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Fenech C, Winters BL, Otsu Y, Aubrey KR. Supraspinal glycinergic neurotransmission in pain: A scoping review of current literature. J Neurochem 2024. [PMID: 39075923 DOI: 10.1111/jnc.16191] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2024] [Revised: 07/16/2024] [Accepted: 07/16/2024] [Indexed: 07/31/2024]
Abstract
The neurotransmitter glycine is an agonist at the strychnine-sensitive glycine receptors. In addition, it has recently been discovered to act at two new receptors, the excitatory glycine receptor and metabotropic glycine receptor. Glycine's neurotransmitter roles have been most extensively investigated in the spinal cord, where it is known to play essential roles in pain, itch, and motor function. In contrast, less is known about supraspinal glycinergic functions, and their contributions to pain circuits are largely unrecognized. As glycinergic neurons are absent from cortical regions, a clearer understanding of how supraspinal glycine modulates pain could reveal new pharmacological targets. This review aims to synthesize the published research on glycine's role in the adult brain, highlighting regions where glycine signaling may modulate pain responses. This was achieved through a scoping review methodology identifying several key regions of supraspinal pain circuitry where glycine signaling is involved. Therefore, this review unveils critical research gaps for supraspinal glycine's potential roles in pain and pain-associated responses, encouraging researchers to consider glycinergic neurotransmission more widely when investigating neural mechanisms of pain.
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Affiliation(s)
- Caitlin Fenech
- Pain Management Research Institute, Kolling Institute, Royal North Shore Hospital, St Leonards, New South Wales, Australia
- Faculty of Medicine and Health, University of Sydney, Sydney, New South Wales, Australia
| | - Bryony L Winters
- Pain Management Research Institute, Kolling Institute, Royal North Shore Hospital, St Leonards, New South Wales, Australia
- Discipline of Pharmacology, School of Pharmacy, Faculty of Medicine and Health, University of Sydney, Sydney, New South Wales, Australia
| | - Yo Otsu
- Pain Management Research Institute, Kolling Institute, Royal North Shore Hospital, St Leonards, New South Wales, Australia
- Faculty of Medicine and Health, University of Sydney, Sydney, New South Wales, Australia
| | - Karin R Aubrey
- Pain Management Research Institute, Kolling Institute, Royal North Shore Hospital, St Leonards, New South Wales, Australia
- Faculty of Medicine and Health, University of Sydney, Sydney, New South Wales, Australia
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2
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Untiet V. Astrocytic chloride regulates brain function in health and disease. Cell Calcium 2024; 118:102855. [PMID: 38364706 DOI: 10.1016/j.ceca.2024.102855] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2023] [Revised: 02/02/2024] [Accepted: 02/06/2024] [Indexed: 02/18/2024]
Abstract
Chloride ions (Cl-) play a pivotal role in synaptic inhibition in the central nervous system, primarily mediated through ionotropic mechanisms. A recent breakthrough emphathizes the significant influence of astrocytic intracellular chloride concentration ([Cl-]i) regulation, a field still in its early stages of exploration. Typically, the [Cl-]i in most animal cells is maintained at lower levels than the extracellular chloride [Cl-]o, a critical balance to prevent cell swelling due to osmotic pressure. Various Cl- transporters are expressed differently across cell types, fine-tuning the [Cl-]i, while Cl- gradients are utilised by several families of Cl- channels. Although the passive distribution of ions within cells is governed by basic biophysical principles, astrocytes actively expend energy to sustain [Cl-]i at much higher levels than those achieved passively, and much higher than neuronal [Cl-]i. Beyond the role in volume regulation, astrocytic [Cl-]i is dynamically linked to brain states and influences neuronal signalling in actively behaving animals. As a vital component of brain function, astrocytic [Cl-]i also plays a role in the development of disorders where inhibitory transmission is disrupted. This review synthesises the latest insights into astrocytic [Cl-]i, elucidating its role in modulating brain function and its implications in various pathophysiological conditions.
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Affiliation(s)
- Verena Untiet
- Division of Glial Disease and Therapeutics, Center for Translational Neuromedicine, University of Copenhagen, 2200 Copenhagen, Denmark.
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3
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Cortese K, Gagliani MC, Raiteri L. Interactions between Glycine and Glutamate through Activation of Their Transporters in Hippocampal Nerve Terminals. Biomedicines 2023; 11:3152. [PMID: 38137373 PMCID: PMC10740625 DOI: 10.3390/biomedicines11123152] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2023] [Revised: 11/14/2023] [Accepted: 11/17/2023] [Indexed: 12/24/2023] Open
Abstract
Evidence supports the pathophysiological relevance of crosstalk between the neurotransmitters Glycine and Glutamate and their close interactions; some reports even support the possibility of Glycine-Glutamate cotransmission in central nervous system (CNS) areas, including the hippocampus. Functional studies with isolated nerve terminals (synaptosomes) permit us to study transporter-mediated interactions between neurotransmitters that lead to the regulation of transmitter release. Our main aims here were: (i) to investigate release-regulating, transporter-mediated interactions between Glycine and Glutamate in hippocampal nerve terminals and (ii) to determine the coexistence of transporters for Glycine and Glutamate in these terminals. Purified synaptosomes, analyzed at the ultrastructural level via electron microscopy, were used as the experimental model. Mouse hippocampal synaptosomes were prelabeled with [3H]D-Aspartate or [3H]Glycine; the release of radiolabeled tracers was monitored with the superfusion technique. The main findings were that (i) exogenous Glycine stimulated [3H]D-Aspartate release, partly by activation of GlyT1 and in part, unusually, through GlyT2 transporters and that (ii) D-Aspartate stimulated [3H]glycine release by a process that was sensitive to Glutamate transporter blockers. Based on the features of the experimental model used, it is suggested that functional transporters for Glutamate and Glycine coexist in a small subset of hippocampal nerve terminals, a condition that may also be compatible with cotransmission; glycinergic and glutamatergic transporters exhibit different functions and mediate interactions between the neurotransmitters. It is hoped that increased information on Glutamate-Glycine interactions in different areas, including the hippocampus, will contribute to a better knowledge of drugs acting at "glycinergic" targets, currently under study in relation with different CNS pathologies.
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Affiliation(s)
- Katia Cortese
- Department of Experimental Medicine (DIMES), Cellular Electron Microscopy Lab, University of Genoa, 16132 Genoa, Italy; (K.C.); (M.C.G.)
| | - Maria Cristina Gagliani
- Department of Experimental Medicine (DIMES), Cellular Electron Microscopy Lab, University of Genoa, 16132 Genoa, Italy; (K.C.); (M.C.G.)
| | - Luca Raiteri
- Department of Pharmacy (DIFAR), Pharmacology and Toxicology Section, University of Genoa, 16148 Genoa, Italy
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4
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Piniella D, Zafra F. Functional crosstalk of the glycine transporter GlyT1 and NMDA receptors. Neuropharmacology 2023; 232:109514. [PMID: 37003571 DOI: 10.1016/j.neuropharm.2023.109514] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2022] [Revised: 03/10/2023] [Accepted: 03/20/2023] [Indexed: 04/03/2023]
Abstract
NMDA-type glutamate receptors (NMDARs) constitute one of the main glutamate (Glu) targets in the central nervous system and are involved in synaptic plasticity, which is the molecular substrate of learning and memory. Hypofunction of NMDARs has been associated with schizophrenia, while overstimulation causes neuronal death in neurodegenerative diseases or in stroke. The function of NMDARs requires coincidental binding of Glu along with other cellular signals such as neuronal depolarization, and the presence of other endogenous ligands that modulate their activity by allosterism. Among these allosteric modulators are zinc, protons and Gly, which is an obligatory co-agonist. These characteristics differentiate NMDARs from other receptors, and their structural bases have begun to be established in recent years. In this review we focus on the crosstalk between Glu and glycine (Gly), whose concentration in the NMDAR microenvironment is maintained by various Gly transporters that remove or release it into the medium in a regulated manner. The GlyT1 transporter is particularly involved in this task, and has become a target of great interest for the treatment of schizophrenia since its inhibition leads to an increase in synaptic Gly levels that enhances the activity of NMDARs. However, the only drug that has completed phase III clinical trials did not yield the expected results. Notwithstanding, there are additional drugs that continue to be investigated, and it is hoped that knowledge gained from the recently published 3D structure of GlyT1 may allow the rational design of more effective new drugs.
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Affiliation(s)
- Dolores Piniella
- Centro de Biología Molecular Severo Ochoa, Facultad de Ciencias, Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, Madrid, Spain; IdiPAZ, Institute of Health Carlos III (ISCIII), Spain
| | - Francisco Zafra
- Centro de Biología Molecular Severo Ochoa, Facultad de Ciencias, Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, Madrid, Spain; IdiPAZ, Institute of Health Carlos III (ISCIII), Spain.
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Kuhse J, Groeneweg F, Kins S, Gorgas K, Nawrotzki R, Kirsch J, Kiss E. Loss of Extrasynaptic Inhibitory Glycine Receptors in the Hippocampus of an AD Mouse Model Is Restored by Treatment with Artesunate. Int J Mol Sci 2023; 24:ijms24054623. [PMID: 36902054 PMCID: PMC10002537 DOI: 10.3390/ijms24054623] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Revised: 02/14/2023] [Accepted: 02/22/2023] [Indexed: 03/06/2023] Open
Abstract
Alzheimer's disease (AD) is characterized by synaptic failure and neuronal loss. Recently, we demonstrated that artemisinins restored the levels of key proteins of inhibitory GABAergic synapses in the hippocampus of APP/PS1 mice, a model of cerebral amyloidosis. In the present study, we analyzed the protein levels and subcellular localization of α2 and α3 subunits of GlyRs, indicated as the most abundant receptor subtypes in the mature hippocampus, in early and late stages of AD pathogenesis, and upon treatment with two different doses of artesunate (ARS). Immunofluorescence microscopy and Western blot analysis demonstrated that the protein levels of both α2 and α3 GlyRs are considerably reduced in the CA1 and the dentate gyrus of 12-month-old APP/PS1 mice when compared to WT mice. Notably, treatment with low-dose ARS affected GlyR expression in a subunit-specific way; the protein levels of α3 GlyR subunits were rescued to about WT levels, whereas that of α2 GlyRs were not affected significantly. Moreover, double labeling with a presynaptic marker indicated that the changes in GlyR α3 expression levels primarily involve extracellular GlyRs. Correspondingly, low concentrations of artesunate (≤1 µM) also increased the extrasynaptic GlyR cluster density in hAPPswe-transfected primary hippocampal neurons, whereas the number of GlyR clusters overlapping presynaptic VIAAT immunoreactivities remained unchanged. Thus, here we provide evidence that the protein levels and subcellular localization of α2 and α3 subunits of GlyRs show regional and temporal alterations in the hippocampus of APP/PS1 mice that can be modulated by the application of artesunate.
