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Tang Y, Sun Y, Xu R, Huang X, Gu S, Hong C, Liu M, Jiang H, Yang Y, Shi J. Arginine vasopressin differentially modulates
GABA
ergic synaptic transmission onto temperature‐sensitive and temperature‐insensitive neurons in the rat preoptic area. Eur J Neurosci 2018; 47:866-886. [DOI: 10.1111/ejn.13868] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2017] [Revised: 02/09/2018] [Accepted: 02/09/2018] [Indexed: 11/27/2022]
Affiliation(s)
- Yu Tang
- Department of Neurobiology School of Basic Medicine Tongji Medical College Huazhong University of Science and Technology Wuhan Hubei 430030 China
- Key Laboratory of Thermoregulatory and Inflammation of Sichuan Higher Education Institutes Chengdu Medical College Chengdu Sichuan China
- Department of Physiology Chengdu Medical College Chengdu Sichuan China
| | - Yan‐Ni Sun
- Department of Medical Laboratory Chengdu Medical College Chengdu Sichuan China
| | - Run Xu
- Department of Medical Laboratory Chengdu Medical College Chengdu Sichuan China
| | - Xiao Huang
- Department of Public Health Chengdu Medical College Chengdu Sichuan China
| | - Shuang Gu
- Department of Public Health Chengdu Medical College Chengdu Sichuan China
| | - Cheng‐Cheng Hong
- Department of Public Health Chengdu Medical College Chengdu Sichuan China
| | - Mi‐Jia Liu
- School of Clinical Medicine Chengdu Medical College Chengdu Sichuan China
| | - Heng Jiang
- Department of Medical Laboratory Chengdu Medical College Chengdu Sichuan China
| | - Yong‐Lu Yang
- Key Laboratory of Thermoregulatory and Inflammation of Sichuan Higher Education Institutes Chengdu Medical College Chengdu Sichuan China
| | - Jing Shi
- Department of Neurobiology School of Basic Medicine Tongji Medical College Huazhong University of Science and Technology Wuhan Hubei 430030 China
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Colmers PLW, Bains JS. Balancing tonic and phasic inhibition in hypothalamic corticotropin-releasing hormone neurons. J Physiol 2018; 596:1919-1929. [PMID: 29419884 DOI: 10.1113/jp275588] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2017] [Accepted: 01/29/2018] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS GABA transporter (GAT) blockade recruits extrasynaptic GABAA receptors (GABAA Rs) and amplifies constitutive presynaptic GABAB R activity. Extrasynaptic GABAA Rs contribute to a tonic current. Corticosteroids increase the tonic current mediated by extrasynaptic GABAA Rs. ABSTRACT Corticotropin-releasing hormone (CRH) neurons in the paraventricular nucleus of the hypothalamus (PVN) are integratory hubs that regulate the endocrine response to stress. GABA inputs provide a basal inhibitory tone that constrains this system and circulating glucocorticoids (CORT) are important feedback controllers of CRH output. Surprisingly little is known about the direct effects of CORT on GABA synapses in PVN. Here we used whole-cell patch clamp recordings from CRH neurons in mouse hypothalamic brain slices to examine the effects of CORT on synaptic and extrasynaptic GABA signalling. We show that GABA transporters (GATs) limit constitutive activation of presynaptic GABAB receptors and ensure high release probability at GABA synapses. GATs in combination with GABAB receptors also curtail extrasynaptic GABAA R signalling. CORT has no effect on synaptic GABA signalling, but increases extrasynaptic GABA tone through upregulation of postsynaptic GABAA receptors. These data show that efficient GABA clearance and autoinhibition control the balance between synaptic (phasic) and extrasynaptic (tonic) inhibition in PVN CRH neurons. This balance is shifted towards increased extrasynaptic inhibition by CORT.
