester, MN 55905, USA
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Purushotham SS, Buskila Y. Astrocytic modulation of neuronal signalling. FRONTIERS IN NETWORK PHYSIOLOGY 2023; 3:1205544. [PMID: 37332623 PMCID: PMC10269688 DOI: 10.3389/fnetp.2023.1205544] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Accepted: 05/18/2023] [Indexed: 06/20/2023]
Abstract
Neuronal signalling is a key element in neuronal communication and is essential for the proper functioning of the CNS. Astrocytes, the most prominent glia in the brain play a key role in modulating neuronal signalling at the molecular, synaptic, cellular, and network levels. Over the past few decades, our knowledge about astrocytes and their functioning has evolved from considering them as merely a brain glue that provides structural support to neurons, to key communication elements. Astrocytes can regulate the activity of neurons by controlling the concentrations of ions and neurotransmitters in the extracellular milieu, as well as releasing chemicals and gliotransmitters that modulate neuronal activity. The aim of this review is to summarise the main processes through which astrocytes are modulating brain function. We will systematically distinguish between direct and indirect pathways in which astrocytes affect neuronal signalling at all levels. Lastly, we will summarize pathological conditions that arise once these signalling pathways are impaired focusing on neurodegeneration.
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Affiliation(s)
| | - Yossi Buskila
- School of Medicine, Western Sydney University, Campbelltown, NSW, Australia
- The MARCS Institute, Western Sydney University, Campbelltown, NSW, Australia
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Brunskine C, Passlick S, Henneberger C. Structural Heterogeneity of the GABAergic Tripartite Synapse. Cells 2022; 11:cells11193150. [PMID: 36231112 PMCID: PMC9563275 DOI: 10.3390/cells11193150] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2022] [Revised: 09/29/2022] [Accepted: 10/04/2022] [Indexed: 11/22/2022] Open
Abstract
The concept of the tripartite synapse describes the close interaction of pre- and postsynaptic elements and the surrounding astrocyte processes. For glutamatergic synapses, it is established that the presence of astrocytic processes and their structural arrangements varies considerably between and within brain regions and between synapses of the same neuron. In contrast, less is known about the organization of astrocytic processes at GABAergic synapses although bi-directional signaling is known to exist at these synapses too. Therefore, we established super-resolution expansion microscopy of GABAergic synapses and nearby astrocytic processes in the stratum radiatum of the mouse hippocampal CA1 region. By visualizing the presynaptic vesicular GABA transporter and the postsynaptic clustering protein gephyrin, we documented the subsynaptic heterogeneity of GABAergic synaptic contacts. We then compared the volume distribution of astrocytic processes near GABAergic synapses between individual synapses and with glutamatergic synapses. We made two novel observations. First, astrocytic processes were more abundant at the GABAergic synapses with large postsynaptic gephyrin clusters. Second, astrocytic processes were less abundant in the vicinity of GABAergic synapses compared to glutamatergic, suggesting that the latter may be selectively approached by astrocytes. Because of the GABA transporter distribution, we also speculate that this specific arrangement enables more efficient re-uptake of GABA into presynaptic terminals.
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Affiliation(s)
- Cindy Brunskine
- Institute of Cellular Neurosciences, Medical Faculty, University of Bonn, 53127 Bonn, Germany
| | - Stefan Passlick
- Institute of Cellular Neurosciences, Medical Faculty, University of Bonn, 53127 Bonn, Germany
| | - Christian Henneberger
- Institute of Cellular Neurosciences, Medical Faculty, University of Bonn, 53127 Bonn, Germany
- German Center for Neurodegenerative Diseases (DZNE), 53127 Bonn, Germany
- Correspondence:
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Mermer F, Poliquin S, Zhou S, Wang X, Ding Y, Yin F, Shen W, Wang J, Rigsby K, Xu D, Mack T, Nwosu G, Flamm C, Stein M, Kang JQ. Astrocytic GABA transporter 1 deficit in novel SLC6A1 variants mediated epilepsy: Connected from protein destabilization to seizures in mice and humans. Neurobiol Dis 2022; 172:105810. [PMID: 35840120 PMCID: PMC9472560 DOI: 10.1016/j.nbd.2022.105810] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Revised: 06/16/2022] [Accepted: 06/30/2022] [Indexed: 11/23/2022] Open
Abstract
OBJECTIVE Mutations in γ-aminobutyric acid (GABA) transporter 1 (GAT-1)-encoding SLC6A1 have been associated with myoclonic atonic epilepsy and other phenotypes. We determined the patho-mechanisms of the mutant GAT-1, in order to identify treatment targets. METHODS We conducted whole-exome sequencing of patients with myoclonic atonic epilepsy (MAE) and characterized the seizure phenotypes and EEG patterns. We studied the protein stability and structural changes with homology modeling and machine learning tools. We characterized the function and trafficking of the mutant GAT-1 with 3H radioactive GABA uptake assay and confocal microscopy. We utilized different models including a knockin mouse and human astrocytes derived from induced pluripotent stem cells (iPSCs). We focused on astrocytes because of their direct impact of astrocytic GAT-1 in seizures. RESULTS We identified four novel SLC6A1 variants associated with MAE and 2 to 4 Hz spike-wave discharges as a common EEG feature. Machine learning tools predicted that the variant proteins are destabilized. The variant protein had reduced expression and reduced GABA uptake due to endoplasmic reticular retention. The consistent observation was made in cortical and thalamic astrocytes from variant-knockin mice and human iPSC-derived astrocytes. The Slc6a+/A288V mouse, representative of MAE, had increased 5-7 Hz spike-wave discharges and absence seizures. INTERPRETATION SLC6A1 variants in various locations of the protein peptides can cause MAE with similar seizure phenotypes and EEG features. Reduced GABA uptake is due to decreased functional GAT-1, which, in thalamic astrocytes, could result in increased extracellular GABA accumulation and enhanced tonic inhibition, leading to seizures and abnormal EEGs.
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Affiliation(s)
- Felicia Mermer
- Department of Neurology, Vanderbilt University Medical Center, USA
| | - Sarah Poliquin
- The Neuroscience Program, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Shuizhen Zhou
- Department of Neurology, Children's Hospital, Fudan University, Shanghai, China
| | | | - Yifeng Ding
- Department of Neurology, Children's Hospital, Fudan University, Shanghai, China
| | - Fei Yin
- Department of Neurology, Xiangya Hospital of The Central-Southern University in Changsha, China
| | - Wangzhen Shen
- Department of Neurology, Vanderbilt University Medical Center, USA
| | - Juexin Wang
- Department of Electrical Engineering & Computer Science and Christopher S. Bond Life Sciences Center, University of Missouri, Columbia, MO 65211, USA
| | - Kathryn Rigsby
- The Neuroscience Program, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Dong Xu
- Department of Electrical Engineering & Computer Science and Christopher S. Bond Life Sciences Center, University of Missouri, Columbia, MO 65211, USA
| | - Taralynn Mack
- The Neuroscience Program, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Gerald Nwosu
- The Neuroscience Program, Vanderbilt University Medical Center, Nashville, TN 37232, USA; Vanderbilt University-Meharry Medical College Alliance, Nashville, TN, 37232, USA
| | - Carson Flamm
- The Neuroscience Program, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Matthew Stein
- The Neuroscience Program, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Jing-Qiong Kang
- Department of Neurology, Vanderbilt University Medical Center, USA; Department of Pharmacology, Vanderbilt University, USA; Vanderbilt Kennedy Center of Human Development, University Medical Center, Nashville, TN, 37232, USA.
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Jomura R, Akanuma SI, Tachikawa M, Hosoya KI. SLC6A and SLC16A family of transporters: Contribution to transport of creatine and creatine precursors in creatine biosynthesis and distribution. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2022; 1864:183840. [PMID: 34921896 DOI: 10.1016/j.bbamem.2021.183840] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Revised: 12/06/2021] [Accepted: 12/09/2021] [Indexed: 11/16/2022]
Abstract
Creatine (Cr) is needed to maintain high energy levels in cells. Since Cr plays reportedly a critical role in neurodevelopment and the immune system, Cr dynamics should be strictly regulated to control these physiological events. This review focuses on the role of transporters that recognize Cr and/or Cr precursors. Our previous studies revealed physiological roles of SLC6A and SLC16A family transporters in Cr dynamics. Creatine transporter (CRT/SLC6A8) contributes to the influx transport of Cr in Cr distribution. γ-Aminobutyric acid transporter 2 (GAT2/SLC6A13) mediates incorporation of guanidinoacetate (GAA), a Cr precursor, in the process of Cr biosynthesis. Monocarboxylate transporter 12 (MCT12/SLC16A12) functions as an efflux transporter for Cr and GAA, and contributes to the process of Cr biosynthesis. Accordingly, the SLC6A and SLC16A family of transporters play important roles in the process of Cr biosynthesis and distribution via permeation of Cr and Cr precursors across the plasma membrane.
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Affiliation(s)
- Ryuta Jomura
- Department of Pharmaceutics, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, 2630 Sugitani, Toyama 930-0194, Japan.
| | - Shin-Ichi Akanuma
- Department of Pharmaceutics, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, 2630 Sugitani, Toyama 930-0194, Japan.
| | - Masanori Tachikawa
- Graduate School of Biomedical Sciences, Tokushima University, 1-78-1 Shomachi, Tokushima 770-8505, Japan.
| | - Ken-Ichi Hosoya
- Department of Pharmaceutics, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, 2630 Sugitani, Toyama 930-0194, Japan.
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6
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Abstract
Drug addiction remains a key biomedical challenge facing current neuroscience research. In addition to neural mechanisms, the focus of the vast majority of studies to date, astrocytes have been increasingly recognized as an "accomplice." According to the tripartite synapse model, astrocytes critically regulate nearby pre- and postsynaptic neuronal substrates to craft experience-dependent synaptic plasticity, including synapse formation and elimination. Astrocytes within brain regions that are implicated in drug addiction exhibit dynamic changes in activity upon exposure to cocaine and subsequently undergo adaptive changes themselves during chronic drug exposure. Recent results have identified several key astrocytic signaling pathways that are involved in cocaine-induced synaptic and circuit adaptations. In this review, we provide a brief overview of the role of astrocytes in regulating synaptic transmission and neuronal function, and discuss how cocaine influences these astrocyte-mediated mechanisms to induce persistent synaptic and circuit alterations that promote cocaine seeking and relapse. We also consider the therapeutic potential of targeting astrocytic substrates to ameliorate drug-induced neuroplasticity for behavioral benefits. While primarily focusing on cocaine-induced astrocytic responses, we also include brief discussion of other drugs of abuse where data are available.
