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Mansouri M, Kremser L, Nguyen TP, Kasugai Y, Caberlotto L, Gassmann M, Sarg B, Lindner H, Bettler B, Carboni L, Ferraguti F. Protein Networks Associated with Native Metabotropic Glutamate 1 Receptors (mGlu 1) in the Mouse Cerebellum. Cells 2023; 12:1325. [PMID: 37174725 PMCID: PMC10177021 DOI: 10.3390/cells12091325] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2023] [Revised: 04/28/2023] [Accepted: 04/30/2023] [Indexed: 05/15/2023] Open
Abstract
The metabotropic glutamate receptor 1 (mGlu1) plays a pivotal role in synaptic transmission and neuronal plasticity. Despite the fact that several interacting proteins involved in the mGlu1 subcellular trafficking and intracellular transduction mechanisms have been identified, the protein network associated with this receptor in specific brain areas remains largely unknown. To identify novel mGlu1-associated protein complexes in the mouse cerebellum, we used an unbiased tissue-specific proteomic approach, namely co-immunoprecipitation followed by liquid chromatography/tandem mass spectrometry analysis. Many well-known protein complexes as well as novel interactors were identified, including G-proteins, Homer, δ2 glutamate receptor, 14-3-3 proteins, and Na/K-ATPases. A novel putative interactor, KCTD12, was further investigated. Reverse co-immunoprecipitation with anti-KCTD12 antibodies revealed mGlu1 in wild-type but not in KCTD12-knock-out homogenates. Freeze-fracture replica immunogold labeling co-localization experiments showed that KCTD12 and mGlu1 are present in the same nanodomain in Purkinje cell spines, although at a distance that suggests that this interaction is mediated through interposed proteins. Consistently, mGlu1 could not be co-immunoprecipitated with KCTD12 from a recombinant mammalian cell line co-expressing the two proteins. The possibility that this interaction was mediated via GABAB receptors was excluded by showing that mGlu1 and KCTD12 still co-immunoprecipitated from GABAB receptor knock-out tissue. In conclusion, this study identifies tissue-specific mGlu1-associated protein clusters including KCTD12 at Purkinje cell synapses.
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Affiliation(s)
- Mahnaz Mansouri
- Department of Pharmacology, Medical University of Innsbruck, 6020 Innsbruck, Austria; (M.M.); (Y.K.)
| | - Leopold Kremser
- Institute of Medical Biochemistry, Protein Core Facility, Medical University of Innsbruck, 6020 Innsbruck, Austria; (L.K.); (B.S.); (H.L.)
| | | | - Yu Kasugai
- Department of Pharmacology, Medical University of Innsbruck, 6020 Innsbruck, Austria; (M.M.); (Y.K.)
| | - Laura Caberlotto
- Centre for Computational and Systems Biology (COSBI), The Microsoft Research University of Trento, 38068 Rovereto, Italy;
| | - Martin Gassmann
- Department of Biomedicine, Pharmazentrum, University of Basel, 4056 Basel, Switzerland; (M.G.); (B.B.)
| | - Bettina Sarg
- Institute of Medical Biochemistry, Protein Core Facility, Medical University of Innsbruck, 6020 Innsbruck, Austria; (L.K.); (B.S.); (H.L.)
| | - Herbert Lindner
- Institute of Medical Biochemistry, Protein Core Facility, Medical University of Innsbruck, 6020 Innsbruck, Austria; (L.K.); (B.S.); (H.L.)
| | - Bernhard Bettler
- Department of Biomedicine, Pharmazentrum, University of Basel, 4056 Basel, Switzerland; (M.G.); (B.B.)
| | - Lucia Carboni
- Department of Pharmacy and Biotechnology, Alma Mater Studiorum University of Bologna, 40126 Bologna, Italy;
| | - Francesco Ferraguti
- Department of Pharmacology, Medical University of Innsbruck, 6020 Innsbruck, Austria; (M.M.); (Y.K.)
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Nicoletti F, Di Menna L, Iacovelli L, Orlando R, Zuena AR, Conn PJ, Dogra S, Joffe ME. GPCR interactions involving metabotropic glutamate receptors and their relevance to the pathophysiology and treatment of CNS disorders. Neuropharmacology 2023; 235:109569. [PMID: 37142158 DOI: 10.1016/j.neuropharm.2023.109569] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Revised: 04/18/2023] [Accepted: 05/02/2023] [Indexed: 05/06/2023]
Abstract
Cellular responses to metabotropic glutamate (mGlu) receptor activation are shaped by mechanisms of receptor-receptor interaction. mGlu receptor subtypes form homodimers, intra- or inter-group heterodimers, and heteromeric complexes with other G protein-coupled receptors (GPCRs). In addition, mGlu receptors may functionally interact with other receptors through the βγ subunits released from G proteins in response to receptor activation or other mechanisms. Here, we discuss the interactions between (i) mGlu1 and GABAB receptors in cerebellar Purkinje cells; (ii) mGlu2 and 5-HT2Aserotonergic receptors in the prefrontal cortex; (iii) mGlu5 and A2A receptors or mGlu5 and D1 dopamine receptors in medium spiny projection neurons of the indirect and direct pathways of the basal ganglia motor circuit; (iv) mGlu5 and A2A receptors in relation to the pathophysiology of Alzheimer's disease; and (v) mGlu7 and A1 adenosine or α- or β1 adrenergic receptors. In addition, we describe in detail a novel form of non-heterodimeric interaction between mGlu3 and mGlu5 receptors, which appears to be critically involved in mechanisms of activity-dependent synaptic plasticity in the prefrontal cortex and hippocampus. Finally, we highlight the potential implication of these interactions in the pathophysiology and treatment of cerebellar disorders, schizophrenia, Alzheimer's disease, Parkinson's disease, l-DOPA-induced dyskinesias, stress-related disorders, and cognitive dysfunctions.
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Affiliation(s)
- Ferdinando Nicoletti
- Department of Physiology and Pharmacology, Sapienza University of Rome, Italy; IRCCS Neuromed, Pozzilli, Italy.
| | | | - Luisa Iacovelli
- Department of Physiology and Pharmacology, Sapienza University of Rome, Italy
| | - Rosamaria Orlando
- Department of Physiology and Pharmacology, Sapienza University of Rome, Italy; IRCCS Neuromed, Pozzilli, Italy
| | - Anna Rita Zuena
- Department of Physiology and Pharmacology, Sapienza University of Rome, Italy
| | - P Jeffrey Conn
- Department of Pharmacology, Italy; Warren Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, TN, 37232, USA
| | - Shalini Dogra
- Department of Pharmacology, Italy; Warren Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, TN, 37232, USA
| | - Max E Joffe
- Translational Neuroscience Program, Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA, 15219, USA
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3
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Ethanol blocks a novel form of iLTD, but not iLTP of inhibitory inputs to VTA GABA neurons. Neuropsychopharmacology 2023:10.1038/s41386-023-01554-y. [PMID: 36899030 PMCID: PMC10354227 DOI: 10.1038/s41386-023-01554-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Revised: 02/14/2023] [Accepted: 02/16/2023] [Indexed: 03/12/2023]
Abstract
The ventral tegmental area (VTA) is an essential component of the mesocorticolimbic dopamine (DA) circuit that processes reward and motivated behaviors. The VTA contains DA neurons essential in this process, as well as GABAergic inhibitory cells that regulate DA cell activity. In response to drug exposure, synaptic connections of the VTA circuit can be rewired via synaptic plasticity-a phenomenon thought to be responsible for the pathology of drug dependence. While synaptic plasticity to VTA DA neurons as well as prefrontal cortex to nucleus accumbens GABA neurons are well studied, VTA GABA cell plasticity, specifically inhibitory inputs to VTA GABA neurons, is less understood. Therefore, we investigated the plasticity of these inhibitory inputs. Using whole cell electrophysiology in GAD67-GFP mice to identify GABA cells, we observed that these VTA GABA cells experience either inhibitory GABAergic long-term potentiation (iLTP) or inhibitory long-term depression (iLTD) in response to a 5 Hz stimulus. Paired pulse ratios, coefficient of variance, and failure rates suggest a presynaptic mechanism for both plasticity types, where iLTP is NMDA receptor-dependent and iLTD is GABAB receptor-dependent-this being the first report of iLTD onto VTA GABA cells. As illicit drug exposure can alter VTA plasticity, we employed chronic intermittent exposure (CIE) to ethanol (EtOH) vapor in male and female mice to examine its potential impact on VTA GABA input plasticity. Chronic EtOH vapor exposure produced measurable behavioral changes illustrating dependence and concomitantly prevented previously observed iLTD, which continued in air-exposed controls, illustrating the impact of EtOH on VTA neurocircuitry and suggesting physiologic mechanisms at play in alcohol use disorder and withdrawal states. Taken together, these novel findings of unique GABAergic synapses exhibiting either iLTP or iLTD within the mesolimbic circuit, and EtOH blockade specifically of iLTD, characterize inhibitory VTA plasticity as a malleable, experience-dependent system modified by EtOH.
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Parmar S, Tadavarty R, Sastry BR. G-protein coupled receptors and synaptic plasticity in sleep deprivation. World J Psychiatry 2021; 11:954-980. [PMID: 34888167 PMCID: PMC8613756 DOI: 10.5498/wjp.v11.i11.954] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Revised: 06/05/2021] [Accepted: 09/19/2021] [Indexed: 02/06/2023] Open
Abstract
Insufficient sleep has been correlated to many physiological and psychoneurological disorders. Over the years, our understanding of the state of sleep has transcended from an inactive period of rest to a more active state involving important cellular and molecular processes. In addition, during sleep, electrophysiological changes also occur in pathways in specific regions of the mammalian central nervous system (CNS). Activity mediated synaptic plasticity in the CNS can lead to long-term and sometimes permanent strengthening and/or weakening synaptic strength affecting neuronal network behaviour. Memory consolidation and learning that take place during sleep cycles, can be affected by changes in synaptic plasticity during sleep disturbances. G-protein coupled receptors (GPCRs), with their versatile structural and functional attributes, can regulate synaptic plasticity in CNS and hence, may be potentially affected in sleep deprived conditions. In this review, we aim to discuss important functional changes that can take place in the CNS during sleep and sleep deprivation and how changes in GPCRs can lead to potential problems with therapeutics with pharmacological interventions.
