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Cahill MK, Collard M, Tse V, Reitman ME, Etchenique R, Kirst C, Poskanzer KE. Network-level encoding of local neurotransmitters in cortical astrocytes. Nature 2024; 629:146-153. [PMID: 38632406 PMCID: PMC11062919 DOI: 10.1038/s41586-024-07311-5] [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: 04/03/2023] [Accepted: 03/13/2024] [Indexed: 04/19/2024]
Abstract
Astrocytes, the most abundant non-neuronal cell type in the mammalian brain, are crucial circuit components that respond to and modulate neuronal activity through calcium (Ca2+) signalling1-7. Astrocyte Ca2+ activity is highly heterogeneous and occurs across multiple spatiotemporal scales-from fast, subcellular activity3,4 to slow, synchronized activity across connected astrocyte networks8-10-to influence many processes5,7,11. However, the inputs that drive astrocyte network dynamics remain unclear. Here we used ex vivo and in vivo two-photon astrocyte imaging while mimicking neuronal neurotransmitter inputs at multiple spatiotemporal scales. We find that brief, subcellular inputs of GABA and glutamate lead to widespread, long-lasting astrocyte Ca2+ responses beyond an individual stimulated cell. Further, we find that a key subset of Ca2+ activity-propagative activity-differentiates astrocyte network responses to these two main neurotransmitters, and may influence responses to future inputs. Together, our results demonstrate that local, transient neurotransmitter inputs are encoded by broad cortical astrocyte networks over a minutes-long time course, contributing to accumulating evidence that substantial astrocyte-neuron communication occurs across slow, network-level spatiotemporal scales12-14. These findings will enable future studies to investigate the link between specific astrocyte Ca2+ activity and specific functional outputs, which could build a consistent framework for astrocytic modulation of neuronal activity.
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Affiliation(s)
- Michelle K Cahill
- Department of Biochemistry & Biophysics, University of California, San Francisco, CA, USA
- Neuroscience Graduate Program, University of California, San Francisco, CA, USA
| | - Max Collard
- Department of Biochemistry & Biophysics, University of California, San Francisco, CA, USA
- Neuroscience Graduate Program, University of California, San Francisco, CA, USA
| | - Vincent Tse
- Department of Biochemistry & Biophysics, University of California, San Francisco, CA, USA
| | - Michael E Reitman
- Department of Biochemistry & Biophysics, University of California, San Francisco, CA, USA
- Neuroscience Graduate Program, University of California, San Francisco, CA, USA
| | - Roberto Etchenique
- Departamento de Química Inorgánica, Analítica y Química Física, INQUIMAE, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, CONICET, Buenos Aires, Argentina
| | - Christoph Kirst
- Neuroscience Graduate Program, University of California, San Francisco, CA, USA
- Department of Anatomy, University of California, San Francisco, CA, USA
- Kavli Institute for Fundamental Neuroscience, San Francisco, CA, USA
- Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Kira E Poskanzer
- Department of Biochemistry & Biophysics, University of California, San Francisco, CA, USA.
- Neuroscience Graduate Program, University of California, San Francisco, CA, USA.
- Kavli Institute for Fundamental Neuroscience, San Francisco, CA, USA.
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2
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Khodaie B, Edelmann E, Leßmann V. Distinct GABAergic modulation of timing-dependent LTP in CA1 pyramidal neurons along the longitudinal axis of the mouse hippocampus. iScience 2024; 27:109320. [PMID: 38487018 PMCID: PMC10937841 DOI: 10.1016/j.isci.2024.109320] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2023] [Revised: 01/25/2024] [Accepted: 02/20/2024] [Indexed: 03/17/2024] Open
Abstract
Synaptic plasticity in the hippocampus underlies episodic memory formation, with dorsal hippocampus being instrumental for spatial memory whereas ventral hippocampus is crucial for emotional learning. Here, we studied how GABAergic inhibition regulates physiologically relevant low repeat spike timing-dependent LTP (t-LTP) at Schaffer collateral-CA1 synapses along the dorsoventral hippocampal axis. We used two t-LTP protocols relying on only 6 repeats of paired spike-firing in pre- and postsynaptic cells within 10 s that differ in postsynaptic firing patterns. GABAA receptor mechanisms played a greater role in blocking 6× 1:1 t-LTP that recruits single postsynaptic action potentials. 6× 1:4 t-LTP that depends on postsynaptic burst-firing unexpectedly required intact GABAB receptor signaling. The magnitude of both t-LTP-forms decreased along the dorsoventral axis, despite increasing excitability and basal synaptic strength in this direction. This suggests that GABAergic inhibition contributes to the distinct roles of dorsal and ventral hippocampus in memory formation.
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Affiliation(s)
- Babak Khodaie
- Institut für Physiologie, Otto-von-Guericke-Universität (OVGU), Medizinische Fakultät, 39120 Magdeburg, Germany
- OVGU International ESF-funded Graduate School ABINEP, 39104 Magdeburg, Germany
| | - Elke Edelmann
- Institut für Physiologie, Otto-von-Guericke-Universität (OVGU), Medizinische Fakultät, 39120 Magdeburg, Germany
- Center for Behavioral Brain Sciences, 39104 Magdeburg, Germany
- OVGU International ESF-funded Graduate School ABINEP, 39104 Magdeburg, Germany
| | - Volkmar Leßmann
- Institut für Physiologie, Otto-von-Guericke-Universität (OVGU), Medizinische Fakultät, 39120 Magdeburg, Germany
- Center for Behavioral Brain Sciences, 39104 Magdeburg, Germany
- OVGU International ESF-funded Graduate School ABINEP, 39104 Magdeburg, Germany
- DZPG (German Center of Mental Health), partner site Halle/Jena/Magdeburg (CIRC), Magdeburg, Germany
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3
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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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4
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Olivero G, Grilli M, Marchi M, Pittaluga A. Metamodulation of presynaptic NMDA receptors: New perspectives for pharmacological interventions. Neuropharmacology 2023; 234:109570. [PMID: 37146939 DOI: 10.1016/j.neuropharm.2023.109570] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Revised: 04/26/2023] [Accepted: 05/02/2023] [Indexed: 05/07/2023]
Abstract
Metamodulation shifted the scenario of the central neuromodulation from a simplified unimodal model to a multimodal one. It involves different receptors/membrane proteins physically associated or merely colocalized that act in concert to control the neuronal functions influencing each other. Defects or maladaptation of metamodulation would subserve neuropsychiatric disorders or even synaptic adaptations relevant to drug dependence. Therefore, this "vulnerability" represents a main issue to be deeply analyzed to predict its aetiopathogenesis, but also to propose targeted pharmaceutical interventions. The review focusses on presynaptic release-regulating NMDA receptors and on some of the mechanisms of their metamodulation described in the literature. Attention is paid to the interactors, including both ionotropic and metabotropic receptors, transporters and intracellular proteins, which metamodulate their responsiveness in physiological conditions but also undergo adaptation that are relevant to neurological dysfunctions. All these structures are attracting more and more the interest as promising druggable targets for the treatment of NMDAR-related central diseases: these substances would not exert on-off control of the colocalized NMDA receptors (as usually observed with NMDAR full agonists/antagonists), but rather modulate their functions, with the promise of limiting side effects that would favor their translation from preclinic to clinic.
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Affiliation(s)
- Guendalina Olivero
- Department of Pharmacy, University of Genoa, Viale Cembrano 4, 16148, Genoa, Italy
| | - Massimo Grilli
- Department of Pharmacy, University of Genoa, Viale Cembrano 4, 16148, Genoa, Italy; Inter-University Center for the Promotion of the 3Rs Principles in Teaching & Research (Centro 3R), 16148, Genoa, Italy.
| | - Mario Marchi
- Department of Pharmacy, University of Genoa, Viale Cembrano 4, 16148, Genoa, Italy
| | - Anna Pittaluga
- Department of Pharmacy, University of Genoa, Viale Cembrano 4, 16148, Genoa, Italy; Inter-University Center for the Promotion of the 3Rs Principles in Teaching & Research (Centro 3R), 16148, Genoa, Italy
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5
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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: 10] [Impact Index Per Article: 10.0] [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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6
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Guidolin D, Tortorella C, Marcoli M, Cervetto C, Maura G, Agnati LF. Receptor-receptor interactions and microvesicle exchange as mechanisms modulating signaling between neurons and astrocytes. Neuropharmacology 2023; 231:109509. [PMID: 36935005 DOI: 10.1016/j.neuropharm.2023.109509] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2022] [Revised: 02/21/2023] [Accepted: 03/16/2023] [Indexed: 03/19/2023]
Abstract
It is well known that astrocytes play a significant metabolic role in the nervous tissue, maintaining the homeostasis of the extracellular space and of the blood-brain barrier, and providing trophic support to neurons. In addition, however, evidence exists indicating astrocytes as important elements for brain activity through signaling exchange with neurons. Astrocytes, indeed, can sense synaptic activity and their molecular machinery responds to neurotransmitters released by neurons with cytoplasmic Ca2+ elevations that, in turn, stimulate the release of neuroactive substances (gliotransmitters) influencing nearby neurons. In both cell types the recognition and transduction of this complex pattern of signals is mediated by specific receptors that are also involved in mechanisms tuning the intercellular cross-talk between astrocytes and neurons. Two of these mechanisms are the focus of the present discussion. The first concerns direct receptor-receptor interactions leading to the formation at the cell membrane of multimeric receptor complexes. The cooperativity that emerges in the actions of orthosteric and allosteric ligands of the monomers forming the assembly provides the cell decoding apparatus with sophisticated and flexible dynamics in terms of recognition and signal transduction pathways. A further mechanism of plasticity involving receptors is based on the transfer of elements of the cellular signaling apparatus via extracellular microvesicles acting as protective containers, which can lead to transient changes in the transmitting/decoding capabilities of the target cell.