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Affiliation(s)
- Jochen Kuhse
- Institute of Anatomy and Cell Biology, University of Heidelberg, 69117 Heidelberg, Germany
| | - Femke Groeneweg
- Institute of Anatomy and Cell Biology, University of Heidelberg, 69117 Heidelberg, Germany
- Institute of Neuroanatomy, Medical Faculty Mannheim, University Heidelberg, 68167 Mannheim, Germany
| | - Stefan Kins
- Department of Human Biology and Human Genetics, University of Kaiserslautern-Landau, 67663 Kaiserslautern, Germany
| | - Karin Gorgas
- Institute of Anatomy and Cell Biology, University of Heidelberg, 69117 Heidelberg, Germany
| | - Ralph Nawrotzki
- Institute of Anatomy and Cell Biology, University of Heidelberg, 69117 Heidelberg, Germany
| | - Joachim Kirsch
- Institute of Anatomy and Cell Biology, University of Heidelberg, 69117 Heidelberg, Germany
| | - Eva Kiss
- Institute of Anatomy and Cell Biology, University of Heidelberg, 69117 Heidelberg, Germany
- Department of Cellular and Molecular Biology, George Emil Palade University of Medicine, Pharmacy, Science and Technology of Târgu Mureș, 540142 Târgu Mures, Romania
- Correspondence:
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Solntseva EI, Bukanova JV, Skrebitsky VG, Kudova E. Pregnane neurosteroids exert opposite effects on GABA and glycine-induced chloride current in isolated rat neurons. Hippocampus 2022; 32:552-563. [PMID: 35703084 DOI: 10.1002/hipo.23449] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Revised: 05/16/2022] [Accepted: 06/01/2022] [Indexed: 11/11/2022]
Abstract
The ability of endogenous neurosteroids (NSs) with pregnane skeleton modified at positions C-3 and C-5 to modulate the functional activity of inhibitory glycine receptors (GlyR) and ionotropic ɣ-aminobutyric acid receptors (GABAA R) was estimated. The glycine and GABA-induced chloride current (IGly and IGABA ) were measured in isolated pyramidal neurons of the rat hippocampus and in isolated rat cerebellar Purkinje cells, respectively. Our experiments demonstrated that pregnane NSs affected IGABA and IGly in a different manner. At low concentrations (up to 5 μM), tested pregnane NSs increased or did not change the peak amplitude of the IGABA , but reduced the IGly by decreasing the peak amplitude and/or accelerating desensitization. Namely, allopregnanolone (ALLO), epipregnanolone (EPI), pregnanolone (PA), pregnanolone sulfate (PAS) and 5β-dihydroprogesterone (5β-DHP) enhanced the IGABA in Purkinje cells. Dose-response curves plotted in the concentration range from 1 nM to 100 μM were smooth for EPI and 5β-DHP, but bell-shaped for ALLO, PA and PAS. The peak amplitude of the IGly was reduced by PA, PAS, and 5α- and 5β-DHP. In contrast, ALLO, ISO and EPI did not modulate it. Dose-response curves for the inhibition of the IGly peak amplitude were smooth for all active compounds. All NSs accelerated desensitization of the IGly . The dose-response relationship for this effect was smooth for ALLO, PA, PAS and 5β-DHP, but it was U-shaped for EPI, 5α-DHP and ISO. These results, together with our previous results on NSs with androstane skeleton, offer comprehensive overview for understanding the mechanisms of effects of NSs on IGly and IGABA .
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Affiliation(s)
- Elena I Solntseva
- Functional Synaptology Laboratory, Brain Research Department, Research Center of Neurology, Moscow, Russia
| | - Julia V Bukanova
- Functional Synaptology Laboratory, Brain Research Department, Research Center of Neurology, Moscow, Russia
| | - Vladimir G Skrebitsky
- Functional Synaptology Laboratory, Brain Research Department, Research Center of Neurology, Moscow, Russia
| | - Eva Kudova
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Prague, Czech Republic
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Eulenburg V, Hülsmann S. Synergistic Control of Transmitter Turnover at Glycinergic Synapses by GlyT1, GlyT2, and ASC-1. Int J Mol Sci 2022; 23:ijms23052561. [PMID: 35269698 PMCID: PMC8909939 DOI: 10.3390/ijms23052561] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Revised: 02/21/2022] [Accepted: 02/23/2022] [Indexed: 01/25/2023] Open
Abstract
In addition to being involved in protein biosynthesis and metabolism, the amino acid glycine is the most important inhibitory neurotransmitter in caudal regions of the brain. These functions require a tight regulation of glycine concentration not only in the synaptic cleft, but also in various intracellular and extracellular compartments. This is achieved not only by confining the synthesis and degradation of glycine predominantly to the mitochondria, but also by the action of high-affinity large-capacity glycine transporters that mediate the transport of glycine across the membranes of presynaptic terminals or glial cells surrounding the synapses. Although most cells at glycine-dependent synapses express more than one transporter with high affinity for glycine, their synergistic functional interaction is only poorly understood. In this review, we summarize our current knowledge of the two high-affinity transporters for glycine, the sodium-dependent glycine transporters 1 (GlyT1; SLC6A9) and 2 (GlyT2; SLC6A5) and the alanine–serine–cysteine-1 transporter (Asc-1; SLC7A10).
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Affiliation(s)
- Volker Eulenburg
- Department for Anesthesiology and Intensive Care, Faculty of Medicine, University of Leipzig, Liebigstraße 20, D-04103 Leipzig, Germany
- Correspondence: (V.E.); (S.H.)
| | - Swen Hülsmann
- Department for Anesthesiology, University Medical Center, Georg-August University, Humboldtallee 23, D-37073 Göttingen, Germany
- Correspondence: (V.E.); (S.H.)
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8
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Bregestovski PD, Ponomareva DN. Photochromic Modulation of Cys-loop
Ligand-gated Ion Channels. J EVOL BIOCHEM PHYS+ 2021. [DOI: 10.1134/s0022093021020162] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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9
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The anticonvulsant zonisamide positively modulates recombinant and native glycine receptors at clinically relevant concentrations. Neuropharmacology 2020; 182:108371. [PMID: 33122032 DOI: 10.1016/j.neuropharm.2020.108371] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Revised: 09/04/2020] [Accepted: 10/23/2020] [Indexed: 12/29/2022]
Abstract
GABAA and glycine receptors mediate fast synaptic inhibitory neurotransmission. Despite studies showing that activation of cerebral glycine receptors could be a potential strategy in the treatment of epilepsy, few studies have assessed the effects of existing anticonvulsant therapies on recombinant or native glycine receptors. We, therefore, evaluated the actions of a series of anticonvulsants at recombinant human homo-oligomeric glycine receptor α1, α2 and α3 subtypes expressed in Xenopus oocytes using two-electrode voltage-clamp methods, and then assessed the most effective drug at native glycine receptors from entorhinal cortex neurons using whole-cell voltage-clamp recordings. Ganaxolone, tiagabine and zonisamide positively modulated glycine induced currents at recombinant homomeric glycine receptors. Of these, zonisamide was the most efficacious and exhibited an EC50 value ranging between 450 and 560 μM at α1, α2 and α3 subtypes. These values were not significantly different indicating a non-selective modulation of glycine receptors. Using a therapeutic concentration of zonisamide (100 μM), the potency of glycine was significantly shifted from 106 to 56 μM at α1, 185 to 112 μM at α2, and 245 to 91 μM at α3 receptors. Furthermore, zonisamide (100 μM) potentiated exogenous homomeric and heteromeric glycine mediated currents from layer II pyramidal cells of the lateral or medial entorhinal cortex. As therapeutic concentrations of zonisamide positively modulate recombinant and native glycine receptors, we propose that the anticonvulsant effects of zonisamide may, at least in part, be mediated via this action.
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Nguyen HTT, Jang SH, Park SJ, Cho DH, Han SK. Potentiation of the Glycine Response by Bisphenol A, an Endocrine Disrupter, on the Substantia Gelatinosa Neurons of the Trigeminal Subnucleus Caudalis in Mice. Chem Res Toxicol 2020; 33:782-788. [PMID: 31997638 DOI: 10.1021/acs.chemrestox.9b00405] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Lamina II, also called the substantia gelatinosa (SG) of the medullary dorsal horn (the trigeminal subnucleus caudalis, Vc), is thought to play an essential role in the control of orofacial nociception because it receives the nociceptive signals from primary afferents, including thin myelinated Aδ- and unmyelinated C-fibers. Glycine, the main inhibitory neurotransmitter in the central nervous system, plays an essential role in the transference of nociceptive messages from the periphery to higher brain regions. Bisphenol A (BPA) is reported to alter the morphological and functional characteristics of neuronal cells and to be an effector of a great number of ion channels in the central nervous system. However, the electrophysiological effects of BPA on the glycine receptors of SG neurons in the Vc have not been well studied. Therefore, in this study, we used the whole-cell patch-clamp technique to determine the effect of BPA on the glycine response in SG neurons of the Vc in male mice. We demonstrated that in early neonatal mice (0-3 postnatal day mice), BPA did not affect the glycine-induced inward current. However, in the juvenile and adult groups, BPA enhanced the glycine-mediated responses. Heteromeric glycine receptors were involved in the modulation by BPA. The interaction between BPA and glycine appears to have a significant role in regulating transmission in the nociceptive pathway.
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Affiliation(s)
- Hoang Thi Thanh Nguyen
- Department of Oral Physiology, School of Dentistry and Institute of Oral Bioscience, Jeonbuk National University, Jeonju, 54896, Republic of Korea.,Faculty of Odonto-Stomatology, Hue University of Medicine and Pharmacy, Hue University, Hue, Vietnam
| | - Seon Hui Jang
- Department of Oral Physiology, School of Dentistry and Institute of Oral Bioscience, Jeonbuk National University, Jeonju, 54896, Republic of Korea
| | - Soo Joung Park
- Department of Oral Physiology, School of Dentistry and Institute of Oral Bioscience, Jeonbuk National University, Jeonju, 54896, Republic of Korea
| | - Dong Hyu Cho
- Department of Obstetrics and Gynecology, Jeonbuk National University Medical School, Institute of Clinical Medicine of Jeonbuk National University-Biomedical Research Institute and Institute for Medical Sciences, Jeonbuk National University Hospital, Jeonju, 54907, Republic of Korea
| | - Seong Kyu Han
- Department of Oral Physiology, School of Dentistry and Institute of Oral Bioscience, Jeonbuk National University, Jeonju, 54896, Republic of Korea
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Sato K. Why does a steep caudal-rostral gradient exist in glycine content in the brain? Med Hypotheses 2018; 120:1-3. [DOI: 10.1016/j.mehy.2018.08.010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2018] [Revised: 08/01/2018] [Accepted: 08/07/2018] [Indexed: 10/28/2022]
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12
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Zafra F, Ibáñez I, Bartolomé-Martín D, Piniella D, Arribas-Blázquez M, Giménez C. Glycine Transporters and Its Coupling with NMDA Receptors. ADVANCES IN NEUROBIOLOGY 2018; 16:55-83. [PMID: 28828606 DOI: 10.1007/978-3-319-55769-4_4] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Glycine plays two roles in neurotransmission. In caudal areas like the spinal cord and the brainstem, it acts as an inhibitory neurotransmitter, but in all regions of the CNS, it also works as a co-agonist with L-glutamate at N-methyl-D-aspartate receptors (NMDARs). The glycine fluxes in the CNS are regulated by two specific transporters for glycine, GlyT1 and GlyT2, perhaps with the cooperation of diverse neutral amino acid transporters like Asc-1 or SNAT5/SN2. While GlyT2 and Asc-1 are neuronal proteins, GlyT1 and SNAT5 are mainly astrocytic, although neuronal forms of GlyT1 also exist. GlyT1 has attracted considerable interest from the medical community and the pharmaceutical industry since compelling evidence indicates a clear association with the functioning of NMDARs, whose activity is decreased in various psychiatric illnesses. By controlling extracellular glycine, transporter inhibitors might potentiate the activity of NMDARs without activating excitotoxic processes. Physiologically, GlyT1 is a central actor in the cross talk between glutamatergic, glycinergic, dopaminergic, and probably other neurotransmitter systems. Many of these relationships begin to be unraveled by studies performed in recent years using genetic and pharmacological models. These studies are also clarifying the interactions between glycine, glycine transporters, and other co-agonists of the glycine site of NMDARs like D-serine. These findings are also relevant to understand the pathophysiology of devastating diseases like schizophrenia, depression, anxiety, epilepsy, stroke, and chronic pain.