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Affiliation(s)
- Shweta Parmar
- Department of Anesthesiology, Pharmacology and Therapeutics, The University of British Columbia, Vancouver V6T 1Z3, British Columbia, Canada
| | - Ramakrishna Tadavarty
- Department of Anesthesiology, Pharmacology and Therapeutics, The University of British Columbia, Vancouver V6T 1Z3, British Columbia, Canada
| | - Bhagavatula R Sastry
- Department of Anesthesiology, Pharmacology and Therapeutics, The University of British Columbia, Vancouver V6T 1Z3, British Columbia, Canada
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Lippiello P, Hoxha E, Tempia F, Miniaci MC. GIRK1-Mediated Inwardly Rectifying Potassium Current Is a Candidate Mechanism Behind Purkinje Cell Excitability, Plasticity, and Neuromodulation. THE CEREBELLUM 2021; 19:751-761. [PMID: 32617840 DOI: 10.1007/s12311-020-01158-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
G-protein-coupled inwardly rectifying potassium (GIRK) channels contribute to the resting membrane potential of many neurons and play an important role in controlling neuronal excitability. Although previous studies have revealed a high expression of GIRK subunits in the cerebellum, their functional role has never been clearly described. Using patch-clamp recordings in mice cerebellar slices, we examined the properties of the GIRK currents in Purkinje cells (PCs) and investigated the effects of a selective agonist of GIRK1-containing channels, ML297 (ML), on PC firing and synaptic plasticity. We demonstrated that GIRK channel activation decreases the PC excitability by inhibiting both sodium and calcium spikes and, in addition, modulates the complex spike response evoked by climbing fiber stimulation. Our results indicate that GIRK channels have also a marked effect on synaptic plasticity of the parallel fiber-PC synapse, as the application of ML297 increased the expression of LTP while preventing LTD. We, therefore, propose that the recruitment of GIRK channels represents a crucial mechanism by which neuromodulators can control synaptic strength and membrane conductance for proper refinement of the neural network involved in memory storage and higher cognitive functions.
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Affiliation(s)
- Pellegrino Lippiello
- Department of Pharmacy, School of Medicine, University of Naples Federico II, Naples, Italy
| | - Eriola Hoxha
- Department of Neuroscience, University of Turin, Turin, Italy.,Neuroscience Institute Cavalieri Ottolenghi (NICO), Turin, Italy
| | - Filippo Tempia
- Department of Neuroscience, University of Turin, Turin, Italy. .,Neuroscience Institute Cavalieri Ottolenghi (NICO), Turin, Italy. .,National Institute of Neuroscience (INN), Turin, Italy.
| | - Maria Concetta Miniaci
- Department of Pharmacy, School of Medicine, University of Naples Federico II, Naples, Italy.
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mGluR1 signaling in cerebellar Purkinje cells: Subcellular organization and involvement in cerebellar function and disease. Neuropharmacology 2021; 194:108629. [PMID: 34089728 DOI: 10.1016/j.neuropharm.2021.108629] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Revised: 05/19/2021] [Accepted: 05/20/2021] [Indexed: 11/20/2022]
Abstract
The cerebellum is essential for the control, coordination, and learning of movements, and for certain aspects of cognitive function. Purkinje cells are the sole output neurons in the cerebellar cortex and therefore play crucial roles in the diverse functions of the cerebellum. The type 1 metabotropic glutamate receptor (mGluR1) is prominently enriched in Purkinje cells and triggers downstream signaling pathways that are required for functional and structural plasticity, and for synaptic responses. To understand how mGluR1 contributes to cerebellar functions, it is important to consider not only the operational properties of this receptor, but also its spatial organization and the molecular interactions that enable its proper functioning. In this review, we highlight how mGluR1 and its related signaling molecules are organized into tightly coupled microdomains to fulfill physiological functions. We also describe emerging evidence that altered mGluR1 signaling in Purkinje cells underlies cerebellar dysfunction in ataxias of human patients and mouse models.
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ZFP804A mutant mice display sex-dependent schizophrenia-like behaviors. Mol Psychiatry 2021; 26:2514-2532. [PMID: 33303946 PMCID: PMC8440220 DOI: 10.1038/s41380-020-00972-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Revised: 10/20/2020] [Accepted: 11/24/2020] [Indexed: 12/22/2022]
Abstract
Genome-wide association studies uncovered the association of ZNF804A (Zinc-finger protein 804A) with schizophrenia (SZ). In vitro data have indicated that ZNF804A might exert its biological roles by regulating spine and neurite morphogenesis. However, no in vivo data are available for the role of ZNF804A in psychiatric disorders in general, SZ in particular. We generated ZFP804A mutant mice, and they showed deficits in contextual fear and spatial memory. We also observed the sensorimotor gating impairment, as revealed by the prepulse inhibition test, but only in female ZFP804A mutant mice from the age of 6 months. Notably, the PPI difference between the female mutant and control mice was no longer existed with the administration of Clozapine or after the ovariectomy. Hippocampal long-term potentiation was normal in both genders of the mutant mice. Long-term depression was absent in male mutants, but facilitated in the female mutants. Protein levels of hippocampal serotonin-6 receptor and GABAB1 receptor were increased, while those of cortical dopamine 2 receptor were decreased in the female mutants with no obvious changes in the male mutants. Moreover, the spine density was reduced in the cerebral cortex and hippocampus of the mutant mice. Knockdown of ZFP804A impaired the neurite morphogenesis of cortical and hippocampal neurons, while its overexpression enhanced neurite morphogenesis only in the cortical neurons in vitro. Our data collectively support the idea that ZFP804A/ZNF804A plays important roles in the cognitive functions and sensorimotor gating, and its dysfunction may contribute to SZ, particularly in the female patients.
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Long-term potentiation of glycinergic synapses by semi-natural stimulation patterns during tonotopic map refinement. Sci Rep 2020; 10:16899. [PMID: 33037263 PMCID: PMC7547119 DOI: 10.1038/s41598-020-73050-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2020] [Accepted: 09/10/2020] [Indexed: 12/22/2022] Open
Abstract
Before the onset of hearing, cochlea-generated patterns of spontaneous spike activity drive the maturation of central auditory circuits. In the glycinergic sound localization pathway from the medial nucleus of the trapezoid body (MNTB) to the lateral superior olive (LSO) this spontaneous activity guides the strengthening and silencing of synapses which underlies tonotopic map refinement. However, the mechanisms by which patterned activity regulates synaptic refinement in the MNTB-LSO pathway are still poorly understood. To address this question, we recorded from LSO neurons in slices from prehearing mice while stimulating MNTB afferents with stimulation patterns that mimicked those present in vivo. We found that these semi-natural stimulation patterns reliably elicited a novel form of long-term potentiation (LTP) of MNTB-LSO synapses. Stimulation patterns that lacked the characteristic high-frequency (200 Hz) component of prehearing spike activity failed to elicit potentiation. LTP was calcium dependent, required the activation of both g-protein coupled GABAB and metabotropic glutamate receptors and involved an increase in postsynaptic glycine receptor-mediated currents. Our results provide a possible mechanism linking spontaneous spike bursts to tonotopic map refinement and further highlight the importance of the co-release of GABA and glutamate from immature glycinergic MNTB terminals.
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Sakairi H, Kamikubo Y, Abe M, Ikeda K, Ichiki A, Tabata T, Kano M, Sakurai T. G Protein-Coupled Glutamate and GABA Receptors Form Complexes and Mutually Modulate Their Signals. ACS Chem Neurosci 2020; 11:567-578. [PMID: 31977183 DOI: 10.1021/acschemneuro.9b00599] [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] [Indexed: 01/09/2023] Open
Abstract
Molecular networks containing various proteins mediate many types of cellular processes. Elucidation of how the proteins interact will improve our understanding of the molecular integration and physiological and pharmacological propensities of the network. One of the most complicated and unexplained interactions between proteins is the inter-G protein-coupled receptor (GPCR) interaction. Recently, many studies have suggested that an interaction between neurotransmitter GPCRs may mediate diverse modalities of neural responses. The B-type gamma-aminobutyric acid (GABA) receptor (GBR) and type-1 metabotropic glutamate receptor (mGluR1) are GPCRs for GABA and glutamate, respectively, and each plays distinct roles in controlling neurotransmission. We have previously reported the possibility of their functional interaction in central neurons. Here, we examined the interaction of these GPCRs using stable cell lines and rat cerebella. Cell-surface imaging and coimmunoprecipitation analysis revealed that these GPCRs interact on the cell surface. Furthermore, fluorometry revealed that these GPCRs mutually modulate signal transduction. These findings provide solid evidence that mGluR1 and GBR have intrinsic abilities to form complexes and to mutually modulate signaling. These findings indicate that synaptic plasticity relies on a network of proteins far more complex than previously assumed.
