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Kumar J, Popescu GK, Gantz SC. GluD receptors are functional ion channels. Biophys J 2023; 122:2383-2395. [PMID: 37177782 PMCID: PMC10323023 DOI: 10.1016/j.bpj.2023.05.012] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2023] [Revised: 04/27/2023] [Accepted: 05/09/2023] [Indexed: 05/15/2023] Open
Abstract
In this article, we review contemporary evidence that GluD receptors are functional ion channels whose depolarizing currents contribute to their biological functions, akin to all other members of the ionotropic glutamate receptor (iGluR) family.
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Affiliation(s)
- Janesh Kumar
- Laboratory of Membrane Protein Biology, Council of Scientific and Industrial Research (CSIR)-Centre for Cellular and Molecular Biology, Hyderabad, Telangana, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, India
| | - Gabriela K Popescu
- Department of Biochemistry, Jacobs School of Medicine and Biomedical Sciences, University of Buffalo, SUNY, Buffalo, New York
| | - Stephanie C Gantz
- Department of Molecular Physiology and Biophysics, Carver College of Medicine, University of Iowa, Iowa City, Iowa; Iowa Neuroscience Institute, University of Iowa, Iowa City, Iowa.
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2
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Tomagra G, Franchino C, Cesano F, Chiarion G, de lure A, Carbone E, Calabresi P, Mesin L, Picconi B, Marcantoni A, Carabelli V. Alpha-synuclein oligomers alter the spontaneous firing discharge of cultured midbrain neurons. Front Cell Neurosci 2023; 17:1078550. [PMID: 36744002 PMCID: PMC9896582 DOI: 10.3389/fncel.2023.1078550] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2022] [Accepted: 01/06/2023] [Indexed: 01/21/2023] Open
Abstract
The aim of this work was to monitor the effects of extracellular α-synuclein on the firing activity of midbrain neurons dissociated from substantia nigra TH-GFP mice embryos and cultured on microelectrode arrays (MEA). We monitored the spontaneous firing discharge of the network for 21 days after plating and the role of glutamatergic and GABAergic inputs in regulating burst generation and network synchronism. Addition of GABA A , AMPA and NMDA antagonists did not suppress the spontaneous activity but allowed to identify three types of neurons that exhibited different modalities of firing and response to applied L-DOPA: high-rate (HR) neurons, low-rate pacemaking (LR-p), and low-rate non-pacemaking (LR-np) neurons. Most HR neurons were insensitive to L-DOPA, while the majority of LR-p neurons responded with a decrease of the firing discharge; less defined was the response of LR-np neurons. The effect of exogenous α-synuclein (α-syn) on the firing discharge of midbrain neurons was then studied by varying the exposure time (0-48 h) and the α-syn concentration (0.3-70 μM), while the formation of α-syn oligomers was monitored by means of AFM. Independently of the applied concentration, acute exposure to α-syn monomers did not exert any effect on the spontaneous firing rate of HR, LR-p, and LR-np neurons. On the contrary, after 48 h exposure, the firing activity was drastically altered at late developmental stages (14 days in vitro, DIV, neurons): α-syn oligomers progressively reduced the spontaneous firing discharge (IC50 = 1.03 μM), impaired burst generation and network synchronism, proportionally to the increased oligomer/monomer ratio. Different effects were found on early-stage developed neurons (9 DIV), whose firing discharge remained unaltered, regardless of the applied α-syn concentration and the exposure time. Our findings unravel, for the first time, the variable effects of exogenous α-syn at different stages of midbrain network development and provide new evidence for the early detection of neuronal function impairment associated to aggregated forms of α-syn.
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Affiliation(s)
- Giulia Tomagra
- Drug Science Department, University of Torino, Turin, Italy
- Nanostructured Interfaces and Surfaces Inter-Departmental Research Centre, Turin, Italy
| | | | - Federico Cesano
- Nanostructured Interfaces and Surfaces Inter-Departmental Research Centre, Turin, Italy
- Department of Chemistry and INSTM-UdR Torino, Turin, Italy
| | - Giovanni Chiarion
- Mathematical Biology and Physiology, Department of Electronics and Telecommunications, Turin, Italy
| | - Antonio de lure
- Laboratory Experimental Neurophysiology, IRCCS San Raffaele Rome, Rome, Italy
| | - Emilio Carbone
- Drug Science Department, University of Torino, Turin, Italy
- Nanostructured Interfaces and Surfaces Inter-Departmental Research Centre, Turin, Italy
| | - Paolo Calabresi
- Neurological Clinic, Fondazione Policlinico Universitario Agostino Gemelli IRCCS, Rome, Italy
- Neurology, Department of Neuroscience, Faculty of Medicine, Università Cattolica del “Sacro Cuore,”Rome, Italy
| | - Luca Mesin
- Mathematical Biology and Physiology, Department of Electronics and Telecommunications, Turin, Italy
| | - Barbara Picconi
- Laboratory Experimental Neurophysiology, IRCCS San Raffaele Rome, Rome, Italy
- Dipartimento di Scienze Umane e Promozione della Qualitá della Vita, Telematic University San Raffaele Roma, Rome, Italy
| | - Andrea Marcantoni
- Drug Science Department, University of Torino, Turin, Italy
- Nanostructured Interfaces and Surfaces Inter-Departmental Research Centre, Turin, Italy
| | - Valentina Carabelli
- Drug Science Department, University of Torino, Turin, Italy
- Nanostructured Interfaces and Surfaces Inter-Departmental Research Centre, Turin, Italy
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3
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Chen M, Liu F, Wen L, Hu X. Nonlinear relationship between CAN current and C a 2 + influx underpins synergistic action of muscarinic and NMDA receptors on bursts induction in midbrain dopaminergic neurons. Cogn Neurodyn 2022; 16:719-731. [PMID: 35603052 PMCID: PMC9120320 DOI: 10.1007/s11571-021-09740-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Revised: 10/08/2021] [Accepted: 10/19/2021] [Indexed: 12/29/2022] Open
Abstract
Bursting of midbrain dopamine (DA) neurons is believed to represent an important reward signal that instructs and reinforces goal-directed behaviors. In DA neurons, many afferents, including cholinergic and glutamatergic inputs, induce bursting, and it is suggested that a synergy exists between these afferents in bursting induction. However, the underlying mechanisms of the role and the synergy of muscarinic receptors (mAChRs) and NMDA receptors (NMDARs) in bursting induction remain unclear. Present work bestowed analysis using a mathematical model of DA neurons to demonstrate the underlying mechanisms. Activation of mAChRs, leading to rapid translocation of TRPC channels to cell surface, recruited C a 2 + -activated nonspecific (CAN) current ( I CAN ), meanwhile NMDARs excitation triggered C a 2 + influx, which induced the positive feedback loop of C a 2 + and I CAN , respectively, yielded a robust ramping depolarization with a superimposed high-frequency spiking. In some DA cells, neither NMDARs nor mAChRs induced positive feedback loop unless they were activated simultaneously to induce bursting. Our experimental results verified those theoretical findings. These together unveil the underlying mechanisms of the role and synergy of mAChRs and NMDARs in bursting induction emerge from the nonlinear relationship between C a 2 + influx and I CAN . Given the diverse and complex nature of neural circuitry and the DA neuron heterogeneity, our work provides new insights to understand specific afferents, the synergy between those afferents, and the differences in intrinsic excitability to be integrated by the bursting to accurately characterize the dopamine signals in the valances of reward and reinforcement, and a broad spectrum of neuropsychiatric disorders.