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Affiliation(s)
- Diego Guidolin
- Department of Neuroscience, Section of Anatomy, University of Padova, 35121, Padova, Italy.
| | - Cinzia Tortorella
- Department of Neuroscience, Section of Anatomy, University of Padova, 35121, Padova, Italy
| | - Manuela Marcoli
- Department of Pharmacy, Center of Excellence for Biomedical Research, University of Genova, 16126, Genova, Italy
| | - Chiara Cervetto
- Department of Pharmacy, Center of Excellence for Biomedical Research, University of Genova, 16126, Genova, Italy
| | - Guido Maura
- Department of Pharmacy, Center of Excellence for Biomedical Research, University of Genova, 16126, Genova, Italy
| | - Luigi F Agnati
- Department of Biomedical Sciences, University of Modena and Reggio Emilia, 41125, Modena, Italy
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7
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Sanchez GM, Incedal TC, Prada J, O'Callaghan P, Dyachok O, Echeverry S, Dumral Ö, Nguyen PM, Xie B, Barg S, Kreuger J, Dandekar T, Idevall-Hagren O. The β-cell primary cilium is an autonomous Ca2+ compartment for paracrine GABA signaling. J Cell Biol 2023; 222:213674. [PMID: 36350286 DOI: 10.1083/jcb.202108101] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Revised: 04/11/2022] [Accepted: 10/12/2022] [Indexed: 11/11/2022] Open
Abstract
The primary cilium is an organelle present in most adult mammalian cells that is considered as an antenna for sensing the local microenvironment. Here, we use intact mouse pancreatic islets of Langerhans to investigate signaling properties of the primary cilium in insulin-secreting β-cells. We find that GABAB1 receptors are strongly enriched at the base of the cilium, but are mobilized to more distal locations upon agonist binding. Using cilia-targeted Ca2+ indicators, we find that activation of GABAB1 receptors induces selective Ca2+ influx into primary cilia through a mechanism that requires voltage-dependent Ca2+ channel activation. Islet β-cells utilize cytosolic Ca2+ increases as the main trigger for insulin secretion, yet we find that increases in cytosolic Ca2+ fail to propagate into the cilium, and that this isolation is largely due to enhanced Ca2+ extrusion in the cilium. Our work reveals local GABA action on primary cilia that involves Ca2+ influx and depends on restricted Ca2+ diffusion between the cilium and cytosol.
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Affiliation(s)
| | | | - Juan Prada
- Department of Bioinformatics, University of Würzburg, Würzburg, Germany
| | - Paul O'Callaghan
- Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden
| | - Oleg Dyachok
- Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden
| | | | - Özge Dumral
- Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden
| | - Phuoc My Nguyen
- Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden
| | - Beichen Xie
- Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden
| | - Sebastian Barg
- Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden
| | - Johan Kreuger
- Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden
| | - Thomas Dandekar
- Department of Bioinformatics, University of Würzburg, Würzburg, Germany
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8
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Johnson CS, Mermelstein PG. The interaction of membrane estradiol receptors and metabotropic glutamate receptors in adaptive and maladaptive estradiol-mediated motivated behaviors in females. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2023; 168:33-91. [PMID: 36868633 DOI: 10.1016/bs.irn.2022.11.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Estrogen receptors were initially identified as intracellular, ligand-regulated transcription factors that result in genomic change upon ligand binding. However, rapid estrogen receptor signaling initiated outside of the nucleus was also known to occur via mechanisms that were less clear. Recent studies indicate that these traditional receptors, estrogen receptor α and estrogen receptor β, can also be trafficked to act at the surface membrane. Signaling cascades from these membrane-bound estrogen receptors (mERs) can rapidly alter cellular excitability and gene expression, particularly through the phosphorylation of CREB. A principal mechanism of neuronal mER action has been shown to occur through glutamate-independent transactivation of metabotropic glutamate receptors (mGlu), which elicits multiple signaling outcomes. The interaction of mERs with mGlu has been shown to be important in many diverse functions in females, including driving motivated behaviors. Experimental evidence suggests that a large part of estradiol-induced neuroplasticity and motivated behaviors, both adaptive and maladaptive, occurs through estradiol-dependent mER activation of mGlu. Herein we will review signaling through estrogen receptors, both "classical" nuclear receptors and membrane-bound receptors, as well as estradiol signaling through mGlu. We will focus on how the interactions of these receptors and their downstream signaling cascades are involved in driving motivated behaviors in females, discussing a representative adaptive motivated behavior (reproduction) and maladaptive motivated behavior (addiction).
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Affiliation(s)
- Caroline S Johnson
- Department of Neuroscience, University of Minnesota, Minneapolis, MN, United States
| | - Paul G Mermelstein
- Department of Neuroscience, University of Minnesota, Minneapolis, MN, United States.
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9
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Olivero G, Vergassola M, Cisani F, Roggeri A, Pittaluga A. Presynaptic Release-regulating Metabotropic Glutamate Receptors: An Update. Curr Neuropharmacol 2021; 18:655-672. [PMID: 31775600 PMCID: PMC7457419 DOI: 10.2174/1570159x17666191127112339] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Revised: 11/15/2019] [Accepted: 11/22/2019] [Indexed: 12/18/2022] Open
Abstract
Metabotropic glutamate (mGlu) receptors represent the largest family of glutamate receptors in mammals and act as fine tuners of the chemical transmission in central nervous system (CNS). In the last decade, results concerning the expression and the subcellular localization of mGlu receptors further clarified their role in physio-pathological conditions. Concomitantly, their pharmacological characterization largely improved thanks to the identification of new compounds (chemical ligands and antibodies recognizing epitopic sequences of the receptor proteins) that allowed to decipher the protein compositions of the naive receptors. mGlu receptors are expressed at the presynaptic site of chemical synapses. Here, they modulate intraterminal enzymatic pathways controlling the migration and the fusion of vesicles to synaptic membranes as well as the phosphorylation of colocalized receptors. Both the control of transmitter exocytosis and the phosphorylation of colocalized receptors elicited by mGlu receptors are relevant events that dictate the plasticity of nerve terminals, and account for the main role of presynaptic mGlu receptors as modulators of neuronal signalling. The role of the presynaptic mGlu receptors in the CNS has been the matter of several studies and this review aims at briefly summarizing the recent observations obtained with isolated nerve endings (we refer to as synaptosomes). We focus on the pharmacological characterization of these receptors and on their receptor-receptor interaction / oligo-dimerization in nerve endings that could be relevant to the development of new therapeutic approaches for the cure of central pathologies.
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Affiliation(s)
| | | | | | | | - Anna Pittaluga
- Department of Pharmacy, University of Genoa, Genoa, Italy.,Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS) Ospedale Policlinico San Martino, Genoa, Italy
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10
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Hirono M, Yanagawa Y. Endocannabinoids regulate cerebellar GABAergic transmission in a synapse type-dependent manner. J Neurosci Res 2020; 99:898-913. [PMID: 33271631 DOI: 10.1002/jnr.24765] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2019] [Revised: 11/03/2020] [Accepted: 11/14/2020] [Indexed: 12/28/2022]
Abstract
Endocannabinoids (eCBs) act as ubiquitous modulators of synaptic transmission via the activation of cannabinoid receptors (CBRs). Cerebellar Purkinje cells (PCs) make strong inhibitory synaptic contacts not only with neurons in the deep cerebellar nuclei (DCN) but also with Lugaro cells and globular cells, whose cell bodies are located underneath the PC layer. However, little is known about the modulatory actions of eCBs on GABA release from PC axon terminals. Here, we examined the effects of eCBs on the GABAergic transmission at PC-globular cell synapses and PC-large DCN neuron synapses electrophysiologically using mouse cerebellar slices. We showed that the types 1 and 2 CBR agonist WIN55212 did not affect either spontaneous or miniature inhibitory postsynaptic currents (IPSCs) in globular cells under control conditions and in a state of enhanced synaptic activity. By contrast, another Gi/o protein-coupled receptor agonist, baclofen, significantly reduced the miniature IPSC frequency in globular cells. WIN55212 had no effects on IPSCs in large DCN neurons. A type 2 CBR agonist, HU308, also had no effects on IPSCs in either globular cells or large DCN neurons. Moreover, the PCs' target neurons did not elicit depolarization-induced suppression of inhibition. These results suggest the lack of a functional role of CBRs at PCs' axon terminals. This is in sharp contrast to the fact that PCs receive abundant excitatory and inhibitory inputs that are under eCB-mediated presynaptic inhibitory modulation. The actions of eCBs are selective to distinct synapses and possibly contribute to information processes and rigorous signal transmission in the cerebellum.
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Affiliation(s)
- Moritoshi Hirono
- Organization for Research Initiatives and Development, Doshisha University, Kyoto, Japan.,Laboratory for Motor Learning Control, RIKEN BSI, Wako, Japan
| | - Yuchio Yanagawa
- Department of Genetic and Behavioral Neuroscience, Gunma University Graduate School of Medicine, Maebashi, Japan
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11
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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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12
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Irie T, Yamazaki D, Kikura-Hanajiri R. F-phenibut (β-(4-Fluorophenyl)-GABA), a potent GABA B receptor agonist, activates an outward-rectifying K + current and suppresses the generation of action potentials in mouse cerebellar Purkinje cells. Eur J Pharmacol 2020; 884:173437. [PMID: 32735986 DOI: 10.1016/j.ejphar.2020.173437] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Revised: 07/27/2020] [Accepted: 07/27/2020] [Indexed: 11/15/2022]
Abstract
The GABA analog phenibut (β-Phenyl-GABA) is a GABAB receptor agonist that has been licensed for various uses in Russia. Phenibut is also available as a dietary supplement from online vendors worldwide, and previous studies have indicated that phenibut overdose results in intoxication, withdrawal symptoms, and addiction. F-phenibut (β-(4-Fluorophenyl)-GABA), a derivative of phenibut, has not been approved for clinical use. However, it is also available as a nootropic supplement from online suppliers. F-phenibut binds to GABAB with a higher affinity than phenibut; therefore, F-phenibut may lead to more serious intoxication than phenibut. However, the mechanisms by which F-phenibut acts on GABAB receptors and influences neuronal function remain unknown. In the present study, we compared the potency of F-phenibut, phenibut, and the GABAB agonist (±)-baclofen (baclofen) using in vitro patch-clamp recordings obtained from mouse cerebellar Purkinje cells slice preparations Our findings indicate that F-phenibut acted as a potent GABAB agonist. EC50 of outward current density evoked by the three GABAB agonists decreased in the following order: phenibut (1362 μM) > F-phenibut (23.3 μM) > baclofen (6.0 μM). The outward current induced by GABAB agonists was an outward-rectifying K+ current, in contrast to the previous finding that GABAB agonists activates an inward-rectifying K+ current. The K+ current recorded in the present study was insensitive to extracellular Ba2+, intra- or extracellular Cs+, and intra- or extracellular tetraethylammonium-Cl. Moreover, F-phenibut suppressed action potential generation in Purkinje cells. Thus, abuse of F-phenibut may lead to severe damage by inhibiting the excitability of GABAB-expressing neurons.