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Affiliation(s)
- Hakushun Sakairi
- Department of Pharmacology, Juntendo University School of Medicine, Hongo 2-1-1, Bunkyo-ku, Tokyo 113-8421, Japan
| | - Yuji Kamikubo
- Department of Pharmacology, Juntendo University School of Medicine, Hongo 2-1-1, Bunkyo-ku, Tokyo 113-8421, Japan
| | - Masayoshi Abe
- Laboratory for Biological Information Processing, Faculty of Engineering and Graduate School of Science and Engineering, University of Toyama, 3190 Gofuku, Toyama, Toyama 930-8555, Japan
| | - Keisuke Ikeda
- Laboratory for Biological Information Processing, Faculty of Engineering and Graduate School of Science and Engineering, University of Toyama, 3190 Gofuku, Toyama, Toyama 930-8555, Japan
| | - Arata Ichiki
- Laboratory for Biological Information Processing, Faculty of Engineering and Graduate School of Science and Engineering, University of Toyama, 3190 Gofuku, Toyama, Toyama 930-8555, Japan
| | - Toshihide Tabata
- Laboratory for Biological Information Processing, Faculty of Engineering and Graduate School of Science and Engineering, University of Toyama, 3190 Gofuku, Toyama, Toyama 930-8555, Japan
| | - Masanobu Kano
- Department of Neurophysiology, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Tokyo 113-0033, Japan
| | - Takashi Sakurai
- Department of Pharmacology, Juntendo University School of Medicine, Hongo 2-1-1, Bunkyo-ku, Tokyo 113-8421, Japan
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Kamikubo Y, Yamana T, Hashimoto Y, Sakurai T. Induction of Oxidative Stress and Cell Death in Neural Cells by Silica Nanoparticles. ACS Chem Neurosci 2019; 10:304-312. [PMID: 30230808 DOI: 10.1021/acschemneuro.8b00248] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Silica nanoparticles (SiNPs) are produced on an industrial scale and used in various fields including health care, because silica is stable, inexpensive, and easy to handle. Despite these benefits, there is concern that exposure to SiNPs may lead to adverse effects in certain types of cells or tissues, such as hemolysis, immune responses, and developmental abnormalities in the brain and developing embryos. Although investigations on the toxicity of SiNPs against neurons are essential for medicinal use, only a few studies have assessed the direct effects of SiNPs on cells derived from the central nervous system. In this study, we investigated the toxic effects of SiNPs on primary cultures of hippocampal cells, using SiNPs with diameters of 10-1500 nm. We showed that treatment with SiNPs caused oxidative stress and cell death. Furthermore, we found that these cytotoxicities were dependent on the particle size, concentration, and surface charge of SiNPs, as well as the treatment temperature. The toxicity was reduced by SiNP surface functionalization or protein coating and by pretreating cells with an antioxidant, suggesting that contact-induced oxidative stress may be partially responsible for SiNP-induced cell death. These data will be valuable for utilizing SiNPs in biomedical applications.
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Affiliation(s)
- Yuji Kamikubo
- Department of Pharmacology, Juntendo University School of Medicine, Hongo 2-1-1, Bunkyo-ku, Tokyo 113-8421, Japan
| | - Tomohito Yamana
- Department of Pharmacology, Juntendo University School of Medicine, Hongo 2-1-1, Bunkyo-ku, Tokyo 113-8421, Japan
| | - Yoshie Hashimoto
- Department of Pharmacology, Juntendo University School of Medicine, Hongo 2-1-1, Bunkyo-ku, Tokyo 113-8421, Japan
| | - Takashi Sakurai
- Department of Pharmacology, Juntendo University School of Medicine, Hongo 2-1-1, Bunkyo-ku, Tokyo 113-8421, Japan
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Langlois LD, Dacher M, Nugent FS. Dopamine Receptor Activation Is Required for GABAergic Spike Timing-Dependent Plasticity in Response to Complex Spike Pairing in the Ventral Tegmental Area. Front Synaptic Neurosci 2018; 10:32. [PMID: 30297996 PMCID: PMC6160785 DOI: 10.3389/fnsyn.2018.00032] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Accepted: 08/30/2018] [Indexed: 01/06/2023] Open
Abstract
One of the most influential synaptic learning rules explored in the past decades is activity dependent spike-timing-dependent plasticity (STDP). In STDP, synapses are either potentiated or depressed based on the order of pre- and postsynaptic neuronal activation within narrow, milliseconds-long, time intervals. STDP is subject to neuromodulation by dopamine (DA), a potent neurotransmitter that significantly impacts synaptic plasticity and reward-related behavioral learning. Previously, we demonstrated that GABAergic synapses onto ventral tegmental area (VTA) DA neurons are able to express STDP (Kodangattil et al., 2013), however it is still unclear whether DA modulates inhibitory STDP in the VTA. Here, we used whole-cell recordings in rat midbrain slices to investigate whether DA D1-like and/or D2-like receptor (D1R/D2R) activation is required for induction of STDP in response to a complex pattern of spiking. We found that VTA but not Substantia nigra pars compact (SNc) DA neurons exhibit long-term depression (LTDGABA) in response to a combination of positive (pre-post) and negative (post-pre) timing of spiking (a complex STDP protocol). Blockade of either D1Rs or D2Rs prevented the induction of LTDGABA while activation of D1Rs did not affect the plasticity in response to this complex STDP protocol in VTA DA neurons.Our data suggest that this DA-dependent GABAergic STDP is selectively expressed at GABAergic synapses onto VTA DA neurons which could be targeted by drugs of abuse to mediate drug-induced modulation of DA signaling within the VTA, as well as in VTA-projection areas, thereby affecting reward-related learning and drug-associated memories.
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Affiliation(s)
- Ludovic D Langlois
- Department of Pharmacology, F. Edward Hebert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, MD, United States
| | - Matthieu Dacher
- Department of Pharmacology, F. Edward Hebert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, MD, United States
| | - Fereshteh S Nugent
- Department of Pharmacology, F. Edward Hebert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, MD, United States
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TERUNUMA M. Diversity of structure and function of GABA B receptors: a complexity of GABA B-mediated signaling. PROCEEDINGS OF THE JAPAN ACADEMY. SERIES B, PHYSICAL AND BIOLOGICAL SCIENCES 2018; 94:390-411. [PMID: 30541966 PMCID: PMC6374141 DOI: 10.2183/pjab.94.026] [Citation(s) in RCA: 71] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2018] [Accepted: 10/09/2018] [Indexed: 05/24/2023]
Abstract
γ-aminobutyric acid type B (GABAB) receptors are broadly expressed in the nervous system and play an important role in neuronal excitability. GABAB receptors are G protein-coupled receptors that mediate slow and prolonged inhibitory action, via activation of Gαi/o-type proteins. GABAB receptors mediate their inhibitory action through activating inwardly rectifying K+ channels, inactivating voltage-gated Ca2+ channels, and inhibiting adenylate cyclase. Functional GABAB receptors are obligate heterodimers formed by the co-assembly of R1 and R2 subunits. It is well established that GABAB receptors interact not only with G proteins and effectors but also with various proteins. This review summarizes the structure, subunit isoforms, and function of GABAB receptors, and discusses the complexity of GABAB receptors, including how receptors are localized in specific subcellular compartments, the mechanism regulating cell surface expression and mobility of the receptors, and the diversity of receptor signaling through receptor crosstalk and interacting proteins.
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Affiliation(s)
- Miho TERUNUMA
- Division of Oral Biochemistry, Graduate School of Medical and Dental Sciences, Niigata University, Niigata, Japan
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13
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Differential association of GABA B receptors with their effector ion channels in Purkinje cells. Brain Struct Funct 2017; 223:1565-1587. [PMID: 29177691 PMCID: PMC5869904 DOI: 10.1007/s00429-017-1568-y] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Accepted: 11/10/2017] [Indexed: 11/23/2022]
Abstract
Metabotropic GABAB receptors mediate slow inhibitory effects presynaptically and postsynaptically through the modulation of different effector signalling pathways. Here, we analysed the distribution of GABAB receptors using highly sensitive SDS-digested freeze-fracture replica labelling in mouse cerebellar Purkinje cells. Immunoreactivity for GABAB1 was observed on presynaptic and, more abundantly, on postsynaptic compartments, showing both scattered and clustered distribution patterns. Quantitative analysis of immunoparticles revealed a somato-dendritic gradient, with the density of immunoparticles increasing 26-fold from somata to dendritic spines. To understand the spatial relationship of GABAB receptors with two key effector ion channels, the G protein-gated inwardly rectifying K+ (GIRK/Kir3) channel and the voltage-dependent Ca2+ channel, biochemical and immunohistochemical approaches were performed. Co-immunoprecipitation analysis demonstrated that GABAB receptors co-assembled with GIRK and CaV2.1 channels in the cerebellum. Using double-labelling immunoelectron microscopic techniques, co-clustering between GABAB1 and GIRK2 was detected in dendritic spines, whereas they were mainly segregated in the dendritic shafts. In contrast, co-clustering of GABAB1 and CaV2.1 was detected in dendritic shafts but not spines. Presynaptically, although no significant co-clustering of GABAB1 and GIRK2 or CaV2.1 channels was detected, inter-cluster distance for GABAB1 and GIRK2 was significantly smaller in the active zone than in the dendritic shafts, and that for GABAB1 and CaV2.1 was significantly smaller in the active zone than in the dendritic shafts and spines. Thus, GABAB receptors are associated with GIRK and CaV2.1 channels in different subcellular compartments. These data provide a better framework for understanding the different roles played by GABAB receptors and their effector ion channels in the cerebellar network.
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Cai S, Fischer QS, He Y, Zhang L, Liu H, Daw NW, Yang Y. GABAB receptor-dependent bidirectional regulation of critical period ocular dominance plasticity in cats. PLoS One 2017; 12:e0180162. [PMID: 28662175 PMCID: PMC5491141 DOI: 10.1371/journal.pone.0180162] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2017] [Accepted: 06/09/2017] [Indexed: 01/05/2023] Open
Abstract
Gama amino butyric acid (GABA) inhibition plays an important role in the onset and offset of the critical period for ocular dominance (OD) plasticity in the primary visual cortex. Previous studies have focused on the involvement of GABAA receptors, while the potential contribution of GABAB receptors to OD plasticity has been neglected. In this study, the GABAB receptor antagonist SCH50911 or agonist baclofen was infused into the primary visual cortex of cats concurrently with a period of monocular deprivation (MD). Using single-unit recordings we found that the OD shift induced by four days of MD during the critical period was impaired by infusion of the antagonist SCH50911, but enhanced by infusion of the agonist baclofen. In contrast, seven days of MD in adult cats did not induce any significant OD shift, even when combined with the infusion of SCH50911 or baclofen. Together, these findings indicate that an endogenous GABAB receptor-mediated inhibition contributes to juvenile, but not adult, OD plasticity.