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Affiliation(s)
- Mengjiao Chen
- College of Life Sciences, Leshan Normal University, Leshan, 614000 China
- Key Laboratory of Sichuan Institute for Protecting Endangered Birds in the Southwest Mountains, Leshan Normal University, Leshan, 614000 China
- Key Laboratory of MOE for Modern Teaching Technology, Shaanxi Normal University, Xi’an, 710062 China
| | - Fangqing Liu
- College of Life Sciences, Leshan Normal University, Leshan, 614000 China
- Key Laboratory of Sichuan Institute for Protecting Endangered Birds in the Southwest Mountains, Leshan Normal University, Leshan, 614000 China
| | - Longying Wen
- College of Life Sciences, Leshan Normal University, Leshan, 614000 China
- Key Laboratory of Sichuan Institute for Protecting Endangered Birds in the Southwest Mountains, Leshan Normal University, Leshan, 614000 China
| | - Xia Hu
- College of Life Sciences, Leshan Normal University, Leshan, 614000 China
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4
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Shao J, Liu Y, Gao D, Tu J, Yang F. Neural Burst Firing and Its Roles in Mental and Neurological Disorders. Front Cell Neurosci 2021; 15:741292. [PMID: 34646123 PMCID: PMC8502892 DOI: 10.3389/fncel.2021.741292] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Accepted: 08/26/2021] [Indexed: 11/29/2022] Open
Abstract
Neural firing patterns are critical for specific information coding and transmission, and abnormal firing is implicated in a series of neural pathologies. Recent studies have indicated that enhanced burst firing mediated by T-type voltage-gated calcium channels (T-VGCCs) in specific neuronal subtypes is involved in several mental or neurological disorders such as depression and epilepsy, while suppression of T-VGCCs relieve related symptoms. Burst firing consists of groups of relatively high-frequency spikes separated by quiescence. Neurons in a variety of brain areas, including the thalamus, hypothalamus, cortex, and hippocampus, display burst firing, but the ionic mechanisms that generating burst firing and the related physiological functions vary among regions. In this review, we summarize recent findings on the mechanisms underlying burst firing in various brain areas, as well as the roles of burst firing in several mental and neurological disorders. We also discuss the ion channels and receptors that may regulate burst firing directly or indirectly, with these molecules highlighted as potential intervention targets for the treatment of mental and neurological disorders.
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Affiliation(s)
- Jie Shao
- The Brain Cognition and Brain Disease Institute, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen-Hong Kong Institute of Brain Science-Shenzhen Fundamental Research Institutions, Shenzhen, China.,Shenzhen College of Advanced Technology, University of Chinese Academy of Sciences, Beijing, China
| | - Yunhui Liu
- The Brain Cognition and Brain Disease Institute, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen-Hong Kong Institute of Brain Science-Shenzhen Fundamental Research Institutions, Shenzhen, China
| | - Dashuang Gao
- The Brain Cognition and Brain Disease Institute, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen-Hong Kong Institute of Brain Science-Shenzhen Fundamental Research Institutions, Shenzhen, China.,Shenzhen College of Advanced Technology, University of Chinese Academy of Sciences, Beijing, China
| | - Jie Tu
- The Brain Cognition and Brain Disease Institute, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen-Hong Kong Institute of Brain Science-Shenzhen Fundamental Research Institutions, Shenzhen, China.,Shenzhen College of Advanced Technology, University of Chinese Academy of Sciences, Beijing, China
| | - Fan Yang
- The Brain Cognition and Brain Disease Institute, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen-Hong Kong Institute of Brain Science-Shenzhen Fundamental Research Institutions, Shenzhen, China.,Shenzhen College of Advanced Technology, University of Chinese Academy of Sciences, Beijing, China
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5
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Gautron S. Trace Amine-Associated Receptor 1 Regulates Central Effects of Monoamine Oxidase Inhibitors: Involvement of Tyramine and Glutamate. Biol Psychiatry 2021; 90:2-3. [PMID: 34140118 DOI: 10.1016/j.biopsych.2021.04.021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/28/2021] [Accepted: 04/28/2021] [Indexed: 11/26/2022]
Affiliation(s)
- Sophie Gautron
- Institute of Biology Paris-Seine, Institut National de la Santé et de la Recherche Médicale, Centre National de la Recherche Scientifique, Sorbonne Université, Paris, France.
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6
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Ledonne A, Mercuri NB. Insights on the Functional Interaction between Group 1 Metabotropic Glutamate Receptors (mGluRI) and ErbB Receptors. Int J Mol Sci 2020; 21:ijms21217913. [PMID: 33114459 PMCID: PMC7662933 DOI: 10.3390/ijms21217913] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2020] [Revised: 10/23/2020] [Accepted: 10/23/2020] [Indexed: 11/16/2022] Open
Abstract
It is well-appreciated that phosphorylation is an essential post-translational mechanism of regulation for several proteins, including group 1 metabotropic glutamate receptors (mGluRI), mGluR1, and mGluR5 subtypes. While contributions of various serine/threonine protein kinases on mGluRI modulation have been recognized, the functional role of tyrosine kinases (TKs) is less acknowledged. Here, while describing current evidence supporting that mGluRI are targets of TKs, we mainly focus on the modulatory roles of the ErbB tyrosine kinases receptors—activated by the neurotrophic factors neuregulins (NRGs)—on mGluRI function. Available evidence suggests that mGluRI activity is tightly dependent on ErbB signaling, and that ErbB’s modulation profoundly influences mGluRI-dependent effects on neurotransmission, neuronal excitability, synaptic plasticity, and learning and memory processes.