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Affiliation(s)
- Francisco Zafra
- Centro de Biología Molecular Severo Ochoa, Facultad de Ciencias, Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, C / Nicolás Cabrera, 1, 28049, Madrid, Spain. .,Centro de Investigación Biomédica en Red de Enfermedades Raras and IdiPAZ, Instituto de Salud Carlos III, Madrid, Spain.
| | - Ignacio Ibáñez
- Centro de Biología Molecular Severo Ochoa, Facultad de Ciencias, Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, C / Nicolás Cabrera, 1, 28049, Madrid, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Raras and IdiPAZ, Instituto de Salud Carlos III, Madrid, Spain
| | - David Bartolomé-Martín
- Centro de Biología Molecular Severo Ochoa, Facultad de Ciencias, Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, C / Nicolás Cabrera, 1, 28049, Madrid, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Raras and IdiPAZ, Instituto de Salud Carlos III, Madrid, Spain
| | - Dolores Piniella
- Centro de Biología Molecular Severo Ochoa, Facultad de Ciencias, Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, C / Nicolás Cabrera, 1, 28049, Madrid, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Raras and IdiPAZ, Instituto de Salud Carlos III, Madrid, Spain
| | - Marina Arribas-Blázquez
- Centro de Biología Molecular Severo Ochoa, Facultad de Ciencias, Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, C / Nicolás Cabrera, 1, 28049, Madrid, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Raras and IdiPAZ, Instituto de Salud Carlos III, Madrid, Spain
| | - Cecilio Giménez
- Centro de Biología Molecular Severo Ochoa, Facultad de Ciencias, Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, C / Nicolás Cabrera, 1, 28049, Madrid, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Raras and IdiPAZ, Instituto de Salud Carlos III, Madrid, Spain
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13
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Monitoring hippocampal glycine with the computationally designed optical sensor GlyFS. Nat Chem Biol 2018; 14:861-869. [DOI: 10.1038/s41589-018-0108-2] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2017] [Accepted: 06/21/2018] [Indexed: 01/01/2023]
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14
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Lagache T, Grassart A, Dallongeville S, Faklaris O, Sauvonnet N, Dufour A, Danglot L, Olivo-Marin JC. Mapping molecular assemblies with fluorescence microscopy and object-based spatial statistics. Nat Commun 2018; 9:698. [PMID: 29449608 PMCID: PMC5814551 DOI: 10.1038/s41467-018-03053-x] [Citation(s) in RCA: 64] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Accepted: 01/17/2018] [Indexed: 12/20/2022] Open
Abstract
Elucidating protein functions and molecular organisation requires to localise precisely single or aggregated molecules and analyse their spatial distributions. We develop a statistical method SODA (Statistical Object Distance Analysis) that uses either micro- or nanoscopy to significantly improve on standard co-localisation techniques. Our method considers cellular geometry and densities of molecules to provide statistical maps of isolated and associated (coupled) molecules. We use SODA with three-colour structured-illumination microscopy (SIM) images of hippocampal neurons, and statistically characterise spatial organisation of thousands of synapses. We show that presynaptic synapsin is arranged in asymmetric triangle with the 2 postsynaptic markers homer and PSD95, indicating a deeper localisation of homer. We then determine stoichiometry and distance between localisations of two synaptic vesicle proteins with 3D-STORM. These findings give insights into the protein organisation at the synapse, and prove the efficiency of SODA to quantitatively assess the geometry of molecular assemblies.
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Affiliation(s)
- Thibault Lagache
- Institut Pasteur, BioImage Analysis Unit. CNRS UMR 3691. 25 rue du Docteur Roux, 75724, Paris Cedex 15, France
- Department of Biological Sciences, Columbia University, New York, NY, USA
| | - Alexandre Grassart
- Institut Pasteur, Molecular Microbial Pathogenesis Unit. INSERM U1202. 28 rue du Docteur Roux, 75724, Paris Cedex 15, France
| | - Stéphane Dallongeville
- Institut Pasteur, BioImage Analysis Unit. CNRS UMR 3691. 25 rue du Docteur Roux, 75724, Paris Cedex 15, France
| | - Orestis Faklaris
- CNRS UMR7592, Institut Jacques Monod, Université Paris Diderot, 15 rue Hélène Brion, 75013, Paris, France
| | - Nathalie Sauvonnet
- Institut Pasteur, Molecular Microbial Pathogenesis Unit. INSERM U1202. 28 rue du Docteur Roux, 75724, Paris Cedex 15, France
| | - Alexandre Dufour
- Institut Pasteur, BioImage Analysis Unit. CNRS UMR 3691. 25 rue du Docteur Roux, 75724, Paris Cedex 15, France
| | - Lydia Danglot
- Inserm U894 Center for Psychiatry and Neuroscience, Team Membrane traffic in healthy and diseased brain, 102-108 rue de la Santé, 75014, Paris, France.
| | - Jean-Christophe Olivo-Marin
- Institut Pasteur, BioImage Analysis Unit. CNRS UMR 3691. 25 rue du Docteur Roux, 75724, Paris Cedex 15, France.
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15
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Morais TP, Coelho D, Vaz SH, Sebastião AM, Valente CA. Glycine Receptor Activation Impairs ATP-Induced Calcium Transients in Cultured Cortical Astrocytes. Front Mol Neurosci 2018; 10:444. [PMID: 29386993 PMCID: PMC5776331 DOI: 10.3389/fnmol.2017.00444] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Accepted: 12/20/2017] [Indexed: 12/20/2022] Open
Abstract
In central nervous system, glycine receptor (GlyR) is mostly expressed in the spinal cord and brainstem, but glycinergic transmission related elements have also been identified in the brain. Astrocytes are active elements at the tripartite synapse, being responsible for the maintenance of brain homeostasis and for the fine-tuning of synaptic activity. These cells communicate, spontaneously or in response to a stimulus, by elevations in their cytosolic calcium (calcium transients, Ca2+T) that can be propagated to other cells. How these Ca2+T are negatively modulated is yet poorly understood. In this work, we evaluated GlyR expression and its role on calcium signaling modulation in rat brain astrocytes. We first proved that GlyR, predominantly subunits α2 and β, was expressed in brain astrocytes and its localization was confirmed in the cytoplasm and astrocytic processes by immunohistochemistry assays. Calcium imaging experiments in cultured astrocytes showed that glycine (500 μM), a GlyR agonist, caused a concentration-dependent reduction in ATP-induced Ca2+T, an effect abolished by the GlyR antagonist, strychnine (0.8 μM), as well as by nocodazole (1 μM), known to impair GlyR anchorage to the plasma membrane. This effect was mimicked by activation of GABAAR, another Cl--permeable channel. In summary, we demonstrated that GlyR activation in astrocytes mediates an inhibitory effect upon ATP induced Ca2+T, which most probably involves changes in membrane permeability to Cl- and requires GlyR anchorage at the plasma membrane. GlyR in astrocytes may thus be part of a mechanism to modulate astrocyte-to-neuron communication.
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Affiliation(s)
- Tatiana P. Morais
- Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal
| | - David Coelho
- Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal
| | - Sandra H. Vaz
- Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal
| | - Ana M. Sebastião
- Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal
| | - Cláudia A. Valente
- Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal
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16
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Redefining progressive encephalomyelitis with rigidity and myoclonus after the discovery of antibodies to glycine receptors. Curr Opin Neurol 2017; 30:310-316. [DOI: 10.1097/wco.0000000000000450] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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17
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Romei C, Bonifacino T, Milanese M, Usai C, Raiteri L. Colocalization of neurotransmitter transporters on the plasma membrane of the same nerve terminal may reflect cotransmission. Brain Res Bull 2016; 127:100-110. [DOI: 10.1016/j.brainresbull.2016.08.013] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Revised: 06/22/2016] [Accepted: 08/22/2016] [Indexed: 12/24/2022]
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18
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Advances in understanding the functions of native GlyT1 and GlyT2 neuronal glycine transporters. Neurochem Int 2016; 99:169-177. [DOI: 10.1016/j.neuint.2016.07.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2016] [Revised: 07/05/2016] [Accepted: 07/05/2016] [Indexed: 11/20/2022]
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19
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Microtubule-associated protein 1B (MAP1B)-deficient neurons show structural presynaptic deficiencies in vitro and altered presynaptic physiology. Sci Rep 2016; 6:30069. [PMID: 27425640 PMCID: PMC4948024 DOI: 10.1038/srep30069] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2016] [Accepted: 06/28/2016] [Indexed: 11/20/2022] Open
Abstract
Microtubule-associated protein 1B (MAP1B) is expressed predominantly during the early stages of development of the nervous system, where it regulates processes such as axonal guidance and elongation. Nevertheless, MAP1B expression in the brain persists in adult stages, where it participates in the regulation of the structure and physiology of dendritic spines in glutamatergic synapses. Moreover, MAP1B expression is also found in presynaptic synaptosomal preparations. In this work, we describe a presynaptic phenotype in mature neurons derived from MAP1B knockout (MAP1B KO) mice. Mature neurons express MAP1B, and its deficiency does not alter the expression levels of a subgroup of other synaptic proteins. MAP1B KO neurons display a decrease in the density of presynaptic and postsynaptic terminals, which involves a reduction in the density of synaptic contacts, and an increased proportion of orphan presynaptic terminals. Accordingly, MAP1B KO neurons present altered synaptic vesicle fusion events, as shown by FM4-64 release assay, and a decrease in the density of both synaptic vesicles and dense core vesicles at presynaptic terminals. Finally, an increased proportion of excitatory immature symmetrical synaptic contacts in MAP1B KO neurons was detected. Altogether these results suggest a novel role for MAP1B in presynaptic structure and physiology regulation in vitro.