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Affiliation(s)
- Tomohiko Irie
- Division of Pharmacology, National Institute of Health Sciences, 3-25-26 Tonomachi, Kawasaki-ku, Kawasaki City, Kanagawa, 210-9501, Japan.
| | - Daiju Yamazaki
- Division of Pharmacology, National Institute of Health Sciences, 3-25-26 Tonomachi, Kawasaki-ku, Kawasaki City, Kanagawa, 210-9501, Japan
| | - Ruri Kikura-Hanajiri
- Division of Pharmacognosy, Phytochemistry, and Narcotics, National Institute of Health Sciences, 3-25-26 Tonomachi, Kawasaki-ku, Kawasaki City, Kanagawa, 210-9501, Japan
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13
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Mechanisms and Regulation of Neuronal GABA B Receptor-Dependent Signaling. Curr Top Behav Neurosci 2020; 52:39-79. [PMID: 32808092 DOI: 10.1007/7854_2020_129] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
γ-Aminobutyric acid B receptors (GABABRs) are broadly expressed throughout the central nervous system where they play an important role in regulating neuronal excitability and synaptic transmission. GABABRs are G protein-coupled receptors that mediate slow and sustained inhibitory actions via modulation of several downstream effector enzymes and ion channels. GABABRs are obligate heterodimers that associate with diverse arrays of proteins to form modular complexes that carry out distinct physiological functions. GABABR-dependent signaling is fine-tuned and regulated through a multitude of mechanisms that are relevant to physiological and pathophysiological states. This review summarizes the current knowledge on GABABR signal transduction and discusses key factors that influence the strength and sensitivity of GABABR-dependent signaling in neurons.
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14
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Nardone R, Sebastianelli L, Brigo F, Golaszewski S, Trinka E, Pucks-Faes E, Saltuari L, Versace V. Effects of intrathecal baclofen therapy in subjects with disorders of consciousness: a reappraisal. J Neural Transm (Vienna) 2020; 127:1209-1215. [PMID: 32710152 DOI: 10.1007/s00702-020-02233-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Accepted: 07/14/2020] [Indexed: 01/16/2023]
Abstract
Baclofen is a structural analogue of gamma-amino-butyric acid (GABA), which reduces spastic hypertonia of striated muscle due to a mechanism of GABAB-ergic inhibition of mono- and polysynaptic reflexes at the spinal level. There are reports of patients with severe disorders of consciousness that presented a substantial improvement following intrathecal baclofen (ITB) administration for severe spasticity. The neural mechanisms underlying the clinical recovery after ITB have not yet been clarified. Baclofen could modulate sleep-wake cycles that may be dysregulated and thus interfere with alertness and awareness. The diminished proprioceptive and nociceptive sensory inputs may relieve thalamo-cortical neural networks involved in maintaining the consciousness of the self and the world. ITB treatment might also promote the recovery of an impaired GABAergic cortical tone, restoring the balance between excitatory and inhibitory cortical activity. Furthermore, glutamatergic synapses are directly or indirectly modulated by GABAB-ergic receptors. Neurophysiological techniques (such as transcranial magnetic stimulation, electroencephalography, or the combination of both) can be helpful to explore the effects of intrathecal or oral baclofen on the modulation of neural cortical circuits in humans with disorders of consciousness.
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Affiliation(s)
- Raffaele Nardone
- Department of Neurology, Hospital of Merano (SABES-ASDAA), Merano-Meran, Italy. .,Department of Neurology, Christian Doppler Klinik, Paracelsus Medical University, Salzburg, Austria. .,Spinal Cord Injury and Tissue Regeneration Center, Salzburg, Austria. .,Karl Landsteiner Institut für Neurorehabilitation und Raumfahrtneurologie, Salzburg, Austria.
| | - Luca Sebastianelli
- Department of Neurorehabilitation, Hospital of Vipiteno, Vipiteno, Italy.,Research Unit for Neurorehabilitation South Tyrol, Bolzano, Italy
| | - Francesco Brigo
- Department of Neurology, Hospital of Merano (SABES-ASDAA), Merano-Meran, Italy.,Department of Neuroscience, Biomedicine and Movement Science, University of Verona, Verona, Italy
| | - Stefan Golaszewski
- Department of Neurology, Christian Doppler Klinik, Paracelsus Medical University, Salzburg, Austria.,Karl Landsteiner Institut für Neurorehabilitation und Raumfahrtneurologie, Salzburg, Austria
| | - Eugen Trinka
- Department of Neurology, Christian Doppler Klinik, Paracelsus Medical University, Salzburg, Austria.,Centre for Cognitive Neurosciences Salzburg, Salzburg, Austria.,University for Medical Informatics and Health Technology, UMIT, Hall in Tirol, Austria
| | | | - Leopold Saltuari
- Department of Neurorehabilitation, Hospital of Vipiteno, Vipiteno, Italy.,Research Unit for Neurorehabilitation South Tyrol, Bolzano, Italy
| | - Viviana Versace
- Department of Neurology, Hospital of Merano (SABES-ASDAA), Merano-Meran, Italy.,Research Unit for Neurorehabilitation South Tyrol, Bolzano, Italy
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15
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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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16
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Moreno-Rius J. Opioid addiction and the cerebellum. Neurosci Biobehav Rev 2019; 107:238-251. [DOI: 10.1016/j.neubiorev.2019.09.015] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Revised: 09/06/2019] [Accepted: 09/10/2019] [Indexed: 01/10/2023]
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17
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Borroto-Escuela DO, Fuxe K. Oligomeric Receptor Complexes and Their Allosteric Receptor-Receptor Interactions in the Plasma Membrane Represent a New Biological Principle for Integration of Signals in the CNS. Front Mol Neurosci 2019; 12:230. [PMID: 31607863 PMCID: PMC6773811 DOI: 10.3389/fnmol.2019.00230] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2018] [Accepted: 09/09/2019] [Indexed: 12/14/2022] Open
Abstract
G protein-coupled receptors (GPCRs) not only exist as monomers but also as homomers and heteromers in which allosteric receptor-receptor interactions take place, modulating the functions of the participating GPCR protomers. GPCRs can also form heteroreceptor complexes with ionotropic receptors and receptor tyrosine kinases modulating their function. Furthermore, adaptor proteins interact with receptor protomers and modulate their interactions. The state of the art is that the allosteric receptor-receptor interactions are reciprocal, highly dynamic and substantially alter the signaling, trafficking, recognition and pharmacology of the participating protomers. The pattern of changes appears to be unique for each heteromer and can favor antagonistic or facilitatory interactions or switch the G protein coupling from e.g., Gi/o to Gq or to beta-arrestin signaling. It lends a new dimension to molecular integration in the nervous system. Future direction should be aimed at determining the receptor interface involving building models of selected heterodimers. This will make design of interface-interfering peptides that specifically disrupt the heterodimer possible. This will help to determine the functional role of the allosteric receptor-receptor interactions as well as the integration of signals at the plasma membrane by the heteroreceptor complexes, vs. integration of the intracellular signaling pathways. Integration of signals also at the plasma membrane seems crucial in view of the hypothesis that learning and memory at a molecular level takes place by reorganization of homo and heteroreceptor complexes in the postsynaptic membrane. Homo and heteroreceptor complexes are in balance with each other, and their disbalance is linked to disease. Targeting heteroreceptor complexes represents a novel strategy for the treatment of brain disorders.
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Affiliation(s)
- Dasiel O. Borroto-Escuela
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
- Department of Biomolecular Science, Section of Physiology, University of Urbino, Campus Scientifico Enrico Mattei, Urbino, Italy
- Grupo Bohío-Estudio, Observatorio Cubano de Neurociencias, Yaguajay, Cuba
| | - Kjell Fuxe
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
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18
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Diverse Actions of Astrocytes in GABAergic Signaling. Int J Mol Sci 2019; 20:ijms20122964. [PMID: 31216630 PMCID: PMC6628243 DOI: 10.3390/ijms20122964] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2019] [Revised: 06/10/2019] [Accepted: 06/14/2019] [Indexed: 01/06/2023] Open
Abstract
An imbalance of excitatory and inhibitory neurotransmission leading to over excitation plays a crucial role in generating seizures, while enhancing GABAergic mechanisms are critical in terminating seizures. In recent years, it has been reported in many studies that astrocytes are deeply involved in synaptic transmission. Astrocytes form a critical component of the “tripartite” synapses by wrapping around the pre- and post-synaptic elements. From this location, astrocytes are known to greatly influence the dynamics of ions and transmitters in the synaptic cleft. Despite recent extensive research on excitatory tripartite synapses, inhibitory tripartite synapses have received less attention, even though they influence inhibitory synaptic transmission by affecting chloride and GABA concentration dynamics. In this review, we will discuss the diverse actions of astrocytic chloride and GABA homeostasis at GABAergic tripartite synapses. We will then consider the pathophysiological impacts of disturbed GABA homeostasis at the tripartite synapse.
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19
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Durkee CA, Covelo A, Lines J, Kofuji P, Aguilar J, Araque A. G i/o protein-coupled receptors inhibit neurons but activate astrocytes and stimulate gliotransmission. Glia 2019; 67:1076-1093. [PMID: 30801845 DOI: 10.1002/glia.23589] [Citation(s) in RCA: 125] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2018] [Revised: 12/06/2018] [Accepted: 12/26/2018] [Indexed: 12/31/2022]
Abstract
G protein-coupled receptors (GPCRs) play key roles in intercellular signaling in the brain. Their effects on cellular function have been largely studied in neurons, but their functional consequences on astrocytes are less known. Using both endogenous and chemogenetic approaches with DREADDs, we have investigated the effects of Gq and Gi/o GPCR activation on astroglial Ca2+ -based activity, gliotransmitter release, and the functional consequences on neuronal electrical activity. We found that while Gq GPCR activation led to cellular activation in both neurons and astrocytes, Gi/o GPCR activation led to cellular inhibition in neurons and cellular activation in astrocytes. Astroglial activation by either Gq or Gi/o protein-mediated signaling stimulated gliotransmitter release, which increased neuronal excitability. Additionally, activation of Gq and Gi/o DREADDs in vivo increased astrocyte Ca2+ activity and modified neuronal network electrical activity. Present results reveal additional complexity of the signaling consequences of excitatory and inhibitory neurotransmitters in astroglia-neuron network operation and brain function.