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Affiliation(s)
- Ada Ledonne
- Department of Experimental Neuroscience, IRCCS Fondazione Santa Lucia, 00143 Rome, Italy
- Correspondence: ; Tel.: +39-06-50170-3160
| | - Nicola B. Mercuri
- Department of Experimental Neuroscience, IRCCS Fondazione Santa Lucia, 00143 Rome, Italy
- Department of Systems Medicine, Università di Roma “Tor Vergata”, 00133 Rome, Italy;
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7
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Neurotensin receptors inhibit mGluR I responses in nigral dopaminergic neurons via a process that undergoes functional desensitization by G-protein coupled receptor kinases. Neuropharmacology 2019; 155:76-88. [PMID: 31128122 DOI: 10.1016/j.neuropharm.2019.05.026] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2018] [Revised: 05/09/2019] [Accepted: 05/19/2019] [Indexed: 12/15/2022]
Abstract
Neurotensin (NT) is a 13-amino acid peptide acting as a neuromodulator in the CNS. NT immunoreactive cell bodies, synaptic terminals and receptors (NTS) are intimately associated with the dopaminergic system. In fact, NT exerts a stimulatory action on the dopaminergic (DAergic) neurons of substantia nigra pars compacta (SNpc) and ventral tegmental area by activating a mixed cation conductance, reducing D2-autoinhibition and modulating NMDA and AMPA transmission. In the present work, we describe an inhibitory effect of NT on metabotropic glutamate receptor I (mGluR I) actions in rat SNpc DAergic neurons. NTS and mGluR I share the same Gαq/11-PLC-IP3-Ca2+ intracellular pathway which causes either activation of unspecific cationic conductance or intracellular Ca2+ accumulation. We find that NT inhibits both inward current and the associated intracellular calcium elevation, elicited by the selective mGluR I agonist S-DHPG, in a concentration-dependent manner. This effect is mediated by type 1/2 NT receptors (NTS1/2), as revealed by pharmacological analysis. Activation of other metabotropic receptors, such as muscarinic and GABAB, does not inhibit mGluR I inward currents. PKC, MEK 1-2, calcineurin, clathrin-dependent endocytosis and intracellular Ca2+ elevation are not involved in the NT-mediated modulation of mGluR I responses. Interestingly, inhibition of G-protein coupled receptor kinases (GRKs) 2/3 exacerbates the NT-induced mGluR I inhibition while sustaining the NT-induced inward current during repeated agonist stimulation. These data suggest that GRKs are key molecules regulating either the NT excitation or the cross-talk between NTS1/2 and mGluR I in DAergic neurons of rat midbrain by tuning the degree of NTS1/2 desensitization.
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8
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Ledonne A, Mercuri NB. mGluR1-Dependent Long Term Depression in Rodent Midbrain Dopamine Neurons Is Regulated by Neuregulin 1/ErbB Signaling. Front Mol Neurosci 2018; 11:346. [PMID: 30327588 PMCID: PMC6174199 DOI: 10.3389/fnmol.2018.00346] [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: 05/24/2018] [Accepted: 09/04/2018] [Indexed: 11/22/2022] Open
Abstract
Increasing evidence demonstrates that the neurotrophic factor Neuregulin 1 (NRG1) and its receptors, ErbB tyrosine kinases, modulate midbrain dopamine (DA) transmission. We have previously reported that NRG1/ErbB signaling is essential for proper metabotropic glutamate receptors 1 (mGluR1) functioning in midbrain DA neurons, thus the functional interaction between ErbB receptors and mGluR1 regulates neuronal excitation and in vivo striatal DA release. While it is widely recognized that mGluR1 play a pivotal role in long-term modifications of synaptic transmission in several brain areas, specific mGluR1-dependent forms of synaptic plasticity in substantia nigra pars compacta (SNpc) DA neurons have not been described yet. Here, first we aimed to detect and characterize mGluR1-dependent glutamatergic long-term depression (LTD) in SNpc DA neurons. Second, we tested the hypothesis that endogenous ErbB signaling, by affecting mGluR1, fine-tunes glutamatergic synaptic plasticity in DA cells. We found that either pharmacological or synaptic activation of mGluR1 causes an LTD of AMPAR-mediated transmission in SNpc DA neurons from mice and rat slices, which is reliant on endogenous NRG1/ErbB signaling. Indeed, LTD is counteracted by a broad spectrum ErbB inhibitor. Moreover, the intracellular injection of pan-ErbB- or ErbB2 inhibitors inside DA neurons reduces mGluR1-dependent LTD, suggesting an involvement of ErbB2/ErbB4-containing receptors. Interestingly, exogenous NRG1 fosters LTD expression during minimal mGluRI activation. These results enlarge our cognizance on mGluR1 relevance in the induction of a novel form of long-term synaptic plasticity in SNpc DA neurons and describe a new NRG1/ErbB-dependent mechanism shaping glutamatergic transmission in DA cells. This might have important implications either in DA-dependent behaviors and learning/memory processes or in DA-linked diseases.
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Affiliation(s)
- Ada Ledonne
- Department of Experimental Neuroscience, IRCCS Santa Lucia Foundation, Rome, Italy
| | - Nicola Biagio Mercuri
- Department of Experimental Neuroscience, IRCCS Santa Lucia Foundation, Rome, Italy.,Department of Systems Medicine, University of Rome Tor Vergata, Rome, Italy
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9
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GluD1, linked to schizophrenia, controls the burst firing of dopamine neurons. Mol Psychiatry 2018; 23:691-700. [PMID: 28696429 PMCID: PMC5822454 DOI: 10.1038/mp.2017.137] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/18/2016] [Revised: 05/11/2017] [Accepted: 05/15/2017] [Indexed: 01/08/2023]
Abstract
Human mutations of the GRID1 gene encoding the orphan delta1 glutamate receptor-channel (GluD1) are associated with schizophrenia but the explicit role of GluD1 in brain circuits is unknown. Based on the known function of its paralog GluD2 in cerebellum, we searched for a role of GluD1 in slow glutamatergic transmission mediated by metabotropic receptor mGlu1 in midbrain dopamine neurons, whose dysfunction is a hallmark of schizophrenia. We found that an mGlu1 agonist elicits a slow depolarizing current in HEK cells co-expressing mGlu1 and GluD1, but not in cells expressing mGlu1 or GluD1 alone. This current is abolished by additional co-expression of a dominant-negative GluD1 dead pore mutant. We then characterized mGlu1-dependent currents in dopamine neurons from midbrain slices. Both the agonist-evoked and the slow postsynaptic currents are abolished by expression of the dominant-negative GluD1 mutant, pointing to the involvement of native GluD1 channels in these currents. Likewise, both mGlu1-dependent currents are suppressed in GRID1 knockout mice, which reportedly display endophenotypes relevant for schizophrenia. It is known that mGlu1 activation triggers the transition from tonic to burst firing of dopamine neurons, which signals salient stimuli and encodes reward prediction. In vivo recordings of dopamine neurons showed that their spontaneous burst firing is abolished in GRID1 knockout mice or upon targeted expression of the dominant-negative GluD1 mutant in wild-type mice. Our results de-orphanize GluD1, unravel its key role in slow glutamatergic transmission and provide insights into how GRID1 gene alterations can lead to dopaminergic dysfunctions in schizophrenia.