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Affiliation(s)
- Phillip L W Colmers
- Hotchkiss Brain Institute and the Department of Physiology & Pharmacology, Cumming School of Medicine, University of Calgary, 3330 Hospital Drive NW, Calgary, AB, T2N 4N1, Canada
| | - Jaideep S Bains
- Hotchkiss Brain Institute and the Department of Physiology & Pharmacology, Cumming School of Medicine, University of Calgary, 3330 Hospital Drive NW, Calgary, AB, T2N 4N1, Canada
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3
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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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Czell D, Efe T, Preuss M, Schofer MD, Becker R. Influence of Intraventricular Application of Baclofen on Arterial Blood Pressure and Neurotransmitter Concentrations in the Hypothalamic Paraventricular Nucleus of Rats. Neurochem Res 2011; 37:381-6. [DOI: 10.1007/s11064-011-0621-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2011] [Revised: 09/22/2011] [Accepted: 09/23/2011] [Indexed: 11/30/2022]
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Wang Y, Neubauer FB, Lüscher HR, Thurley K. GABAB receptor-dependent modulation of network activity in the rat prefrontal cortex in vitro. Eur J Neurosci 2010; 31:1582-94. [PMID: 20525071 DOI: 10.1111/j.1460-9568.2010.07191.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
GABA (gamma-aminobutyric acid) can mediate inhibition via pre- and post/extrasynaptic GABA receptors. In this paper we demonstrate potentially post/extrasynaptic GABA(B) receptor-dependent tonic inhibition in L2/3 pyramidal cells of rat medial prefrontal cortex (mPFC) in vitro. First, we show via voltage-clamp experiments the presence of a tonic GABA(B) receptor-dependent outward current in these neurons. This GABA(B)ergic current could be induced by ambient GABA when present at sufficient concentrations. To increase ambient GABA levels in the usually silent slice preparation, we amplified network activity and hence synaptic GABA release with a modified artificial cerebrospinal fluid. The amplitude of tonic GABA(B) current was similar at different temperatures. In addition to the tonic GABA(B) current, we found presynaptic GABA(B) effects, GABA(B)-mediated inhibitory postsynaptic currents and tonic GABA(A) currents. Second, we performed current-clamp experiments to evaluate the functional impact of GABA(B) receptor-mediated inhibition in the mPFC. Activating or inactivating GABA(B) receptors led to rightward (reduction of excitability) or leftward (increase of excitability) shifts, respectively, of the input-output function of mPFC L2/3 pyramidal cells without effects on the slope. Finally, we showed in electrophysiological recordings and epifluorescence Ca(2+)-imaging that GABA(B) receptor-mediated tonic inhibition is capable of regulating network activity. Blocking GABA(B) receptors increased the frequency of excitatory postsynaptic currents impinging on a neuron and prolonged network upstates. These results show that ambient GABA via GABA(B) receptors is powerful enough to modulate neuronal excitability and the activity of neural networks.