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Zhang X, Liu Y, Hong X, Li X, Meshul CK, Moore C, Yang Y, Han Y, Li WG, Qi X, Lou H, Duan S, Xu TL, Tong X. NG2 glia-derived GABA release tunes inhibitory synapses and contributes to stress-induced anxiety. Nat Commun 2021; 12:5740. [PMID: 34593806 PMCID: PMC8484468 DOI: 10.1038/s41467-021-25956-y] [Citation(s) in RCA: 38] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Accepted: 09/09/2021] [Indexed: 11/08/2022] Open
Abstract
NG2 glia, also known as oligodendrocyte precursor cells (OPCs), play an important role in proliferation and give rise to myelinating oligodendrocytes during early brain development. In contrast to other glial cell types, the most intriguing aspect of NG2 glia is their ability to directly sense synaptic inputs from neurons. However, whether this synaptic interaction is bidirectional or unidirectional, or its physiological relevance has not yet been clarified. Here, we report that NG2 glia form synaptic complexes with hippocampal interneurons and that selective photostimulation of NG2 glia (expressing channelrhodopsin-2) functionally drives GABA release and enhances inhibitory synaptic transmission onto proximal interneurons in a microcircuit. The mechanism involves GAD67 biosynthesis and VAMP-2 containing vesicular exocytosis. Further, behavioral assays demonstrate that NG2 glia photoactivation triggers anxiety-like behavior in vivo and contributes to chronic social defeat stress.
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Affiliation(s)
- Xiao Zhang
- Center for Brain Science, Shanghai Children's Medical Center, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
- Department of Anatomy and Physiology, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Yao Liu
- Center for Brain Science, Shanghai Children's Medical Center, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
- Department of Anatomy and Physiology, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Xiaoqi Hong
- Center for Brain Science, Shanghai Children's Medical Center, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
- Department of Anatomy and Physiology, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Xia Li
- Institute of Special Environmental Medicine, Co-innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu, China
| | - Charles K Meshul
- Research Services, VA Medical Center, Portland, OR, USA
- Department of Behavioral Neuroscience and Pathology, Oregon Health & Science University, Portland, OR, USA
| | - Cynthia Moore
- Research Services, VA Medical Center, Portland, OR, USA
| | - Yabing Yang
- Center for Brain Science, Shanghai Children's Medical Center, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
- Department of Anatomy and Physiology, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Yanfei Han
- Department of Anatomy and Physiology, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Wei-Guang Li
- Center for Brain Science, Shanghai Children's Medical Center, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
- Department of Anatomy and Physiology, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Xin Qi
- Center for Brain Science, Shanghai Children's Medical Center, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
- Department of Anatomy and Physiology, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Huifang Lou
- Department of Neurobiology, Key Laboratory of Medical Neurobiology of Ministry of Health of China, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
| | - Shumin Duan
- Department of Neurobiology, Key Laboratory of Medical Neurobiology of Ministry of Health of China, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
| | - Tian-Le Xu
- Center for Brain Science, Shanghai Children's Medical Center, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
- Department of Anatomy and Physiology, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Xiaoping Tong
- Center for Brain Science, Shanghai Children's Medical Center, School of Medicine, Shanghai Jiao Tong University, Shanghai, China.
- Department of Anatomy and Physiology, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
- Shanghai Research Center for Brain Science and Brain-Inspired Intelligence, Shanghai, China.
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8
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Wilson CS, Dohare P, Orbeta S, Nalwalk JW, Huang Y, Ferland RJ, Sah R, Scimemi A, Mongin AA. Late adolescence mortality in mice with brain-specific deletion of the volume-regulated anion channel subunit LRRC8A. FASEB J 2021; 35:e21869. [PMID: 34469026 PMCID: PMC8639177 DOI: 10.1096/fj.202002745r] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Revised: 07/27/2021] [Accepted: 08/09/2021] [Indexed: 11/11/2022]
Abstract
The leucine-rich repeat-containing family 8 member A (LRRC8A) is an essential subunit of the volume-regulated anion channel (VRAC). VRAC is critical for cell volume control, but its broader physiological functions remain under investigation. Recent studies in the field indicate that Lrrc8a disruption in the brain astrocytes reduces neuronal excitability, impairs synaptic plasticity and memory, and protects against cerebral ischemia. In the present work, we generated brain-wide conditional LRRC8A knockout mice (LRRC8A bKO) using NestinCre -driven Lrrc8aflox/flox excision in neurons, astrocytes, and oligodendroglia. LRRC8A bKO animals were born close to the expected Mendelian ratio and developed without overt histological abnormalities, but, surprisingly, all died between 5 and 9 weeks of age with a seizure phenotype, which was confirmed by video and EEG recordings. Brain slice electrophysiology detected changes in the excitability of pyramidal cells and modified GABAergic inputs in the hippocampal CA1 region of LRRC8A bKO. LRRC8A-null hippocampi showed increased immunoreactivity of the astrocytic marker GFAP, indicating reactive astrogliosis. We also found decreased whole-brain protein levels of the GABA transporter GAT-1, the glutamate transporter GLT-1, and the astrocytic enzyme glutamine synthetase. Complementary HPLC assays identified reduction in the tissue levels of the glutamate and GABA precursor glutamine. Together, these findings suggest that VRAC provides vital control of brain excitability in mouse adolescence. VRAC deletion leads to a lethal phenotype involving progressive astrogliosis and dysregulation of astrocytic uptake and supply of amino acid neurotransmitters and their precursors.
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Affiliation(s)
- Corinne S Wilson
- Department of Neuroscience and Experimental Therapeutics, Albany Medical College, Albany, New York, USA
| | - Preeti Dohare
- Department of Neuroscience and Experimental Therapeutics, Albany Medical College, Albany, New York, USA
| | - Shaina Orbeta
- Department of Neuroscience and Experimental Therapeutics, Albany Medical College, Albany, New York, USA
| | - Julia W Nalwalk
- Department of Neuroscience and Experimental Therapeutics, Albany Medical College, Albany, New York, USA
| | - Yunfei Huang
- Department of Neuroscience and Experimental Therapeutics, Albany Medical College, Albany, New York, USA
| | - Russell J Ferland
- Department of Biomedical Sciences, University of New England College of Osteopathic Medicine, Biddeford, Maine, USA
| | - Rajan Sah
- Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Annalisa Scimemi
- Department of Biology, University at Albany, State University of New York, Albany, New York, USA
| | - Alexander A Mongin
- Department of Neuroscience and Experimental Therapeutics, Albany Medical College, Albany, New York, USA
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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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Kantzer CG, Parmigiani E, Cerrato V, Tomiuk S, Knauel M, Jungblut M, Buffo A, Bosio A. ACSA-2 and GLAST classify subpopulations of multipotent and glial-restricted cerebellar precursors. J Neurosci Res 2021; 99:2228-2249. [PMID: 34060113 PMCID: PMC8453861 DOI: 10.1002/jnr.24842] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Revised: 03/12/2021] [Accepted: 03/17/2021] [Indexed: 12/13/2022]
Abstract
The formation of the cerebellum is highly coordinated to obtain its characteristic morphology and all cerebellar cell types. During mouse postnatal development, cerebellar progenitors with astroglial‐like characteristics generate mainly astrocytes and oligodendrocytes. However, a subset of astroglial‐like progenitors found in the prospective white matter (PWM) produces astroglia and interneurons. Characterizing these cerebellar astroglia‐like progenitors and distinguishing their developmental fates is still elusive. Here, we reveal that astrocyte cell surface antigen‐2 (ACSA‐2), lately identified as ATPase, Na+/K+ transporting, beta 2 polypeptide, is expressed by glial precursors throughout postnatal cerebellar development. In contrast to common astrocyte markers, ACSA‐2 appears on PWM cells but is absent on Bergmann glia (BG) precursors. In the adult cerebellum, ACSA‐2 is broadly expressed extending to velate astrocytes in the granular layer, white matter astrocytes, and to a lesser extent to BG. Cell transplantation and transcriptomic analysis revealed that marker staining discriminates two postnatal progenitor pools. One subset is defined by the co‐expression of ACSA‐2 and GLAST and the expression of markers typical of parenchymal astrocytes. These are PWM precursors that are exclusively gliogenic. They produce predominantly white matter and granular layer astrocytes. Another subset is constituted by GLAST positive/ACSA‐2 negative precursors that express neurogenic and BG‐like progenitor genes. This population displays multipotency and gives rise to interneurons besides all glial types, including BG. In conclusion, this work reports about ACSA‐2, a marker that in combination with GLAST enables for the discrimination and isolation of multipotent and glia‐committed progenitors, which generate different types of cerebellar astrocytes.
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Affiliation(s)
- Christina Geraldine Kantzer
- Miltenyi Biotec B.V. & Co. KG, Bergisch Gladbach, Germany.,Department of Cell and Molecular Biology, Karolinska Institute, Solna, Sweden
| | - Elena Parmigiani
- Department of Neuroscience Rita Levi-Montalcini, University of Turin, Turin, Italy.,Neuroscience Institute Cavalieri Ottolenghi, Orbassano, Italy.,Department of Biomedicine, University of Basel, Basel, Switzerland
| | - Valentina Cerrato
- Department of Neuroscience Rita Levi-Montalcini, University of Turin, Turin, Italy.,Neuroscience Institute Cavalieri Ottolenghi, Orbassano, Italy.,Department of Fundamental Neurosciences, University of Lausanne, Lausanne, Switzerland
| | - Stefan Tomiuk
- Miltenyi Biotec B.V. & Co. KG, Bergisch Gladbach, Germany
| | - Michail Knauel
- Miltenyi Biotec B.V. & Co. KG, Bergisch Gladbach, Germany
| | | | - Annalisa Buffo
- Department of Neuroscience Rita Levi-Montalcini, University of Turin, Turin, Italy.,Neuroscience Institute Cavalieri Ottolenghi, Orbassano, Italy
| | - Andreas Bosio
- Miltenyi Biotec B.V. & Co. KG, Bergisch Gladbach, Germany
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11
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Sears SM, Hewett SJ. Influence of glutamate and GABA transport on brain excitatory/inhibitory balance. Exp Biol Med (Maywood) 2021; 246:1069-1083. [PMID: 33554649 DOI: 10.1177/1535370221989263] [Citation(s) in RCA: 76] [Impact Index Per Article: 25.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
An optimally functional brain requires both excitatory and inhibitory inputs that are regulated and balanced. A perturbation in the excitatory/inhibitory balance-as is the case in some neurological disorders/diseases (e.g. traumatic brain injury Alzheimer's disease, stroke, epilepsy and substance abuse) and disorders of development (e.g. schizophrenia, Rhett syndrome and autism spectrum disorder)-leads to dysfunctional signaling, which can result in impaired cognitive and motor function, if not frank neuronal injury. At the cellular level, transmission of glutamate and GABA, the principle excitatory and inhibitory neurotransmitters in the central nervous system control excitatory/inhibitory balance. Herein, we review the synthesis, release, and signaling of GABA and glutamate followed by a focused discussion on the importance of their transport systems to the maintenance of excitatory/inhibitory balance.
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Affiliation(s)
- Sheila Ms Sears
- Department of Biology, Program in Neuroscience, 2029Syracuse University, Syracuse, NY 13244, USA
| | - Sandra J Hewett
- Department of Biology, Program in Neuroscience, 2029Syracuse University, Syracuse, NY 13244, USA
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12
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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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13
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Lago-Baldaia I, Fernandes VM, Ackerman SD. More Than Mortar: Glia as Architects of Nervous System Development and Disease. Front Cell Dev Biol 2020; 8:611269. [PMID: 33381506 PMCID: PMC7767919 DOI: 10.3389/fcell.2020.611269] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Accepted: 11/17/2020] [Indexed: 12/12/2022] Open
Abstract
Glial cells are an essential component of the nervous system of vertebrates and invertebrates. In the human brain, glia are as numerous as neurons, yet the importance of glia to nearly every aspect of nervous system development has only been expounded over the last several decades. Glia are now known to regulate neural specification, synaptogenesis, synapse function, and even broad circuit function. Given their ubiquity, it is not surprising that the contribution of glia to neuronal disease pathogenesis is a growing area of research. In this review, we will summarize the accumulated evidence of glial participation in several distinct phases of nervous system development and organization-neural specification, circuit wiring, and circuit function. Finally, we will highlight how these early developmental roles of glia contribute to nervous system dysfunction in neurodevelopmental and neurodegenerative disorders.