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10
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Levy KA, Brodnik ZD, Shaw JK, Perrey DA, Zhang Y, España RA. Hypocretin receptor 1 blockade produces bimodal modulation of cocaine-associated mesolimbic dopamine signaling. Psychopharmacology (Berl) 2017; 234:2761-2776. [PMID: 28667509 PMCID: PMC5709206 DOI: 10.1007/s00213-017-4673-y] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Accepted: 06/06/2017] [Indexed: 02/07/2023]
Abstract
RATIONALE Cocaine addiction is a chronic psychiatric disorder characterized by pathological motivation to obtain cocaine and behavioral and neurochemical hypersensitivity to cocaine-associated cues. These features of cocaine addiction are thought to be driven by aberrant phasic dopamine signaling. We previously demonstrated that blockade of the hypocretin receptor 1 (HCRTr1) attenuates cocaine self-administration and reduces cocaine-induced enhancement of dopamine signaling. Despite this evidence, the effects of HCRTr1 blockade on endogenous phasic dopamine release are unknown. OBJECTIVE In the current studies, we assessed whether blockade of HCRTr1 alters spontaneous and cue-evoked dopamine release in the nucleus accumbens core of freely moving rats. METHODS We first validated the behavioral and neurochemical effects of the novel, highly selective, HCRTr1 antagonist RTIOX-276 using cocaine self-administration and fast-scan cyclic voltammetry (FSCV) in anesthetized rats. We then used FSCV in freely moving rats to examine whether RTIOX-276 impacts spontaneous and cue-evoked dopamine release. Finally, we used ex vivo slice FSCV to determine whether the effects of RTIOX-276 on dopamine signaling involve dopamine terminal adaptations. RESULTS Doses of RTIOX-276 that attenuate the motivation for cocaine reduce spontaneous dopamine transient amplitude and cue-evoked dopamine release. Further, these doses attenuated cocaine-induced dopamine uptake inhibition at the level of dopamine terminals. CONCLUSION Our results provide support for the standing hypothesis that HCRTr1 blockade suppresses endogenous phasic dopamine signals, likely via actions at dopamine cell bodies. These results also elucidate a second process through which HCRTr1 blockade attenuates the effects of cocaine by reducing cocaine sensitivity at dopamine terminals.
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Affiliation(s)
- KA Levy
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA 19129, U.S.A
| | - ZD Brodnik
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA 19129, U.S.A
| | - JK Shaw
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA 19129, U.S.A
| | - DA Perrey
- Research Triangle Institute, Research Triangle Park, North Carolina 27709, U.S.A
| | - Y Zhang
- Research Triangle Institute, Research Triangle Park, North Carolina 27709, U.S.A
| | - RA España
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA 19129, U.S.A
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11
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Bariselli S, Tzanoulinou S, Glangetas C, Prévost-Solié C, Pucci L, Viguié J, Bezzi P, O'Connor EC, Georges F, Lüscher C, Bellone C. SHANK3 controls maturation of social reward circuits in the VTA. Nat Neurosci 2016; 19:926-934. [PMID: 27273769 PMCID: PMC4948673 DOI: 10.1038/nn.4319] [Citation(s) in RCA: 119] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2016] [Accepted: 05/04/2016] [Indexed: 12/13/2022]
Abstract
Haploinsufficiency of SHANK3, encoding the synapse scaffolding protein SHANK3, leads to a highly penetrant form of Autism Spectrum Disorder (ASD). How SHANK3 insufficiency affects specific neural circuits and this is related to specific ASD symptoms remains elusive. Here we used shRNA to model Shank3 insufficiency in the Ventral Tegmental Area (VTA) of mice. We identified dopamine (DA) and GABA cell-type specific changes in excitatory synapse transmission that converge to reduce DA neuron activity and generate behavioral deficits, including impaired social preference. Administration of a positive allosteric modulator of the type 1 metabotropic glutamate receptors (mGluR1) during the first postnatal week restored DA neuron excitatory synapse transmission and rescued the social preference defects, while optogenetic DA neuron stimulation was sufficient to enhance social preference. Collectively, these data reveal the contribution of impaired VTA function to social behaviors and identify mGluR1 modulation during postnatal development as a potential treatment strategy.
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Affiliation(s)
- Sebastiano Bariselli
- Dept. of Fundamental Neurosciences, University of Lausanne, CH-1005, Lausanne, Switzerland
| | - Stamatina Tzanoulinou
- Dept. of Fundamental Neurosciences, University of Lausanne, CH-1005, Lausanne, Switzerland
| | - Christelle Glangetas
- Dept. of Fundamental Neurosciences, University of Lausanne, CH-1005, Lausanne, Switzerland.,Centre National de la Recherche Scientifique, Interdisciplinary Institute for Neuroscience, UMR 5297, Bordeaux, France.,Université de Bordeaux, Bordeaux, France
| | - Clément Prévost-Solié
- Dept. of Fundamental Neurosciences, University of Lausanne, CH-1005, Lausanne, Switzerland
| | - Luca Pucci
- Dept. of Fundamental Neurosciences, University of Lausanne, CH-1005, Lausanne, Switzerland
| | - Joanna Viguié
- Dept. of Basic Neurosciences, Medical Faculty, University of Geneva, CH-1211 Geneva, Switzerland
| | - Paola Bezzi
- Dept. of Fundamental Neurosciences, University of Lausanne, CH-1005, Lausanne, Switzerland
| | - Eoin C O'Connor
- Dept. of Basic Neurosciences, Medical Faculty, University of Geneva, CH-1211 Geneva, Switzerland
| | - François Georges
- Centre National de la Recherche Scientifique, Interdisciplinary Institute for Neuroscience, UMR 5297, Bordeaux, France.,Université de Bordeaux, Bordeaux, France.,Centre National de la Recherche Scientifique, Neurodegeneratives diseases Institute, UMR 5293, Bordeaux, France
| | - Christian Lüscher
- Dept. of Basic Neurosciences, Medical Faculty, University of Geneva, CH-1211 Geneva, Switzerland.,Clinic of Neurology, Geneva University Hospital, CH-1211 Geneva, Switzerland
| | - Camilla Bellone
- Dept. of Fundamental Neurosciences, University of Lausanne, CH-1005, Lausanne, Switzerland
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12
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Ghrelin and Neurodegenerative Disorders-a Review. Mol Neurobiol 2016; 54:1144-1155. [PMID: 26809582 DOI: 10.1007/s12035-016-9729-1] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2015] [Accepted: 01/14/2016] [Indexed: 12/13/2022]
Abstract
Ghrelin, the endogenous ligand of the growth hormone secretagogue receptor 1a (GHS-R1a), is a gut-derived, orexigenic peptide hormone that primarily regulates growth hormone secretion, food intake, and energy homeostasis. With the wide expression of GHS-R1a in extra-hypothalamic regions, the physiological role of ghrelin is more extensive than solely its involvement in metabolic function. Ghrelin has been shown to be involved in numerous higher brain functions, such as memory, reward, mood, and sleep. Some of these functions are disrupted in neurodegenerative disorders, including Parkinson's disease (PD), Alzheimer's disease (AD), and Huntington's disease (HD). This link between ghrelin and these neurodegenerative diseases is supported by numerous studies. This review aims to provide a comprehensive overview of the most recent evidence of the novel neuromodulatory role of ghrelin in PD, AD, and HD. Moreover, the changes in circulating and/or central ghrelin levels that are associated with disease progression are also postulated to be a biomarker for clinical diagnosis and therapy.