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Affiliation(s)
- Shanshan Cai
- CAS Key Laboratory of Brain Function and Diseases, School of Life Sciences, University of Science and Technology of China, Hefei, China
| | - Quentin S. Fischer
- Department of Ophthalmology and Visual Sciences, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Yu He
- CAS Key Laboratory of Brain Function and Diseases, School of Life Sciences, University of Science and Technology of China, Hefei, China
| | - Li Zhang
- CAS Key Laboratory of Brain Function and Diseases, School of Life Sciences, University of Science and Technology of China, Hefei, China
| | - Hanxiao Liu
- CAS Key Laboratory of Brain Function and Diseases, School of Life Sciences, University of Science and Technology of China, Hefei, China
| | - Nigel W. Daw
- Department of Ophthalmology and Visual Sciences, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Yupeng Yang
- CAS Key Laboratory of Brain Function and Diseases, School of Life Sciences, University of Science and Technology of China, Hefei, China
- Department of Ophthalmology and Visual Sciences, Yale University School of Medicine, New Haven, Connecticut, United States of America
- * E-mail:
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Konishi S. Pursuit of Neurotransmitter Functions: Being Attracted with Fascination of the Synapse. YAKUGAKU ZASSHI 2017; 137:459-475. [PMID: 28381725 DOI: 10.1248/yakushi.16-00258] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In the beginning of the 1970s, only two chemical substances, acetylcholine and γ-aminobutyric acid (GABA), had been definitely established as neurotransmitters. Under such circumstances, I started my scientific career in Professor Masanori Otsuka's lab searching for the transmitter of primary sensory neurons. Until 1976, lines of evidence had accumulated indicating that the undecapeptide substance P could be released as a transmitter from primary afferent fibers into spinal synapses, although the substance P-mediated synaptic response had yet to be identified. Peripheral synapses could serve as a good model and thus, it was demonstrated in the prevertebral sympathetic ganglia by1985 that substance P released from axon collaterals of primary sensory neurons acts as the transmitter mediating non-cholinergic slow excitatory postsynaptic potential (EPSP). At that time, we also found that autonomic synapses were useful to uncover the transmitter role of the opioid peptide enkephalins, whose functions had been unknown since their discovery in 1975. Accordingly, enkephalins were found to serve a transmitter role in mediating presynaptic inhibition of cholinergic fast and non-cholinergic slow transmission in the prevertebral sympathetic ganglia. In 1990s, we attempted to devise a combined technique of brain slices and patch-clamp recordings. We applied it to study the regulatory mechanisms that operate around cerebellar GABAergic inhibitory synapses, because most of the studies then had centered on excitatory synapses and because inhibitory synapses are crucially involved in brain functions and disorders. Consequently, we discovered novel forms of heterosynaptic interactions, dual actions of a single transmitter, and receptor crosstalk, the details of which are described in this review.
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Affiliation(s)
- Shiro Konishi
- Department of Pharmacology, Kagawa School of Pharmaceutical Sciences, Tokushima Bunri University
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Kano M, Watanabe T. Type-1 metabotropic glutamate receptor signaling in cerebellar Purkinje cells in health and disease. F1000Res 2017; 6:416. [PMID: 28435670 PMCID: PMC5381626 DOI: 10.12688/f1000research.10485.1] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 03/30/2017] [Indexed: 01/28/2023] Open
Abstract
The cerebellum is a brain structure involved in coordination, control, and learning of movements, as well as certain aspects of cognitive function. Purkinje cells are the sole output neurons from the cerebellar cortex and therefore play crucial roles in the overall function of the cerebellum. The type-1 metabotropic glutamate receptor (mGluR1) is a key “hub” molecule that is critically involved in the regulation of synaptic wiring, excitability, synaptic response, and synaptic plasticity of Purkinje cells. In this review, we aim to highlight how mGluR1 controls these events in Purkinje cells. We also describe emerging evidence that altered mGluR1 signaling in Purkinje cells underlies cerebellar dysfunctions in several clinically relevant mouse models of human ataxias.
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Affiliation(s)
- Masanobu Kano
- Department of Neurophysiology, Graduate School of Medicine, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Takaki Watanabe
- Department of Neurophysiology, Graduate School of Medicine, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
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Shuvaev AN, Hosoi N, Sato Y, Yanagihara D, Hirai H. Progressive impairment of cerebellar mGluR signalling and its therapeutic potential for cerebellar ataxia in spinocerebellar ataxia type 1 model mice. J Physiol 2016; 595:141-164. [PMID: 27440721 DOI: 10.1113/jp272950] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Accepted: 07/11/2016] [Indexed: 12/12/2022] Open
Abstract
KEY POINTS Spinocerebellar ataxia type 1 (SCA1) is a progressive neurodegenerative disease caused by a gene defect, leading to movement disorder such as cerebellar ataxia. It remains largely unknown which functional defect contributes to the cerebellar ataxic phenotype in SCA1. In this study, we report progressive dysfunction of metabotropic glutamate receptor (mGluR) signalling, which leads to smaller slow synaptic responses, reduced dendritic Ca2+ signals and impaired synaptic plasticity at cerebellar synapses, in the early disease stage of SCA1 model mice. We also show that enhancement of mGluR signalling by a clinically available drug, baclofen, leads to improvement of motor performance in SCA1 mice. SCA1 is an incurable disease with no effective treatment, and our results may provide mechanistic grounds for targeting mGluRs and a novel drug therapy with baclofen to treat SCA1 patients in the future. ABSTRACT Spinocerebellar ataxia type 1 (SCA1) is a progressive neurodegenerative disease that presents with cerebellar ataxia and motor learning defects. Previous studies have indicated that the pathology of SCA1, as well as other ataxic diseases, is related to signalling pathways mediated by the metabotropic glutamate receptor type 1 (mGluR1), which is indispensable for proper motor coordination and learning. However, the functional contribution of mGluR signalling to SCA1 pathology is unclear. In the present study, we show that SCA1 model mice develop a functional impairment of mGluR signalling which mediates slow synaptic responses, dendritic Ca2+ signals, and short- and long-term synaptic plasticity at parallel fibre (PF)-Purkinje cell (PC) synapses in a progressive manner from the early disease stage (5 postnatal weeks) prior to PC death. Notably, impairment of mGluR-mediated dendritic Ca2+ signals linearly correlated with a reduction of PC capacitance (cell surface area) in disease progression. Enhancement of mGluR signalling by baclofen, a clinically available GABAB receptor agonist, led to an improvement of motor performance in SCA1 mice and the improvement lasted ∼1 week after a single application of baclofen. Moreover, the restoration of motor performance in baclofen-treated SCA1 mice matched the functional recovery of mGluR-mediated slow synaptic currents and mGluR-dependent short- and long-term synaptic plasticity. These results suggest that impairment of synaptic mGluR cascades is one of the important contributing factors to cerebellar ataxia in early and middle stages of SCA1 pathology, and that modulation of mGluR signalling by baclofen or other clinical interventions may be therapeutic targets to treat SCA1.
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Affiliation(s)
- Anton N Shuvaev
- Department of Neurophysiology and Neural Repair, Gunma University Graduate School of Medicine, Maebashi, Gunma, 371-8511, Japan.,Research Institute of Molecular Medicine and Pathobiochemistry, Krasnoyarsk State Medical University named after Prof. V. F. Voino-Yasenetsky, Krasnoyarsk, 660022, Russia
| | - Nobutake Hosoi
- Department of Neurophysiology and Neural Repair, Gunma University Graduate School of Medicine, Maebashi, Gunma, 371-8511, Japan
| | - Yamato Sato
- Department of Life Sciences, Graduate School of Arts and Sciences, University of Tokyo, Tokyo, 153-8902, Japan
| | - Dai Yanagihara
- Department of Life Sciences, Graduate School of Arts and Sciences, University of Tokyo, Tokyo, 153-8902, Japan
| | - Hirokazu Hirai
- Department of Neurophysiology and Neural Repair, Gunma University Graduate School of Medicine, Maebashi, Gunma, 371-8511, Japan.,Research Program for Neural Signalling, Division of Endocrinology, Metabolism and Signal Research, Gunma University Initiative for Advanced Research, Maebashi, Gunma, 371-8511, Japan
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Complex formation and functional interaction between adenosine A1 receptor and type-1 metabotropic glutamate receptor. J Pharmacol Sci 2015; 128:125-30. [PMID: 26154847 DOI: 10.1016/j.jphs.2015.06.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2015] [Revised: 06/09/2015] [Accepted: 06/10/2015] [Indexed: 11/24/2022] Open
Abstract
The adenosine A1 receptor (A1R) is a G protein-coupled receptor (GPCR) for adenosine, a ubiquitous neuromodulator, and thus regulates neuronal excitability, as well as arousal and sensitivity to pain. In addition, we have previously described a new mode of action for A1R: in cerebellar Purkinje cells, its activation attenuates neuronal responses to glutamate, as mediated by the type-1 metabotropic glutamate receptor (mGluR1). mGluR1 is also a GPCR, and elicits such responses as long-term depression of the postsynaptic response to glutamate, a cellular basis for cerebellar motor learning. Here, we explore in greater detail the interaction between A1R and mGluR1 using non-neuronal cells. Co-immunoprecipitation and Förster resonance energy transfer (FRET) analysis reveal that A1R and mGluR1 form a complex. Furthermore, we found that mGluR1 activation inhibits A1R signaling, as measured by changes in intracellular cAMP. These findings demonstrate that A1R and mGluR1 have the intrinsic ability to form a heteromeric complex and mutually modulate signaling. This interaction may represent a new form of intriguing GPCR-mediated cellular responses.