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Affiliation(s)
- Ying Wang
- Department of Physiology, University of Bern, Bern, Switzerland
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6
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Guetg N, Seddik R, Vigot R, Turecek R, Gassmann M, Vogt KE, Bräuner-Osborne H, Shigemoto R, Kretz O, Frotscher M, Kulik Á, Bettler B. The GABAB1a isoform mediates heterosynaptic depression at hippocampal mossy fiber synapses. J Neurosci 2009; 29:1414-23. [PMID: 19193888 PMCID: PMC6666076 DOI: 10.1523/jneurosci.3697-08.2009] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2008] [Revised: 12/02/2008] [Accepted: 12/31/2008] [Indexed: 12/22/2022] Open
Abstract
GABA(B) receptor subtypes are based on the subunit isoforms GABA(B1a) and GABA(B1b), which associate with GABA(B2) subunits to form pharmacologically indistinguishable GABA(B(1a,2)) and GABA(B(1b,2)) receptors. Studies with mice selectively expressing GABA(B1a) or GABA(B1b) subunits revealed that GABA(B(1a,2)) receptors are more abundant than GABA(B(1b,2)) receptors at glutamatergic terminals. Accordingly, it was found that GABA(B(1a,2)) receptors are more efficient than GABA(B(1b,2)) receptors in inhibiting glutamate release when maximally activated by exogenous application of the agonist baclofen. Here, we used a combination of genetic, ultrastructural and electrophysiological approaches to analyze to what extent GABA(B(1a,2)) and GABA(B(1b,2)) receptors inhibit glutamate release in response to physiological activation. We first show that at hippocampal mossy fiber (MF)-CA3 pyramidal neuron synapses more GABA(B1a) than GABA(B1b) protein is present at presynaptic sites, consistent with the findings at other glutamatergic synapses. In the presence of baclofen at concentrations >or=1 microm, both GABA(B(1a,2)) and GABA(B(1b,2)) receptors contribute to presynaptic inhibition of glutamate release. However, at lower concentrations of baclofen, selectively GABA(B(1a,2)) receptors contribute to presynaptic inhibition. Remarkably, exclusively GABA(B(1a,2)) receptors inhibit glutamate release in response to synaptically released GABA. Specifically, we demonstrate that selectively GABA(B(1a,2)) receptors mediate heterosynaptic depression of MF transmission, a physiological phenomenon involving transsynaptic inhibition of glutamate release via presynaptic GABA(B) receptors. Our data demonstrate that the difference in GABA(B1a) and GABA(B1b) protein levels at MF terminals is sufficient to produce a strictly GABA(B1a)-specific effect under physiological conditions. This consolidates that the differential subcellular localization of the GABA(B1a) and GABA(B1b) proteins is of regulatory relevance.
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Affiliation(s)
- Nicole Guetg
- Department of Biomedicine, Institute of Physiology, Pharmazentrum, and
- Institute of Anatomy and Cell Biology, Department of Neuroanatomy, University of Freiburg, 79104 Freiburg, Germany
| | - Riad Seddik
- Department of Biomedicine, Institute of Physiology, Pharmazentrum, and
| | - Réjan Vigot
- Department of Biomedicine, Institute of Physiology, Pharmazentrum, and
| | - Rostislav Turecek
- Department of Biomedicine, Institute of Physiology, Pharmazentrum, and
| | - Martin Gassmann
- Department of Biomedicine, Institute of Physiology, Pharmazentrum, and
| | - Kaspar E. Vogt
- Division of Pharmacology and Neurobiology, Biozentrum, University of Basel, 4056 Basel, Switzerland
| | - Hans Bräuner-Osborne
- Department of Biomedicine, Institute of Physiology, Pharmazentrum, and
- Department of Medicinal Chemistry, Faculty of Pharmaceutical Sciences, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Ryuichi Shigemoto
- Division of Cerebral Structure, National Institute for Physiological Sciences, and
- Department of Physiological Sciences, The Graduate University of Advanced Studies (Sokendai), Myodaiji, Okazaki 444-8787, Japan, and
- Solution Oriented Research for Science and Technology, Japan Science and Technology Corporation, Kawaguchi 332-0012, Japan
| | - Oliver Kretz
- Institute of Anatomy and Cell Biology, Department of Neuroanatomy, University of Freiburg, 79104 Freiburg, Germany
| | - Michael Frotscher
- Institute of Anatomy and Cell Biology, Department of Neuroanatomy, University of Freiburg, 79104 Freiburg, Germany
| | - Ákos Kulik
- Institute of Anatomy and Cell Biology, Department of Neuroanatomy, University of Freiburg, 79104 Freiburg, Germany
| | - Bernhard Bettler