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Affiliation(s)
- Inês Lago-Baldaia
- Department of Cell and Developmental Biology, University College London, London, United Kingdom
| | - Vilaiwan M. Fernandes
- Department of Cell and Developmental Biology, University College London, London, United Kingdom
| | - Sarah D. Ackerman
- Institute of Neuroscience, Howard Hughes Medical Institute, University of Oregon, Eugene, OR, United States
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14
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Lyu S, Guo Y, Zhang L, Wang Y, Tang G, Li R, Yang J, Gao S, Ma B, Liu J. Blockade of GABA transporter-1 and GABA transporter-3 in the lateral habenula improves depressive-like behaviors in a rat model of Parkinson's disease. Neuropharmacology 2020; 181:108369. [DOI: 10.1016/j.neuropharm.2020.108369] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Revised: 10/15/2020] [Accepted: 10/19/2020] [Indexed: 12/23/2022]
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15
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Mishima T, Fujiwara T, Kofuji T, Saito A, Terao Y, Akagawa K. Syntaxin 1B regulates synaptic GABA release and extracellular GABA concentration, and is associated with temperature-dependent seizures. J Neurochem 2020; 156:604-613. [PMID: 32858780 DOI: 10.1111/jnc.15159] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Revised: 07/13/2020] [Accepted: 08/11/2020] [Indexed: 11/29/2022]
Abstract
De novo heterozygous mutations in the STX1B gene, encoding syntaxin 1B, cause a familial, fever-associated epilepsy syndrome. Syntaxin 1B is an essential component of the pre-synaptic neurotransmitter release machinery as a soluble N-ethylmaleimide-sensitive factor attachment protein receptor protein that regulates the exocytosis of synaptic vesicles. It is also involved in regulating the functions of the SLC6 family of neurotransmitter transporters that reuptake neurotransmitters, including inhibitory neurotransmitters, such as γ-aminobutyric acid (GABA) and glycine. The purpose of the present study was to elucidate the molecular mechanisms underlying the development of febrile seizures by examining the effects of syntaxin 1B haploinsufficiency on inhibitory synaptic transmission during hyperthermia in a mouse model. Stx1b gene heterozygous knockout (Stx1b+/- ) mice showed increased susceptibility to febrile seizures and drug-induced seizures. In cultured hippocampal neurons, we examined the temperature-dependent properties of neurotransmitter release and reuptake by GABA transporter-1 (GAT-1) at GABAergic neurons using whole-cell patch-clamp recordings. The rate of spontaneous quantal GABA release was reduced in Stx1b+/- mice. The hyperthermic temperature increased the tonic GABAA current in wild-type (WT) synapses, but not in Stx1b+/- synapses. In WT neurons, recurrent bursting activities were reduced in a GABA-dependent manner at hyperthermic temperature; however, this was abolished in Stx1b+/- neurons. The blockade of GAT-1 increased the tonic GABAA current and suppressed recurrent bursting activities in Stx1b+/- neurons at the hyperthermic temperature. These data suggest that functional abnormalities associated with GABA release and reuptake in the pre-synaptic terminals of GABAergic neurons may increase the excitability of the neural circuit with hyperthermia.
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Affiliation(s)
- Tatsuya Mishima
- Department of Medical Physiology, Kyorin University School of Medicine, Mitaka, Tokyo, Japan
| | - Tomonori Fujiwara
- Department of Medical Physiology, Kyorin University School of Medicine, Mitaka, Tokyo, Japan.,Faculty of Health and Medical Care, Saitama Medical University, Hidaka, Saitama, Japan
| | - Takefumi Kofuji
- Department of Medical Physiology, Kyorin University School of Medicine, Mitaka, Tokyo, Japan.,Radioisotope Laboratory, Kyorin University School of Medicine, Mitaka, Tokyo, Japan
| | - Ayako Saito
- Department of Medical Physiology, Kyorin University School of Medicine, Mitaka, Tokyo, Japan
| | - Yasuo Terao
- Department of Medical Physiology, Kyorin University School of Medicine, Mitaka, Tokyo, Japan
| | - Kimio Akagawa
- Department of Medical Physiology, Kyorin University School of Medicine, Mitaka, Tokyo, Japan
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16
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Kim YS, Choi J, Yoon BE. Neuron-Glia Interactions in Neurodevelopmental Disorders. Cells 2020; 9:cells9102176. [PMID: 32992620 PMCID: PMC7601502 DOI: 10.3390/cells9102176] [Citation(s) in RCA: 68] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2020] [Revised: 09/24/2020] [Accepted: 09/24/2020] [Indexed: 12/12/2022] Open
Abstract
Recent studies have revealed synaptic dysfunction to be a hallmark of various psychiatric diseases, and that glial cells participate in synapse formation, development, and plasticity. Glial cells contribute to neuroinflammation and synaptic homeostasis, the latter being essential for maintaining the physiological function of the central nervous system (CNS). In particular, glial cells undergo gliotransmission and regulate neuronal activity in tripartite synapses via ion channels (gap junction hemichannel, volume regulated anion channel, and bestrophin-1), receptors (for neurotransmitters and cytokines), or transporters (GLT-1, GLAST, and GATs) that are expressed on glial cell membranes. In this review, we propose that dysfunction in neuron-glia interactions may contribute to the pathogenesis of neurodevelopmental disorders. Understanding the mechanisms of neuron-glia interaction for synapse formation and maturation will contribute to the development of novel therapeutic targets of neurodevelopmental disorders.
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Affiliation(s)
- Yoo Sung Kim
- Department of Molecular Biology, Dankook University, Cheonan 31116, Korea; (Y.S.K.); (J.C.)
| | - Juwon Choi
- Department of Molecular Biology, Dankook University, Cheonan 31116, Korea; (Y.S.K.); (J.C.)
| | - Bo-Eun Yoon
- Department of Molecular Biology, Dankook University, Cheonan 31116, Korea; (Y.S.K.); (J.C.)
- Department of Nanobiomedical science, Dankook University, Cheonan 31116, Korea
- Correspondence: ; Tel.: +82-41-529-6085
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17
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An Astrocytic Influence on Impaired Tonic Inhibition in Hippocampal CA1 Pyramidal Neurons in a Mouse Model of Rett Syndrome. J Neurosci 2020; 40:6250-6261. [PMID: 32616668 DOI: 10.1523/jneurosci.3042-19.2020] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2019] [Revised: 05/13/2020] [Accepted: 06/10/2020] [Indexed: 01/28/2023] Open
Abstract
Rett syndrome (RTT) is a severe neurodevelopmental disease caused by mutations in the methyl-CpG binding protein 2 (MECP2) gene. Although altered interneuron development and function are clearly demonstrated in RTT mice, a particular mode of inhibition, tonic inhibition, has not been carefully examined. We report here that tonic inhibition is significantly reduced in pyramidal neurons in the CA1 region of the hippocampus in mice where Mecp2 is deleted either in all cells or specifically in astrocytes. Since no change is detected in the level of GABA receptors, such a reduction in tonic inhibition is likely a result of decreased ambient GABA level in the extracellular space. Consistent with this explanation, we observed increased expression of a GABA transporter, GABA transporter 3 (GAT3), in the hippocampus of the Mecp2 KO mice, as well as a corresponding increase of GAT3 current in hippocampal astrocytes. These phenotypes are relevant to RTT because pharmacological blockage of GAT3 can normalize tonic inhibition and intrinsic excitability in CA1 pyramidal neurons, and rescue the phenotype of increased network excitability in acute hippocampal slices from the Mecp2 KO mice. Finally, chronic administration of a GAT3 antagonist improved a composite symptom score and extended lifespan in the Mecp2 KO mice. Only male mice were used in this study. These results not only advance our understanding of RTT etiology by defining a new neuronal phenotype and revealing how it can be influenced by astrocytic alterations, but also reveal potential targets for intervention.SIGNIFICANCE STATEMENT Our study reports a novel phenotype of reduced tonic inhibition in hippocampal CA1 pyramidal neurons in the Rett syndrome mice, reveal a potential mechanism of increased GABA transporter expression/activity in the neighboring astrocytes, describe a disease-relevant consequence in hyperexcitability, and provide preliminary evidence that targeting this phenotype may slow down disease progression in Rett syndrome mice. These results help our understanding of the disease etiology and identify a new therapeutic target for treating Rett syndrome.
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18
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Varga AG, Maletz SN, Bateman JT, Reid BT, Levitt ES. Neurochemistry of the Kölliker-Fuse nucleus from a respiratory perspective. J Neurochem 2020; 156:16-37. [PMID: 32396650 DOI: 10.1111/jnc.15041] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Revised: 04/27/2020] [Accepted: 05/04/2020] [Indexed: 12/11/2022]
Abstract
The Kölliker-Fuse nucleus (KF) is a functionally distinct component of the parabrachial complex, located in the dorsolateral pons of mammals. The KF has a major role in respiration and upper airway control. A comprehensive understanding of the KF and its contributions to respiratory function and dysfunction requires an appreciation for its neurochemical characteristics. The goal of this review is to summarize the diverse neurochemical composition of the KF, focusing on the neurotransmitters, neuromodulators, and neuropeptides present. We also include a description of the receptors expressed on KF neurons and transporters involved in each system, as well as their putative roles in respiratory physiology. Finally, we provide a short section reviewing the literature regarding neurochemical changes in the KF in the context of respiratory dysfunction observed in SIDS and Rett syndrome. By over-viewing the current literature on the neurochemical composition of the KF, this review will serve to aid a wide range of topics in the future research into the neural control of respiration in health and disease.