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20
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Ogino K, Hirata H. Defects of the Glycinergic Synapse in Zebrafish. Front Mol Neurosci 2016; 9:50. [PMID: 27445686 PMCID: PMC4925712 DOI: 10.3389/fnmol.2016.00050] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Accepted: 06/13/2016] [Indexed: 12/26/2022] Open
Abstract
Glycine mediates fast inhibitory synaptic transmission. Physiological importance of the glycinergic synapse is well established in the brainstem and the spinal cord. In humans, the loss of glycinergic function in the spinal cord and brainstem leads to hyperekplexia, which is characterized by an excess startle reflex to sudden acoustic or tactile stimulation. In addition, glycinergic synapses in this region are also involved in the regulation of respiration and locomotion, and in the nociceptive processing. The importance of the glycinergic synapse is conserved across vertebrate species. A teleost fish, the zebrafish, offers several advantages as a vertebrate model for research of glycinergic synapse. Mutagenesis screens in zebrafish have isolated two motor defective mutants that have pathogenic mutations in glycinergic synaptic transmission: bandoneon (beo) and shocked (sho). Beo mutants have a loss-of-function mutation of glycine receptor (GlyR) β-subunit b, alternatively, sho mutant is a glycinergic transporter 1 (GlyT1) defective mutant. These mutants are useful animal models for understanding of glycinergic synaptic transmission and for identification of novel therapeutic agents for human diseases arising from defect in glycinergic transmission, such as hyperekplexia or glycine encephalopathy. Recent advances in techniques for genome editing and for imaging and manipulating of a molecule or a physiological process make zebrafish more attractive model. In this review, we describe the glycinergic defective zebrafish mutants and the technical advances in both forward and reverse genetic approaches as well as in vivo visualization and manipulation approaches for the study of the glycinergic synapse in zebrafish.
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Affiliation(s)
- Kazutoyo Ogino
- Department of Chemistry and Biological Science, College of Science and Engineering, Aoyama Gakuin University Sagamihara, Japan
| | - Hiromi Hirata
- Department of Chemistry and Biological Science, College of Science and Engineering, Aoyama Gakuin University Sagamihara, Japan
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21
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Meunier CNJ, Dallérac G, Le Roux N, Sacchi S, Levasseur G, Amar M, Pollegioni L, Mothet JP, Fossier P. D-Serine and Glycine Differentially Control Neurotransmission during Visual Cortex Critical Period. PLoS One 2016; 11:e0151233. [PMID: 27003418 PMCID: PMC4803205 DOI: 10.1371/journal.pone.0151233] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2015] [Accepted: 02/25/2016] [Indexed: 12/18/2022] Open
Abstract
N-methyl-D-aspartate receptors (NMDARs) play a central role in synaptic plasticity. Their activation requires the binding of both glutamate and d-serine or glycine as co-agonist. The prevalence of either co-agonist on NMDA-receptor function differs between brain regions and remains undetermined in the visual cortex (VC) at the critical period of postnatal development. Here, we therefore investigated the regulatory role that d-serine and/or glycine may exert on NMDARs function and on synaptic plasticity in the rat VC layer 5 pyramidal neurons of young rats. Using selective enzymatic depletion of d-serine or glycine, we demonstrate that d-serine and not glycine is the endogenous co-agonist of synaptic NMDARs required for the induction and expression of Long Term Potentiation (LTP) at both excitatory and inhibitory synapses. Glycine on the other hand is not involved in synaptic efficacy per se but regulates excitatory and inhibitory neurotransmission by activating strychnine-sensitive glycine receptors, then producing a shunting inhibition that controls neuronal gain and results in a depression of synaptic inputs at the somatic level after dendritic integration. In conclusion, we describe for the first time that in the VC both D-serine and glycine differentially regulate somatic depolarization through the activation of distinct synaptic and extrasynaptic receptors.
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Affiliation(s)
- Claire N. J. Meunier
- Institut de Neuroscience Paris-Saclay (NeuroPSI), UMR 9197 CNRS-Université Paris-Sud, Bât 446, F-91405, Orsay cedex, France
| | - Glenn Dallérac
- Aix-Marseille University, CRN2M UMR7286 CNRS, 51 Bd Pierre Dramard, 13344, Marseille, France
| | - Nicolas Le Roux
- Institut de Neuroscience Paris-Saclay (NeuroPSI), UMR 9197 CNRS-Université Paris-Sud, Bât 446, F-91405, Orsay cedex, France
| | - Silvia Sacchi
- Dipartimento di Biotecnologie e Scienze della Vita, Università degli Studi dell’Insubria, via J.H. Dunant 3, Varese, Italy
- “The Protein Factory”, Centro Interuniversitario di Biotecnologie Proteiche, Politecnico di Milano, ICRM-CNR, Milano, Italy
- Università degli Studi dell’Insubria, via Mancinelli 7, Milano, Italy
| | - Grégoire Levasseur
- Aix-Marseille University, CRN2M UMR7286 CNRS, 51 Bd Pierre Dramard, 13344, Marseille, France
| | - Muriel Amar
- Institut de Neuroscience Paris-Saclay (NeuroPSI), UMR 9197 CNRS-Université Paris-Sud, Bât 446, F-91405, Orsay cedex, France
| | - Loredano Pollegioni
- Dipartimento di Biotecnologie e Scienze della Vita, Università degli Studi dell’Insubria, via J.H. Dunant 3, Varese, Italy
- “The Protein Factory”, Centro Interuniversitario di Biotecnologie Proteiche, Politecnico di Milano, ICRM-CNR, Milano, Italy
- Università degli Studi dell’Insubria, via Mancinelli 7, Milano, Italy
| | - Jean-Pierre Mothet
- Aix-Marseille University, CRN2M UMR7286 CNRS, 51 Bd Pierre Dramard, 13344, Marseille, France
- * E-mail: (PF); (JPM)
| | - Philippe Fossier
- Institut de Neuroscience Paris-Saclay (NeuroPSI), UMR 9197 CNRS-Université Paris-Sud, Bât 446, F-91405, Orsay cedex, France
- * E-mail: (PF); (JPM)
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22
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Guan YZ, Ye JH. Glycine blocks long-term potentiation of GABAergic synapses in the ventral tegmental area. Neuroscience 2016; 318:134-42. [PMID: 26806277 DOI: 10.1016/j.neuroscience.2016.01.017] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2015] [Revised: 01/07/2016] [Accepted: 01/08/2016] [Indexed: 10/22/2022]
Abstract
The mesocorticolimbic dopamine system, originating in the ventral tegmental area (VTA) is normally constrained by GABA-mediated synaptic inhibition. Accumulating evidence indicates that long-term potentiation of GABAergic synapses (LTPGABA) in VTA dopamine neurons plays an important role in the actions of drugs of abuse, including ethanol. We previously showed that a single infusion of glycine into the VTA of rats strongly reduces ethanol intake for 24h. In the current study, we examined the effect of glycine on the electrophysiological activities of putative dopamine VTA neurons in midbrain slices from ethanol-naïve rats. We report here that a 15-min exposure to 10 μM glycine prevented trains of high-frequency stimulation (HFS) from producing LTPGABA, which was rescued by the glycine receptor (GlyR) antagonist strychnine. Glycine also concentration-dependently decreased the frequency of spontaneous excitatory postsynaptic currents (sEPSCs). By contrast, glycine pretreatment did not prevent potentiation of inhibitory postsynaptic currents (IPSCs) during a continuous exposure to the nitric oxide (NO) donor, SNAP (S-nitroso-N-acetylpenicillamine), or a brief exposure to 10 μM glycine and 10 μM NMDA (N-methyl-D-aspartate), an agonist of NMDA-type glutamate receptors. Thus, the blockade of LTPGABA by glycine is probably resulted from suppressing glutamate release by activating the GlyRs on the glutamatergic terminals. This effect of glycine may contribute to the reduction in ethanol intake induced by intra-VTA glycine observed in vivo.
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Affiliation(s)
- Y-Z Guan
- Department of Anesthesiology, Pharmacology and Physiology, Rutgers, The State University of New Jersey, New Jersey Medical School, Newark, NJ, USA; Department of Physiology, Mudanjiang Medical University, Mudanjiang, China.
| | - J-H Ye
- Department of Anesthesiology, Pharmacology and Physiology, Rutgers, The State University of New Jersey, New Jersey Medical School, Newark, NJ, USA.
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23
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Aroeira RI, Sebastião AM, Valente CA. BDNF, via truncated TrkB receptor, modulates GlyT1 and GlyT2 in astrocytes. Glia 2015. [DOI: 10.1002/glia.22884] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Affiliation(s)
- Rita I. Aroeira
- Faculty of Medicine, Institute of Pharmacology and Neurosciences, and Unit of Neurosciences, Institute of Molecular Medicine, University of Lisbon; Av. Prof. Egas Moniz Lisbon Portugal
| | - Ana M. Sebastião
- Faculty of Medicine, Institute of Pharmacology and Neurosciences, and Unit of Neurosciences, Institute of Molecular Medicine, University of Lisbon; Av. Prof. Egas Moniz Lisbon Portugal
| | - Cláudia A. Valente
- Faculty of Medicine, Institute of Pharmacology and Neurosciences, and Unit of Neurosciences, Institute of Molecular Medicine, University of Lisbon; Av. Prof. Egas Moniz Lisbon Portugal
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24
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Chen Z, Hu B, Wang F, Du L, Huang B, Li L, Qi J, Wang X. Glycine bidirectionally regulates ischemic tolerance via different mechanisms including NR2A-dependent CREB phosphorylation. J Neurochem 2015; 133:397-408. [PMID: 25418841 DOI: 10.1111/jnc.12994] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2014] [Revised: 11/07/2014] [Accepted: 11/12/2014] [Indexed: 10/24/2022]
Affiliation(s)
- Zheng Chen
- Division of Vascular Surgery, East Hospital; Tongji University School of Medicine; Shanghai China
- Department of Neurosurgery; First Affiliated Hospital of Nanjing Medical University; Nanjing China
- Laboratory of Brain Diseases; College of Basic Medicine; Nanjing University of Chinese Medicine; Nanjing China
| | - Bin Hu
- Jiangsu Key Laboratory of Brain Disease Bioinformation; Research Center for Biochemistry and Molecular Biology; Xuzhou Medical College; Xuzhou Jiangsu China
| | - Fuzhou Wang
- Department of Anesthesiology; Affiliated Nanjing Maternity and Child Health Care Hospital; Nanjing Medical University; Nanjing China
| | - Linlin Du
- Laboratory of Brain Diseases; College of Basic Medicine; Nanjing University of Chinese Medicine; Nanjing China
| | - Baosheng Huang
- Department of Neurosurgery; First Affiliated Hospital of Nanjing Medical University; Nanjing China
| | - Lixin Li
- Department of Neurosurgery; First Affiliated Hospital of Nanjing Medical University; Nanjing China
| | - Jia Qi
- Department of Pharmacy; Xinhua Hospital Affiliated to Shanghai Jiaotong University; Shanghai China
| | - Xiang Wang
- Division of Vascular Surgery, East Hospital; Tongji University School of Medicine; Shanghai China
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25
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Chumakov I, Nabirotchkin S, Cholet N, Milet A, Boucard A, Toulorge D, Pereira Y, Graudens E, Traoré S, Foucquier J, Guedj M, Vial E, Callizot N, Steinschneider R, Maurice T, Bertrand V, Scart-Grès C, Hajj R, Cohen D. Combining two repurposed drugs as a promising approach for Alzheimer's disease therapy. Sci Rep 2015; 5:7608. [PMID: 25566747 PMCID: PMC5378993 DOI: 10.1038/srep07608] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2014] [Accepted: 11/19/2014] [Indexed: 02/08/2023] Open
Abstract
Alzheimer disease (AD) represents a major medical problem where mono-therapeutic interventions demonstrated only a limited efficacy so far. We explored the possibility of developing a combinational therapy that might prevent the degradation of neuronal and endothelial structures in this disease. We argued that the distorted balance between excitatory (glutamate) and inhibitory (GABA/glycine) systems constitutes a therapeutic target for such intervention. We found that a combination of two approved drugs – acamprosate and baclofen – synergistically protected neurons and endothelial structures in vitro against amyloid-beta (Aβ) oligomers. The neuroprotective effects of these drugs were mediated by modulation of targets in GABA/glycinergic and glutamatergic pathways. In vivo, the combination alleviated cognitive deficits in the acute Aβ25–35 peptide injection model and in the mouse mutant APP transgenic model. Several patterns altered in AD were also synergistically normalised. Our results open up the possibility for a promising therapeutic approach for AD by combining repurposed drugs.