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Affiliation(s)
- Caitlin A Durkee
- Department of Neuroscience, University of Minnesota, Minneapolis, Minnesota
| | - Ana Covelo
- Department of Neuroscience, University of Minnesota, Minneapolis, Minnesota
| | - Justin Lines
- Department of Neuroscience, University of Minnesota, Minneapolis, Minnesota
| | - Paulo Kofuji
- Department of Neuroscience, University of Minnesota, Minneapolis, Minnesota
| | - Juan Aguilar
- Laboratory of Experimental Neurophysiology, Hospital Nacional de Parapléjicos, Toledo, Spain
| | - Alfonso Araque
- Department of Neuroscience, University of Minnesota, Minneapolis, Minnesota
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20
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Hellmer CB, Clemons MR, Nawy S, Ichinose T. A group I metabotropic glutamate receptor controls synaptic gain between rods and rod bipolar cells in the mouse retina. Physiol Rep 2018; 6:e13885. [PMID: 30338673 PMCID: PMC6194217 DOI: 10.14814/phy2.13885] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2018] [Revised: 09/10/2018] [Accepted: 09/16/2018] [Indexed: 11/24/2022] Open
Abstract
The canonical mGluR6-Trpm1 pathway that generates the sign-inverting signal between photoreceptors and ON bipolar cells has been well described. However, one type of ON bipolar cell, the rod bipolar cell (RBC), additionally is thought to express the group I mGluRs whose function is unknown. We examined the role of group I mGluRs in mouse RBCs and here provide evidence that it controls synaptic gain between rods and RBCs. In dark-adapted conditions, the mGluR1 antagonists LY367385 and (RS)-1-Aminoindan-1,5-dicarboxylic acid, but not the mGluR5 antagonist 2-Methyl-6-(phenylethynyl)pyridine hydrochloride reduced the light-evoked responses in RBCs indicating that mGluR1, but not mGluR5, serves to potentiate RBC responses. Perturbing the downstream phospholipase C (PLC)-protein kinase C (PKC) pathway by inhibiting PLC, tightly buffering intracellular Ca2+ , or preventing its release from intracellular stores reduced the synaptic potentiation by mGluR1. The effect of mGluR1 activation was dependent upon adaptation state, strongly increasing the synaptic gain in dark-, but not in light-adapted retinas, or in the presence of a moderate background light, consistent with the idea that mGluR1 activation requires light-dependent glutamate release from rods. Moreover, immunostaining revealed that protein kinase Cα (PKCα) is more strongly expressed in RBC dendrites in dark-adapted conditions, revealing an additional mechanism behind the loss of mGluR1 potentiation. In light-adapted conditions, exogenous activation of mGluR1 with the agonist 3,5-Dihydroxyphenylglycine increased the mGluR6 currents in some RBCs and decreased it in others, suggesting an additional action of mGluR1 that is unmasked in the light-adapted state. Elevating intracellular free Ca2+ , consistently resulted in a decrease in synaptic gain. Our results provide evidence that mGluR1 controls the synaptic gain in RBCs.
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Affiliation(s)
- Chase B. Hellmer
- Department of Ophthalmology, Visual and Anatomical SciencesWayne State University School of MedicineDetroitMichigan48201
| | - Melissa Rampino Clemons
- Dominic P Purpura Dept. of NeuroscienceAlbert Einstein College of Medicine BronxBronxNew York10461
| | - Scott Nawy
- Dominic P Purpura Dept. of NeuroscienceAlbert Einstein College of Medicine BronxBronxNew York10461
- Department of Ophthalmology and Visual SciencesUniversity of Nebraska Medical CenterOmahaNebraska68198
| | - Tomomi Ichinose
- Department of Ophthalmology, Visual and Anatomical SciencesWayne State University School of MedicineDetroitMichigan48201
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21
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Vergassola M, Olivero G, Cisani F, Usai C, Bossi S, Puliti A, Pittaluga A. Presynaptic mGlu1 Receptors Control GABA B Receptors in an Antagonist-Like Manner in Mouse Cortical GABAergic and Glutamatergic Nerve Endings. Front Mol Neurosci 2018; 11:324. [PMID: 30279647 PMCID: PMC6153310 DOI: 10.3389/fnmol.2018.00324] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2018] [Accepted: 08/22/2018] [Indexed: 01/03/2023] Open
Abstract
Mouse cortical GABAergic synaptosomes possess presynaptic inhibitory GABAB autoreceptors. Accordingly, (±)baclofen (3 μM) inhibits in a CGP53423-sensitive manner the 12 mM KCl-evoked release of preloaded [3H]GABA. Differently, the existence of presynaptic release-regulating metabotropic glutamate type 1 (mGlu1) heteroreceptors in these terminals is still matter of discussion, although confocal microscopy unveiled the existence of mGlu1α with GABAB1 or GABAB2 proteins in cortical VGAT-positive synaptosomes. The group I mGlu agonist 3,5-DHPG failed to modify on its own the 12 mM KCl-evoked [3H]GABA exocytosis from cortical nerve endings, but, when added concomitantly to the GABAB agonist, it significantly reduced the 3 μM (±)baclofen-induced inhibition of [3H]GABA exocytosis. Conversely, the mGlu1 antagonist LY367385 (0.03–1 μM), inactive on its own on GABA exocytosis, amplified the 3 μM (±)baclofen-induced inhibition of [3H]GABA overflow. The ( ± )baclofen-induced inhibition of [3H]GABA exocytosis was more pronounced in cortical synaptosomes from Grm1crv4/crv4 mice, which bear a spontaneous mutation of the Grm1 gene leading to the functional inactivation of the mGlu1 receptor. Inasmuch, the expression of GABAB2 receptor protein in cortical synaptosomal lysates from Grm1crv4/crv4 mice was increased when compared to controls. Altogether, these observations seem best interpreted by assuming that mGlu1 coexist with GABAB receptors in GABAergic cortical synaptosomes, where they control GABA receptors in an antagonist-like manner. We then asked whether the mGlu1-mediated control of GABAB receptors is restricted to GABAergic terminals, or if it occurs also in other subpopulations of nerve endings. Release-regulating GABAB receptors also exist in glutamatergic nerve endings. (±)baclofen (1 μM) diminished the 12 mM KCl-evoked [3H]D-aspartate overflow. Also in these terminals, the concomitant presence of 1 μM LY367385, inactive on its own, significantly amplified the inhibitory effect exerted by (±)baclofen on [3H]D-aspartate exocytosis. Confocal microscopy confirmed the colocalization of mGlu1 with GABAB1 and GABAB2 labeling in vesicular glutamate type1 transporter-positive particles. Our results support the conclusion that mGlu1 receptors modulate in an antagonist-like manner presynaptic release-regulating GABAB receptors. This receptor–receptor interaction could be neuroprotective in central disease typified by hyperglutamatergicity.
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Affiliation(s)
| | | | | | - Cesare Usai
- Institute of Biophysics, National Research Council, Genoa, Italy
| | - Simone Bossi
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, University of Genoa, Genoa, Italy
| | - Aldamaria Puliti
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, University of Genoa, Genoa, Italy.,IRCCS Istituto Giannina Gaslini, Genoa, Italy.,Center of Excellence for Biomedical Research, University of Genoa, Genoa, Italy
| | - Anna Pittaluga
- Department of Pharmacy, University of Genoa, Genoa, Italy.,Center of Excellence for Biomedical Research, University of Genoa, Genoa, Italy
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22
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Tian J, Zhu MX. GABA B Receptors Augment TRPC3-Mediated Slow Excitatory Postsynaptic Current to Regulate Cerebellar Purkinje Neuron Response to Type-1 Metabotropic Glutamate Receptor Activation. Cells 2018; 7:cells7080090. [PMID: 30060610 PMCID: PMC6116156 DOI: 10.3390/cells7080090] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2018] [Revised: 07/18/2018] [Accepted: 07/27/2018] [Indexed: 02/02/2023] Open
Abstract
During strong parallel fiber stimulation, glutamate released at parallel fiber-Purkinje cell synapses activates type-1 metabotropic glutamate receptor (mGluR1) to trigger a slow excitatory postsynaptic current (sEPSC) in cerebellar Purkinje neurons. The sEPSC is mediated by transient receptor potential canonical 3 (TRPC3) channels. Often co-localized with mGluR1 in Purkinje neuron dendrites are type B γ-aminobutyric acid receptors (GABABRs) that respond to inhibitory synaptic inputs from interneurons located in the molecular layer of cerebellar cortex. It has been shown that activation of postsynaptic GABABRs potentiates mGluR1 activation-evoked sEPSC in Purkinje cells, but the underlying molecular mechanism remains elusive. Here we report that the augmentation of mGluR1-sEPSC by GABABR activation in Purkinje neurons is completely absent in TRPC3 knockout mice, but totally intact in TRPC1-, TRPC4-, and TRPC1,4,5,6-knockout mice, suggesting that TRPC3 is the only TRPC isoform that mediates the potentiation. Moreover, our results indicate that the potentiation reflects a postsynaptic mechanism that requires both GABABRs and mGluR1 because it is unaffected by blocking neurotransmission with tetrodotoxin but blocked by inhibiting either GABABRs or mGluR1. Furthermore, we show that the co-stimulation of GABABRs has an effect on shaping the response of Purkinje cell firing to mGluR1-sEPSC, revealing a new function of inhibitory input on excitatory neurotransmission. We conclude that postsynaptic GABABRs regulate Purkinje cell responses to strong glutamatergic stimulation through modulation of mGluR1-TRPC3 coupling. Since mGluR1-TRPC3 coupling is essential in cerebellar long-term depression, synapse elimination, and motor coordination, our findings may have implications in essential cerebellar functions, such as motor coordination and learning.