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Kantamneni S. Cross-talk and regulation between glutamate and GABAB receptors. Front Cell Neurosci 2015; 9:135. [PMID: 25914625 PMCID: PMC4392697 DOI: 10.3389/fncel.2015.00135] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2014] [Accepted: 03/23/2015] [Indexed: 12/16/2022] Open
Abstract
Brain function depends on co-ordinated transmission of signals from both excitatory and inhibitory neurotransmitters acting upon target neurons. NMDA, AMPA and mGluR receptors are the major subclasses of glutamate receptors that are involved in excitatory transmission at synapses, mechanisms of activity dependent synaptic plasticity, brain development and many neurological diseases. In addition to canonical role of regulating presynaptic release and activating postsynaptic potassium channels, GABAB receptors also regulate glutamate receptors. There is increasing evidence that metabotropic GABAB receptors are now known to play an important role in modulating the excitability of circuits throughout the brain by directly influencing different types of postsynaptic glutamate receptors. Specifically, GABAB receptors affect the expression, activity and signaling of glutamate receptors under physiological and pathological conditions. Conversely, NMDA receptor activity differentially regulates GABAB receptor subunit expression, signaling and function. In this review I will describe how GABAB receptor activity influence glutamate receptor function and vice versa. Such a modulation has widespread implications for the control of neurotransmission, calcium-dependent neuronal function, pain pathways and in various psychiatric and neurodegenerative diseases.
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Affiliation(s)
- Sriharsha Kantamneni
- Bradford School of Pharmacy, School of Life Sciences, University of Bradford Bradford, West Yorkshire, UK
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20
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Hawkes R. Purkinje cell stripes and long-term depression at the parallel fiber-Purkinje cell synapse. Front Syst Neurosci 2014; 8:41. [PMID: 24734006 PMCID: PMC3975104 DOI: 10.3389/fnsys.2014.00041] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2013] [Accepted: 03/07/2014] [Indexed: 12/13/2022] Open
Abstract
The cerebellar cortex comprises a stereotyped array of transverse zones and parasagittal stripes, built around multiple Purkinje cell subtypes, which is highly conserved across birds and mammals. This architecture is revealed in the restricted expression patterns of numerous molecules, in the terminal fields of the afferent projections, in the distribution of interneurons, and in the functional organization. This review provides an overview of cerebellar architecture with an emphasis on attempts to relate molecular architecture to the expression of long-term depression (LTD) at the parallel fiber-Purkinje cell (pf-PC) synapse.
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Affiliation(s)
- Richard Hawkes
- Department of Cell Biology and Anatomy, University of Calgary Calgary, AB, Canada ; Hotchkiss Brain Institute, University of Calgary Calgary, AB, Canada ; Genes and Development Research Group, Faculty of Medicine, University of Calgary Calgary, AB, Canada
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Abstract
The broad connectivity of inhibitory interneurons and the capacity of inhibitory synapses to be plastic make them ideal regulators of the level of excitability of many neurons simultaneously. Whether inhibitory synaptic plasticity may also contribute to the selective regulation of single neurons and local microcircuits activity has not been investigated. Here we demonstrate that in rat primary visual cortex inhibitory synaptic plasticity is connection specific and depends on the activation of postsynaptic GABAB-Gi/o protein signaling. Through the activation of this intracellular signaling pathway, inhibitory plasticity can alter the state of a single postsynaptic neuron and directly affect the induction of plasticity at its glutamatergic inputs. This interaction is modulated by sensory experience. Our data demonstrate that in recurrent circuits, excitatory and inhibitory forms of synaptic plasticity are not integrated as independent events, but interact to cooperatively drive the activity-dependent rewiring of local microcircuits.
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22
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Xu C, Zhang W, Rondard P, Pin JP, Liu J. Complex GABAB receptor complexes: how to generate multiple functionally distinct units from a single receptor. Front Pharmacol 2014; 5:12. [PMID: 24575041 PMCID: PMC3920572 DOI: 10.3389/fphar.2014.00012] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2013] [Accepted: 01/22/2014] [Indexed: 01/05/2023] Open
Abstract
The main inhibitory neurotransmitter, GABA, acts on both ligand-gated and G protein-coupled receptors, the GABAA/C and GABAB receptors, respectively. The later play important roles in modulating many synapses, both at the pre- and post-synaptic levels, and are then still considered as interesting targets to treat a number of brain diseases, including addiction. For many years, several subtypes of GABAB receptors were expected, but cloning revealed only two genes that work in concert to generate a single type of GABAB receptor composed of two subunits. Here we will show that the signaling complexity of this unit receptor type can be largely increased through various ways, including receptor stoichiometry, subunit isoforms, cell-surface expression and localization, crosstalk with other receptors, or interacting proteins. These recent data revealed how complexity of a receptor unit can be increased, observation that certainly are not unique to the GABAB receptor.
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Affiliation(s)
- Chanjuan Xu
- Cellular Signaling Laboratory, Key Laboratory of Molecular Biophysics of Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology Wuhan, China
| | - Wenhua Zhang
- Cellular Signaling Laboratory, Key Laboratory of Molecular Biophysics of Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology Wuhan, China
| | - Philippe Rondard
- Institut de Génomique Fonctionnelle, CNRS UMR5203, INSERM U661, Universités de Montpellier I & II Montpellier, France
| | - Jean-Philippe Pin
- Institut de Génomique Fonctionnelle, CNRS UMR5203, INSERM U661, Universités de Montpellier I & II Montpellier, France
| | - Jianfeng Liu
- Cellular Signaling Laboratory, Key Laboratory of Molecular Biophysics of Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology Wuhan, China
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Functional cooperation of metabotropic adenosine and glutamate receptors regulates postsynaptic plasticity in the cerebellum. J Neurosci 2014; 33:18661-71. [PMID: 24259587 DOI: 10.1523/jneurosci.5567-12.2013] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
G-protein-coupled receptors (GPCRs) may form heteromeric complexes and cooperatively mediate cellular responses. Although heteromeric GPCR complexes are suggested to occur in many neurons, their contribution to neuronal function remains unclear. We address this question using two GPCRs expressed in cerebellar Purkinje cells: adenosine A1 receptor (A1R), which regulates neurotransmitter release and neuronal excitability in central neurons, and type-1 metabotropic glutamate receptor (mGluR1), which mediates cerebellar long-term depression, a form of synaptic plasticity crucial for cerebellar motor learning. We examined interaction between these GPCRs by immunocytochemical, biochemical, and Förster resonance energy transfer analyses in cultured mouse Purkinje cells and heterologous expression cells. These analyses revealed that the GPCRs closely colocalized and formed heteromeric complexes on the cell surfaces. Furthermore, our electrophysiological analysis showed that CSF levels (40-400 nm) of adenosine or synthetic A1R agonists with comparable potencies blocked mGluR1-mediated long-term depression of the postsynaptic glutamate-responsiveness (glu-LTD) of cultured Purkinje cells. A similar dose of the A1R agonist decreased the ligand affinity of mGluR1 and did not affect depolarization-induced Ca(2+) influx, which is an essential factor in inducing glu-LTD. The A1R agonist did not affect glu-LTD mimicked by direct activation of protein kinase C. These results suggest that A1R blocked glu-LTD by decreasing the ligand sensitivity of mGluR1, but not the coupling efficacy from mGluR1 to the intracellular signaling cascades. These findings provide a new insight into neuronal GPCR signaling and demonstrate a novel regulatory mechanism of synaptic plasticity.
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Shirai Y, Sasajima T, Uchiyama S, Takegoshi Y, Tsushima E, Tabata T. [Activation of cerebellar B-type γ-aminobutyric acid receptor modulates optokinetic reflex adaptation]. YAKUGAKU ZASSHI 2013; 134:439-45. [PMID: 24304601 DOI: 10.1248/yakushi.13-00233] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The cerebellar cortex, the brain region responsible for motor coordination and learning expresses a high density of B-type γ-aminobutyric acid receptor (GABAbR). Previous in vitro and in situ studies indicated that cerebellar GABAbR may mediate multiple forms of inhibitory and excitatory modulation of cerebellar circuits. Nevertheless, the in vivo influence of cerebellar GABAbR activation is unclear. As the first step in addressing this issue, we examined how pharmacological activation of cerebellar GABAbR modulates optokinetic reflex (OKR), an involuntary cerebellum-dependent eye movement for stabilizing the retinal image against the drift of the visual scene. We injected baclofen, a GABAbR-selective agonist, or control saline into the cerebellar flocculi of adult mice and then performed 1-h OKR measurement sessions on two consecutive days. In the day 1 session, the baclofen (5 nM)-injected mice and control mice showed similar initial OKR gains and similar training-induced increases in the OKR gain (OKR adaptation). This result suggests that GABAbR activation does not affect cerebellar computation for executing OKR and formation of short-term memory for OKR adaptation. At the beginning of the day 2 session, the baclofen (5 nM or 50 μM)-injected mice showed an OKR gain higher than that achieved in the day 1 session while the control mice did not. This result suggests that GABAbR activation may facilitate the formation of OKR adaptation-related long-term memory. These findings provide a new insight into the functional architecture of the cerebellar circuits and indicate GABAbR to be a new target of pharmacological therapy against diseases with cerebellar dysfunction.