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Affiliation(s)
- Adrienn G Varga
- Department of Pharmacology and Therapeutics, University of Florida, Gainesville, FL, USA.,Department of Physical Therapy, Center for Respiratory Research and Rehabilitation, University of Florida, Gainesville, FL, USA
| | - Sebastian N Maletz
- Department of Pharmacology and Therapeutics, University of Florida, Gainesville, FL, USA
| | - Jordan T Bateman
- Department of Pharmacology and Therapeutics, University of Florida, Gainesville, FL, USA.,Department of Physical Therapy, Center for Respiratory Research and Rehabilitation, University of Florida, Gainesville, FL, USA
| | - Brandon T Reid
- Department of Pharmacology and Therapeutics, University of Florida, Gainesville, FL, USA
| | - Erica S Levitt
- Department of Pharmacology and Therapeutics, University of Florida, Gainesville, FL, USA.,Department of Physical Therapy, Center for Respiratory Research and Rehabilitation, University of Florida, Gainesville, FL, USA
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19
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Łątka K, Jończyk J, Bajda M. γ-Aminobutyric acid transporters as relevant biological target: Their function, structure, inhibitors and role in the therapy of different diseases. Int J Biol Macromol 2020; 158:S0141-8130(20)32987-1. [PMID: 32360967 DOI: 10.1016/j.ijbiomac.2020.04.126] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2020] [Revised: 04/17/2020] [Accepted: 04/18/2020] [Indexed: 12/13/2022]
Abstract
γ-Aminobutyric acid (GABA) is a major inhibitory neurotransmitter in the nervous system. It plays a crucial role in many physiological processes. Upon release from the presynaptic element, it is removed from the synaptic cleft by reuptake due to the action of GABA transporters (GATs). GATs belong to a large SLC6 protein family whose characteristic feature is sodium-dependent relocation of neurotransmitters through the cell membrane. GABA transporters are characterized in many contexts, but their spatial structure is not fully known. They are divided into four types, which differ in occurrence and role. Herein, the special attention was paid to these transporting proteins. This comprehensive review presents the current knowledge about GABA transporters. Their distribution in the body, physiological functions and possible utilization in the therapy of different diseases were fully discussed. The important structural features were described based on published data, including sequence analysis, mutagenesis studies, and comparison with known SLC6 transporters for leucine (LeuT), dopamine (DAT) and serotonin (SERT). Moreover, the most important inhibitors of GABA transporters of various basic scaffolds, diverse selectivity and potency were presented.
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Affiliation(s)
- Kamil Łątka
- Jagiellonian University Medical College, Faculty of Pharmacy, Department of Physicochemical Drug Analysis, 30-688 Cracow, Medyczna 9, Poland
| | - Jakub Jończyk
- Jagiellonian University Medical College, Faculty of Pharmacy, Department of Physicochemical Drug Analysis, 30-688 Cracow, Medyczna 9, Poland
| | - Marek Bajda
- Jagiellonian University Medical College, Faculty of Pharmacy, Department of Physicochemical Drug Analysis, 30-688 Cracow, Medyczna 9, Poland.
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20
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Sills GJ, Rogawski MA. Mechanisms of action of currently used antiseizure drugs. Neuropharmacology 2020; 168:107966. [PMID: 32120063 DOI: 10.1016/j.neuropharm.2020.107966] [Citation(s) in RCA: 241] [Impact Index Per Article: 60.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Revised: 01/09/2020] [Accepted: 01/12/2020] [Indexed: 02/08/2023]
Abstract
Antiseizure drugs (ASDs) prevent the occurrence of seizures; there is no evidence that they have disease-modifying properties. In the more than 160 years that orally administered ASDs have been available for epilepsy therapy, most agents entering clinical practice were either discovered serendipitously or with the use of animal seizure models. The ASDs originating from these approaches act on brain excitability mechanisms to interfere with the generation and spread of epileptic hyperexcitability, but they do not address the specific defects that are pathogenic in the epilepsies for which they are prescribed, which in most cases are not well understood. There are four broad classes of such ASD mechanisms: (1) modulation of voltage-gated sodium channels (e.g. phenytoin, carbamazepine, lamotrigine), voltage-gated calcium channels (e.g. ethosuximide), and voltage-gated potassium channels [e.g. retigabine (ezogabine)]; (2) enhancement of GABA-mediated inhibitory neurotransmission (e.g. benzodiazepines, tiagabine, vigabatrin); (3) attenuation of glutamate-mediated excitatory neurotransmission (e.g. perampanel); and (4) modulation of neurotransmitter release via a presynaptic action (e.g. levetiracetam, brivaracetam, gabapentin, pregabalin). In the past two decades there has been great progress in identifying the pathophysiological mechanisms of many genetic epilepsies. Given this new understanding, attempts are being made to engineer specific small molecule, antisense and gene therapies that functionally reverse or structurally correct pathogenic defects in epilepsy syndromes. In the near future, these new therapies will begin a paradigm shift in the treatment of some rare genetic epilepsy syndromes, but targeted therapies will remain elusive for the vast majority of epilepsies until their causes are identified. This article is part of the special issue entitled 'New Epilepsy Therapies for the 21st Century - From Antiseizure Drugs to Prevention, Modification and Cure of Epilepsy'.
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Affiliation(s)
- Graeme J Sills
- School of Life Sciences, University of Glasgow, Glasgow, UK.
| | - Michael A Rogawski
- Department of Neurology, School of Medicine, University of California, Davis, Sacramento, CA, USA; Department of Pharmacology, School of Medicine, University of California, Davis, Sacramento, CA, USA
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21
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Verkhratsky A, Rose CR. Na +-dependent transporters: The backbone of astroglial homeostatic function. Cell Calcium 2019; 85:102136. [PMID: 31835178 DOI: 10.1016/j.ceca.2019.102136] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2019] [Revised: 11/30/2019] [Accepted: 11/30/2019] [Indexed: 01/30/2023]
Abstract
Astrocytes are the principal homeostatic cells of the central nerves system (CNS) that support the CNS function at all levels of organisation, from molecular to organ. Several fundamental homeostatic functions of astrocytes are mediated through plasmalemmal pumps and transporters; most of which are also regulated by the transplasmalemmal gradient of Na+ ions. Neuronal activity as well as mechanical or chemical stimulation of astrocytes trigger plasmalemmal Na+ fluxes, which in turn generate spatio-temporally organised transient changes in the cytosolic Na+ concentration, which represent the substrate of astroglial Na+ signalling. Astroglial Na+ signals link and coordinate neuronal activity and CNS homeostatic demands with the astroglial homeostatic response.
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Affiliation(s)
- Alexei Verkhratsky
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, M13 9PT, UK; Achucarro Centre for Neuroscience, IKERBASQUE, Basque Foundation for Science, 48011, Bilbao, Spain.
| | - Christine R Rose
- Institute of Neurobiology, Faculty of Mathematics and Natural Sciences, Heinrich Heine University Düsseldorf, Universitätsstrasse 1, D-40225, Düsseldorf, Germany
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22
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Fattorini G, Catalano M, Melone M, Serpe C, Bassi S, Limatola C, Conti F. Microglial expression of GAT-1 in the cerebral cortex. Glia 2019; 68:646-655. [PMID: 31692106 DOI: 10.1002/glia.23745] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2019] [Revised: 10/12/2019] [Accepted: 10/18/2019] [Indexed: 01/08/2023]
Abstract
Microglial cells are the immune cells of the brain that, by sensing the microenvironment, permit a correct brain development and function. They communicate with other glial cells and with neurons, releasing and responding to a number of molecules that exert effects on surrounding cells. Among these, neurotransmitters and, in particular, gamma-aminobutyric acid (GABA) has recently gained interest in this context. We demonstrated the expression of GABA transporter 1 (GAT-1) in microglial cells both in soma and cell processes. We show that microglial cell treatment with 1,2,5,6-tetrahydro-1-[2-[[(diphenylmethylene)amino]oxy]ethyl]-3-pyridinecarboxylic acid hydrochloride (NNC-711), a potent and selective GAT-1 inhibitor, significantly reduced Na+ -dependent GABA uptake. On the other hand, GABA uptake was significantly increased by cell treatment with (S)-1-[2-[tris(4-methoxyphenyl)methoxy]ethyl]-3-piperidinecarboxylic acid (SNAP-5114), a GAT-2/3 inhibitor, and this effect was completely blocked by the botulinum toxin BoNT/C1, that specifically cleaves and inactives syntaxin 1A (STX1A). Overall, these findings show that microglial cells express GAT-1 and indicate that STX1A plays an important role in the regulation of GAT-1-dependent GABA uptake in microglia.
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Affiliation(s)
- Giorgia Fattorini
- Department of Experimental and Clinical Medicine, Section of Neuroscience and Cell Biology, Università Politecnica delle Marche, Ancona, Italy.,Center for Neurobiology of Aging, IRCCS INRCA, Ancona, Italy
| | - Myriam Catalano
- Department of Physiology and Pharmacology, Sapienza University of Rome, Laboratory Affiliated to Istituto Pasteur Italia, Rome, Italy
| | - Marcello Melone
- Department of Experimental and Clinical Medicine, Section of Neuroscience and Cell Biology, Università Politecnica delle Marche, Ancona, Italy.,Center for Neurobiology of Aging, IRCCS INRCA, Ancona, Italy
| | - Carmela Serpe
- Department of Physiology and Pharmacology, Sapienza University of Rome, Laboratory Affiliated to Istituto Pasteur Italia, Rome, Italy
| | - Silvia Bassi
- Department of Experimental and Clinical Medicine, Section of Neuroscience and Cell Biology, Università Politecnica delle Marche, Ancona, Italy
| | - Cristina Limatola
- Department of Physiology and Pharmacology, Sapienza University of Rome, Laboratory Affiliated to Istituto Pasteur Italia, Rome, Italy.,IRCCS Neuromed, Via Atinense, Pozzilli, Italy
| | - Fiorenzo Conti
- Department of Experimental and Clinical Medicine, Section of Neuroscience and Cell Biology, Università Politecnica delle Marche, Ancona, Italy.,Center for Neurobiology of Aging, IRCCS INRCA, Ancona, Italy
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23
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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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24
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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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25
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Hannou L, Roy P, Ballester Roig MN, Mongrain V. Transcriptional control of synaptic components by the clock machinery. Eur J Neurosci 2019; 51:241-267. [DOI: 10.1111/ejn.14294] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2018] [Revised: 11/01/2018] [Accepted: 11/27/2018] [Indexed: 12/21/2022]
Affiliation(s)
- Lydia Hannou
- Center for Advanced Research in Sleep Medicine and Research CenterHôpital du Sacré‐Cœur de Montréal (CIUSSS‐NIM) Montreal Quebec Canada
- Department of PsychiatryUniversité de Montréal Montreal Quebec Canada
| | - Pierre‐Gabriel Roy
- Center for Advanced Research in Sleep Medicine and Research CenterHôpital du Sacré‐Cœur de Montréal (CIUSSS‐NIM) Montreal Quebec Canada
- Department of NeuroscienceUniversité de Montréal Montreal Quebec Canada
| | - Maria Neus Ballester Roig
- Center for Advanced Research in Sleep Medicine and Research CenterHôpital du Sacré‐Cœur de Montréal (CIUSSS‐NIM) Montreal Quebec Canada
- Department of NeuroscienceUniversité de Montréal Montreal Quebec Canada
| | - Valérie Mongrain
- Center for Advanced Research in Sleep Medicine and Research CenterHôpital du Sacré‐Cœur de Montréal (CIUSSS‐NIM) Montreal Quebec Canada
- Department of NeuroscienceUniversité de Montréal Montreal Quebec Canada
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26
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Mederos S, González-Arias C, Perea G. Astrocyte-Neuron Networks: A Multilane Highway of Signaling for Homeostatic Brain Function. Front Synaptic Neurosci 2018; 10:45. [PMID: 30542276 PMCID: PMC6277918 DOI: 10.3389/fnsyn.2018.00045] [Citation(s) in RCA: 81] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2018] [Accepted: 11/12/2018] [Indexed: 12/22/2022] Open
Abstract
Research on glial cells over the past 30 years has confirmed the critical role of astrocytes in pathophysiological brain states. However, most of our knowledge about astrocyte physiology and of the interactions between astrocytes and neurons is based on the premises that astrocytes constitute a homogeneous cell type, without considering the particular properties of the circuits or brain nuclei in which the astrocytes are located. Therefore, we argue that more-sophisticated experiments are required to elucidate the specific features of astrocytes in different brain regions, and even within different layers of a particular circuit. Thus, in addition to considering the diverse mechanisms used by astrocytes to communicate with neurons and synaptic partners, it is necessary to take into account the cellular heterogeneity that likely contributes to the outcomes of astrocyte-neuron signaling. In this review article, we briefly summarize the current data regarding the anatomical, molecular and functional properties of astrocyte-neuron communication, as well as the heterogeneity within this communication.