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Affiliation(s)
- Jinbin Tian
- Department of Integrative Biology and Pharmacology, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, TX 77030, USA.
| | - Michael X Zhu
- Department of Integrative Biology and Pharmacology, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, TX 77030, USA.
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23
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Borroto-Escuela DO, Tarakanov AO, Brito I, Fuxe K. Glutamate heteroreceptor complexes in the brain. Pharmacol Rep 2018; 70:936-950. [PMID: 32002960 DOI: 10.1016/j.pharep.2018.04.002] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2018] [Revised: 03/26/2018] [Accepted: 04/09/2018] [Indexed: 10/17/2022]
Abstract
The existence of mGluR, NMDAR, AMPAR and putative KAR heteroreceptor complexes in synaptic and extrasynaptic regions of brain glutamate synapses represents a major integrative mechanism. Our aim in the current article is to analyze if the formation of the different types glutamate hetereceptor complexes involves the contribution of triplet amino acid homologies (protriplets) in a postulated receptor interface based on the triplet puzzle theory. Seven main sets (lists) of receptor pairs in databases were used containing various sets (lists) of human receptor heteromers and nonheteromers obtained from the available scientific publications including the publically available GPCR-hetnet database. Brain mGluR1-mGluR5 and mGluR2-mGluR4 isoreceptor complexes were demonstrated with a predominant extrasynaptic localization at a post- and prejunctional localization. The existence of putative mGluR4-mGluR7 heteroreceptor complexes in the basal ganglia is proposed. Metabotropic glutamate receptor subtypes also participated in the formation of a large number of heteroreceptor complexes like mGluR1-A1R, mGluR5-A2AR, mGluR5-D2R and D2R-A2AR-mGluR5, located in relation to glutamate synapses, especially in the basal ganglia. A putative mGluR1-GABAB1/2 heterocomplex may also exist. NMDAR heteroreceptor complexes were also demonstrated as a fundamental integrative mechanism in the glutamate synapse and its extrasynaptic membranes. It represented fundamental work on inter alia NMDAR-mGluR5, NMDAR-D1R and NMDAR-D2R heteroreceptor complexes involving both antagonistic and facilitatory allosteric receptor-receptor interactions. As to AMPA receptors, a heterocomplex was found for the interaction between IFNgR1 and the AMPAR mediated via the subunit GluA1 which may be of relevance for neuroinflammation. AMPAR-D2R heteroreceptor complexes were also demonstrated. Besides glutamate heteroreceptor complexes and their allosteric receptor-receptor interactions, a significant mechanism for the functional crosstalk can also be phosphorylation and/or reorganization of adapter proteins with dynamic binding to the two receptors modulating the allosteric receptor mechanism.
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Affiliation(s)
- Dasiel O Borroto-Escuela
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden.,Department of Biomolecular Science, Section of Physiology, University of Urbino, Campus Scientifico Enrico Mattei, Urbino, Italy.,Grupo Bohío-Estudio, Observatorio Cubano de Neurociencias, Yaguajay, Cuba
| | - Alexander O Tarakanov
- St. Petersburg Institute for Informatics and Automation, Russian Academy of Sciences, Saint Petersburg, Russia
| | - Ismel Brito
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden.,Grupo Bohío-Estudio, Observatorio Cubano de Neurociencias, Yaguajay, Cuba
| | - Kjell Fuxe
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden.
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Bushart DD, Chopra R, Singh V, Murphy GG, Wulff H, Shakkottai VG. Targeting potassium channels to treat cerebellar ataxia. Ann Clin Transl Neurol 2018; 5:297-314. [PMID: 29560375 PMCID: PMC5846455 DOI: 10.1002/acn3.527] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2017] [Revised: 12/14/2017] [Accepted: 12/18/2017] [Indexed: 12/22/2022] Open
Abstract
Objective Purkinje neuron dysfunction is associated with cerebellar ataxia. In a mouse model of spinocerebellar ataxia type 1 (SCA1), reduced potassium channel function contributes to altered membrane excitability resulting in impaired Purkinje neuron spiking. We sought to determine the relationship between altered membrane excitability and motor dysfunction in SCA1 mice. Methods Patch-clamp recordings in acute cerebellar slices and motor phenotype testing were used to identify pharmacologic agents which improve Purkinje neuron physiology and motor performance in SCA1 mice. Additionally, we retrospectively reviewed records of patients with SCA1 and other autosomal-dominant SCAs with prominent Purkinje neuron involvement to determine whether currently approved potassium channel activators were tolerated. Results Activating calcium-activated and subthreshold-activated potassium channels improved Purkinje neuron spiking impairment in SCA1 mice (P < 0.05). Additionally, dendritic hyperexcitability was improved by activating subthreshold-activated potassium channels but not calcium-activated potassium channels (P < 0.01). Improving spiking and dendritic hyperexcitability through a combination of chlorzoxazone and baclofen produced sustained improvements in motor dysfunction in SCA1 mice (P < 0.01). Retrospective review of SCA patient records suggests that co-treatment with chlorzoxazone and baclofen is tolerated. Interpretation Targeting both altered spiking and dendritic membrane excitability is associated with sustained improvements in motor performance in SCA1 mice, while targeting altered spiking alone produces only short-term improvements in motor dysfunction. Potassium channel activators currently in clinical use are well tolerated and may provide benefit in SCA patients. Future clinical trials with potassium channel activators are warranted in cerebellar ataxia.
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Affiliation(s)
- David D Bushart
- Department of Molecular & Integrative Physiology University of Michigan Ann Arbor Michigan
| | - Ravi Chopra
- Department of Neurology University of Michigan Ann Arbor Michigan
| | - Vikrant Singh
- Department of Pharmacology University of California Davis California
| | - Geoffrey G Murphy
- Department of Molecular & Integrative Physiology University of Michigan Ann Arbor Michigan.,Molecular & Behavioral Neuroscience Institute University of Michigan Ann Arbor Michigan
| | - Heike Wulff
- Department of Pharmacology University of California Davis California
| | - Vikram G Shakkottai
- Department of Molecular & Integrative Physiology University of Michigan Ann Arbor Michigan.,Department of Neurology University of Michigan Ann Arbor Michigan
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Booker SA, Loreth D, Gee AL, Watanabe M, Kind PC, Wyllie DJ, Kulik Á, Vida I. Postsynaptic GABABRs Inhibit L-Type Calcium Channels and Abolish Long-Term Potentiation in Hippocampal Somatostatin Interneurons. Cell Rep 2018; 22:36-43. [DOI: 10.1016/j.celrep.2017.12.021] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2017] [Revised: 10/14/2017] [Accepted: 12/06/2017] [Indexed: 11/24/2022] Open
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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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Correa AMB, Guimarães JDS, Dos Santos E Alhadas E, Kushmerick C. Control of neuronal excitability by Group I metabotropic glutamate receptors. Biophys Rev 2017; 9:835-845. [PMID: 28836161 PMCID: PMC5662043 DOI: 10.1007/s12551-017-0301-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2017] [Accepted: 07/27/2017] [Indexed: 12/12/2022] Open
Abstract
Metabotropic glutamate (mGlu) receptors couple through G proteins to regulate a large number of cell functions. Eight mGlu receptor isoforms have been cloned and classified into three Groups based on sequence, signal transduction mechanisms and pharmacology. This review will focus on Group I mGlu receptors, comprising the isoforms mGlu1 and mGlu5. Activation of these receptors initiates both G protein-dependent and -independent signal transduction pathways. The G-protein-dependent pathway involves mainly Gαq, which can activate PLCβ, leading initially to the formation of IP3 and diacylglycerol. IP3 can release Ca2+ from cellular stores resulting in activation of Ca2+-dependent ion channels. Intracellular Ca2+, together with diacylglycerol, activates PKC, which has many protein targets, including ion channels. Thus, activation of the G-protein-dependent pathway affects cellular excitability though several different effectors. In parallel, G protein-independent pathways lead to activation of non-selective cationic currents and metabotropic synaptic currents and potentials. Here, we provide a survey of the membrane transport proteins responsible for these electrical effects of Group I metabotropic glutamate receptors.
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Affiliation(s)
- Ana Maria Bernal Correa
- Graduate Program in Physiology and Pharmacology, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | | | | | - Christopher Kushmerick
- Graduate Program in Physiology and Pharmacology, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil.
- Departamento de Fisiologia e Biofísica - ICB, UFMG, Av. Pres. Antônio Carlos, 6627 - Pampulha, Belo Horizonte, MG, 31270-901, Brazil.
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28
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Tatti R, Haley MS, Swanson O, Tselha T, Maffei A. Neurophysiology and Regulation of the Balance Between Excitation and Inhibition in Neocortical Circuits. Biol Psychiatry 2017; 81:821-831. [PMID: 27865453 PMCID: PMC5374043 DOI: 10.1016/j.biopsych.2016.09.017] [Citation(s) in RCA: 105] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/04/2016] [Revised: 08/25/2016] [Accepted: 09/15/2016] [Indexed: 12/18/2022]
Abstract
Brain function relies on the ability of neural networks to maintain stable levels of activity, while experiences sculpt them. In the neocortex, the balance between activity and stability relies on the coregulation of excitatory and inhibitory inputs onto principal neurons. Shifts of excitation or inhibition result in altered excitability impaired processing of incoming information. In many neurodevelopmental and neuropsychiatric disorders, the excitability of local circuits is altered, suggesting that their pathophysiology may involve shifts in synaptic excitation, inhibition, or both. Most studies focused on identifying the cellular and molecular mechanisms controlling network excitability to assess whether they may be altered in animal models of disease. The impact of changes in excitation/inhibition balance on local circuit and network computations is not clear. Here we report findings on the integration of excitatory and inhibitory inputs in healthy cortical circuits and discuss how shifts in excitation/inhibition balance may relate to pathological phenotypes.
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Affiliation(s)
- Roberta Tatti
- Dept. of Neurobiology and Behavior, SUNY-Stony Brook, Stony Brook, NY 11794
| | - Melissa S. Haley
- Dept. of Neurobiology and Behavior, SUNY-Stony Brook, Stony Brook, NY 11794
| | - Olivia Swanson
- Dept. of Neurobiology and Behavior, SUNY-Stony Brook, Stony Brook, NY 11794
| | - Tenzin Tselha
- Dept. of Neurobiology and Behavior, SUNY-Stony Brook, Stony Brook, NY 11794
| | - Arianna Maffei
- Department of Neurobiology and Behavior, Stony Brook University, The State University of New York, Stony Brook, New York.