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13
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Neuregulin 1 signalling modulates mGluR1 function in mesencephalic dopaminergic neurons. Mol Psychiatry 2015; 20:959-73. [PMID: 25266126 DOI: 10.1038/mp.2014.109] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/13/2014] [Revised: 07/01/2014] [Accepted: 07/23/2014] [Indexed: 02/07/2023]
Abstract
Neuregulin 1 (NRG1) is a trophic factor that has an essential role in the nervous system by modulating neurodevelopment, neurotransmission and synaptic plasticity. Despite the evidence that NRG1 and its receptors, ErbB tyrosine kinases, are expressed in mesencephalic dopaminergic nuclei and their functional alterations are reported in schizophrenia and Parkinson's disease, the role of NRG1/ErbB signalling in dopaminergic neurons remains unclear. Here we found that NRG1 selectively increases the metabotropic glutamate receptor 1 (mGluR1)-activated currents by inducing synthesis and trafficking to membrane of functional receptors and stimulates phosphatidylinositol 3-kinase-Akt-mammalian target of rapamycin (PI3K-Akt-mTOR) pathway, which is required for mGluR1 function. Notably, an endogenous NRG1/ErbB tone is necessary to maintain mGluR1 function, by preserving its surface membrane expression in dopaminergic neurons. Consequently, it enables striatal mGluR1-induced dopamine outflow in in vivo conditions. Our results identify a novel role of NRG1 in the dopaminergic neurons, whose functional alteration might contribute to devastating diseases, such as schizophrenia and Parkinson's disease.
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Nesfatin-1 Decreases Excitability of Dopaminergic Neurons in the Substantia Nigra. J Mol Neurosci 2013; 52:419-24. [DOI: 10.1007/s12031-013-0169-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2013] [Accepted: 10/31/2013] [Indexed: 11/26/2022]
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15
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Peptide hormone ghrelin enhances neuronal excitability by inhibition of Kv7/KCNQ channels. Nat Commun 2013; 4:1435. [PMID: 23385580 DOI: 10.1038/ncomms2439] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2012] [Accepted: 01/03/2013] [Indexed: 12/11/2022] Open
Abstract
The gut-derived orexigenic peptide hormone ghrelin enhances neuronal firing in the substantia nigra pars compacta, where dopaminergic neurons modulate the function of the nigrostriatal system for motor coordination. Here we describe a novel mechanism by which ghrelin enhances firing of nigral dopaminergic neurons by inhibiting voltage-gated potassium Kv7/KCNQ/M-channels through its receptor GHS-R1a and activation of the PLC-PKC pathway. Brain slice recordings of substantia nigra pars compacta neurons reveal that ghrelin inhibits native Kv7/KCNQ/M-currents. This effect is abolished by selective inhibitors of GHS-R1a, PLC and PKC. Transgenic suppression of native Kv7/KCNQ/M-channels in mice or channel blockade with XE991 abolishes ghrelin-induced hyperexcitability. In vivo, intracerebroventricular ghrelin administration causes increased dopamine release and turnover in the striatum. Microinjection of ghrelin or XE991 into substantia nigra pars compacta results in contralateral dystonic posturing, and attenuation of catalepsy elicited by systemic administration of the D2 receptor antagonist haloperidol. Our findings indicate that the ghrelin/KCNQ signalling is likely a common pathway utilized by the nervous system.
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Metabotropic glutamate receptor 5 antagonist 2-methyl-6-(phenylethynyl)pyridine (MPEP) microinfusions into the nucleus accumbens shell or ventral tegmental area attenuate the reinforcing effects of nicotine in rats. Neuropharmacology 2011; 61:1399-405. [PMID: 21896278 DOI: 10.1016/j.neuropharm.2011.08.028] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2010] [Revised: 08/03/2011] [Accepted: 08/19/2011] [Indexed: 12/13/2022]
Abstract
Systemic administration of the mGlu5 receptor antagonist 2-methyl-6-(phenylethynyl)-pyridine (MPEP) was previously shown to selectively attenuate nicotine self-administration without affecting food-maintained responding in rats. Glutamatergic neurotransmission in the ventral tegmental area (VTA) and nucleus accumbens (NAcc) shell plays an important role in the reinforcing effects of nicotine. To determine the brain sites that may mediate the systemic effects of MPEP on nicotine self-administration, the present study investigated the effects of MPEP microinfusions into the VTA or the NAcc shell on nicotine and food self-administration in separate groups of rats. Administration of low MPEP doses (0, 0.5, 1, and 2 μg/0.5 μl/side) microinfused into the NAcc shell had no effect on nicotine self-administration, whereas higher MPEP doses (0, 10, 20, and 40 μg/0.5 μl/side) microinfused into the NAcc shell dose-dependently attenuated nicotine self-administration without affecting food-maintained responding. Microinfusions of MPEP into the VTA (0, 10, 20, and 40 μg/0.5 μl/side) significantly decreased both nicotine and food self-administration at 20 μg/0.5 μl/side but did not affect responding for either reinforcer at 40μg/0.5 μl/side. This lack of effect of 40 μg/0.5 μl/side MPEP on either nicotine or food self-administration when administered into the VTA may be attributable either to actions of MPEP at presynaptic mGlu5 receptors or at targets other than mGlu5 receptors. Importantly, anatomical control injections 2mm above the NAcc shell or the VTA using the most effective MPEP dose in the two regions did not result in attenuation of nicotine self-administration. In conclusion, MPEP microinfusions in the VTA or NAcc shell attenuates the reinforcing effects of nicotine possibly via blockade of mGlu5 receptors located in these regions.
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Mrejeru A, Wei A, Ramirez JM. Calcium-activated non-selective cation currents are involved in generation of tonic and bursting activity in dopamine neurons of the substantia nigra pars compacta. J Physiol 2011; 589:2497-514. [PMID: 21486760 DOI: 10.1113/jphysiol.2011.206631] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Nigral dopamine neurons are transiently activated by high frequency glutamatergic inputs relaying reward-predicting sensory information. The tonic firing pattern of dopamine cells responds to these inputs with a transient burst of spikes that requires NMDA receptors. Here, we show that NMDA receptor activation further excites the cell by recruiting a calcium-activated non-selective cation current (ICAN) capable of generating a plateau potential. Burst firing in vitro is eliminated after blockade of ICAN with flufenamic acid, 9-phenanthrol, or intracellular BAPTA. ICAN is likely to be mediated by a transient receptor potential (TRP) channel, and RT-PCR was used to confirm expression of TRPM2 and TRPM4mRNA in substantia nigra pars compacta.We propose that ICAN is selectively activated during burst firing to boost NMDA currents and allow plateau potentials. This boost mechanism may render DA cells vulnerable to excitotoxicity.