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Affiliation(s)
- Ilya Chumakov
- Pharnext, 11 rue des Peupliers, 92130 Issy-Les-Moulineaux, France
| | | | - Nathalie Cholet
- Pharnext, 11 rue des Peupliers, 92130 Issy-Les-Moulineaux, France
| | - Aude Milet
- Pharnext, 11 rue des Peupliers, 92130 Issy-Les-Moulineaux, France
| | - Aurélie Boucard
- Pharnext, 11 rue des Peupliers, 92130 Issy-Les-Moulineaux, France
| | - Damien Toulorge
- Pharnext, 11 rue des Peupliers, 92130 Issy-Les-Moulineaux, France
| | - Yannick Pereira
- Pharnext, 11 rue des Peupliers, 92130 Issy-Les-Moulineaux, France
| | - Esther Graudens
- Pharnext, 11 rue des Peupliers, 92130 Issy-Les-Moulineaux, France
| | - Sory Traoré
- Pharnext, 11 rue des Peupliers, 92130 Issy-Les-Moulineaux, France
| | - Julie Foucquier
- Pharnext, 11 rue des Peupliers, 92130 Issy-Les-Moulineaux, France
| | - Mickael Guedj
- Pharnext, 11 rue des Peupliers, 92130 Issy-Les-Moulineaux, France
| | - Emmanuel Vial
- Pharnext, 11 rue des Peupliers, 92130 Issy-Les-Moulineaux, France
| | | | | | - Tangui Maurice
- 1] Université de Montpellier 2, 34095 Montpellier, France; Inserm, U710, 34095 Montpellier, France; EPHE, 75017 Paris, France [2] Amylgen, 2196 bd de la Lironde, 34980 Montferrier-sur-Lez, France
| | - Viviane Bertrand
- Pharnext, 11 rue des Peupliers, 92130 Issy-Les-Moulineaux, France
| | | | - Rodolphe Hajj
- Pharnext, 11 rue des Peupliers, 92130 Issy-Les-Moulineaux, France
| | - Daniel Cohen
- Pharnext, 11 rue des Peupliers, 92130 Issy-Les-Moulineaux, France
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26
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Liu Y, Huang D, Wen R, Chen X, Yi H. Glycine receptor-mediated inhibition of medial prefrontal cortical pyramidal cells. Biochem Biophys Res Commun 2014; 456:666-9. [PMID: 25511697 DOI: 10.1016/j.bbrc.2014.12.014] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2014] [Accepted: 12/04/2014] [Indexed: 01/06/2023]
Abstract
Using whole-cell patch clamp recording on medial prefrontal cortical slices of rats aged 17-33 postnatal days, we demonstrated the glycine-induced strychnine-sensitive outward currents. The amplitude of the peak current increased with the concentrations of glycine with an EC50 of 74.7 μM. Application of 1μM strychnine alone to cells caused a slight inward current without blocking the sIPSCs, indicating that GlyRs in the mPFC are activated by an endogenous ligand that can be released tonically. Glycine reversibly depressed firing rate in cells from both layer 6 and layer 3, with significantly greater inhibition on the former than the latter (EC50 12.9 vs 85.6 μM). Glycine hyperpolarized membrane potential in cells of both layer 6 and layer 3 depending on its concentrations, with an IC50 of 99.1 and 207.2 μM, respectively. We propose that GlyRs participate in a novel inhibitory mechanism in mPFC, modulating neuronal activity. This finding further supports an important role of GlyR in cortical function and dysfunction.
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Affiliation(s)
- Yuwei Liu
- Department of Anatomy, School of Medicine, Jianghan University, Wuhan 430056, Hubei Province, China.
| | - Dan Huang
- Department of Physiology, School of Medicine, Jianghan University, Wuhan 430056, Hubei Province, China
| | - Ruojian Wen
- Department of Physiology, School of Medicine, Jianghan University, Wuhan 430056, Hubei Province, China
| | - Xiaoqing Chen
- Department of Pharmacology, School of Medicine, Jianghan University, Wuhan 430056, Hubei Province, China
| | - Huilin Yi
- Department of Anatomy, School of Medicine, Jianghan University, Wuhan 430056, Hubei Province, China
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27
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Zhang XY, Ji F, Wang N, Chen LL, Tian T, Lu W. Glycine induces bidirectional modifications in N-methyl-D-aspartate receptor-mediated synaptic responses in hippocampal CA1 neurons. J Biol Chem 2014; 289:31200-11. [PMID: 25231980 DOI: 10.1074/jbc.m114.570630] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Glycine can persistently potentiate or depress AMPA responses through differential actions on two binding sites: NMDA and glycine receptors. Whether glycine can induce long-lasting modifications in NMDA responses, however, remains unknown. Here, we report that glycine induces long-term potentiation (LTP) or long-term depression (LTD) of NMDA responses (Gly-LTP(NMDA) or Gly-LTD(NMDA)) in a dose-dependent manner in hippocampal CA1 neurons. These modifications of NMDA responses depend on NMDAR activation. In addition, the induction of Gly-LTP(NMDA) requires binding of glycine with NMDARs, whereas Gly-LTD(NMDA) requires that glycine bind with both sites on NMDARs and GlyRs. Moreover, activity-dependent exocytosis and endocytosis of postsynaptic NMDARs underlie glycine-induced bidirectional modification of NMDA excitatory postsynaptic currents. Thus, we conclude that glycine at different levels induces bidirectional plasticity of NMDA responses through differentially regulating NMDA receptor trafficking. Our present findings reveal important functions of the two glycine binding sites in gating the direction of synaptic plasticity in NMDA responses.
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Affiliation(s)
- Xiao-Yan Zhang
- From the Department of Neurobiology, Nanjing Medical University, Nanjing, Jiangsu Province 210029
| | - Fang Ji
- From the Department of Neurobiology, Nanjing Medical University, Nanjing, Jiangsu Province 210029
| | - Ning Wang
- From the Department of Neurobiology, Nanjing Medical University, Nanjing, Jiangsu Province 210029, The Key Laboratory of Developmental Genes and Human Disease, Ministry of Education, Institute of Life Sciences, Southeast University, Nanjing, Jiangsu Province 210096, China, and
| | - Lin-Lin Chen
- From the Department of Neurobiology, Nanjing Medical University, Nanjing, Jiangsu Province 210029
| | - Tian Tian
- From the Department of Neurobiology, Nanjing Medical University, Nanjing, Jiangsu Province 210029
| | - Wei Lu
- From the Department of Neurobiology, Nanjing Medical University, Nanjing, Jiangsu Province 210029, The Key Laboratory of Developmental Genes and Human Disease, Ministry of Education, Institute of Life Sciences, Southeast University, Nanjing, Jiangsu Province 210096, China, and Co-innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu Province 226001, China
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28
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Linsalata AE, Chen X, Winters CA, Reese TS. Electron tomography on γ-aminobutyric acid-ergic synapses reveals a discontinuous postsynaptic network of filaments. J Comp Neurol 2014; 522:921-36. [PMID: 23982982 DOI: 10.1002/cne.23453] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2012] [Revised: 08/05/2013] [Accepted: 08/13/2013] [Indexed: 12/16/2022]
Abstract
The regulation of synaptic strength at γ-aminobutyric acid (GABA)-ergic synapses is dependent on the dynamic capture, retention, and modulation of GABA A-type receptors by cytoplasmic proteins at GABAergic postsynaptic sites. How these proteins are oriented and organized in the postsynaptic cytoplasm is not yet established. To better understand these structures and gain further insight into the mechanisms by which they regulate receptor populations at postsynaptic sites, we utilized electron tomography to examine GABAergic synapses in dissociated rat hippocampal cultures. GABAergic synapses were identified and selected for tomography by using a set of criteria derived from the structure of immunogold-labeled GABAergic synapses. Tomography revealed a complex postsynaptic network composed of filaments that extend ∼ 100 nm into the cytoplasm from the postsynaptic membrane. The distribution of these postsynaptic filaments was strikingly similar to that of the immunogold label for gephyrin. Filaments were interconnected through uniform patterns of contact, forming complexes composed of 2-12 filaments each. Complexes did not link to form an integrated, continuous scaffold, suggesting that GABAergic postsynaptic specializations are less rigidly organized than glutamatergic postsynaptic densities.
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Affiliation(s)
- Alexander E Linsalata
- Laboratory of Neurobiology, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, 20892
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29
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Pinto MCX, Simão F, da Costa FLP, Rosa DV, de Paiva MJN, Resende RR, Romano-Silva MA, Gomez MV, Gomez RS. Sarcosine preconditioning induces ischemic tolerance against global cerebral ischemia. Neuroscience 2014; 271:160-9. [PMID: 24797328 DOI: 10.1016/j.neuroscience.2014.04.054] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2014] [Revised: 04/09/2014] [Accepted: 04/24/2014] [Indexed: 02/01/2023]
Abstract
Brain ischemic tolerance is an endogenous protective mechanism activated by a preconditioning stimulus that is closely related to N-methyl-d-aspartate receptor (NMDAR). Glycine transporter type 1 (GlyT-1) inhibitors potentiate NMDAR and suggest an alternative strategy for brain preconditioning. The aim of this work was to evaluate the effects of brain preconditioning induced by sarcosine, a GlyT-1 inhibitor, against global cerebral ischemia and its relation to NMDAR. Sarcosine was administered over 7 days (300 or 500 mg/kg/day, ip) before the induction of a global cerebral ischemia model in Wistar rats (male, 8-week-old). It was observed that sarcosine preconditioning reduced cell death in rat hippocampi submitted to cerebral ischemia. Hippocampal levels of glycine were decreased in sarcosine-treated animals, which was associated with a reduction of [(3)H] glycine uptake and a decrease in glycine transporter expression (GlyT-1 and GlyT-2). The expression of glycine receptors and the NR1 and NR2A subunits of NMDAR were not affected by sarcosine preconditioning. However, sarcosine preconditioning reduced the expression of the NR2B subunits of NMDAR. In conclusion, these data demonstrate that sarcosine preconditioning induces ischemic tolerance against global cerebral ischemia and this neuroprotective state is associated with changes in glycine transport and reduction of NR2B-containing NMDAR expression.