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Affiliation(s)
- Sara Mederos
- Department of Functional and Systems Neurobiology, Instituto Cajal (IC), CSIC, Madrid, Spain
| | - Candela González-Arias
- Department of Functional and Systems Neurobiology, Instituto Cajal (IC), CSIC, Madrid, Spain
| | - Gertrudis Perea
- Department of Functional and Systems Neurobiology, Instituto Cajal (IC), CSIC, Madrid, Spain
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27
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Deemyad T, Lüthi J, Spruston N. Astrocytes integrate and drive action potential firing in inhibitory subnetworks. Nat Commun 2018; 9:4336. [PMID: 30337521 PMCID: PMC6194108 DOI: 10.1038/s41467-018-06338-3] [Citation(s) in RCA: 69] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2018] [Accepted: 08/27/2018] [Indexed: 12/29/2022] Open
Abstract
Many brain functions depend on the ability of neural networks to temporally integrate transient inputs to produce sustained discharges. This can occur through cell-autonomous mechanisms in individual neurons and through reverberating activity in recurrently connected neural networks. We report a third mechanism involving temporal integration of neural activity by a network of astrocytes. Previously, we showed that some types of interneurons can generate long-lasting trains of action potentials (barrage firing) following repeated depolarizing stimuli. Here we show that calcium signaling in an astrocytic network correlates with barrage firing; that active depolarization of astrocyte networks by chemical or optogenetic stimulation enhances; and that chelating internal calcium, inhibiting release from internal stores, or inhibiting GABA transporters or metabotropic glutamate receptors inhibits barrage firing. Thus, networks of astrocytes influence the spatiotemporal dynamics of neural networks by directly integrating neural activity and driving barrages of action potentials in some populations of inhibitory interneurons. Specific types of inhibitory neurons exhibit prolonged, high-frequency barrages of action potentials. Here, the authors show that astrocytes might mediate such barrage firing.
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Affiliation(s)
- Tara Deemyad
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, 20147, USA.,Department of Neurobiology, School of Medicine, University of Pittsburgh, Pittsburgh, PA, 15213, USA
| | - Joel Lüthi
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, 20147, USA.,Institute of Molecular Life Sciences, University of Zürich, Zürich, 8057, Switzerland
| | - Nelson Spruston
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, 20147, USA.
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28
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Matos M, Bosson A, Riebe I, Reynell C, Vallée J, Laplante I, Panatier A, Robitaille R, Lacaille JC. Astrocytes detect and upregulate transmission at inhibitory synapses of somatostatin interneurons onto pyramidal cells. Nat Commun 2018; 9:4254. [PMID: 30315174 PMCID: PMC6185912 DOI: 10.1038/s41467-018-06731-y] [Citation(s) in RCA: 65] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2017] [Accepted: 09/12/2018] [Indexed: 01/14/2023] Open
Abstract
Astrocytes are important regulators of excitatory synaptic networks. However, astrocytes regulation of inhibitory synaptic systems remains ill defined. This is particularly relevant since GABAergic interneurons regulate the activity of excitatory cells and shape network function. To address this issue, we combined optogenetics and pharmacological approaches, two-photon confocal imaging and whole-cell recordings to specifically activate hippocampal somatostatin or paravalbumin-expressing interneurons (SOM-INs or PV-INs), while monitoring inhibitory synaptic currents in pyramidal cells and Ca2+ responses in astrocytes. We found that astrocytes detect SOM-IN synaptic activity via GABABR and GAT-3-dependent Ca2+ signaling mechanisms, the latter triggering the release of ATP. In turn, ATP is converted into adenosine, activating A1Rs and upregulating SOM-IN synaptic inhibition of pyramidal cells, but not PV-IN inhibition. Our findings uncover functional interactions between a specific subpopulation of interneurons, astrocytes and pyramidal cells, involved in positive feedback autoregulation of dendritic inhibition of pyramidal cells.
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Affiliation(s)
- Marco Matos
- Département de Neurosciences, Faculté de Médecine, Université de Montréal, PO Box 6128, Station Centre-Ville, Montreal, QC, H3C 3J7, Canada
- Groupe de Recherche sur le Système Nerveux Central, Université de Montréal, PO Box 6128, Station Centre-Ville, Montreal, QC, H3C 3J7, Canada
| | - Anthony Bosson
- Département de Neurosciences, Faculté de Médecine, Université de Montréal, PO Box 6128, Station Centre-Ville, Montreal, QC, H3C 3J7, Canada
- Groupe de Recherche sur le Système Nerveux Central, Université de Montréal, PO Box 6128, Station Centre-Ville, Montreal, QC, H3C 3J7, Canada
| | - Ilse Riebe
- Département de Neurosciences, Faculté de Médecine, Université de Montréal, PO Box 6128, Station Centre-Ville, Montreal, QC, H3C 3J7, Canada
- Groupe de Recherche sur le Système Nerveux Central, Université de Montréal, PO Box 6128, Station Centre-Ville, Montreal, QC, H3C 3J7, Canada
| | - Clare Reynell
- Département de Neurosciences, Faculté de Médecine, Université de Montréal, PO Box 6128, Station Centre-Ville, Montreal, QC, H3C 3J7, Canada
- Groupe de Recherche sur le Système Nerveux Central, Université de Montréal, PO Box 6128, Station Centre-Ville, Montreal, QC, H3C 3J7, Canada
| | - Joanne Vallée
- Département de Neurosciences, Faculté de Médecine, Université de Montréal, PO Box 6128, Station Centre-Ville, Montreal, QC, H3C 3J7, Canada
- Groupe de Recherche sur le Système Nerveux Central, Université de Montréal, PO Box 6128, Station Centre-Ville, Montreal, QC, H3C 3J7, Canada
| | - Isabel Laplante
- Département de Neurosciences, Faculté de Médecine, Université de Montréal, PO Box 6128, Station Centre-Ville, Montreal, QC, H3C 3J7, Canada
- Groupe de Recherche sur le Système Nerveux Central, Université de Montréal, PO Box 6128, Station Centre-Ville, Montreal, QC, H3C 3J7, Canada
| | - Aude Panatier
- Neurocentre Magendie, Inserm U1215, 33077, Bordeaux, France
- Université de Bordeaux, 33077, Bordeaux, France
| | - Richard Robitaille
- Département de Neurosciences, Faculté de Médecine, Université de Montréal, PO Box 6128, Station Centre-Ville, Montreal, QC, H3C 3J7, Canada.
- Groupe de Recherche sur le Système Nerveux Central, Université de Montréal, PO Box 6128, Station Centre-Ville, Montreal, QC, H3C 3J7, Canada.
| | - Jean-Claude Lacaille
- Département de Neurosciences, Faculté de Médecine, Université de Montréal, PO Box 6128, Station Centre-Ville, Montreal, QC, H3C 3J7, Canada.
- Groupe de Recherche sur le Système Nerveux Central, Université de Montréal, PO Box 6128, Station Centre-Ville, Montreal, QC, H3C 3J7, Canada.
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29
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Mayorquin LC, Rodriguez AV, Sutachan JJ, Albarracín SL. Connexin-Mediated Functional and Metabolic Coupling Between Astrocytes and Neurons. Front Mol Neurosci 2018; 11:118. [PMID: 29695954 PMCID: PMC5905222 DOI: 10.3389/fnmol.2018.00118] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2017] [Accepted: 03/27/2018] [Indexed: 01/24/2023] Open
Abstract
The central nervous system (CNS) requires sophisticated regulation of neuronal activity. This modulation is partly accomplished by non-neuronal cells, characterized by the presence of transmembrane gap junctions (GJs) and hemichannels (HCs). This allows small molecule diffusion to guarantee neuronal synaptic activity and plasticity. Astrocytes are metabolically and functionally coupled to neurons by the uptake, binding and recycling of neurotransmitters. In addition, astrocytes release metabolites, such as glutamate, glutamine, D-serine, adenosine triphosphate (ATP) and lactate, regulating synaptic activity and plasticity by pre- and postsynaptic mechanisms. Uncoupling neuroglial communication leads to alterations in synaptic transmission that can be detrimental to neuronal circuit function and behavior. Therefore, understanding the pathways and mechanisms involved in this intercellular communication is fundamental for the search of new targets that can be used for several neurological disease treatments. This review will focus on molecular mechanisms mediating physiological and pathological coupling between astrocytes and neurons through GJs and HCs.
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Affiliation(s)
- Lady C Mayorquin
- Departamento de Nutrición y Bioquímica, Facultad de Ciencias, Pontificia Universidad Javeriana, Bogotá, Colombia
| | - Andrea V Rodriguez
- Departamento de Nutrición y Bioquímica, Facultad de Ciencias, Pontificia Universidad Javeriana, Bogotá, Colombia
| | - Jhon-Jairo Sutachan
- Departamento de Nutrición y Bioquímica, Facultad de Ciencias, Pontificia Universidad Javeriana, Bogotá, Colombia
| | - Sonia L Albarracín
- Departamento de Nutrición y Bioquímica, Facultad de Ciencias, Pontificia Universidad Javeriana, Bogotá, Colombia
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30
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Tachikawa M, Yashiki A, Akanuma SI, Matsukawa H, Ide S, Minami M, Hosoya KI. Astrocytic γ-aminobutyric acid (GABA) transporters mediate guanidinoacetate transport in rat brain. Neurochem Int 2018; 113:1-7. [DOI: 10.1016/j.neuint.2017.11.013] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2017] [Revised: 11/11/2017] [Accepted: 11/22/2017] [Indexed: 10/18/2022]
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31
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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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32
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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: 945] [Impact Index Per Article: 157.5] [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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33
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Heterogeneity and function of hippocampal macroglia. Cell Tissue Res 2017; 373:653-670. [PMID: 29204745 DOI: 10.1007/s00441-017-2746-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2017] [Accepted: 11/16/2017] [Indexed: 12/26/2022]
Abstract
The contribution of glial cells to normal and impaired hippocampal function is increasingly being recognized, although important questions as to the mechanisms that these cells use for their crosstalk with neurons and capillaries are still unanswered or lead to controversy. Astrocytes in the hippocampus are morphologically variable and a single cell contacts with its processes more than 100,000 synapses. They predominantly express inward rectifier K+ channels and transporters serving homeostatic function but may also release gliotransmitters to modify neuronal signaling and brain circulation. Intracellular Ca2+ transients are key events in the interaction of astrocytes with neurons and the vasculature. Hippocampal NG2 glia represent a population of cells with proliferative capacity throughout adulthood. Intriguingly, they receive direct synaptic input from pyramidal neurons and interneurons and express a multitude of ion channels and receptors. Despite in-depth knowledge about the features of these transmembrane proteins, the physiological impact of NG2 glial cells and their synaptic input remain nebulous. Because of the low abundance of oligodendrocytes in the hippocampus, limited information is available about their specific properties. Given the multitude of signaling molecules expressed by the various types of hippocampal glial cells (and because of space constraints), we focus, in this review, on those properties that are considered key for the interaction of the respective cell type with its neighborhood.