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Affiliation(s)
- Ana Mrejeru
- Committee on Neurobiology, University of Chicago, Chicago, IL 60637, USA
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18
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Olijslagers JE, Werkman TR, McCreary AC, Kruse CG, Wadman WJ. Modulation of midbrain dopamine neurotransmission by serotonin, a versatile interaction between neurotransmitters and significance for antipsychotic drug action. Curr Neuropharmacol 2010; 4:59-68. [PMID: 18615139 DOI: 10.2174/157015906775203020] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2005] [Revised: 08/23/2005] [Accepted: 09/17/2005] [Indexed: 11/22/2022] Open
Abstract
Schizophrenia has been associated with a dysfunction of brain dopamine (DA). This, so called, DA hypothesis has been refined as new insights into the pathophysiology of schizophrenia have emerged. Currently, dysfunction of prefrontocortical glutamatergic and GABAergic projections and dysfunction of serotonin (5-HT) systems are also thought to play a role in the pathophysiology of schizophrenia. Refinements of the DA hypothesis have lead to the emergence of new pharmacological targets for antipsychotic drug development. It was shown that effective antipsychotic drugs with a low liability for inducing extra-pyramidal side-effects have affinities for a range of neurotransmitter receptors in addition to DA receptors, suggesting that a combination of neurotransmitter receptor affinities may be favorable for treatment outcome.This review focuses on the interaction between DA and 5-HT, as most antipsychotics display affinity for 5-HT receptors. We will discuss DA/5-HT interactions at the level of receptors and G protein-coupled potassium channels and consequences for induction of depolarization blockade with specific attention to DA neurons in the ventral tegmental area (VTA) and the substantia nigra zona compacta (SN), neurons implicated in treatment efficacy and the side-effects of schizophrenia, respectively. Moreover, it has been reported that electrophysiological interactions between DA and 5-HT show subtle, but important, differences between the SN and the VTA which could explain (in part) the effectiveness and lower propensity to induce side-effects of the newer atypical antipsychotic drugs. In that respect the functional implications of DA/5-HT interactions for schizophrenia will be discussed.
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Affiliation(s)
- J E Olijslagers
- Center for NeuroScience-Swammerdam Institute for Life Sciences, University of Amsterdam, Kruislaan 320, 1098 SM Amsterdam, The Netherlands.
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19
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Lee CR, Tepper JM. Basal ganglia control of substantia nigra dopaminergic neurons. JOURNAL OF NEURAL TRANSMISSION. SUPPLEMENTUM 2010:71-90. [PMID: 20411769 DOI: 10.1007/978-3-211-92660-4_6] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/27/2023]
Abstract
Although substantia nigra dopaminergic neurons are spontaneously active both in vivo and in vitro, this activity does not depend on afferent input as these neurons express an endogenous calcium-dependent oscillatory mechanism sufficient to drive action potential generation. However, afferents to these neurons, a large proportion of them GABAergic and arising from other nuclei in the basal ganglia, play a crucial role in modulating the activity of dopaminergic neurons. In the absence of afferent activity or when in brain slices, dopaminergic neurons fire in a very regular, pacemaker-like mode. Phasic activity in GABAergic, glutamatergic, and cholinergic inputs modulates the pacemaker activity into two other modes. The most common is a random firing pattern in which interspike intervals assume a Poisson-like distribution, and a less common pattern, often in response to a conditioned stimulus or a reward in which the neurons fire bursts of 2-8 spikes time-locked to the stimulus. Typically in vivo, all three firing patterns are observed, intermixed, in single nigrostriatal neurons varying over time. Although the precise mechanism(s) underlying the burst are currently the focus of intensive study, it is obvious that bursting must be triggered by afferent inputs. Most of the afferents to substantia nigra pars compacta dopaminergic neurons comprise monosynaptic inputs from GABAergic projection neurons in the ipsilateral neostriatum, the globus pallidus, and the substantia nigra pars reticulata. A smaller fraction of the basal ganglia inputs, something less than 30%, are glutamatergic and arise principally from the ipsilateral subthalamic nucleus and pedunculopontine nucleus. The pedunculopontine nucleus also sends a cholinergic input to nigral dopaminergic neurons. The GABAergic pars reticulata projection neurons also receive inputs from all of these sources, in some cases relaying them disynaptically to the dopaminergic neurons, thereby playing a particularly significant role in setting and/or modulating the firing pattern of the nigrostriatal neurons.
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Affiliation(s)
- Christian R Lee
- Department of Neurosurgery, New York University School of Medicine, 4 New York, NY 10016, USA.
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20
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Johnson KA, Conn PJ, Niswender CM. Glutamate receptors as therapeutic targets for Parkinson's disease. CNS & NEUROLOGICAL DISORDERS DRUG TARGETS 2009; 8:475-91. [PMID: 19702565 DOI: 10.2174/187152709789824606] [Citation(s) in RCA: 177] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2009] [Accepted: 07/23/2009] [Indexed: 12/21/2022]
Abstract
Parkinson's disease (PD) is a neurodegenerative disorder characterized by motor symptoms including tremor and bradykinesia. The primary pathophysiology underlying PD is the degeneration of dopaminergic neurons of the substantia nigra pars compacta. Loss of these neurons causes pathological changes in neurotransmission in the basal ganglia motor circuit. The ability of ionotropic and metabotropic glutamate receptors to modulate neurotransmission throughout the basal ganglia suggests that these receptors may be targets for reversing the effects of altered neurotransmission in PD. Studies in animal models suggest that modulating the activity of these receptors may alleviate the primary motor symptoms of PD as well as side effects induced by dopamine replacement therapy. Moreover, glutamate receptor ligands may slow disease progression by delaying progressive dopamine neuron degeneration. Antagonists of NMDA receptors have shown promise in reversing motor symptoms, levodopa-induced dyskinesias, and neurodegeneration in preclinical PD models. The effects of drugs targeting AMPA receptors are more complex; while antagonists of these receptors exhibit utility in the treatment of levodopa-induced dyskinesias, AMPA receptor potentiators show promise for neuroprotection. Pharmacological modulation of metabotropic glutamate receptors (mGluRs) may hold even more promise for PD treatment due to the ability of mGluRs to fine-tune neurotransmission. Antagonists of mGluR5, as well as activators of group II mGluRs and mGluR4, have shown promise in several animal models of PD. These drugs reverse motor deficits in addition to providing protection against neurodegeneration. Glutamate receptors therefore represent exciting targets for the development of novel pharmacological therapies for PD.