- Department of Biomedicine, Institute of Physiology, Pharmazentrum, and
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Genest SE, Balon N, Laforest S, Drolet G, Kinkead R. Neonatal maternal separation and enhancement of the hypoxic ventilatory response in rat: the role of GABAergic modulation within the paraventricular nucleus of the hypothalamus. J Physiol 2007; 583:299-314. [PMID: 17569732 PMCID: PMC2277229 DOI: 10.1113/jphysiol.2007.135160] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Neonatal maternal separation (NMS) affects respiratory control development as adult male (but not female) rats previously subjected to NMS show a hypoxic ventilatory response 25% greater than controls. The paraventricular nucleus of the hypothalamus (PVN) is an important modulator of respiratory activity. In the present study, we hypothesized that in awake rats, altered GABAergic inhibition within the PVN contributes to the enhancement of hypoxic ventilatory response observed in rats previously subjected to NMS. During normoxia, the increase in minute ventilation following microinjection of bicuculline (1 mm) within the PVN is greater in NMS versus control rats. These data show that regulation of ventilatory activity related to tonic inhibition of the PVN is more important in NMS than control rats. Microinjection of GABA or muscimol (1 mM) attenuated the ventilatory response to hypoxia (12% O2) in NMS rats only. The higher efficiency of microinjections in NMS rats is supported by results from GABAA receptor autoradiography which revealed a 22% increase in GABAA receptor binding sites within the PVN of NMS rats versus controls. Despite this increase, however, NMS rats still show a larger hypoxic ventilatory response than controls, suggesting that within the PVN the larger number of GABAA receptors either compensate for (1) a deficient GABAergic modulation, (2) an increase in the efficacy of excitatory inputs converging onto this structure, or (3) both. Together, these results show that the life-long consequences of NMS are far reaching as they can compromise the development of vital homeostatic function in a way that may predispose to respiratory disorders.
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Affiliation(s)
- Sophie-Emmanuelle Genest
- Pediatrics, Centre de Recherche du Centre Hospitalier Universitaire de Québec, Université LavalQuébec, QC, Canada
- Neuroscience Research Units, Centre de Recherche du Centre Hospitalier Universitaire de Québec, Université LavalQuébec, QC, Canada
| | - Norbert Balon
- Pediatrics, Centre de Recherche du Centre Hospitalier Universitaire de Québec, Université LavalQuébec, QC, Canada
| | - Sylvie Laforest
- Neuroscience Research Units, Centre de Recherche du Centre Hospitalier Universitaire de Québec, Université LavalQuébec, QC, Canada
| | - Guy Drolet
- Neuroscience Research Units, Centre de Recherche du Centre Hospitalier Universitaire de Québec, Université LavalQuébec, QC, Canada
| | - Richard Kinkead
- Pediatrics, Centre de Recherche du Centre Hospitalier Universitaire de Québec, Université LavalQuébec, QC, Canada
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Ulrich D, Bettler B. GABA(B) receptors: synaptic functions and mechanisms of diversity. Curr Opin Neurobiol 2007; 17:298-303. [PMID: 17433877 DOI: 10.1016/j.conb.2007.04.001] [Citation(s) in RCA: 123] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2007] [Accepted: 04/05/2007] [Indexed: 12/20/2022]
Abstract
GABA(B) receptors are the G-protein-coupled receptors for GABA, the main inhibitory neurotransmitter in the mammalian central nervous system. They are implicated in a variety of neurological and psychiatric disorders. With the cloning of GABA(B) receptors ten years ago, substantial progress was made in our understanding of this receptor system. Here, we review current concepts of synaptic GABA(B) functions and present the evidence that points to specific roles for receptor subtypes. We discuss ultrastructural studies revealing that most GABA(B) receptors are located remote from GABAergic terminals, which raises questions as to when such receptors become activated. Finally, we provide possible explanations for the perplexing situation that GABA(B) receptor subtypes that have indistinguishable properties in vitro generate distinct GABA(B) responses in vivo.
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Affiliation(s)
- Daniel Ulrich
- Pharmazentrum, Institute of Physiology, University of Basel, Klingelbergstrasse 50-70, CH-4056 Basel, Switzerland
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