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34
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Impaired expression of GABA transporters in the human Alzheimer’s disease hippocampus, subiculum, entorhinal cortex and superior temporal gyrus. Neuroscience 2017; 351:108-118. [DOI: 10.1016/j.neuroscience.2017.03.041] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2016] [Revised: 03/20/2017] [Accepted: 03/25/2017] [Indexed: 11/20/2022]
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35
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Fattorini G, Melone M, Sánchez-Gómez MV, Arellano RO, Bassi S, Matute C, Conti F. GAT-1 mediated GABA uptake in rat oligodendrocytes. Glia 2017; 65:514-522. [PMID: 28071826 DOI: 10.1002/glia.23108] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2015] [Revised: 11/30/2016] [Accepted: 12/05/2016] [Indexed: 01/18/2023]
Abstract
Stimulated by the results of a recent paper on the effects of tiagabine, a selective inhibitor of the main GABA transporter GAT-1, on oligodendrogenesis, we verified the possibility that GAT-1 may be expressed in oligodendrocytes using immunocytochemical methods and functional assays. Light microscopic analysis of the subcortical white matter of all animals revealed the presence of numerous GAT-1+ cells of different size (from 3 to 29 µm) and morphology. An electron microscope analysis revealed that, besides fibrous astrocytes and interstitial neurons, GAT-1 immunoreactivity was present in immature and mature oligodendrocytes. Co-localization studies between GAT-1 and markers specific for oligodendrocytes (NG2 and RIP) showed that about 12% of GAT-1 positive cells in the white matter were immature oligodendrocytes, while about 15% were mature oligodendrocytes. In vitro functional assays showed that oligodendrocytes exhibit tiagabine-sensitive Na+ -dependent GABA uptake. Although relationships between GABA and oligodendrocytes have been known for many years, this is the first demonstration that GAT-1 is expressed in oligodendrocytes. The present results on the one hand definitely closes the era of "neuronal" and "glial" GABA transporters, on the other they suggest that oligodendrocytes may contribute to pathophysiology of the several diseases in which GAT-1 have been implicated to date. GLIA 2017;65:514-522.
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Affiliation(s)
- Giorgia Fattorini
- Department of Experimental and Clinical Medicine, Section of Neuroscience and Cell Biology, Università Politecnica delle Marche, Ancona, 60026, Italy.,Center for Neurobiology of Aging, INRCA IRCCS, Ancona, 60121, Italy
| | - Marcello Melone
- Department of Experimental and Clinical Medicine, Section of Neuroscience and Cell Biology, Università Politecnica delle Marche, Ancona, 60026, Italy.,Center for Neurobiology of Aging, INRCA IRCCS, Ancona, 60121, Italy
| | - María Victoria Sánchez-Gómez
- Achucarro Basque Center for Neuroscience, CIBERNED, and Departamento de Neurociencias, Universidad del País Vasco, Leioa, 48940, Spain
| | - Rogelio O Arellano
- Instituto de Neurobiología, Universidad Nacional Autónoma de México, Querétaro, México
| | - Silvia Bassi
- Department of Experimental and Clinical Medicine, Section of Neuroscience and Cell Biology, Università Politecnica delle Marche, Ancona, 60026, Italy
| | - Carlos Matute
- Achucarro Basque Center for Neuroscience, CIBERNED, and Departamento de Neurociencias, Universidad del País Vasco, Leioa, 48940, Spain
| | - Fiorenzo Conti
- Department of Experimental and Clinical Medicine, Section of Neuroscience and Cell Biology, Università Politecnica delle Marche, Ancona, 60026, Italy.,Center for Neurobiology of Aging, INRCA IRCCS, Ancona, 60121, Italy.,Fondazione di Medicina Molecolare, Università Politecnica delle Marche, Ancona, 60026, Italy
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36
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Albers HE, Walton JC, Gamble KL, McNeill JK, Hummer DL. The dynamics of GABA signaling: Revelations from the circadian pacemaker in the suprachiasmatic nucleus. Front Neuroendocrinol 2017; 44:35-82. [PMID: 27894927 PMCID: PMC5225159 DOI: 10.1016/j.yfrne.2016.11.003] [Citation(s) in RCA: 70] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/30/2016] [Revised: 10/16/2016] [Accepted: 11/22/2016] [Indexed: 12/31/2022]
Abstract
Virtually every neuron within the suprachiasmatic nucleus (SCN) communicates via GABAergic signaling. The extracellular levels of GABA within the SCN are determined by a complex interaction of synthesis and transport, as well as synaptic and non-synaptic release. The response to GABA is mediated by GABAA receptors that respond to both phasic and tonic GABA release and that can produce excitatory as well as inhibitory cellular responses. GABA also influences circadian control through the exclusively inhibitory effects of GABAB receptors. Both GABA and neuropeptide signaling occur within the SCN, although the functional consequences of the interactions of these signals are not well understood. This review considers the role of GABA in the circadian pacemaker, in the mechanisms responsible for the generation of circadian rhythms, in the ability of non-photic stimuli to reset the phase of the pacemaker, and in the ability of the day-night cycle to entrain the pacemaker.
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Affiliation(s)
- H Elliott Albers
- Center for Behavioral Neuroscience, Atlanta, GA 30302, United States; Neuroscience Institute, Georgia State University, Atlanta, GA 30302, United States.
| | - James C Walton
- Center for Behavioral Neuroscience, Atlanta, GA 30302, United States; Neuroscience Institute, Georgia State University, Atlanta, GA 30302, United States
| | - Karen L Gamble
- Department of Psychiatry and Behavioral Neurobiology, University of Alabama at Birmingham, Birmingham, AL 35294, United States
| | - John K McNeill
- Center for Behavioral Neuroscience, Atlanta, GA 30302, United States; Neuroscience Institute, Georgia State University, Atlanta, GA 30302, United States
| | - Daniel L Hummer
- Center for Behavioral Neuroscience, Atlanta, GA 30302, United States; Department of Psychology, Morehouse College, Atlanta, GA 30314, United States
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37
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Boddum K, Jensen TP, Magloire V, Kristiansen U, Rusakov DA, Pavlov I, Walker MC. Astrocytic GABA transporter activity modulates excitatory neurotransmission. Nat Commun 2016; 7:13572. [PMID: 27886179 PMCID: PMC5133667 DOI: 10.1038/ncomms13572] [Citation(s) in RCA: 132] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2016] [Accepted: 10/14/2016] [Indexed: 12/12/2022] Open
Abstract
Astrocytes are ideally placed to detect and respond to network activity. They express ionotropic and metabotropic receptors, and can release gliotransmitters. Astrocytes also express transporters that regulate the extracellular concentration of neurotransmitters. Here we report a previously unrecognized role for the astrocytic GABA transporter, GAT-3. GAT-3 activity results in a rise in astrocytic Na+ concentrations and a consequent increase in astrocytic Ca2+ through Na+/Ca2+ exchange. This leads to the release of ATP/adenosine by astrocytes, which then diffusely inhibits neuronal glutamate release via activation of presynaptic adenosine receptors. Through this mechanism, increases in astrocytic GAT-3 activity due to GABA released from interneurons contribute to 'diffuse' heterosynaptic depression. This provides a mechanism for homeostatic regulation of excitatory transmission in the hippocampus.
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Affiliation(s)
- Kim Boddum
- Department of Clinical and Experimental Epilepsy, UCL Institute of Neurology, University College London, Queen Square, London WC1N 3BG, UK.,Faculty of Health and Medical Sciences, Department of Drug Design and Pharmacology, University of Copenhagen, Universitetsparken 2, 2100 Copenhagen, Denmark
| | - Thomas P Jensen
- Department of Clinical and Experimental Epilepsy, UCL Institute of Neurology, University College London, Queen Square, London WC1N 3BG, UK
| | - Vincent Magloire
- Department of Clinical and Experimental Epilepsy, UCL Institute of Neurology, University College London, Queen Square, London WC1N 3BG, UK
| | - Uffe Kristiansen
- Faculty of Health and Medical Sciences, Department of Drug Design and Pharmacology, University of Copenhagen, Universitetsparken 2, 2100 Copenhagen, Denmark
| | - Dmitri A Rusakov
- Department of Clinical and Experimental Epilepsy, UCL Institute of Neurology, University College London, Queen Square, London WC1N 3BG, UK
| | - Ivan Pavlov
- Department of Clinical and Experimental Epilepsy, UCL Institute of Neurology, University College London, Queen Square, London WC1N 3BG, UK
| | - Matthew C Walker
- Department of Clinical and Experimental Epilepsy, UCL Institute of Neurology, University College London, Queen Square, London WC1N 3BG, UK
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38
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Danbolt NC, Zhou Y, Furness DN, Holmseth S. Strategies for immunohistochemical protein localization using antibodies: What did we learn from neurotransmitter transporters in glial cells and neurons. Glia 2016; 64:2045-2064. [PMID: 27458697 DOI: 10.1002/glia.23027] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2016] [Revised: 06/19/2016] [Accepted: 06/21/2016] [Indexed: 12/11/2022]
Abstract
Immunocytochemistry and Western blotting are still major methods for protein localization, but they rely on the specificity of the antibodies. Validation of antibody specificity remains challenging mostly because ideal negative controls are often unavailable. Further, immunochemical labeling patterns are also influenced by a number of other factors such as postmortem changes, fixation procedures and blocking agents as well as the general assay conditions (e.g., buffers, temperature, etc.). Western blotting similarly depends on tissue collection and sample preparation as well as the electrophoretic separation, transfer to blotting membranes and the immunochemical probing of immobilized molecules. Publication of inaccurate information on protein distribution has downstream consequences for other researchers because the interpretation of physiological and pharmacological observations depends on information on where ion channels, receptors, enzymes or transporters are located. Despite numerous reports, some of which are strongly worded, erroneous localization data are being published. Here we describe the extent of the problem and illustrate the nature of the pitfalls with examples from studies of neurotransmitter transporters. We explain the importance of supplementing immunochemical observations with other measurements (e.g., mRNA levels and distribution, protein activity, mass spectrometry, electrophysiological recordings, etc.) and why quantitative considerations are integral parts of the quality control. Further, we propose a practical strategy for researchers who plan to embark on a localization study. We also share our thoughts about guidelines for quality control. GLIA 2016;64:2045-2064.