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Affiliation(s)
- Yoshihiro Shirai
- Laboratory for Neural Information Technology, Graduate School of Sciences and Engineering, University of Toyama
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25
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Moreau AW, Kullmann DM. NMDA receptor-dependent function and plasticity in inhibitory circuits. Neuropharmacology 2013; 74:23-31. [DOI: 10.1016/j.neuropharm.2013.03.004] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2012] [Revised: 02/20/2013] [Accepted: 03/01/2013] [Indexed: 01/22/2023]
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Co-application of the GABAB receptor agonist, baclofen, and the mGlu receptor agonist, L-CCG-I, facilitates [3H]GABA release from rat cortical nerve endings. J Neural Transm (Vienna) 2013; 120:1641-9. [DOI: 10.1007/s00702-013-1057-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2013] [Accepted: 06/19/2013] [Indexed: 02/06/2023]
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27
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Ikeda K, Satake S, Onaka T, Sugimoto H, Takeda N, Imoto K, Kawakami K. Enhanced inhibitory neurotransmission in the cerebellar cortex of Atp1a3-deficient heterozygous mice. J Physiol 2013; 591:3433-49. [PMID: 23652595 DOI: 10.1113/jphysiol.2012.247817] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Dystonia is characterized by excessive involuntary and prolonged simultaneous contractions of both agonist and antagonist muscles. Although the basal ganglia have long been proposed as the primary region, recent studies indicated that the cerebellum also plays a key role in the expression of dystonia. One hereditary form of dystonia, rapid-onset dystonia with parkinsonism (RDP), is caused by loss of function mutations of the gene for the Na pump α3 subunit (ATP1A3). Little information is available on the affected brain regions and mechanism for dystonia by the mutations in RDP. The Na pump is composed of α and β subunits and maintains ionic gradients of Na(+) and K(+) across the cell membrane. The gradients are utilized for neurotransmitter reuptake and their alteration modulates neural excitability. To provide insight into the molecular aetiology of RDP, we generated and analysed knockout heterozygous mice (Atp1a3(+/-)). Atp1a3(+/-) showed increased symptoms of dystonia that is induced by kainate injection into the cerebellar vermis. Atp1a3 mRNA was highly expressed in Purkinje cells and molecular-layer interneurons, and its product was concentrated at Purkinje cell soma, the site of abundant vesicular γ-aminobutyric acid transporter (VGAT) signal, suggesting the presynaptic localization of the α3 subunit in the inhibitory synapse. Electrophysiological studies showed that the inhibitory neurotransmission at molecular-layer interneuron-Purkinje cell synapses was enhanced in Atp1a3(+/-) cerebellar cortex, and that the enhancement originated via a presynaptic mechanism. Our results shed light on the role of Atp1a3 in the inhibitory synapse, and potential involvement of inhibitory synaptic dysfunction for the pathophysiology of dystonia.
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Affiliation(s)
- Keiko Ikeda
- Division of Biology, Center for Molecular Medicine, Jichi Medical University, Yakushiji 3311-1, Shimotsuke, Tochigi 329-0498, Japan.
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A-kinase anchoring protein-calcineurin signaling in long-term depression of GABAergic synapses. J Neurosci 2013; 33:2650-60. [PMID: 23392692 DOI: 10.1523/jneurosci.2037-12.2013] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The postsynaptic scaffolding A-kinase anchoring protein 79/150 (AKAP79/150) signaling complex regulates excitatory synaptic transmission and strength through tethering protein kinase A (PKA), PKC, and calcineurin (CaN) to the postsynaptic densities of neurons (Sanderson and Dell'Acqua, 2011), but its role in inhibitory synaptic transmission and plasticity is unknown. Using immunofluorescence and whole-cell patch-clamp recording in rat midbrain slices, we show that activation of postsynaptic D(2)-like family of dopamine (DA) receptor in the ventral tegmental area (VTA) induces long-term depression (LTD) of GABAergic synapses on DA neurons through an inositol triphosphate receptor-mediated local rise in postsynaptic Ca(2+) and CaN activation accompanied by PKA inhibition, which requires AKAP150 as a bridging signaling molecule. Our data also illuminate a requirement for a clathrin-mediated internalization of GABA(A) receptors in expression of LTD(GABA). Moreover, disruption of AKAP-PKA anchoring does not affect glutamatergic synapses onto DA neurons, suggesting that the PKA-AKAP-CaN complex is uniquely situated at GABA(A) receptor synapses in VTA DA neurons to regulate plasticity associated with GABA(A) receptors. Drug-induced modulation of GABAergic plasticity in the VTA through such novel signaling mechanisms has the potential to persistently alter the output of individual DA neurons and of the VTA, which may contribute to the reinforcing or addictive properties of drugs of abuse.
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29
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Dynamic impact of temporal context of Ca²⁺ signals on inhibitory synaptic plasticity. Sci Rep 2011; 1:143. [PMID: 22355660 PMCID: PMC3216624 DOI: 10.1038/srep00143] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2011] [Accepted: 10/14/2011] [Indexed: 11/14/2022] Open
Abstract
Neuronal activity-dependent synaptic plasticity, a basis for learning and memory, is tightly correlated with the pattern of increase in intracellular Ca2+ concentration ([Ca2+]i). Here, using combined application of electrophysiological experiments and systems biological simulation, we show that such a correlation dynamically changes depending on the context of [Ca2+]i increase. In a cerebellar Purkinje cell, long-term potentiation of inhibitory GABAA receptor responsiveness (called rebound potentiation; RP) was induced by [Ca2+]i increase in a temporally integrative manner through sustained activation of Ca2+/calmodulin-dependent protein kinase II (CaMKII). However, the RP establishment was canceled by coupling of two patterns of RP-inducing [Ca2+]i increase depending on the temporal sequence. Negative feedback signaling by phospho-Thr305/306 CaMKII detected the [Ca2+]i context, and assisted the feedforward inhibition of CaMKII through PDE1, resulting in the RP impairment. The [Ca2+]i context-dependent dynamic regulation of synaptic plasticity might contribute to the temporal refinement of information flow in neuronal networks.
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Kueh S, Dempster J, Head S, Morley J. Reduced postsynaptic GABAA receptor number and enhanced gaboxadol induced change in holding currents in Purkinje cells of the dystrophin-deficient mdx mouse. Neurobiol Dis 2011; 43:558-64. [DOI: 10.1016/j.nbd.2011.05.002] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2010] [Revised: 04/18/2011] [Accepted: 05/05/2011] [Indexed: 10/18/2022] Open
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Gutierrez DV, Mark MD, Masseck O, Maejima T, Kuckelsberg D, Hyde RA, Krause M, Kruse W, Herlitze S. Optogenetic control of motor coordination by Gi/o protein-coupled vertebrate rhodopsin in cerebellar Purkinje cells. J Biol Chem 2011; 286:25848-58. [PMID: 21628464 PMCID: PMC3138296 DOI: 10.1074/jbc.m111.253674] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2011] [Revised: 05/26/2011] [Indexed: 01/22/2023] Open
Abstract
G protein-coupled receptors are involved in the modulation of complex neuronal networks in the brain. To investigate the impact of a cell-specific G(i/o) protein-mediated signaling pathway on brain function, we created a new optogenetic mouse model in which the G(i/o) protein-coupled receptor vertebrate rhodopsin can be cell-specifically expressed with the aid of Cre recombinase. Here we use this mouse model to study the functional impact of G(i/o) modulation in cerebellar Purkinje cells (PCs). We show that in vivo light activation of vertebrate rhodopsin specifically expressed in PCs reduces simple spike firing that is comparable with the reduction in firing observed for the activation of cerebellar G(i/o)-coupled GABA(B) receptors. Notably, the light exposure of the cerebellar vermis in freely moving mice changes the motor behavior. Thus, our studies directly demonstrate that spike modulation via G(i/o)-mediated signaling in cerebellar PCs affects motor coordination and show a new promising approach for studying the physiological function of G protein-coupled receptor-mediated signaling in a cell type-specific manner.
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Affiliation(s)
- Davina V. Gutierrez
- the Department of Neurosciences, Case Western Reserve University, Cleveland, Ohio 44106
| | - Melanie D. Mark
- From the Department of Zoology and Neurobiology, ND7/31, Ruhr-University Bochum, Universitätsstrasse 150, D-44780 Bochum, Germany and
| | - Olivia Masseck
- From the Department of Zoology and Neurobiology, ND7/31, Ruhr-University Bochum, Universitätsstrasse 150, D-44780 Bochum, Germany and
| | - Takashi Maejima
- From the Department of Zoology and Neurobiology, ND7/31, Ruhr-University Bochum, Universitätsstrasse 150, D-44780 Bochum, Germany and
| | - Denise Kuckelsberg
- From the Department of Zoology and Neurobiology, ND7/31, Ruhr-University Bochum, Universitätsstrasse 150, D-44780 Bochum, Germany and
| | - Robert A. Hyde
- the Department of Neurosciences, Case Western Reserve University, Cleveland, Ohio 44106
| | - Martin Krause
- From the Department of Zoology and Neurobiology, ND7/31, Ruhr-University Bochum, Universitätsstrasse 150, D-44780 Bochum, Germany and
| | - Wolfgang Kruse
- From the Department of Zoology and Neurobiology, ND7/31, Ruhr-University Bochum, Universitätsstrasse 150, D-44780 Bochum, Germany and
| | - Stefan Herlitze
- From the Department of Zoology and Neurobiology, ND7/31, Ruhr-University Bochum, Universitätsstrasse 150, D-44780 Bochum, Germany and
- the Department of Neurosciences, Case Western Reserve University, Cleveland, Ohio 44106
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Broussard DM, Titley HK, Antflick J, Hampson DR. Motor learning in the VOR: the cerebellar component. Exp Brain Res 2011; 210:451-63. [PMID: 21336828 DOI: 10.1007/s00221-011-2589-z] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2010] [Accepted: 01/31/2011] [Indexed: 12/23/2022]
Abstract
This paper reviews results that support a model in which memory for VOR gain is initially encoded in the flocculus, and in which cerebellar LTD and LTP are responsible for gain increases and gain decreases, respectively. We also review data suggesting that after it is encoded, motor memory can either be disrupted, possibly by a local mechanism, or else consolidated. We show that consolidation can be rapid, in which case the frequency dependence of learning is unchanged and we will argue that this is consistent with a local mechanism of consolidation. In the longer term, however, the available evidence supports the transfer of memory out of the flocculus. In new experiments reported here, we address the mechanism of memory encoding. Pharmacological evidence shows that both mGluR1 and GABA(B) receptors in the flocculus are necessary for gain-up, but not for gain-down learning. Immunohistochemical experiments show that the two receptors are largely segregated on different dendritic spines on Purkinje cells. Together with what is already known of the mechanisms of cerebellar LTD and LTP, our data suggest that the direction of learning may be determined by interactions among groups of spines. Our results also provide new evidence for the existence of frequency channels for vestibular signals within the cerebellar cortex.