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Affiliation(s)
- Kari A Johnson
- Department of Pharmacology, Vanderbilt University, Nashville, TN, USA
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Electrophysiological characteristics of dopamine neurons: a 35-year update. JOURNAL OF NEURAL TRANSMISSION. SUPPLEMENTUM 2009:103-19. [PMID: 20411771 DOI: 10.1007/978-3-211-92660-4_8] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
This chapter consists of four sections. The first section provides a general description of the electrophysiological characteristics of dopamine (DA) neurons in both the substantia nigra and ventral tegmental area. Emphasis is placed on the differences between DA and neighboring non-DA neurons. The second section discusses the ionic mechanisms underlying the generation of action potential in DA cells. Evidence is provided to suggest that these mechanisms differ not only between DA and non-DA neurons but also between DA cells located in different areas, with different projection sites and at different developmental stages. Some of the differences may play a critical role in the vulnerability of a DA neuron to cell death. The third section describes the firing patterns of DA cells. Data are presented to show that the current "80/160 ms" criteria for burst identification need to be revised and that the burst firing, originally described by Bunney et al., can be described as slow oscillations in firing rate. In the ventral tegmental area, the slow oscillations are, at least partially, derived from the prefrontal cortex and part of prefrontal information is transferred to DA cells indirectly through inhibitory neurons. The final section focuses on the feedback regulation of DA cells. New evidence suggests that DA autoreceptors are coupled to multiple effectors, and both D1 and D2-like receptors are involved in long-loop feedback control of DA neurons. Because of the presence of multiple feedback and nonfeedback pathways, the effect of a drug on a DA neuron can be far more complex than an inhibition or excitation. A better understanding of the intrinsic properties of DA neurons and their regulation by afferent input will, in time, help to point to the way to more effective and safer treatments for disorders including schizophrenia, drug addiction, and Parkinson's disease.
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22
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Shimo Y, Wichmann T. Neuronal activity in the subthalamic nucleus modulates the release of dopamine in the monkey striatum. Eur J Neurosci 2008; 29:104-13. [PMID: 19087163 DOI: 10.1111/j.1460-9568.2008.06565.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The primate subthalamic nucleus (STN) is commonly seen as a relay nucleus between the external and internal pallidal segments, and as an input station for cortical and thalamic information into the basal ganglia. In rodents, STN activity is also known to influence neuronal activity in the dopaminergic substantia nigra pars compacta (SNc) through inhibitory and excitatory mono- and polysynaptic pathways. Although the anatomical connections between STN and SNc are not entirely the same in primates as in rodents, the electrophysiologic and microdialysis experiments presented here show directly that this functional interaction can also be demonstrated in primates. In three Rhesus monkeys, extracellular recordings from SNc during microinjections into the STN revealed that transient pharmacologic activation of the STN by the acetylcholine receptor agonist carbachol substantially increased burst firing of single nigral neurons. Transient inactivation of the STN with microinjections of the GABA-A receptor agonist muscimol had the opposite effect. While the firing rates of individual SNc neurons changed in response to the activation or inactivation of the STN, these changes were not consistent across the entire population of SNc cells. Permanent lesions of the STN, produced in two animals with the fiber-sparing neurotoxin ibotenic acid, reduced burst firing and firing rates of SNc neurons, and substantially decreased dopamine levels in the primary recipient area of SNc projections, the striatum, as measured with microdialysis. These results suggest that activity in the primate SNc is prominently influenced by neuronal discharge in the STN, which may thus alter dopamine release in the striatum.
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Affiliation(s)
- Yasushi Shimo
- Department of Neurology, School of Medicine, Emory University, Atlanta, GA, USA
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Blythe SN, Atherton JF, Bevan MD. Synaptic activation of dendritic AMPA and NMDA receptors generates transient high-frequency firing in substantia nigra dopamine neurons in vitro. J Neurophysiol 2007; 97:2837-50. [PMID: 17251363 DOI: 10.1152/jn.01157.2006] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Transient high-frequency activity of substantia nigra dopamine neurons is critical for striatal synaptic plasticity and associative learning. However, the mechanisms underlying this mode of activity are poorly understood because, in contrast to other rapidly firing neurons, high-frequency activity is not evoked by somatic current injection. Previous studies have suggested that activation of dendritic N-methyl-d-aspartate (NMDA) receptors and/or G-protein-coupled receptor (GPCR)-mediated reduction of action potential afterhyperpolarization and/or activation of cation channels underlie high-frequency activity. To address their relative contribution, transient high-frequency activity was evoked using local electrical stimulation (1 s, 10-100 Hz) in brain slices prepared from p15-p25 rats in the presence of GABA and D2 dopamine receptor antagonists. The frequency, pattern, and morphology of action potentials evoked under these conditions were similar to those observed in vivo. Evoked activity and reductions in action potential afterhyperpolarization were diminished greatly by application of alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) or NMDA receptor selective antagonists and abolished completely by co-application of AMPA and NMDA antagonists. In contrast, application of glutamatergic and cholinergic GPCR antagonists moderately enhanced evoked activity. Dendritic pressure-pulse application of glutamate evoked high-frequency activity that was similarly sensitive to antagonism of AMPA or NMDA receptors. Taken together, these data suggest that dendritic AMPA and NMDA receptor-mediated synaptic conductances are sufficient to generate transient high-frequency activity in substantia nigra dopamine neurons by rapidly but transiently overwhelming the conductances underlying action potential afterhyperpolarization and/or engaging postsynaptic voltage-dependent ion channels in a manner that overcomes the limiting effects of afterhyperpolarization.