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Affiliation(s)
- M C X Pinto
- INCT de Medicina Molecular, Faculdade de Medicina, Universidade Federal de Minas Gerais, Avenida Alfredo Balena 190, 30130-100 Belo Horizonte, MG, Brazil; Departamento de Cirurgia, Faculdade de Medicina, Universidade Federal de Minas Gerais, Avenida Alfredo Balena, 190, 30130-100 Belo Horizonte, MG, Brazil.
| | - F Simão
- Laboratório de Neurociências, Instituto de Pesquisas Biomédicas, Pontifícia Universidade Católica do Rio Grande do Sul, Avenida Ipiranga 6690, 90610-000 Porto Alegre, RS, Brazil
| | - F L P da Costa
- INCT de Medicina Molecular, Faculdade de Medicina, Universidade Federal de Minas Gerais, Avenida Alfredo Balena 190, 30130-100 Belo Horizonte, MG, Brazil; Departamento de Cirurgia, Faculdade de Medicina, Universidade Federal de Minas Gerais, Avenida Alfredo Balena, 190, 30130-100 Belo Horizonte, MG, Brazil
| | - D V Rosa
- INCT de Medicina Molecular, Faculdade de Medicina, Universidade Federal de Minas Gerais, Avenida Alfredo Balena 190, 30130-100 Belo Horizonte, MG, Brazil
| | - M J N de Paiva
- Departamento de Bioquímica e Imunologia, Instituto de Ciência Biológicas, Universidade Federal de Minas Gerais, Avenida Antônio Carlos, 6627, 31270-901 Belo Horizonte, MG, Brazil
| | - R R Resende
- Departamento de Bioquímica e Imunologia, Instituto de Ciência Biológicas, Universidade Federal de Minas Gerais, Avenida Antônio Carlos, 6627, 31270-901 Belo Horizonte, MG, Brazil
| | - M A Romano-Silva
- INCT de Medicina Molecular, Faculdade de Medicina, Universidade Federal de Minas Gerais, Avenida Alfredo Balena 190, 30130-100 Belo Horizonte, MG, Brazil
| | - M V Gomez
- Instituto de Ensino e Pesquisa da Santa Casa de Belo Horizonte, R. Domingos Vieira, 590, Belo Horizonte, MG, Brazil
| | - R S Gomez
- Departamento de Cirurgia, Faculdade de Medicina, Universidade Federal de Minas Gerais, Avenida Alfredo Balena, 190, 30130-100 Belo Horizonte, MG, Brazil.
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30
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Amyloid β peptide (25–35) in picomolar concentrations modulates the function of glycine receptors in rat hippocampal pyramidal neurons through interaction with extracellular site(s). Brain Res 2014; 1558:1-10. [DOI: 10.1016/j.brainres.2014.02.031] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2013] [Revised: 02/14/2014] [Accepted: 02/17/2014] [Indexed: 01/08/2023]
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31
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Notelaers K, Rocha S, Paesen R, Swinnen N, Vangindertael J, Meier JC, Rigo JM, Ameloot M, Hofkens J. Membrane distribution of the glycine receptor α3 studied by optical super-resolution microscopy. Histochem Cell Biol 2014; 142:79-90. [PMID: 24553792 DOI: 10.1007/s00418-014-1197-y] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/09/2014] [Indexed: 11/24/2022]
Abstract
In this study, the effect of glycine receptor (GlyR) α3 alternative RNA splicing on the distribution of receptors in the membrane of human embryonic kidney 293 cells is investigated using optical super-resolution microscopy. Direct stochastic optical reconstruction microscopy is used to image both α3K and α3L splice variants individually and together using single- and dual-color imaging. Pair correlation analysis is used to extract quantitative measures from the resulting images. Autocorrelation analysis of the individually expressed variants reveals clustering of both variants, yet with differing properties. The cluster size is increased for α3L compared to α3K (mean radius 92 ± 4 and 56 ± 3 nm, respectively), yet an even bigger difference is found in the cluster density (9,870 ± 1,433 and 1,747 ± 200 μm(-2), respectively). Furthermore, cross-correlation analysis revealed that upon co-expression, clusters colocalize on the same spatial scales as for individually expressed receptors (mean co-cluster radius 94 ± 6 nm). These results demonstrate that RNA splicing determines GlyR α3 membrane distribution, which has consequences for neuronal GlyR physiology and function.
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Affiliation(s)
- Kristof Notelaers
- Biomedical Research Institute, Hasselt University and School of Life Sciences, Transnational University Limburg, Agoralaan Gebouw C, 3590, Diepenbeek, Belgium
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32
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Bukanova JV, Solntseva EI, Kondratenko RV, Skrebitsky VG. Glycine receptor in hippocampal neurons as a target for action of extracellular cyclic nucleotides. Neurosci Lett 2013; 561:58-63. [PMID: 24373992 DOI: 10.1016/j.neulet.2013.12.037] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2013] [Revised: 12/10/2013] [Accepted: 12/17/2013] [Indexed: 11/17/2022]
Abstract
Cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP) are well known intracellular second messengers. At present study, we describe the effects of extracellularly applied cAMP and cGMP on glycine-induced chloride currents (I(Gly)) in isolated rat hippocampal pyramidal neurons. 50 or 500 μM glycine was applied for 600 ms with 1 min intervals. cAMP and cGMP were co-applied with glycine. We found that both cAMP and cGMP rapidly, reversibly and in a dose-dependent manner accelerated the I(Gly) desensitization. The effect was more prominent on I(Gly) induced by 500 μM than by 50 μM glycine. Dose-response curves were constructed in the 0.1-100,000 nM range of cAMP and cGMP concentrations. They demonstrate that threshold concentration of both compounds was about 1 nM and maximal effect was manifested at 100 nM. When cAMP and cGMP were added to the recording pipette, their extracellular application caused the effects similar to those obtained with normal intracellular medium. The effects of cyclic nucleotides remained unchanged in the presence of the antagonist of adenosine receptors in extracellular solution, and the agonist of adenosine receptors did not mimic the effect of cyclic nucleotides. The changes in the decay kinetics were equally pronounced at negative and positive membrane potentials. When co-administered 1 nM cAMP and 1 nM cGMP caused a weaker effect than either of the compounds alone which suggests a negative interaction between binding sites for cAMP and cGMP. This work describes a novel mode of action of cyclic nucleotides, namely, the modulation of GlyRs functions from extracellular side.
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Affiliation(s)
- Julia V Bukanova
- Research Center of Neurology, Russian Academy of Medical Sciences, Moscow, Russia
| | - Elena I Solntseva
- Research Center of Neurology, Russian Academy of Medical Sciences, Moscow, Russia.
| | - Rodion V Kondratenko
- Research Center of Neurology, Russian Academy of Medical Sciences, Moscow, Russia
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33
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Avila A, Nguyen L, Rigo JM. Glycine receptors and brain development. Front Cell Neurosci 2013; 7:184. [PMID: 24155690 PMCID: PMC3800850 DOI: 10.3389/fncel.2013.00184] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2013] [Accepted: 10/01/2013] [Indexed: 12/21/2022] Open
Abstract
Glycine receptors (GlyRs) are ligand-gated chloride ion channels that mediate fast inhibitory neurotransmission in the spinal cord and the brainstem. There, they are mainly involved in motor control and pain perception in the adult. However, these receptors are also expressed in upper regions of the central nervous system, where they participate in different processes including synaptic neurotransmission. Moreover, GlyRs are present since early stages of brain development and might influence this process. Here, we discuss the current state of the art regarding GlyRs during embryonic and postnatal brain development in light of recent findings about the cellular and molecular mechanisms that control brain development.
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Affiliation(s)
- Ariel Avila
- Cell Physiology, BIOMED Research Institute, Hasselt University Diepenbeek, Belgium ; Groupe Interdisciplinaire Génoprotéomique Appliquée-Neurosciences, Centre Hospitalier Universitaire Sart Tilman, University of Liége Liège, Belgium ; Groupe Interdisciplinaire Génoprotéomique Appliquée-Research, Centre Hospitalier Universitaire Sart Tilman, University of Liège Liège, Belgium
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34
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Muller E, Bakkar W, Martina M, Sokolovski A, Wong A, Legendre P, Bergeron R. Vesicular storage of glycine in glutamatergic terminals in mouse hippocampus. Neuroscience 2013; 242:110-27. [DOI: 10.1016/j.neuroscience.2013.03.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2013] [Revised: 03/06/2013] [Accepted: 03/10/2013] [Indexed: 11/15/2022]
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35
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Cox DJ, Racca C. Differential dendritic targeting of AMPA receptor subunit mRNAs in adult rat hippocampal principal neurons and interneurons. J Comp Neurol 2013; 521:1954-2007. [DOI: 10.1002/cne.23292] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2011] [Revised: 12/13/2012] [Accepted: 12/14/2012] [Indexed: 12/19/2022]
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36
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Gardella E, Romei C, Cavallero A, Trapella C, Fedele E, Raiteri L. Neuropeptide S inhibits release of 5-HT and glycine in mouse amygdala and frontal/prefrontal cortex through activation of the neuropeptide S receptor. Neurochem Int 2013; 62:360-6. [DOI: 10.1016/j.neuint.2013.02.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2012] [Revised: 01/29/2013] [Accepted: 02/04/2013] [Indexed: 01/27/2023]
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37
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Wlodarczyk AI, Sylantyev S, Herd MB, Kersanté F, Lambert JJ, Rusakov DA, Linthorst ACE, Semyanov A, Belelli D, Pavlov I, Walker MC. GABA-independent GABAA receptor openings maintain tonic currents. J Neurosci 2013; 33:3905-14. [PMID: 23447601 PMCID: PMC3591781 DOI: 10.1523/jneurosci.4193-12.2013] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2012] [Revised: 01/02/2013] [Accepted: 01/12/2013] [Indexed: 11/21/2022] Open
Abstract
Activation of GABA(A) receptors (GABA(A)Rs) produces two forms of inhibition: phasic inhibition generated by the rapid, transient activation of synaptic GABA(A)Rs by presynaptic GABA release, and tonic inhibition generated by the persistent activation of perisynaptic or extrasynaptic GABA(A)Rs, which can detect extracellular GABA. Such tonic GABA(A)R-mediated currents are particularly evident in dentate granule cells in which they play a major role in regulating cell excitability. Here we show that in rat dentate granule cells in ex vivo hippocampal slices, tonic currents are predominantly generated by GABA-independent GABA(A) receptor openings. This tonic GABA(A)R conductance is resistant to the competitive GABA(A)R antagonist SR95531 (gabazine), which at high concentrations acts as a partial agonist, but can be blocked by an open channel blocker, picrotoxin. When slices are perfused with 200 nm GABA, a concentration that is comparable to CSF concentrations but is twice that measured by us in the hippocampus in vivo using zero-net-flux microdialysis, negligible GABA is detected by dentate granule cells. Spontaneously opening GABA(A)Rs, therefore, maintain dentate granule cell tonic currents in the face of low extracellular GABA concentrations.