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Lee SH. Platform Technologies for Research on the G Protein Coupled Receptor: Applications to Drug Discovery Research. Biomol Ther (Seoul) 2011. [DOI: 10.4062/biomolther.2011.19.1.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
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Sherin A, Peeyush KT, Naijil G, Chinthu R, Paulose CS. Hypoglycemia induced behavioural deficit and decreased GABA receptor, CREB expression in the cerebellum of streptozoticin induced diabetic rats. Brain Res Bull 2010; 83:360-6. [PMID: 20851745 DOI: 10.1016/j.brainresbull.2010.09.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2010] [Revised: 08/12/2010] [Accepted: 09/02/2010] [Indexed: 11/25/2022]
Abstract
Intensive glycemic control during diabetes is associated with an increased incidence of hypoglycemia, which is the major barrier in blood glucose homeostasis during diabetes therapy. The CNS neurotransmitters play an important role in the regulation of glucose homeostasis. In the present study, we showed the effects of hypoglycemia in diabetic and non- diabetic rats on motor functions and alterations of GABA receptor and CREB expression in the cerebellum. Cerebellar dysfunction is associated with seizure generation, motor deficits and memory impairment. Scatchard analysis of [(3)H]GABA binding in the cerebellum of diabetic hypoglycemic and control hypoglycemic rats showed significant (P<0.01) decrease in B(max) and K(d) compared to diabetic and control rats. Real-time PCR amplification of GABA receptor subunit GABA(Aα1) and GAD showed significant (P<0.001) down-regulation in the cerebellum of hypoglycemic rats compared to diabetic and control rats. Confocal imaging study confirmed the decreased GABA receptors in hypoglycemic rats. CREB mRNA expression was down-regulated during recurrent hypoglycemia. Both diabetic and non-diabetic hypoglycemic rats showed impaired performance in grid walk test compared to diabetic and control. Impaired GABA receptor and CREB expression along with motor function deficit were more prominent in hypoglycemic rats than hyperglycemic which showed that hypoglycemia is causing more neuronal damage at molecular level. These molecular changes observed during hypo/hyperglycemia contribute to motor and learning deficits which has clinical significance in diabetes treatment.
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Affiliation(s)
- A Sherin
- Molecular Neurobiology and Cell Biology Unit, Centre for Neuroscience, Department of Biotechnology, Cochin University of Science and Technology, Cochin 682 022, Kerala, India
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The mammalian interaural time difference detection circuit is differentially controlled by GABAB receptors during development. J Neurosci 2010; 30:9715-27. [PMID: 20660254 DOI: 10.1523/jneurosci.1552-10.2010] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Throughout development GABA(B) receptors (GABA(B)Rs) are widely expressed in the mammalian brain. In mature auditory brainstem neurons, GABA(B)Rs are involved in the short-term regulation of the strength and dynamics of excitatory and inhibitory inputs, thus modulating sound analysis. During development, GABA(B)Rs also contribute to long-term changes in input strength. Using a combination of whole-cell patch-clamp recordings in acute brain slices and immunostainings in gerbils, we characterized developmental changes in GABA(B)R-mediated regulation of synaptic inputs to neurons in the medial superior olive (MSO), an auditory brainstem nucleus that analyzes interaural time differences (ITDs). Here, we show that, before hearing onset, GABA(B)R-mediated depression of transmitter release is much stronger for excitation than inhibition, whereas in mature animals GABA(B)Rs mainly control the inhibition. During the same developmental period, GABA(B)R immunoreactivity shifts from the dendritic to the somatic region of the MSO. Furthermore, only before hearing onset (postnatal day 12), stimulation of the fibers originating in the medial and the lateral nucleus of the trapezoid body (MNTB and LNTB) activates GABA(B)Rs on both the inhibitory and the excitatory inputs. After hearing onset, GAD65-positive endings devoid of glycine transporter reactivity suggest GABA release from sources other than the MNTB and LNTB. At this age, pharmacological increase of spontaneous synaptic release activates GABA(B)Rs only on the inhibitory inputs. This indicates not only a profound inhibitory effect of GABA(B)Rs on the major inputs to MSO neurons in neonatal animals but also a direct modulatory role of GABA(B)Rs for ITD analysis in the MSO of adult animals.
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Heskin-Sweezie R, Titley HK, Baizer JS, Broussard DM. Type B GABA receptors contribute to the restoration of balance during vestibular compensation in mice. Neuroscience 2010; 169:302-14. [PMID: 20394801 PMCID: PMC2910079 DOI: 10.1016/j.neuroscience.2010.04.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2010] [Revised: 03/23/2010] [Accepted: 04/05/2010] [Indexed: 10/19/2022]
Abstract
Following unilateral vestibular damage (UVD), vestibular compensation restores both static and dynamic vestibular reflexes. The cerebellar cortex provides powerful GABAergic inhibitory input to the vestibular nuclei which is necessary for compensation. Metabotropic GABA type B (GABA(B)) receptors in the vestibular nuclei are thought to be involved. However, the contribution of GABA(B) receptors may differ between static and dynamic compensation. We tested static and dynamic postural reflexes and gait in young mice, while they compensated for UVD caused by injection of air into the vestibular labyrinth. The effects of an agonist (baclofen), an antagonist (CGP56433A) and a positive allosteric modulator (CGP7930) of the GABA(B) receptor were evaluated during compensation. Static postural reflexes recovered very rapidly in our model, and baclofen slightly accelerated recovery. However, CGP56433A significantly impaired static compensation. Dynamic reflexes were evaluated by balance-beam performance and by gait; both showed significant decrements following UVD and performance improved over the next 2 days. Both CGP56433A and baclofen temporarily impaired the ability to walk on a balance beam after UVD. Two days later, there were no longer any significant effects of drug treatments on balance-beam performance. Baclofen slightly accelerated the recovery of stride length on a flat surface, but CGP7930 worsened the gait impairment following UVD. Using immunohistochemistry, we confirmed that GABA(B) receptors are abundantly expressed on the vestibulospinal neurons of Deiters in mice. Our results suggest that GABA(B) receptors contribute to the compensation of static vestibular reflexes following unilateral peripheral damage. We also conclude that impairment of the first stage of compensation, static recovery, does not necessarily result in an impairment of dynamic recovery in the long term.
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Affiliation(s)
| | | | - Joan S. Baizer
- Department of Physiology and Biophysics, University at Buffalo
| | - Dianne M. Broussard
- Department of Physiology, University of Toronto
- Division of Neurology, Department of Medicine, University of Toronto
- Division of Fundamental Neurobiology, Toronto Western Research Institute, University Health Network, Toronto
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Mathew J, Soman S, Sadanandan J, Paulose CS. Decreased GABA receptor in the striatum and spatial recognition memory deficit in epileptic rats: effect of Bacopa monnieri and bacoside-A. JOURNAL OF ETHNOPHARMACOLOGY 2010; 130:255-261. [PMID: 20451596 DOI: 10.1016/j.jep.2010.04.043] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/30/2009] [Revised: 04/10/2010] [Accepted: 04/28/2010] [Indexed: 05/29/2023]
Abstract
AIM OF THE STUDY Gamma-aminobutyric acid A receptors are the principal mediators of synaptic inhibition in striatal neurons and play an important role in preventing the spreading of seizures through the striatum. In the present study, effect of Bacopa monnieri (L.) Pennel and its active component bacoside-A on spatial recognition memory deficit and alterations of GABA receptor in the striatum of epileptic rats were investigated. MATERIALS AND METHODS Total GABA and GABA(A) receptor numbers in the control and epileptic rats were evaluated using [(3)H]GABA and [(3)H]bicuculline binding. GABA(Aalpha1,) GABA(Aalpha5,) GABA(Agamma3) and GABA(Adelta) gene expressions were studied. Behavioral performance was assed using Y-maze. RESULTS Scatchard analysis of [(3)H]GABA and [(3)H]bicuculline in the striatum of epileptic rats showed significant decrease in B(max) compared to control. Real-Time PCR amplification of GABA(A) receptor subunits such as GABA(Aalpha1,) GABA(Aalpha5) and GABA(Adelta), were down regulated (p<0.001) in the striatum of epileptic rats compared to control. Epileptic rats have deficit in Y-maze performance. Bacopa monnieri and bacoside-A treatment reversed these changes to near control. CONCLUSION Our results suggest that decreased GABA receptors in the striatum have an important role in epilepsy associated motor learning deficits and Bacopa monnieri and bacoside-A has a beneficial effect in the management of epilepsy.