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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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30
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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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31
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Shi W, Lu Y. Metabotropic glutamate and GABA receptors modulate cellular excitability and glutamatergic transmission in chicken cochlear nucleus angularis neurons. Hear Res 2017; 346:14-24. [PMID: 28104407 DOI: 10.1016/j.heares.2017.01.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/05/2016] [Revised: 12/20/2016] [Accepted: 01/12/2017] [Indexed: 12/25/2022]
Abstract
Neurons in the avian cochlear nucleus angularis (NA) receive glutamatergic input from the auditory nerve, and GABAergic input from the superior olivary nucleus. Physiologically heterogeneous, NA neurons perform multiple functions including encoding sound intensity information. Using in vitro whole-cell patch recordings from acute brain slices and immunohistochemistry staining, we investigated neuromodulation mediated by metabotropic glutamate and GABA receptors (mGluRs and GABABRs) in NA neurons. Based on their intrinsic firing patterns in response to somatic current injections, NA neurons were classified into onset, damped, and tonic cells. Pharmacological activation of group II mGluRs, group III mGluRs, and GABABRs, by their respective agonists, suppressed the cellular excitability of non-onset firing NA neurons. Each of these agonists inhibited the glutamatergic transmission in NA neurons, in a cell type-independent manner. The frequency but not the amplitude of spontaneous release of glutamate was reduced by each of these agonists, suggesting that the modulation of the glutamatergic transmission was via presynaptic actions. Interestingly, activation of group I mGluRs increased cellular excitability and suppressed glutamatergic transmission in non-onset neurons. These results elaborate that auditory processing in NA neurons is subject to neuromodulation mediated by metabotropic receptors activated by native neurotransmitters released at NA.
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Affiliation(s)
- Wei Shi
- Department of Anatomy and Neurobiology, College of Medicine, Northeast Ohio Medical University, Rootstown, OH 44272, USA; School of Biomedical Sciences, Kent State University, Kent, OH 44240, USA; School of Life Science, Tsinghua University, Beijing, 100084, PR China.
| | - Yong Lu
- Department of Anatomy and Neurobiology, College of Medicine, Northeast Ohio Medical University, Rootstown, OH 44272, USA; School of Biomedical Sciences, Kent State University, Kent, OH 44240, USA.
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32
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Affiliation(s)
- Visou Ady
- Department of Biology, McGill University, Montreal, H3G 0B1, Canada
| | - Alanna J Watt
- Department of Biology, McGill University, Montreal, H3G 0B1, Canada
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33
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Hannan S, Gerrow K, Triller A, Smart TG. Phospho-dependent Accumulation of GABABRs at Presynaptic Terminals after NMDAR Activation. Cell Rep 2016; 16:1962-73. [PMID: 27498877 PMCID: PMC4987283 DOI: 10.1016/j.celrep.2016.07.021] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Revised: 04/19/2016] [Accepted: 07/09/2016] [Indexed: 11/24/2022] Open
Abstract
Here, we uncover a mechanism for regulating the number of active presynaptic GABAB receptors (GABABRs) at nerve terminals, an important determinant of neurotransmitter release. We find that GABABRs gain access to axon terminals by lateral diffusion in the membrane. Their relative accumulation is dependent upon agonist activation and the presence of the two distinct sushi domains that are found only in alternatively spliced GABABR1a subunits. Following brief activation of NMDA receptors (NMDARs) using glutamate, GABABR diffusion is reduced, causing accumulation at presynaptic terminals in a Ca(2+)-dependent manner that involves phosphorylation of GABABR2 subunits at Ser783. This signaling cascade indicates how synaptically released glutamate can initiate, via a feedback mechanism, increased levels of presynaptic GABABRs that limit further glutamate release and excitotoxicity.
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Affiliation(s)
- Saad Hannan
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London WC1E 6BT, UK
| | - Kim Gerrow
- Biologie Cellulaire de la Synapse, Inserm U1024, Institute of Biology, École Normale Supérieure (ENS), 46 rue d'Ulm, Paris 75005, France
| | - Antoine Triller
- Biologie Cellulaire de la Synapse, Inserm U1024, Institute of Biology, École Normale Supérieure (ENS), 46 rue d'Ulm, Paris 75005, France
| | - Trevor G Smart
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London WC1E 6BT, UK.
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34
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mGlu5-GABAB interplay in animal models of positive, negative and cognitive symptoms of schizophrenia. Neurochem Int 2015; 88:97-109. [DOI: 10.1016/j.neuint.2015.03.010] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2014] [Revised: 03/17/2015] [Accepted: 03/23/2015] [Indexed: 11/19/2022]
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35
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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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36
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Degro CE, Kulik A, Booker SA, Vida I. Compartmental distribution of GABAB receptor-mediated currents along the somatodendritic axis of hippocampal principal cells. Front Synaptic Neurosci 2015; 7:6. [PMID: 25852540 PMCID: PMC4369648 DOI: 10.3389/fnsyn.2015.00006] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2014] [Accepted: 02/15/2015] [Indexed: 02/02/2023] Open
Abstract
Activity of cortical principal cells is controlled by the GABAergic system providing inhibition in a compartmentalized manner along their somatodendritic axis. While GABAAR-mediated inhibitory synaptic transmission has been extensively characterized in hippocampal principal cells, little is known about the distribution of postsynaptic effects of GABABRs. In the present study, we have investigated the functional localization of GABABRs and their effector inwardly rectifying potassium (Kir3) channels by combining electrophysiological recordings in acute rat hippocampal slices, high-resolution immunoelectron microscopic analysis and single cell simulations. Pharmacologically isolated slow inhibitory postsynaptic currents were elicited in the three major hippocampal principal cell types by endogenous GABA released by electrical stimulation, photolysis of caged-GABA, as well as the canonical agonist baclofen, with the highest amplitudes observed in the CA3. Spatially restricted currents were assessed along the axis of principal cells by uncaging GABA in the different hippocampal layers. GABABR-mediated currents were present along the entire somatodendritic axis of principal cells, but non-uniformly distributed: largest currents and the highest conductance densities determined in the simulations were consistently found on the distal apical dendrites. Finally, immunocytochemical localization of GABABRs and Kir3 channels showed that distributions overlap but their densities diverge, particularly on the basal dendrites of pyramidal cells. GABABRs current amplitudes and the conductance densities correlated better with Kir3 density, suggesting a bottlenecking effect defined by the effector channel. These data demonstrate a compartmentalized distribution of the GABABR-Kir3 signaling cascade and suggest differential control of synaptic transmission, dendritic integration and synaptic plasticity at afferent pathways onto hippocampal principal cells.
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Affiliation(s)
- Claudius E Degro
- Institute for Integrative Neuroanatomy, Neurocure Cluster of Excellence, Charité Universitätsmedizin Berlin Germany
| | - Akos Kulik
- Institute for Physiology II, Bioss Centre for Biological Signalling Studies, University of Freiburg Freiburg Germany
| | - Sam A Booker
- Institute for Integrative Neuroanatomy, Neurocure Cluster of Excellence, Charité Universitätsmedizin Berlin Germany
| | - Imre Vida
- Institute for Integrative Neuroanatomy, Neurocure Cluster of Excellence, Charité Universitätsmedizin Berlin Germany
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Otsu Y, Marcaggi P, Feltz A, Isope P, Kollo M, Nusser Z, Mathieu B, Kano M, Tsujita M, Sakimura K, Dieudonné S. Activity-dependent gating of calcium spikes by A-type K+ channels controls climbing fiber signaling in Purkinje cell dendrites. Neuron 2014; 84:137-151. [PMID: 25220810 PMCID: PMC4183427 DOI: 10.1016/j.neuron.2014.08.035] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/17/2014] [Indexed: 12/01/2022]
Abstract
In cerebellar Purkinje cell dendrites, heterosynaptic calcium signaling induced by the proximal climbing fiber (CF) input controls plasticity at distal parallel fiber (PF) synapses. The substrate and regulation of this long-range dendritic calcium signaling are poorly understood. Using high-speed calcium imaging, we examine the role of active dendritic conductances. Under basal conditions, CF stimulation evokes T-type calcium signaling displaying sharp proximodistal decrement. Combined mGluR1 receptor activation and depolarization, two activity-dependent signals, unlock P/Q calcium spikes initiation and propagation, mediating efficient CF signaling at distal sites. These spikes are initiated in proximal smooth dendrites, independently from somatic sodium action potentials, and evoke high-frequency bursts of all-or-none fast-rising calcium transients in PF spines. Gradual calcium spike burst unlocking arises from increasing inactivation of mGluR1-modulated low-threshold A-type potassium channels located in distal dendrites. Evidence for graded activity-dependent CF calcium signaling at PF synapses refines current views on cerebellar supervised learning rules.
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Affiliation(s)
- Yo Otsu
- Inhibitory Transmission Team, IBENS, CNRS UMR UMR8197, INSERM U1024, Ecole Normale Supérieure, 75005 Paris, France
| | - Païkan Marcaggi
- Inhibitory Transmission Team, IBENS, CNRS UMR UMR8197, INSERM U1024, Ecole Normale Supérieure, 75005 Paris, France
| | - Anne Feltz
- Cerebellum Group, IBENS, CNRS UMR UMR8197, INSERM U1024, Ecole Normale Supérieure, 75005 Paris, France
| | - Philippe Isope
- Institut des Neurosciences Cellulaires et Intégratives, CNRS UPR 3212, 67000-Strasbourg, France
| | - Mihaly Kollo
- Laboratory of Cellular Neurophysiology, Institute of Experimental Medicine of the Hungarian Academy of Sciences, 1083 Budapest, Hungary
| | - Zoltan Nusser
- Laboratory of Cellular Neurophysiology, Institute of Experimental Medicine of the Hungarian Academy of Sciences, 1083 Budapest, Hungary
| | - Benjamin Mathieu
- Imaging Facility, IBENS, CNRS UMR 8197, INSERM U1024, Ecole Normale Supérieure, 75005 Paris, France
| | - Masanobu Kano
- Department of Neurophysiology, Graduate School of Medicine, University of Tokyo, Tokyo 113-0033, Japan
| | - Mika Tsujita
- Center for Transdisciplinary Research, Niigata University, Niigata 950-2181, Japan
| | - Kenji Sakimura
- Department of Cellular Neurobiology, Brain Research Institute, Niigata University, Niigata 951-8585, Japan
| | - Stéphane Dieudonné
- Inhibitory Transmission Team, IBENS, CNRS UMR UMR8197, INSERM U1024, Ecole Normale Supérieure, 75005 Paris, France.