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Affiliation(s)
- Niels Christian Danbolt
- Neurotransporter Group, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway.
| | - Yun Zhou
- Neurotransporter Group, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
| | - David N Furness
- School of Life Sciences, Keele University, Keele, Staffs, United Kingdom
| | - Silvia Holmseth
- Neurotransporter Group, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
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39
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Liao C, Han Q, Ma Y, Su B. Age-related gene expression change of GABAergic system in visual cortex of rhesus macaque. Gene 2016; 590:227-33. [PMID: 27196061 DOI: 10.1016/j.gene.2016.05.010] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2015] [Revised: 05/03/2016] [Accepted: 05/08/2016] [Indexed: 01/31/2023]
Abstract
Degradation of visual function is a common phenomenon during aging and likely mediated by change in the impaired central visual pathway. Treatment with GABA or its agonist could recover the ability of visual neurons in the primary visual cortex of senescent macaques. However, little is known about how GABAergic system change is related to the aged degradation of visual function in nonhuman primate. With the use of quantitative PCR method, we measured the expression change of 24 GABA related genes in the primary visual cortex (Brodmann's 17) of different age groups. In this study, both of mRNA and protein of glutamic acid decarboxylase (GAD65) were measured by real-time RT-PCR and Western blot, respectively. Results revealed that the level of GAD65 message was not significantly altered, but the proteins were significantly decreased in the aged monkey. As GAD65 plays an important role in GABA synthesis, the down-regulation of GAD65 protein was likely the key factor leading to the observed GABA reduction in the primary visual cortex of the aged macaques. In addition, 7 of 14 GABA receptor genes were up-regulated and one GABA receptor gene was significantly reduced during aging process even after Banjamini correction for multiple comparisons (P<0.05). These results suggested that the dysregulation of GAD65 protein might contribute to some age-related neural visual dysfunctions and most of GABA receptor genes induce a clear indication of compensatory effect for the reduced GABA release in the healthy aged monkey cortex.
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Affiliation(s)
- Chenghong Liao
- Key Laboratory of Tropical Biological Resources of Ministry of Education, Hainan University, Haikou, 570228, China; Laboratory of Tropical Veterinary Medicine and Vector Biology, College of Agriculture, Hainan University, Haikou, 570228, China
| | - Qian Han
- Key Laboratory of Tropical Biological Resources of Ministry of Education, Hainan University, Haikou, 570228, China; Laboratory of Tropical Veterinary Medicine and Vector Biology, College of Agriculture, Hainan University, Haikou, 570228, China
| | - Yuanye Ma
- Laboratory of the Primate Model for Brain Diseases and Key Laboratory of Animal Models and Human Disease Mechanisms of the Chinese Academy of Sciences & Yunnan Province, Kunming Institute of Zoology, Kunming 650223, China; State Key Laboratory of Brain and Cognitive Sciences, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China; Yunnan Key Laboratory of Primate Biomedical Research, Kunming, Yunnan, China
| | - Bing Su
- State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming 650223, China.
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40
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Moldavan M, Cravetchi O, Williams M, Irwin RP, Aicher SA, Allen CN. Localization and expression of GABA transporters in the suprachiasmatic nucleus. Eur J Neurosci 2015; 42:3018-32. [PMID: 26390912 DOI: 10.1111/ejn.13083] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2015] [Revised: 08/12/2015] [Accepted: 09/17/2015] [Indexed: 01/25/2023]
Abstract
GABA is a principal neurotransmitter in the suprachiasmatic hypothalamic nucleus (SCN), the master circadian clock. Despite the importance of GABA and GABA uptake for functioning of the circadian pacemaker, the localization and expression of GABA transporters (GATs) in the SCN has not been investigated. The present studies used Western blot analysis, immunohistochemistry and electron microscopy to demonstrate the presence of GABA transporter 1 (GAT1) and GAT3 in the SCN. By using light microscopy, GAT1 and GAT3 were co-localized throughout the SCN, but were not expressed in the perikarya of arginine vasopressin- or vasoactive intestinal peptide-immunoreactive (-ir) neurons of adult rats, nor in the neuronal processes labelled with the neurofilament heavy chain. Using electron microscopy, GAT1- and GAT3-ir was found in glial processes surrounding unlabelled neuronal perikarya, axons, dendrites, and enveloped symmetric and asymmetric axo-dendritic synapses. Glial fibrillary acidic protein-ir astrocytes grown in cell culture were immunopositive for GAT1 and GAT3 and both GATs could be observed in the same glial cell. These data demonstrate that synapses in the SCN function as 'tripartite' synapses consisting of presynaptic axon terminals, postsynaptic membranes and astrocytes that contain GABA transporters. This model suggests that astrocytes expressing both GATs may regulate the extracellular GABA, and thereby modulate the activity of neuronal networks in the SCN.
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Affiliation(s)
- Michael Moldavan
- Oregon Institute of Occupational Health Sciences, Oregon Health & Science University, 3181 S.W. Sam Jackson Park Road, Portland, OR, 97239-3098, USA
| | - Olga Cravetchi
- Oregon Institute of Occupational Health Sciences, Oregon Health & Science University, 3181 S.W. Sam Jackson Park Road, Portland, OR, 97239-3098, USA
| | - Melissa Williams
- Physiology and Pharmacology, Oregon Health & Science University, Portland, OR, USA
| | - Robert P Irwin
- Oregon Institute of Occupational Health Sciences, Oregon Health & Science University, 3181 S.W. Sam Jackson Park Road, Portland, OR, 97239-3098, USA
| | - Sue A Aicher
- Physiology and Pharmacology, Oregon Health & Science University, Portland, OR, USA
| | - Charles N Allen
- Oregon Institute of Occupational Health Sciences, Oregon Health & Science University, 3181 S.W. Sam Jackson Park Road, Portland, OR, 97239-3098, USA.,Department of Behavioral Neuroscience, Oregon Health & Science University, Portland, OR, USA
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Ambient GABA modulates septo-hippocampal inhibitory terminals via presynaptic GABAb receptors. Neuropharmacology 2015; 88:55-62. [PMID: 25446671 DOI: 10.1016/j.neuropharm.2014.10.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2014] [Revised: 10/03/2014] [Accepted: 10/05/2014] [Indexed: 12/17/2022]
Abstract
The septo-hippocampal GABAergic pathway connects inhibitory neurons in the medial septum with hippocampal interneurons. Phasic release of GABA from septo-hippocampal terminals is thought to play an important role in shaping hippocampal network activity during behavior. Here, we found that GABA release from septo-hippocampal terminals is under negative feedback from the hippocampal local inhibitory network. We found that the strength of septo-hippocampal GABAergic inhibition is constrained by presynaptic GABAb receptors that are activated by ambient GABA during states of increased hippocampal network activity.
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Synaptic GABA release prevents GABA transporter type-1 reversal during excessive network activity. Nat Commun 2015; 6:6597. [PMID: 25798861 PMCID: PMC4374149 DOI: 10.1038/ncomms7597] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2014] [Accepted: 02/10/2015] [Indexed: 12/15/2022] Open
Abstract
GABA transporters control extracellular GABA, which regulates the key aspects of neuronal and network behaviour. A prevailing view is that modest neuronal depolarization results in GABA transporter type-1 (GAT-1) reversal causing non-vesicular GABA release into the extracellular space during intense network activity. This has important implications for GABA uptake-targeting therapies. Here we combined a realistic kinetic model of GAT-1 with experimental measurements of tonic GABAA receptor currents in ex vivo hippocampal slices to examine GAT-1 operation under varying network conditions. Our simulations predict that synaptic GABA release during network activity robustly prevents GAT-1 reversal. We test this in the 0 Mg2+ model of epileptiform discharges using slices from healthy and chronically epileptic rats and find that epileptiform activity is associated with increased synaptic GABA release and is not accompanied by GAT-1 reversal. We conclude that sustained efflux of GABA through GAT-1 is unlikely to occur during physiological or pathological network activity. Membrane depolarization during increased neuronal activity as seen during epilepsy has been suggested to easily reverse neuronal GABA transporters. Here the authors use modelling and experimental data and challenge this view by showing that synaptic GABA release during excessive neuronal firing averts reversal of GABA uptake.
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Siucinska E, Hamed A, Jasinska M. Increases in the numerical density of GAT-1 positive puncta in the barrel cortex of adult mice after fear conditioning. PLoS One 2014; 9:e110493. [PMID: 25333489 PMCID: PMC4204871 DOI: 10.1371/journal.pone.0110493] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2014] [Accepted: 09/19/2014] [Indexed: 11/19/2022] Open
Abstract
Three days of fear conditioning that combines tactile stimulation of a row of facial vibrissae (conditioned stimulus, CS) with a tail shock (unconditioned stimulus, UCS) expands the representation of “trained” vibrissae, which can be demonstrated by labeling with 2-deoxyglucose in layer IV of the barrel cortex. We have also shown that functional reorganization of the primary somatosensory cortex (S1) increases GABAergic markers in the hollows of “trained” barrels of the adult mouse. This study investigated how whisker-shock conditioning (CS+UCS) affected the expression of puncta of a high-affinity GABA plasma membrane transporter GAT-1 in the barrel cortex of mice 24 h after associative learning paradigm. We found that whisker-shock conditioning (CS+UCS) led to increase expression of neuronal and astroglial GAT-1 puncta in the “trained” row compared to controls: Pseudoconditioned, CS-only, UCS-only and Naïve animals. These findings suggest that fear conditioning specifically induces activation of systems regulating cellular levels of the inhibitory neurotransmitter GABA.
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Affiliation(s)
- Ewa Siucinska
- Department of Molecular and Cellular Neurobiology, Nencki Institute of Experimental Biology, Warsaw, Poland
- * E-mail:
| | - Adam Hamed
- Department of Neurochemistry, Institute of Psychiatry and Neurology, Warsaw, Poland
| | - Malgorzata Jasinska
- Department of Histology, Jagiellonian University Medical College, Krakow, Poland
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Scimemi A. Structure, function, and plasticity of GABA transporters. Front Cell Neurosci 2014; 8:161. [PMID: 24987330 PMCID: PMC4060055 DOI: 10.3389/fncel.2014.00161] [Citation(s) in RCA: 162] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2014] [Accepted: 05/27/2014] [Indexed: 11/13/2022] Open
Abstract
GABA transporters belong to a large family of neurotransmitter:sodium symporters. They are widely expressed throughout the brain, with different levels of expression in different brain regions. GABA transporters are present in neurons and in astrocytes and their activity is crucial to regulate the extracellular concentration of GABA under basal conditions and during ongoing synaptic events. Numerous efforts have been devoted to determine the structural and functional properties of GABA transporters. There is also evidence that the expression of GABA transporters on the cell membrane and their lateral mobility can be modulated by different intracellular signaling cascades. The strength of individual synaptic contacts and the activity of entire neuronal networks may be finely tuned by altering the density, distribution and diffusion rate of GABA transporters within the cell membrane. These findings are intriguing because they suggest the existence of complex regulatory systems that control the plasticity of GABAergic transmission in the brain. Here we review the current knowledge on the structural and functional properties of GABA transporters and highlight the molecular mechanisms that alter the expression and mobility of GABA transporters at central synapses.