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Affiliation(s)
- Jobin Mathew
- Centre for Neuroscience, Department of Biotechnology, Cochin University of Science and Technology, Cochin, Kerala, India
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Mathew J, Peeyush Kumar T, Khan RS, Paulose CS. Behavioral deficit and decreased GABA receptor functional regulation in the cerebellum of epileptic rats: effect of Bacopa monnieri and bacoside A. Epilepsy Behav 2010; 17:441-7. [PMID: 20153260 DOI: 10.1016/j.yebeh.2010.01.012] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/25/2009] [Revised: 01/11/2010] [Accepted: 01/11/2010] [Indexed: 11/28/2022]
Abstract
In the present study, the effects of Bacopa monnieri and its active component, bacoside A, on motor deficit and alterations of GABA receptor functional regulation in the cerebellum of epileptic rats were investigated. Scatchard analysis of [(3)H]GABA and [(3)H]bicuculline in the cerebellum of epileptic rats revealed a significant decrease in B(max) compared with control. Real-time polymerase chain reaction amplification of GABA(A) receptor subunits-GABA(Aalpha1), GABA(Aalpha5,) and GABA(Adelta)-was downregulated (P<0.001) in the cerebellum of epileptic rats compared with control rats. Epileptic rats exhibit deficits in radial arm and Y-maze performance. Treatment with B. monnieri and bacoside A reversed these changes to near-control levels. Our results suggest that changes in GABAergic activity, motor learning, and memory deficit are induced by the occurrence of repetitive seizures. Treatment with B. monnieri and bacoside A prevents the occurrence of seizures thereby reducing the impairment of GABAergic activity, motor learning, and memory deficit.
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Affiliation(s)
- Jobin Mathew
- Department of Biotechnology, Molecular Neurobiology and Cell Biology Unit, Centre for Neuroscience, Cochin University of Science and Technology, Kerala, India
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GABAB Receptor-Mediated Modulation of Metabotropic Glutamate Signaling and Synaptic Plasticity in Central Neurons. GABABRECEPTOR PHARMACOLOGY - A TRIBUTE TO NORMAN BOWERY 2010; 58:149-73. [DOI: 10.1016/s1054-3589(10)58007-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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40
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Rives ML, Vol C, Fukazawa Y, Tinel N, Trinquet E, Ayoub MA, Shigemoto R, Pin JP, Prézeau L. Crosstalk between GABAB and mGlu1a receptors reveals new insight into GPCR signal integration. EMBO J 2009; 28:2195-208. [PMID: 19590495 DOI: 10.1038/emboj.2009.177] [Citation(s) in RCA: 93] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2008] [Accepted: 05/29/2009] [Indexed: 12/22/2022] Open
Abstract
G protein-coupled receptors (GPCRs) have critical functions in intercellular communication. Although a wide range of different receptors have been identified in the same cells, the mechanism by which signals are integrated remains elusive. The ability of GPCRs to form dimers or larger hetero-oligomers is thought to generate such signal integration. We examined the molecular mechanisms responsible for the GABA(B) receptor-mediated potentiation of the mGlu receptor signalling reported in Purkinje neurons. We showed that this effect does not require a physical interaction between both receptors. Instead, it is the result of a more general mechanism in which the betagamma subunits produced by the Gi-coupled GABA(B) receptor enhance the mGlu-mediated Gq response. Most importantly, this mechanism could be generally applied to other pairs of Gi- and Gq-coupled receptors and the signal integration varied depending on the time delay between activation of each receptor. Such a mechanism helps explain specific properties of cells expressing two different Gi- and Gq-coupled receptors activated by a single transmitter, or properties of GPCRs naturally coupled to both types of the G protein.
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Affiliation(s)
- Marie-Laure Rives
- Department of Molecular Pharmacology, CNRS, UMR 5203, Institut de Génomique fonctionnelle, Montpellier, France
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Lu H, Esquivel AV, Bower JM. 3D electron microscopic reconstruction of segments of rat cerebellar Purkinje cell dendrites receiving ascending and parallel fiber granule cell synaptic inputs. J Comp Neurol 2009; 514:583-94. [PMID: 19363797 DOI: 10.1002/cne.22041] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Growing physiological evidence suggests that there are functional differences between synapses made by the ascending and parallel fiber segments of the granule axon on cerebellar Purkinje cells. Supporting this view, our previous electron microscopic studies suggested that these synapses also contacted different regions of the Purkinje cell dendrite, and in particular that ascending segment synapses are made exclusively on the smallest diameter Purkinje cell dendrites. In the current study we used serial electron microscopic techniques to reconstruct Purkinje cell dendritic segments up to almost 10 mum in length. Using a combination of anatomical and immunological labeling techniques we identified the ascending or parallel fiber origins of the excitatory synaptic inputs onto dendritic spines, as well as the location of inhibitory synapses made directly on the dendritic shaft. The results confirmed that there are regions of the Purkinje cell dendrite receiving exclusively ascending or parallel fiber synapses and that ascending segment synapses are only found on small-diameter dendrites. In addition, we describe for the first time small-diameter dendritic regions contacted by both types of excitatory synapses. While our data suggest that the majority of inhibitory inputs to the Purkinje cell tree are associated with parallel fiber synaptic inputs, we also found inhibitory inputs on dendritic regions with mixed ascending and parallel fiber inputs, or exclusively parallel fiber inputs. The finding that ascending and parallel fiber inputs can be segregated on the Purkinje cell dendritic tree provides further evidence that these excitatory granule cell synaptic inputs may be functionally distinct.
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Affiliation(s)
- Huo Lu
- Research Imaging Center, University of Texas Health Science Center at San Antonio, San Antonio, Texas 78229, USA.
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Synaptic mGluR activation drives plasticity of calcium-permeable AMPA receptors. Nat Neurosci 2009; 12:593-601. [PMID: 19377472 DOI: 10.1038/nn.2309] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2008] [Accepted: 03/03/2009] [Indexed: 11/08/2022]
Abstract
In contrast with conventional NMDA receptor-dependent synaptic plasticity, the synaptic events controlling the plasticity of GluR2-lacking Ca(2+)-permeable AMPA receptors (CP-AMPARs) remain unclear. At parallel fiber synapses onto cerebellar stellate cells, Ca(2+) influx through AMPARs triggers a switch in AMPAR subunit composition, resulting in loss of Ca(2+) permeabilty. Paradoxically, synaptically induced depolarization will suppress this Ca(2+) entry by promoting polyamine block of CP-AMPARs. We therefore examined other mechanisms that may control this receptor regulation under physiological conditions. We found that activation of both mGluRs and CP-AMPARs is necessary and sufficient to drive an AMPAR subunit switch and that by enhancing mGluR activity, GABA(B)R activation promotes this plasticity. Furthermore, we found that mGluRs and GABA(B)Rs are tonically activated, thus setting the basal tone for EPSC amplitude and rectification. Regulation by both excitatory and inhibitory inputs provides an unexpected mechanism that determines the potential of these synapses to show dynamic changes in AMPAR Ca(2+) permeability.
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Kano M, Hashimoto K, Tabata T. Type-1 metabotropic glutamate receptor in cerebellar Purkinje cells: a key molecule responsible for long-term depression, endocannabinoid signalling and synapse elimination. Philos Trans R Soc Lond B Biol Sci 2008; 363:2173-86. [PMID: 18339599 DOI: 10.1098/rstb.2008.2270] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
The cerebellum is a brain structure involved in the coordination, control and learning of movements, and elucidation of its function is an important issue. Japanese scholars have made seminal contributions in this field of neuroscience. Electrophysiological studies of the cerebellum have a long history in Japan since the pioneering works by Ito and Sasaki. Elucidation of the basic circuit diagram of the cerebellum in the 1960s was followed by the construction of cerebellar network theories and finding of their neural correlates in the 1970s. A theoretically predicted synaptic plasticity, long-term depression (LTD) at parallel fibre to Purkinje cell synapse, was demonstrated experimentally in 1982 by Ito and co-workers. Since then, Japanese neuroscientists from various disciplines participated in this field and have made major contributions to elucidate molecular mechanisms underlying LTD. An important pathway for LTD induction is type-1 metabotropic glutamate receptor (mGluR1) and its downstream signal transduction in Purkinje cells. Sugiyama and co-workers demonstrated the presence of mGluRs and Nakanishi and his pupils identified the molecular structures and functions of the mGluR family. Moreover, the authors contributed to the discovery and elucidation of several novel functions of mGluR1 in cerebellar Purkinje cells. mGluR1 turned out to be crucial for the release of endocannabinoid from Purkinje cells and the resultant retrograde suppression of transmitter release. It was also found that mGluR1 and its downstream signal transduction in Purkinje cells are indispensable for the elimination of redundant synapses during post-natal cerebellar development. This article overviews the seminal works by Japanese neuroscientists, focusing on mGluR1 signalling in cerebellar Purkinje cells.
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Affiliation(s)
- Masanobu Kano
- Department of Cellular Neuroscience, Osaka University, 2-2 Yamada-oka, Suita, Osaka 565-0871, Japan.
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Abstract
Transcranial magnetic stimulation (TMS) and repetitive TMS (rTMS) have been used increasingly over the past few years to study both the pathophysiology of schizophrenia as well as the utility of focal neuromodulation as a novel treatment for schizophrenia. rTMS treatment studies to date have explored its effect on both positive and negative symptoms by targeting cortical regions thought to underlie these symptom clusters. Studies on auditory hallucinations have been largely positive, while efficacy for negative symptoms is equivocal. A better understanding of the functional abnormalities that accompany symptoms may facilitate the development of rTMS as a treatment modality. Furthermore, schizophrenia patients appear to have abnormal cortical inhibition, consistent with GABA and dopamine abnormalities in schizophrenia. The effect of TMS on GABA and dopamine neurotransmission has not been clearly delineated. Given the variability in cortical response to rTMS in schizophrenia, methods to optimize dosage are essential. Consideration of these factors among others may broaden the scope of utility of TMS for schizophrenia as well as enhance its efficacy.
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Cudmore RH, Goaillard JM, Debanne D. Inhibition facilitates depression. J Physiol 2007; 585:323. [PMID: 18056114 DOI: 10.1113/jphysiol.2007.147207] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
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