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Kubota H, Nagao S, Obata K, Hirono M. mGluR1-mediated excitation of cerebellar GABAergic interneurons requires both G protein-dependent and Src-ERK1/2-dependent signaling pathways. PLoS One 2014; 9:e106316. [PMID: 25181481 PMCID: PMC4152260 DOI: 10.1371/journal.pone.0106316] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2013] [Accepted: 08/05/2014] [Indexed: 12/26/2022] Open
Abstract
Stimulation of type I metabotropic glutamate receptors (mGluR1/5) in several neuronal types induces slow excitatory responses through activation of transient receptor potential canonical (TRPC) channels. GABAergic cerebellar molecular layer interneurons (MLIs) modulate firing patterns of Purkinje cells (PCs), which play a key role in cerebellar information processing. MLIs express mGluR1, and activation of mGluR1 induces an inward current, but its precise intracellular signaling pathways are unknown. We found that mGluR1 activation facilitated spontaneous firing of mouse cerebellar MLIs through an inward current mediated by TRPC1 channels. This mGluR1-mediated inward current depends on both G protein-dependent and -independent pathways. The nonselective protein tyrosine kinase inhibitors genistein and AG490 as well as the selective extracellular signal-regulated kinase 1/2 (ERK1/2) inhibitors PD98059 and SL327 suppressed the mGluR1-mediated current responses. Following G protein blockade, the residual mGluR1-mediated inward current was significantly reduced by the selective Src tyrosine kinase inhibitor PP2. In contrast to cerebellar PCs, GABAB receptor activation in MLIs did not alter the mGluR1-mediated inward current, suggesting that there is no cross-talk between mGluR1 and GABAB receptors in MLIs. Thus, activation of mGluR1 facilitates firing of MLIs through the TRPC1-mediated inward current, which depends on not only G protein-dependent but also Src–ERK1/2-dependent signaling pathways, and consequently depresses the excitability of cerebellar PCs.
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Affiliation(s)
- Hideo Kubota
- Materials Management, Medical Hospital, Tokyo Medical and Dental University (TMDU), Bunkyo, Tokyo, Japan
- * E-mail: (HK); (MH)
| | - Soichi Nagao
- Laboratory for Motor Learning Control, RIKEN Brain Science Institute, Wako, Saitama, Japan
| | - Kunihiko Obata
- Obata Research Unit, RIKEN Brain Science Institute, Wako, Saitama, Japan
| | - Moritoshi Hirono
- Laboratory for Motor Learning Control, RIKEN Brain Science Institute, Wako, Saitama, Japan
- Obata Research Unit, RIKEN Brain Science Institute, Wako, Saitama, Japan
- * E-mail: (HK); (MH)
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Tovo-Rodrigues L, Roux A, Hutz MH, Rohde LA, Woods AS. Functional characterization of G-protein-coupled receptors: a bioinformatics approach. Neuroscience 2014; 277:764-79. [PMID: 24997265 DOI: 10.1016/j.neuroscience.2014.06.049] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2014] [Revised: 05/22/2014] [Accepted: 06/18/2014] [Indexed: 12/18/2022]
Abstract
Complex molecular and cellular mechanisms regulate G protein-coupled receptors (GPCRs). It is suggested that proteins intrinsically disordered regions (IDRs) are to play a role in GPCR's intra and extracellular regions plasticity, due to their potential for post-translational modification and interaction with other proteins. These regions are defined as lacking a stable three-dimensional (3D) structure. They are rich in hydrophilic and charged, amino acids and are capable to assume different conformations which allow them to interact with multiple partners. In this study we analyzed 75 GPCR involved in synaptic transmission using computational tools for sequence-based prediction of IDRs within a protein. We also evaluated putative ligand-binding motifs using receptor sequences. The disorder analysis indicated that neurotransmitter GPCRs have a significant amount of disorder in their N-terminus, third intracellular loop (3IL) and C-terminus. About 31%, 39% and 53% of human GPCR involved in synaptic transmission are disordered in these regions. Thirty-three percent of receptors show at least one predicted PEST motif, this being statistically greater than the estimate for the rest of human GPCRs. About 90% of the receptors had at least one putative site for dimerization in their 3IL or C-terminus. ELM instances sampled in these domains were 14-3-3, SH3, SH2 and PDZ motifs. In conclusion, the increased flexibility observed in GPCRs, added to the enrichment of linear motifs, PEST and heteromerization sites, may be critical for the nervous system's functional plasticity.
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Affiliation(s)
- L Tovo-Rodrigues
- Department of Genetics, Federal University of Rio Grande do Sul, Porto Alegre, RS, Brazil; Structural Biology Unit, Integrative Neuroscience Branch, NIDA IRP, NIH, MD, United States
| | - A Roux
- Structural Biology Unit, Integrative Neuroscience Branch, NIDA IRP, NIH, MD, United States
| | - M H Hutz
- Department of Genetics, Federal University of Rio Grande do Sul, Porto Alegre, RS, Brazil
| | - L A Rohde
- Child and Adolescent Psychiatric Division, Department of Psychiatry, Federal University of Rio Grande do Sul, Porto Alegre, RS, Brazil
| | - A S Woods
- Structural Biology Unit, Integrative Neuroscience Branch, NIDA IRP, NIH, MD, United States.
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40
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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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41
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Guyon A. CXCL12 chemokine and its receptors as major players in the interactions between immune and nervous systems. Front Cell Neurosci 2014; 8:65. [PMID: 24639628 PMCID: PMC3944789 DOI: 10.3389/fncel.2014.00065] [Citation(s) in RCA: 127] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2013] [Accepted: 02/13/2014] [Indexed: 11/13/2022] Open
Abstract
The chemokine CXCL12/stromal cell-derived factor 1 alpha has first been described in the immune system where it functions include chemotaxis for lymphocytes and macrophages, migration of hematopoietic cells from fetal liver to bone marrow and the formation of large blood vessels. Among other chemokines, CXCL12 has recently attracted much attention in the brain as it has been shown that it can be produced not only by glial cells but also by neurons. In addition, its receptors CXCR4 and CXCR7, which are belonging to the G protein-coupled receptors family, are abundantly expressed in diverse brain area, CXCR4 being a major co-receptor for human immunodeficiency virus 1 entry. This chemokine system has been shown to play important roles in brain plasticity processes occurring during development but also in the physiology of the brain in normal and pathological conditions. For example, in neurons, CXCR4 stimulation has been shown regulate the synaptic release of glutamate and γ-aminobutyric acid (GABA). It can also act post-synaptically by activating a G protein activated inward rectifier K+ (GIRK), a voltage-gated K channel Kv2.1 associated to neuronal survival, and by increasing high voltage activated Ca2+ currents. In addition, it has been recently evidenced that there are several cross-talks between the CXCL12/CXCR4–7 system and other neurotransmitter systems in the brain (such as GABA, glutamate, opioids, and cannabinoids). Overall, this chemokine system could be one of the key players of the neuro-immune interface that participates in shaping the brain in response to changes in the environment.
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Affiliation(s)
- Alice Guyon
- Institut de Pharmacologie Moléculaire et Cellulaire, UMR 7275 Centre National de la Recherche Scientifique/Université Nice Sophia Antipolis Valbonne, France
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42
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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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43
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Gao Z, van Woerden GM, Elgersma Y, De Zeeuw CI, Hoebeek FE. Distinct roles of α- and βCaMKII in controlling long-term potentiation of GABAA-receptor mediated transmission in murine Purkinje cells. Front Cell Neurosci 2014; 8:16. [PMID: 24550776 PMCID: PMC3910348 DOI: 10.3389/fncel.2014.00016] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2013] [Accepted: 01/10/2014] [Indexed: 01/20/2023] Open
Abstract
Calcium/Calmodulin-dependent kinase type II (CaMKII) is essential for various forms of synaptic plasticity. The predominant α- and βCaMKII isoforms have both been shown to contribute to specific forms of plasticity at excitatory synapses, but little is known about their functions at inhibitory synapses. Here we investigated the role of both isoforms in long-term potentiation of the inhibitory molecular layer interneuron to Purkinje cell synapse (MLI-PC iLTP) upon climbing fiber (CF) stimulation. We demonstrate that deleting either the α- or βCaMKII isoform affected MLI-PC iLTP. In the presence of the PP2B blocker cyclosporin A, CF stimulation elicited iLTP in Camk2b-/- mice, but not in Camk2a-/- mice. Moreover, co-activation of the MLIs and CF suppressed iLTP in wild-type mice through activation of GABAB-receptors, whereas it evoked iLTP in Camk2b-/-. This reversal of the effect of αCaMKII activity in Camk2b-/- mutants upon co-activation did not critically involve protein kinase A, but depended on calcium release from internal stores. Our results indicate that α- and βCaMKII isoforms in Purkinje cells can be differentially activated and serve distinct roles in controlling iLTP. We propose that the CaMKII holo-enzyme may be selectively activated by various GABAB-mediated pathways and that the presence of the βCaMKII isoform determines their impact on inhibitory plasticity.