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Downregulated GABA and BDNF-TrkB pathway in chronic cyclothiazide seizure model. Neural Plast 2014; 2014:310146. [PMID: 24757570 PMCID: PMC3976828 DOI: 10.1155/2014/310146] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2013] [Accepted: 01/28/2014] [Indexed: 12/12/2022] Open
Abstract
Cyclothiazide (CTZ) has been reported to simultaneously enhance glutamate receptor excitation and inhibit GABAA receptor inhibition, and in turn it evokes epileptiform activities in hippocampal neurons. It has also been shown to acutely induce epileptic seizure behavior in freely moving rats. However, whether CTZ induced seizure rats could develop to have recurrent seizure still remains unknown. In the current study, we demonstrated that 46% of the CTZ induced seizure rats developed to have recurrent seizure behavior as well as epileptic EEG with a starting latency between 2 weeks and several months. In those chronic seizure rats 6 months after the seizure induction by the CTZ, our immunohistochemistry results showed that both GAD and GAT-1 were significantly decreased across CA1, CA3, and dentate gyrus area of the hippocampus studied. In addition, both BDNF and its receptor TrkB were also decreased in hippocampus of the chronic CTZ seizure rats. Our results indicate that CTZ induced seizure is capable of developing to have recurrent seizure, and the decreased GABA synthesis and transport as well as the impaired BDNF-TrkB signaling pathway may contribute to the development of the recurrent seizure. Thus, CTZ seizure rats may provide a novel animal model for epilepsy study and anticonvulsant drug testing in the future.
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Wójtowicz AM, Dvorzhak A, Semtner M, Grantyn R. Reduced tonic inhibition in striatal output neurons from Huntington mice due to loss of astrocytic GABA release through GAT-3. Front Neural Circuits 2013; 7:188. [PMID: 24324407 PMCID: PMC3840359 DOI: 10.3389/fncir.2013.00188] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2013] [Accepted: 11/04/2013] [Indexed: 01/17/2023] Open
Abstract
The extracellular concentration of the two main neurotransmitters glutamate and GABA is low but not negligible which enables a number of tonic actions. The effects of ambient GABA vary in a region-, cell-type, and age-dependent manner and can serve as indicators of disease-related alterations. Here we explored the tonic inhibitory actions of GABA in Huntington's disease (HD). HD is a devastating neurodegenerative disorder caused by a mutation in the huntingtin gene. Whole cell patch clamp recordings from striatal output neurons (SONs) in slices from adult wild type mice and two mouse models of HD (Z_Q175_KI homozygotes or R6/2 heterozygotes) revealed an HD-related reduction of the GABA(A) receptor-mediated tonic chloride current (ITonic(GABA)) along with signs of reduced GABA(B) receptor-mediated presynaptic depression of synaptic GABA release. About half of ITonic(GABA) depended on tetrodotoxin-sensitive synaptic GABA release, but the remaining current was still lower in HD. Both in WT and HD, ITonic(GABA) was more prominent during the first 4 h after preparing the slices, when astrocytes but not neurons exhibited a transient depolarization. All further tests were performed within 1–4 h in vitro. Experiments with SNAP5114, a blocker of the astrocytic GABA transporter GAT-3, suggest that in WT but not HD GAT-3 operated in the releasing mode. Application of a transportable substrate for glutamate transporters (D-aspartate 0.1–1 mM) restored the non-synaptic GABA release in slices from HD mice. ITonic(GABA) was also rescued by applying the hyperagonist gaboxadol (0.33 μM). The results lead to the hypothesis that lesion-induced astrocyte depolarization facilitates non-synaptic release of GABA through GAT-3. However, the capacity of depolarized astrocytes to provide GABA for tonic inhibition is strongly reduced in HD.
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Affiliation(s)
- Anna M Wójtowicz
- Cluster of Excellence NeuroCure, University Medicine Charité Berlin, Germany ; Department of Experimental Neurology, University Medicine Charité Berlin, Germany
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Münster-Wandowski A, Gómez-Lira G, Gutiérrez R. Mixed neurotransmission in the hippocampal mossy fibers. Front Cell Neurosci 2013; 7:210. [PMID: 24319410 PMCID: PMC3837298 DOI: 10.3389/fncel.2013.00210] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2013] [Accepted: 10/23/2013] [Indexed: 01/14/2023] Open
Abstract
The hippocampal mossy fibers (MFs), the axons of the granule cells (GCs) of the dentate gyrus, innervate mossy cells and interneurons in the hilus on their way to CA3 where they innervate interneurons and pyramidal cells. Synapses on each target cell have distinct anatomical and functional characteristics. In recent years, the paradigmatic view of the MF synapses being only glutamatergic and, thus, excitatory has been questioned. Several laboratories have provided data supporting the hypothesis that the MFs can transiently release GABA during development and, in the adult, after periods of enhanced excitability. This transient glutamate-GABA co-transmission coincides with the transient up-regulation of the machinery for the synthesis and release of GABA in the glutamatergic GCs. Although some investigators have deemed this evidence controversial, new data has appeared with direct evidence of co-release of glutamate and GABA from single, identified MF boutons. However, this must still be confirmed by other groups and with other methodologies. A second, intriguing observation is that MF activation produced fast spikelets followed by excitatory postsynaptic potentials in a number of pyramidal cells, which, unlike the spikelets, underwent frequency potentiation and were strongly depressed by activation of metabotropic glutamate receptors. The spikelets persisted during blockade of chemical transmission and were suppressed by the gap junction blocker carbenoxolone. These data are consistent with the hypothesis of mixed electrical-chemical synapses between MFs and some pyramidal cells. Dye coupling between these types of principal cells and ultrastructural studies showing the co-existence of AMPA receptors and connexin 36 in this synapse corroborate their presence. A deeper consideration of mixed neurotransmission taking place in this synapse may expand our search and understanding of communication channels between different regions of the mammalian CNS.
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Li ZX, Yu HM, Jiang KW. Tonic GABA inhibition in hippocampal dentate granule cells: its regulation and function in temporal lobe epilepsies. Acta Physiol (Oxf) 2013; 209:199-211. [PMID: 23865761 DOI: 10.1111/apha.12148] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2013] [Revised: 05/06/2013] [Accepted: 07/12/2013] [Indexed: 01/06/2023]
Abstract
Both human and experimental evidence strongly supports the view of brain region- and cell-specific changes in tonic GABA inhibition in temporal lobe epilepsies (TLE). This 'tonic' form of signalling is not time-locked to presynaptic action potentials, which depends upon detection of ambient GABA by extrasynaptic GABAA receptors (GABAA Rs). Extrasynaptic GABAA Rs have distinct physiological and pharmacological features, including high GABA-binding affinity and low desensitization and a variety of the specific subunit combinations (α4δ-,α6δ-,α5γ-,ε-containing receptors). These features closely contribute to the function of tonic GABA current, which is preserved properly or increased in dentate gyrus in models of TLE, even in the face of a loss of synaptic inhibition and inhibitory interneurones. Markedly reduced tonic GABA inhibition may facilitate an episode of epilepsy, while persistent elevated tonic inhibition may contribute to the onset of spontaneous recurrent seizures. In dentate granule cells, tonic GABA inhibition is positively modulated by endogenous neurosteroids and other factors, which undergo changes related to hormonal status after TLE. Tonic inhibition regulates neuronal excitability through its effects on membrane potential by both offsetting the threshold and reducing the frequency of action potentials and input resistance. Therefore, extrasynaptic GABAA Rs are expected to be the most important pharmacological targets in TLE. It is likely that both elevate the ambient GABA concentration and potentiate the tonic currents, contributing to the antiepileptic effects.
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Affiliation(s)
- Z.-X. Li
- Department of Neurology; The Children's Hospital Zhejiang University School of Medicine; Hangzhou; China
| | - H.-M. Yu
- Department of Neonatology; The Children's Hospital Zhejiang University School of Medicine; Hangzhou; China
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Expression of the γ2-subunit distinguishes synaptic and extrasynaptic GABA(A) receptors in NG2 cells of the hippocampus. J Neurosci 2013; 33:12030-40. [PMID: 23864689 DOI: 10.1523/jneurosci.5562-12.2013] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
NG2 cells are equipped with transmitter receptors and receive direct synaptic input from glutamatergic and GABAergic neurons. The functional impact of these neuron-glia synapses is still unclear. Here, we combined functional and molecular techniques to analyze properties of GABA(A) receptors in NG2 cells of the juvenile mouse hippocampus. GABA activated slowly desensitizing responses in NG2 cells, which were mimicked by muscimol and inhibited by bicuculline. To elucidate the subunit composition of the receptors we tested its pharmacological properties. Coapplication of pentobarbital, benzodiazepines, and zolpidem all significantly increased the GABA-evoked responses. The presence of small tonic currents indicated the presence of extrasynaptic GABA(A) receptors. To further analyze the subunit expression, single cell transcript analysis was performed subsequent to functional characterization of NG2 cells. The subunits α1, α2, β3, γ1, and γ2 were most abundantly expressed, matching properties resulting from pharmacological characterization. Importantly, lack of the γ2-subunit conferred a high Zn²⁺ sensitivity to the GABA(A) receptors of NG2 cells. Judging from the zolpidem sensitivity, postsynaptic GABA(A) receptors in NG2 cells contain the γ2-subunit, in contrast to extrasynaptic receptors, which were not modulated by zolpidem. To determine the effect of GABA(A) receptor activation on membrane potential, perforated patch recordings were obtained from NG2 cells. In the current-clamp mode, GABA depolarized the cells to approximately -30 mV, indicating a higher intracellular Cl⁻ concentration (∼50 mM) than previously reported. GABA-induced depolarization in NG2 cells might trigger Ca²⁺ influx through voltage-activated Ca²⁺ channels.
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50
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Wang T, Rusu SI, Hruskova B, Turecek R, Borst JGG. Modulation of synaptic depression of the calyx of Held synapse by GABA(B) receptors and spontaneous activity. J Physiol 2013; 591:4877-94. [PMID: 23940376 DOI: 10.1113/jphysiol.2013.256875] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
The calyx of Held synapse of the medial nucleus of the trapezoid body is a giant axosomatic synapse in the auditory brainstem, which acts as a relay synapse showing little dependence of its synaptic strength on firing frequency. The main mechanism that is responsible for its resistance to synaptic depression is its large number of release sites with low release probability. Here, we investigated the contribution of presynaptic GABA(B) receptors and spontaneous activity to release probability both in vivo and in vitro in young-adult mice. Maximal activation of presynaptic GABA(B) receptors by baclofen reduced synaptic output by about 45% in whole-cell voltage clamp slice recordings, which was accompanied by a reduction in short-term depression. A similar reduction in transmission was observed when baclofen was applied in vivo by microiontophoresis during juxtacellular recordings using piggyback electrodes. No significant change in synaptic transmission was observed during application of the GABA(B) receptor antagonist CGP54626 both during in vivo and slice recordings, suggesting a low ambient GABA concentration. Interestingly, we observed that synapses with a high spontaneous frequency showed almost no synaptic depression during auditory stimulation, whereas synapses with a low spontaneous frequency did depress during noise bursts. Our data thus suggest that spontaneous firing can tonically reduce release probability in vivo. In addition, our data show that the ambient GABA concentration in the auditory brainstem is too low to activate the GABA(B) receptor at the calyx of Held significantly, but that activation of GABA(B) receptors can reduce sound-evoked synaptic depression.
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Affiliation(s)
- Tiantian Wang
- J. G. G. Borst: Department of Neuroscience, Erasmus MC, University Medical Center Rotterdam, Dr. Molewaterplein 50, 3015 GE Rotterdam, The Netherlands.
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