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Affiliation(s)
| | | | - Murray B. Herd
- Division of Neuroscience, Medical Research Institute, Ninewells Hospital & Medical School, Dundee University, Dundee DD1 9SY, United Kingdom
| | - Flavie Kersanté
- Henry Wellcome Laboratories for Integrative Neuroscience and Endocrinology, School of Clinical Sciences, University of Bristol, Bristol BS2 8AE, United Kingdom
| | - Jeremy J. Lambert
- Division of Neuroscience, Medical Research Institute, Ninewells Hospital & Medical School, Dundee University, Dundee DD1 9SY, United Kingdom
| | | | - Astrid C. E. Linthorst
- Henry Wellcome Laboratories for Integrative Neuroscience and Endocrinology, School of Clinical Sciences, University of Bristol, Bristol BS2 8AE, United Kingdom
| | - Alexey Semyanov
- RIKEN Brain Science Institute, Wako-shi 351-0114, Japan, and
- Nizhny Novgorod State University, Nizhny Novgorod 603000, Russia
| | - Delia Belelli
- Division of Neuroscience, Medical Research Institute, Ninewells Hospital & Medical School, Dundee University, Dundee DD1 9SY, United Kingdom
| | - Ivan Pavlov
- UCL Institute of Neurology, London WC1N 3BG, United Kingdom
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38
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Henneberger C, Bard L, King C, Jennings A, Rusakov DA. NMDA Receptor Activation: Two Targets for Two Co-Agonists. Neurochem Res 2013; 38:1156-62. [DOI: 10.1007/s11064-013-0987-2] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2013] [Revised: 01/27/2013] [Accepted: 01/28/2013] [Indexed: 12/01/2022]
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39
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Kunz PA, Burette AC, Weinberg RJ, Philpot BD. Glycine receptors support excitatory neurotransmitter release in developing mouse visual cortex. J Physiol 2012; 590:5749-64. [PMID: 22988142 DOI: 10.1113/jphysiol.2012.241299] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Glycine receptors (GlyRs) are found in most areas of the brain, and their dysfunction can cause severe neurological disorders. While traditionally thought of as inhibitory receptors, presynaptic-acting GlyRs (preGlyRs) can also facilitate glutamate release under certain circumstances, although the underlying molecular mechanisms are unknown. In the current study, we sought to better understand the role of GlyRs in the facilitation of excitatory neurotransmitter release in mouse visual cortex. Using whole-cell recordings, we found that preGlyRs facilitate glutamate release in developing, but not adult, visual cortex. The glycinergic enhancement of neurotransmitter release in early development depends on the high intracellular to extracellular Cl(-) gradient maintained by the Na(+)-K(+)-2Cl(-) cotransporter and requires Ca(2+) entry through voltage-gated Ca(2+) channels. The glycine transporter 1, localized to glial cells, regulates extracellular glycine concentration and the activation of these preGlyRs. Our findings demonstrate a developmentally regulated mechanism for controlling excitatory neurotransmitter release in the neocortex.
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Affiliation(s)
- Portia A Kunz
- Department of Cell Biology and Physiology, University of North Carolina School of Medicine, Campus Box 7545, 115 Mason Farm Rd, Chapel Hill, NC 27599-7545, USA
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40
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Yao W, Ji F, Chen Z, Zhang N, Ren SQ, Zhang XY, Liu SY, Lu W. Glycine Exerts Dual Roles in Ischemic Injury Through Distinct Mechanisms. Stroke 2012; 43:2212-20. [DOI: 10.1161/strokeaha.111.645994] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Wen Yao
- From the Department of Neurobiology, Nanjing Medical University, Nanjing (W.Y., F.J., Z.C., S.R., X.Z., S.L., W.L.); State Key Laboratory of Reproductive Medicine (W.L.); Key Laboratory for Neurodegenerative Disease of Jiangsu Province, Nanjing Medical University, Nanjing (W.Y., F.J., Z.C., N.Z., S.R., X.Z., S.L., W.L.); and Key Laboratory for Human Functional Genomics of Jiangsu Province (W.L.), China
| | - Fang Ji
- From the Department of Neurobiology, Nanjing Medical University, Nanjing (W.Y., F.J., Z.C., S.R., X.Z., S.L., W.L.); State Key Laboratory of Reproductive Medicine (W.L.); Key Laboratory for Neurodegenerative Disease of Jiangsu Province, Nanjing Medical University, Nanjing (W.Y., F.J., Z.C., N.Z., S.R., X.Z., S.L., W.L.); and Key Laboratory for Human Functional Genomics of Jiangsu Province (W.L.), China
| | - Zheng Chen
- From the Department of Neurobiology, Nanjing Medical University, Nanjing (W.Y., F.J., Z.C., S.R., X.Z., S.L., W.L.); State Key Laboratory of Reproductive Medicine (W.L.); Key Laboratory for Neurodegenerative Disease of Jiangsu Province, Nanjing Medical University, Nanjing (W.Y., F.J., Z.C., N.Z., S.R., X.Z., S.L., W.L.); and Key Laboratory for Human Functional Genomics of Jiangsu Province (W.L.), China
| | - Nan Zhang
- From the Department of Neurobiology, Nanjing Medical University, Nanjing (W.Y., F.J., Z.C., S.R., X.Z., S.L., W.L.); State Key Laboratory of Reproductive Medicine (W.L.); Key Laboratory for Neurodegenerative Disease of Jiangsu Province, Nanjing Medical University, Nanjing (W.Y., F.J., Z.C., N.Z., S.R., X.Z., S.L., W.L.); and Key Laboratory for Human Functional Genomics of Jiangsu Province (W.L.), China
| | - Si-Qiang Ren
- From the Department of Neurobiology, Nanjing Medical University, Nanjing (W.Y., F.J., Z.C., S.R., X.Z., S.L., W.L.); State Key Laboratory of Reproductive Medicine (W.L.); Key Laboratory for Neurodegenerative Disease of Jiangsu Province, Nanjing Medical University, Nanjing (W.Y., F.J., Z.C., N.Z., S.R., X.Z., S.L., W.L.); and Key Laboratory for Human Functional Genomics of Jiangsu Province (W.L.), China
| | - Xiao-Yan Zhang
- From the Department of Neurobiology, Nanjing Medical University, Nanjing (W.Y., F.J., Z.C., S.R., X.Z., S.L., W.L.); State Key Laboratory of Reproductive Medicine (W.L.); Key Laboratory for Neurodegenerative Disease of Jiangsu Province, Nanjing Medical University, Nanjing (W.Y., F.J., Z.C., N.Z., S.R., X.Z., S.L., W.L.); and Key Laboratory for Human Functional Genomics of Jiangsu Province (W.L.), China
| | - Su-Yi Liu
- From the Department of Neurobiology, Nanjing Medical University, Nanjing (W.Y., F.J., Z.C., S.R., X.Z., S.L., W.L.); State Key Laboratory of Reproductive Medicine (W.L.); Key Laboratory for Neurodegenerative Disease of Jiangsu Province, Nanjing Medical University, Nanjing (W.Y., F.J., Z.C., N.Z., S.R., X.Z., S.L., W.L.); and Key Laboratory for Human Functional Genomics of Jiangsu Province (W.L.), China
| | - Wei Lu
- From the Department of Neurobiology, Nanjing Medical University, Nanjing (W.Y., F.J., Z.C., S.R., X.Z., S.L., W.L.); State Key Laboratory of Reproductive Medicine (W.L.); Key Laboratory for Neurodegenerative Disease of Jiangsu Province, Nanjing Medical University, Nanjing (W.Y., F.J., Z.C., N.Z., S.R., X.Z., S.L., W.L.); and Key Laboratory for Human Functional Genomics of Jiangsu Province (W.L.), China
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41
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Piccolini V, Cerri S, Romanelli E, Bernocchi G. Interactions of neurotransmitter systems during postnatal development of the rat hippocampal formation: Effects of cisplatin. Exp Neurol 2012; 234:239-52. [DOI: 10.1016/j.expneurol.2011.12.044] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2011] [Revised: 12/21/2011] [Accepted: 12/25/2011] [Indexed: 01/14/2023]
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42
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Jonsson S, Morud J, Pickering C, Adermark L, Ericson M, Söderpalm B. Changes in glycine receptor subunit expression in forebrain regions of the Wistar rat over development. Brain Res 2012; 1446:12-21. [PMID: 22330726 DOI: 10.1016/j.brainres.2012.01.050] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2011] [Revised: 01/19/2012] [Accepted: 01/20/2012] [Indexed: 11/16/2022]
Abstract
Glycine receptors (GlyRs) are pentameric membrane proteins in the form of either α-homomers or α-β heteromers. Four out of five subunits; α1-3 and β, have been found in the mammalian brain. Early studies investigating subunit composition and expression patterns of this receptor have proposed a developmental switch from α2 homomers to α1β heteromers as the CNS matures, a conclusion primarily based on results from the spinal cord. However, our previous results indicate that this might not apply to e.g. the forebrain regions. Here we examined alterations in GlyR expression caused by developmental changes in selected brain areas, focusing on reward-related regions. Animals of several ages (P2, P21 and P60) were included to examine potential changes over time. In accordance with previous reports, a switch in expression was observed in the spinal cord. However, the present results indicate that a decrease in α2 subunit expression is not replaced by α1 subunit expression since the generally low levels, and modest increases, of α1 could hardly replace the reduction in α2-mRNA. Instead mRNA measurements indicate that α2 continues to be the dominating α-subunit also in adult animals, usually in combination with high and stable levels of β-subunit expression. This indicates that alterations in GlyR subunit expression are not simply a maturation effect common for the entire CNS, but rather a unique pattern of transition depending on the region at hand.
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Affiliation(s)
- Susanne Jonsson
- Addiction Biology Unit, Department of Psychiatry and Neurochemistry, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at University of Gothenburg, Sweden.
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43
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Different presynaptic nicotinic receptor subtypes modulate in vivo and in vitro the release of glycine in the rat hippocampus. Neurochem Int 2011; 59:729-38. [DOI: 10.1016/j.neuint.2011.06.022] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2011] [Accepted: 06/27/2011] [Indexed: 01/04/2023]
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44
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Romei C, Di Prisco S, Raiteri M, Raiteri L. Glycine release provoked by disturbed Na+, K+ and Ca2+ homeostasis in cerebellar nerve endings: roles of Ca2+ channels, Na+/Ca2+ exchangers and GlyT2 transporter reversal. J Neurochem 2011; 119:50-63. [DOI: 10.1111/j.1471-4159.2011.07401.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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45
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Chen RQ, Wang SH, Yao W, Wang JJ, Ji F, Yan JZ, Ren SQ, Chen Z, Liu SY, Lu W. Role of glycine receptors in glycine-induced LTD in hippocampal CA1 pyramidal neurons. Neuropsychopharmacology 2011; 36:1948-58. [PMID: 21593734 PMCID: PMC3154115 DOI: 10.1038/npp.2011.86] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Glycine in the hippocampus can exert its effect on both synaptic NMDA receptors (NMDARs) and extrasynaptic functional glycine receptors (GlyRs) via distinct binding sites. Previous studies have reported that glycine induces long-term potentiation (LTP) through the activation of synaptic NMDARs. However, little is known about the potential role of the activated GlyRs that are largely located in extrasynaptic regions. We report here that relatively high levels of glycine achieved either by exogenous glycine application or by the elevation of endogenous glycine accumulation with an antagonist of the glycine transporter induced long-term depression (LTD) of excitatory postsynaptic currents (EPSCs) in hippocampal CA1 pyramidal neurons. The co-application of glycine with the selective GlyR antagonist strychnine changed glycine-induced LTD (Gly-LTD) to LTP. Blocking the postsynaptic GlyR-gated net chloride flux by manipulating intracellular chloride concentrations failed to elicit any changes in EPSCs. These results suggest that GlyRs are involved in Gly-LTD. Furthermore, this new form of chemical LTD was accompanied by the internalization of postsynaptic AMPA receptors and required the activation of NMDARs. Therefore, our present findings reveal an important function of GlyR activation and modulation in gating the direction of synaptic plasticity.