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Affiliation(s)
- Zhenyu Gao
- Department of Neuroscience, Erasmus Medical Centre Rotterdam, Netherlands
| | | | - Ype Elgersma
- Department of Neuroscience, Erasmus Medical Centre Rotterdam, Netherlands
| | - Chris I De Zeeuw
- Department of Neuroscience, Erasmus Medical Centre Rotterdam, Netherlands ; Netherlands Institute for Neuroscience, Royal Academy of Arts and Sciences Amsterdam, Netherlands
| | - Freek E Hoebeek
- Department of Neuroscience, Erasmus Medical Centre Rotterdam, Netherlands
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44
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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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45
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Gaiarsa JL, Porcher C. Emerging neurotrophic role of GABAB receptors in neuronal circuit development. Front Cell Neurosci 2013; 7:206. [PMID: 24282395 PMCID: PMC3824957 DOI: 10.3389/fncel.2013.00206] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2013] [Accepted: 10/18/2013] [Indexed: 12/22/2022] Open
Abstract
The proper development of highly organized structures in the central nervous system is a complex process during which key events – neurogenesis, migration, growth, differentiation, and synaptogenesis – have to take place in an appropriate manner to create functional neuronal networks. It is now well established that GABA, the main inhibitory neurotransmitter in the adult mammalian brain, plays more than a classical inhibitory role and can function as an important developmental signal early in life. GABA binds to chloride-permeable ionotropic GABAA receptors and to G-protein-coupled GABAB receptors (GABAB-Rs). Although most of the trophic actions of GABA have been attributed to the activation of GABAA receptors, recent advances show that GABAB-Rs also regulate fundamental steps of network development. This review summarizes some of the recent progress about the neurotrophic role of GABAB-Rs to neuronal development.
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Affiliation(s)
- Jean-Luc Gaiarsa
- Institut National de la Santé et de la Recherche Médicale U-901 Marseille, France ; Aix-Marseille Université, UMR S901 Marseille, France ; Institut de Neurobiologie de la Méditerranée Marseille, France
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46
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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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47
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Sinchak K, Dewing P, Ponce L, Gomez L, Christensen A, Berger M, Micevych P. Modulation of the arcuate nucleus-medial preoptic nucleus lordosis regulating circuit: a role for GABAB receptors. Horm Behav 2013; 64:136-43. [PMID: 23756153 PMCID: PMC3742545 DOI: 10.1016/j.yhbeh.2013.06.001] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/04/2013] [Revised: 05/29/2013] [Accepted: 06/02/2013] [Indexed: 12/20/2022]
Abstract
Estradiol rapidly activates a microcircuit in the arcuate nucleus of the hypothalamus (ARH) that is needed for maximal female sexual receptivity. Membrane estrogen receptor-α complexes with and signals through the metabotropic glutamate receptor-1a stimulating NPY release within the ARH activating proopiomelanocortin (POMC) neurons. These POMC neurons project to the medial preoptic nucleus (MPN) and release β-endorphin. Estradiol treatment induces activation/internalization of MPN μ-opioid receptors (MOR) to inhibit lordosis. Estradiol membrane action modulates ARH gamma-aminobutyric acid receptor-B (GABAB) activity. We tested the hypothesis that ARH GABAB receptors mediate estradiol-induced MOR activation and facilitation of sexual receptivity. Double-label immunohistochemistry revealed expression of GABAB receptors in NPY, ERα and POMC expressing ARH neurons. Approximately 70% of POMC neurons expressed GABAB receptors. Because estradiol initially activates an inhibitory circuit and maintains activation of this circuit, the effects of blocking GABAB receptors were evaluated before estradiol benzoate (EB) treatment and after at the time of lordosis testing. Bilateral infusions of the GABAB receptor antagonist, CGP52432, into the ARH prior to EB treatment of ovariectomized rats prevented estradiol-induced activation/internalization of MPN MOR, and the rats remained unreceptive. However, in EB-treated rats, bilateral CGP52432 infusions 30 min before behavior testing attenuated MOR internalization and facilitated lordosis. These results indicated that GABAB receptors were located within the lordosis-regulating ARH microcircuit and are necessary for activation and maintenance of the estradiol inhibition of lordosis behavior. Although GABAB receptors positively influence estradiol signaling, they negatively regulate lordosis behavior since GABAB activity maintains the estradiol-induced inhibition.
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MESH Headings
- Animals
- Arcuate Nucleus of Hypothalamus/drug effects
- Arcuate Nucleus of Hypothalamus/physiology
- Estradiol/pharmacology
- Estrogen Receptor alpha/metabolism
- Female
- GABA-B Receptor Antagonists/pharmacology
- Image Processing, Computer-Assisted
- Immunohistochemistry
- Male
- Nerve Net/drug effects
- Nerve Net/physiology
- Neuropeptide Y/metabolism
- Ovariectomy
- Preoptic Area/drug effects
- Preoptic Area/physiology
- Pro-Opiomelanocortin/metabolism
- Rats
- Rats, Long-Evans
- Receptors, GABA-B/drug effects
- Receptors, GABA-B/physiology
- Receptors, Opioid, mu/drug effects
- Receptors, Opioid, mu/physiology
- Sexual Behavior, Animal/drug effects
- Sexual Behavior, Animal/physiology
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Affiliation(s)
- Kevin Sinchak
- Biol. Sci., California State University, Long Beach, Long Beach, CA, USA.
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48
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Tarakanov AO, Fuxe KG. Integrin triplets of marine sponges in the murine and human MHCI-CD8 interface and in the interface of human neural receptor heteromers and subunits. SPRINGERPLUS 2013; 2:128. [PMID: 23556147 PMCID: PMC3612178 DOI: 10.1186/2193-1801-2-128] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/23/2012] [Accepted: 03/11/2013] [Indexed: 11/10/2022]
Abstract
Based on our theory, main triplets of amino acid residues have been discovered in cell-adhesion receptors (integrins) of marine sponges, which participate as homologies in the interface between two major immune molecules, MHC class I (MHCI) and CD8αβ. They appear as homologies also in several human neural receptor heteromers and subunits. The obtained results probably mean that neural and immune receptors also utilize these structural integrin triplets to form heteromers and ion channels, which are required for a tuned and integrated intracellular and intercellular communication and a communication between cells and the extracellular matrix with an origin in sponges, the oldest multicellular animals.
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Affiliation(s)
- Alexander O Tarakanov
- Russian Academy of Sciences, St. Petersburg Institute for Informatics and Automation, Saint Petersburg, Russia
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49
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Todaka H, Tatsukawa T, Hashikawa T, Yanagawa Y, Shibuki K, Nagao S. Heterotrimeric guanosine triphosphate-binding protein-coupled modulatory actions of motilin on K+ channels and postsynaptic γ-aminobutyric acid receptors in mouse medial vestibular nuclear neurons. Eur J Neurosci 2012; 37:339-50. [PMID: 23136934 DOI: 10.1111/ejn.12051] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2012] [Revised: 09/24/2012] [Accepted: 10/01/2012] [Indexed: 11/29/2022]
Abstract
Some central nervous system neurons express receptors of gastrointestinal hormones, but their pharmacological actions are not well known. Previous anatomical and unit recording studies suggest that a group of cerebellar Purkinje cells express motilin receptors, and motilin depresses the spike discharges of vestibular nuclear neurons that receive direct cerebellar inhibition in rats or rabbits. Here, by the slice-patch recording method, we examined the pharmacological actions of motilin on the mouse medial vestibular nuclear neurons (MVNs), which play an important role in the control of ocular reflexes. A small number of MVNs, as well as cerebellar floccular Purkinje cells, were labeled with an anti-motilin receptor antibody. Bath application of motilin (0.1 μm) decreased the discharge frequency of spontaneous action potentials in a group of MVNs in a dose-dependent manner (K(d) , 0.03 μm). The motilin action on spontaneous action potentials was blocked by apamin (100 nm), a blocker of small-conductance Ca(2+) -activated K(+) channels. Furthermore, motilin enhanced the amplitudes of inhibitory postsynaptic currents (IPSCs) and miniature IPSCs, but did not affect the frequencies of miniature IPSCs. Intracellular application of pertussis toxin (PTx) (0.5 μg/μL) or guanosine triphosphate-γ-S (1 mm) depressed the motilin actions on both action potentials and IPSCs. Only 30% of MVNs examined on slices obtained from wild-type mice, but none of the GABAergic MVNs that were studied on slices obtained from vesicular γ-aminobutyric acid transporter-Venus transgenic mice, showed such a motilin response on action potentials and IPSCs. These findings suggest that motilin could modulate small-conductance Ca(2+) -activated K(+) channels and postsynaptic γ-aminobutyric acid receptors through heterotrimeric guanosine triphosphate-binding protein-coupled receptor in a group of glutamatergic MVNs.
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Affiliation(s)
- Hiroshi Todaka
- Laboratory for Motor Learning Control, RIKEN Brain Science Institute, 2-1 Hirosawa, Wako-Shi, Saitama, 351-0198, Japan
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50
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Paul A, Cai Y, Atwal GS, Huang ZJ. Developmental Coordination of Gene Expression between Synaptic Partners During GABAergic Circuit Assembly in Cerebellar Cortex. Front Neural Circuits 2012; 6:37. [PMID: 22754500 PMCID: PMC3385560 DOI: 10.3389/fncir.2012.00037] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2012] [Accepted: 06/01/2012] [Indexed: 01/14/2023] Open
Abstract
The assembly of neural circuits involves multiple sequential steps such as the specification of cell-types, their migration to proper brain locations, morphological and physiological differentiation, and the formation and maturation of synaptic connections. This intricate and often prolonged process is guided by elaborate genetic mechanisms that regulate each step. Evidence from numerous systems suggests that each cell-type, once specified, is endowed with a genetic program that unfolds in response to, and is regulated by, extrinsic signals, including cell–cell and synaptic interactions. To a large extent, the execution of this intrinsic program is achieved by the expression of specific sets of genes that support distinct developmental processes. Therefore, a comprehensive analysis of the developmental progression of gene expression in synaptic partners of neurons may provide a basis for exploring the genetic mechanisms regulating circuit assembly. Here we examined the developmental gene expression profiles of well-defined cell-types in a stereotyped microcircuit of the cerebellar cortex. We found that the transcriptomes of Purkinje cell and stellate/basket cells are highly dynamic throughout postnatal development. We revealed “phasic expression” of transcription factors, ion channels, receptors, cell adhesion molecules, gap junction proteins, and identified distinct molecular pathways that might contribute to sequential steps of cerebellar inhibitory circuit formation. We further revealed a correlation between genomic clustering and developmental co-expression of hundreds of transcripts, suggesting the involvement of chromatin level gene regulation during circuit formation.
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Affiliation(s)
- Anirban Paul
- Cold Spring Harbor Laboratory, Neuroscience Cold Spring Harbor, New York, NY, USA
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