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Affiliation(s)
- Rong-Qing Chen
- Department of Neurobiology, Nanjing Medical University, Nanjing, Jiangsu, People's Republic of China,Key Laboratory for Neurodegenerative Disease of Jiangsu Province, Nanjing Medical University, Nanjing, Jiangsu, People's Republic of China
| | - Shan-Hui Wang
- Department of Neurobiology, Nanjing Medical University, Nanjing, Jiangsu, People's Republic of China,Key Laboratory for Neurodegenerative Disease of Jiangsu Province, Nanjing Medical University, Nanjing, Jiangsu, People's Republic of China
| | - Wen Yao
- Department of Neurobiology, Nanjing Medical University, Nanjing, Jiangsu, People's Republic of China,Key Laboratory for Neurodegenerative Disease of Jiangsu Province, Nanjing Medical University, Nanjing, Jiangsu, People's Republic of China
| | - Jing-Jing Wang
- Department of Neurobiology, Nanjing Medical University, Nanjing, Jiangsu, People's Republic of China,Key Laboratory for Neurodegenerative Disease of Jiangsu Province, Nanjing Medical University, Nanjing, Jiangsu, People's Republic of China
| | - Fang Ji
- Department of Neurobiology, Nanjing Medical University, Nanjing, Jiangsu, People's Republic of China,Key Laboratory for Neurodegenerative Disease of Jiangsu Province, Nanjing Medical University, Nanjing, Jiangsu, People's Republic of China
| | - Jing-Zhi Yan
- Department of Neurobiology, Nanjing Medical University, Nanjing, Jiangsu, People's Republic of China,Key Laboratory for Neurodegenerative Disease of Jiangsu Province, Nanjing Medical University, Nanjing, Jiangsu, People's Republic of China
| | - Si-Qiang Ren
- Department of Neurobiology, Nanjing Medical University, Nanjing, Jiangsu, People's Republic of China,Key Laboratory for Neurodegenerative Disease of Jiangsu Province, Nanjing Medical University, Nanjing, Jiangsu, People's Republic of China
| | - Zheng Chen
- Department of Neurobiology, Nanjing Medical University, Nanjing, Jiangsu, People's Republic of China,Key Laboratory for Neurodegenerative Disease of Jiangsu Province, Nanjing Medical University, Nanjing, Jiangsu, People's Republic of China
| | - Su-Yi Liu
- Department of Neurobiology, Nanjing Medical University, Nanjing, Jiangsu, People's Republic of China,Key Laboratory for Neurodegenerative Disease of Jiangsu Province, Nanjing Medical University, Nanjing, Jiangsu, People's Republic of China
| | - Wei Lu
- Department of Neurobiology, Nanjing Medical University, Nanjing, Jiangsu, People's Republic of China,Key Laboratory for Neurodegenerative Disease of Jiangsu Province, Nanjing Medical University, Nanjing, Jiangsu, People's Republic of China,Laboratory of Reproductive Medicine, Nanjing Medical University, Nanjing, Jiangsu, People's Republic of China,Key Laboratory for Human Functional Genomics of Jiangsu Province, School of Basic Medical Sciences, Nanjing Medical University, Nanjing, Jiangsu, People's Republic of China,Department of Neurobiology, Nanjing Medical University, Nanjing, Jiangsu 210029, People's Republic of China, Tel: +86 25 86862822, Fax: +86 25 86862822, E-mail:
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46
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Aroeira RI, Ribeiro JA, Sebastião AM, Valente CA. Age-related changes of glycine receptor at the rat hippocampus: from the embryo to the adult. J Neurochem 2011; 118:339-53. [PMID: 21272003 DOI: 10.1111/j.1471-4159.2011.07197.x] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Glycinergic inhibitory transmission has been described in spinal cord, but rather disregarded in the brain. The spatial-temporal characterization of glycine receptors (GlyR) in the hippocampus over development is herein reported. GlyR expression increases from late embryonic stage (E18) to 7 days postnatal (P7) and decreases from P7 on. Quantitative real-time PCR showed that GlyR subunit expression changes over neuronal maturation with a preponderance of α2 and α3, over α1 and β. In immature stages, GlyR delineate the cell body of neurons at the Dentate Gyrus and Cornus Ammonis 1 and 3 (CA1/CA3) and are composed of α2 and α3 subunits. At P7, synaptic GlyRα2β can already be observed in the dendritic areas of Dentate Gyrus and of CA1/CA3. In the mature hippocampus, synaptic GlyR decrease and, although a few synaptic GlyRα1β can still be detected in the dendritic layers, extrasynaptic α2/α3-containing GlyR and somatic localized GlyRα3 are the most abundant. Our results point towards an important function of a slow tonic activation of extrasynaptic GlyR, over a fast phasic activation of synaptic GlyRα1β. We clearly show that GlyR are widely expressed in hippocampus and that their subcellular localization and subunit composition change over development.
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Affiliation(s)
- Rita I Aroeira
- Institute of Pharmacology and Neurosciences, Faculty of Medicine, and Unit of Neurosciences, Institute of Molecular Medicine, University of Lisbon, Portugal
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Holter NI, Zylla MM, Zuber N, Bruehl C, Draguhn A. Tonic GABAergic control of mouse dentate granule cells during postnatal development. Eur J Neurosci 2010; 32:1300-9. [PMID: 20846322 DOI: 10.1111/j.1460-9568.2010.07331.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The dentate gyrus is the main hippocampal input structure receiving strong excitatory cortical afferents via the perforant path. Therefore, inhibition at this 'hippocampal gate' is important, particularly during postnatal development, when the hippocampal network is prone to seizures. The present study describes the development of tonic GABAergic inhibition in mouse dentate gyrus. A prominent tonic GABAergic component was already present at early postnatal stages (postnatal day 3), in contrast to the slowly developing phasic postsynaptic GABAergic currents. Tonic currents were mediated by GABA(A) receptors containing α(5)- and δ-subunits, which are sensitive to low ambient GABA concentrations. The extracellular GABA level was determined by synaptic GABA release and GABA uptake via the GABA transporter 1. The contribution of these main regulatory components was surprisingly stable during postnatal granule cell maturation. Throughout postnatal development, tonic GABAergic signals were inhibitory. They increased the action potential threshold of granule cells and reduced network excitability, starting as early as postnatal day 3. Thus, tonic inhibition is already functional at early developmental stages and plays a key role in regulating the excitation/inhibition balance of both the adult and the maturing dentate gyrus.
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Affiliation(s)
- Nadine I Holter
- Institute of Physiology and Pathophysiology, University of Heidelberg, Heidelberg, Germany
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Bernard D, Prasanth KV, Tripathi V, Colasse S, Nakamura T, Xuan Z, Zhang MQ, Sedel F, Jourdren L, Coulpier F, Triller A, Spector DL, Bessis A. A long nuclear-retained non-coding RNA regulates synaptogenesis by modulating gene expression. EMBO J 2010; 29:3082-93. [PMID: 20729808 DOI: 10.1038/emboj.2010.199] [Citation(s) in RCA: 576] [Impact Index Per Article: 41.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2010] [Accepted: 07/16/2010] [Indexed: 12/19/2022] Open
Abstract
A growing number of long nuclear-retained non-coding RNAs (ncRNAs) have recently been described. However, few functions have been elucidated for these ncRNAs. Here, we have characterized the function of one such ncRNA, identified as metastasis-associated lung adenocarcinoma transcript 1 (Malat1). Malat1 RNA is expressed in numerous tissues and is highly abundant in neurons. It is enriched in nuclear speckles only when RNA polymerase II-dependent transcription is active. Knock-down studies revealed that Malat1 modulates the recruitment of SR family pre-mRNA-splicing factors to the transcription site of a transgene array. DNA microarray analysis in Malat1-depleted neuroblastoma cells indicates that Malat1 controls the expression of genes involved not only in nuclear processes, but also in synapse function. In cultured hippocampal neurons, knock-down of Malat1 decreases synaptic density, whereas its over-expression results in a cell-autonomous increase in synaptic density. Our results suggest that Malat1 regulates synapse formation by modulating the expression of genes involved in synapse formation and/or maintenance.
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Affiliation(s)
- Delphine Bernard
- Laboratoire de Biologie Cellulaire de la Synapse, Inserm 1024/CNRS 8197, Institut de Biologie de l'Ecole Normale Supérieure, Paris, France
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Luccini E, Romei C, Di Prisco S, Raiteri M, Raiteri L. Ionic dysregulations typical of ischemia provoke release of glycine and GABA by multiple mechanisms. J Neurochem 2010; 114:1074-84. [PMID: 20524963 DOI: 10.1111/j.1471-4159.2010.06829.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Energy deprivation during ischemia causes dysregulations of ions, particularly sodium, potassium and calcium. Under these conditions, release of neurotransmitters is often enhanced and can occur by multiple mechanisms. The aim of this work was to characterize the modes of exit of glycine and GABA from nerve endings exposed to stimuli known to reproduce some of the ionic changes typical of ischemic conditions. Their approach was chosen instead of application of ischemic conditions because the release evoked during ischemia is mechanistically too heterogeneous. Mouse hippocampus and spinal cord synaptosomes, pre-labeled with [(3)H]glycine or [(3)H]GABA, were exposed in superfusion to 50 mM KCl or to 10 microM veratridine. The evoked overflows differed greatly between the two transmitters and between the two regions examined. Significant portions of the K(+)- and the veratridine-evoked overflows occurred by classical exocytosis. Carrier-mediated release of GABA, but not of glycine, was evoked by high K(+); GABA and, less so, glycine were released through transporter reversal by veratridine. External calcium-dependent overflows were only in part sensitive to omega-conotoxins; significant portions occurred following reversal of the plasmalemmal Na(+)/Ca(2+) exchanger. Finally, a relevant contribution to the overall transmitter overflows came from cytosolic calcium originating through the mitochondrial Na(+)/Ca(2+) exchanger. To conclude, ionic dysregulations typical of ischemia cause neurotransmitter release by heterogeneous mechanisms that differ depending on the transmitters and the CNS regions examined.
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Affiliation(s)
- Elisa Luccini
- Department of Experimental Medicine, University of Genova, Genova, Italy
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Regulation of postsynaptic gephyrin cluster size by protein phosphatase 1. Mol Cell Neurosci 2010; 44:201-9. [PMID: 20206270 DOI: 10.1016/j.mcn.2010.02.007] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2009] [Revised: 02/22/2010] [Accepted: 02/23/2010] [Indexed: 01/21/2023] Open
Abstract
The scaffolding protein gephyrin is essential for the clustering of glycine and GABA(A) receptors (GABA(A)Rs) at inhibitory synapses. Here, we provide evidence that the size of the postsynaptic gephyrin scaffold is controlled by dephosphorylation reactions. Treatment of cultured hippocampal neurons with the protein phosphatase inhibitors calyculin A and okadaic acid reduced the size of postsynaptic gephyrin clusters and increased cytoplasmic gephyrin staining. Protein phosphatase 1 (PP1) was found to colocalize with gephyrin at selected postsynaptic sites and to interact with gephyrin in transfected cells and brain extracts. Alanine or glutamate substitution of the two established serine/threonine phosphorylation sites in gephyrin failed to affect its clustering at inhibitory synapses and its ability to recruit gamma2 subunit containing GABA(A)Rs. Our data are consistent with the postsynaptic gephyrin scaffold acting as a platform for PP1, which regulates gephyrin cluster size by dephosphorylation of gephyrin- or cytoskeleton-associated proteins.
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