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Affiliation(s)
- Sarah N Blythe
- Dept. of Physiology, Feinberg School of Medicine, Northwestern University, 303 E. Chicago Ave., Chicago IL 60611, USA
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Jeong HS, Jang S, Jang MJ, Lee SG, Kim TS, Lee JH, Jun JY, Park JS. Effects of (--)-epigallocatechin-3-gallate on the activity of substantia nigra dopaminergic neurons. Brain Res 2007; 1130:114-8. [PMID: 17174286 DOI: 10.1016/j.brainres.2006.10.078] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2006] [Revised: 09/01/2006] [Accepted: 10/20/2006] [Indexed: 12/01/2022]
Abstract
Despite many studies on the biological and pharmacological properties of (-)-epigallocatechin-3-gallate (EGCG), an active component of green tea, information on neuronal modulation by EGCG is limited. This study was designed to investigate the effects of EGCG on the electrical activity of rat substantia nigra dopaminergic neurons using whole-cell patch clamp recordings. The spike frequency was increased to 6.33+/-0.23 (p<0.05) and 7.15+/-0.29 (p<0.05) by 5 and 10 microM EGCG, respectively, from the control level of 5.49+/-0.19 spikes/second, respectively (n=18). The resting membrane potential of the cells was decreased to -45.66+/-0.45 and -43.99+/-0.87 (p<0.05), by 5 and 10 microM EGCG, respectively, from -47.82+/-0.57 mV. The amplitude of afterhyperpolarization was decreased to 12.73+/-0.45 (p<0.05) and 11.60+/-0.57 (p<0.05) by 5 and 10 microM EGCG, respectively, from 13.80+/-0.31 mV. The neuronal activity of dopaminergic neurons is closely linked to dopamine release. When neurons switch from a single-spike firing to bursts of action potentials, the release of dopamine increases. The above experimental results suggest that EGCG increases the neuronal activity via inhibition of calcium-dependent potassium currents underlying the afterhyperpolarization, and it could act as a facilitating factor that elicits NMDA-dependent bursts of action potentials like apamin or bicuculline methiodide.
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Affiliation(s)
- Han-Seong Jeong
- Department of Physiology, Chonnam National University Medical School, Gwangju 501-190, Korea
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25
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Choi YM, Kim SH, Chung S, Uhm DY, Park MK. Regional interaction of endoplasmic reticulum Ca2+ signals between soma and dendrites through rapid luminal Ca2+ diffusion. J Neurosci 2006; 26:12127-36. [PMID: 17122037 PMCID: PMC6675421 DOI: 10.1523/jneurosci.3158-06.2006] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
The endoplasmic reticulum (ER) Ca2+ store plays a key role in integration and conveyance of Ca2+ signals in highly polarized neurons. The interconnected ER network in neurons generates Ca2+ signals in local domains, but the regional interaction is unclear. Here, we show that continuous or repetitive applications of caffeine produced robust Ca2+ release from the ER Ca2+ store in dendritic areas without severe store depletion, but that similar stimuli applied to soma caused rapid store depletion in acutely isolated midbrain dopamine neurons. Partial emptying of the ER Ca2+ store within a dendrite caused a similar level of store depletion in unstimulated dendrites, as well as in soma. Photobleaching and local stimulation experiments revealed that Ca2+ and the dye trapped within the ER diffused rapidly from the soma to dendrites up to 90 microm, which we could resolve, suggesting that the ER network acts as a functional tunnel for rapid Ca2+ transport. These data imply that the ER in soma acts as a Ca2+ reservoir supplying Ca2+ to the dendritic store, and that the dendritic store, hence, is able to respond to Ca2+-mobilizing input signals endurably.
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Affiliation(s)
- Yu Mi Choi
- Department of Physiology, Sungkyunkwan University School of Medicine and Center For Molecular Medicine, Samsung Biomedical Research Institute, 300 Chunchun-dong, Jangan-ku, Suwon, 440-746, Korea
| | - Shin Hye Kim
- Department of Physiology, Sungkyunkwan University School of Medicine and Center For Molecular Medicine, Samsung Biomedical Research Institute, 300 Chunchun-dong, Jangan-ku, Suwon, 440-746, Korea
| | - Sungkwon Chung
- Department of Physiology, Sungkyunkwan University School of Medicine and Center For Molecular Medicine, Samsung Biomedical Research Institute, 300 Chunchun-dong, Jangan-ku, Suwon, 440-746, Korea
| | - Dae Yong Uhm
- Department of Physiology, Sungkyunkwan University School of Medicine and Center For Molecular Medicine, Samsung Biomedical Research Institute, 300 Chunchun-dong, Jangan-ku, Suwon, 440-746, Korea
| | - Myoung Kyu Park
- Department of Physiology, Sungkyunkwan University School of Medicine and Center For Molecular Medicine, Samsung Biomedical Research Institute, 300 Chunchun-dong, Jangan-ku, Suwon, 440-746, Korea
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Renoldi G, Calcagno E, Borsini F, Invernizzi RW. Stimulation of group I mGlu receptors in the ventrotegmental area enhances extracellular dopamine in the rat medial prefrontal cortex. J Neurochem 2006; 100:1658-66. [PMID: 17176263 DOI: 10.1111/j.1471-4159.2006.04317.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Group I mGlu receptors have been implicated in the control of brain dopamine release. However, the receptor subtype involved and the precise site of action have not been determined. In this study we show that (R,S)3,5-dihydroxyphenylglycine (DHPG; 6 and 60 nmol ICV), a selective group I mGlu receptor agonist, raised extracellular dopamine respectively by 176% and 243% of basal values in the medial prefrontal cortex as assessed by in vivo microdialysis in conscious rats. (R,S)2-chloro-5-hydroxyphenylglycine (60 nmol ICV), a selective mGlu5 receptor agonist, raised extracellular dopamine by 396% of basal values. Intra-VTA DHPG (0.6-6 nmol) mimicked ICV injection whereas intracortical infusion (1-1000 micromol/L) had no effect. DHPG-induced rise of extracellular dopamine was reversed by tetrodotoxin and by the selective mGlu1 and mGlu5 receptor antagonists 7(hydroxyimino)cyclopropa[b]chromen-1a-carboxylate (CPCCOEt) and 2-methyl-6-(phenylethynyl)pyridine (MPEP) either ICV or into the ventrotegmental area (VTA), suggesting that neuronal release and both mGlu1 and mGlu5 receptors were involved. These results support the existence of functional mGlu1 and mGlu5 receptors in the VTA regulating the release of dopamine in the medial prefrontal cortex.
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Affiliation(s)
- G Renoldi
- Istituto di Ricerche Farmacologiche "Mario Negri", Milan, Italy
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Canavier CC, Landry RS. An increase in AMPA and a decrease in SK conductance increase burst firing by different mechanisms in a model of a dopamine neuron in vivo. J Neurophysiol 2006; 96:2549-63. [PMID: 16885519 PMCID: PMC2531289 DOI: 10.1152/jn.00704.2006] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
A stylized, symmetric, compartmental model of a dopamine neuron in vivo shows how rate and pattern can be modulated either concurrently or differentially. If two or more parameters in the model are varied concurrently, the baseline firing rate and the extent of bursting become de-correlated, which provides an explanation for the lack of a tight correlation in vivo and is consistent with some independence of the mechanisms that generate baseline firing rates versus bursts. We hypothesize that most bursts are triggered by a barrage of synaptic input and that particularly meaningful stimuli recruit larger numbers of synapses in a more synchronous way. An example of concurrent modulation is that increasing the short-lived AMPA current evokes additional spikes without regard to pattern, producing comparable increases in spike frequency and fraction fired in bursts. On the other hand, blocking the SK current evokes additional bursts by allowing a depolarization that previously produced only a single spike to elicit two or more and elongates existing bursts by the same principle, resulting in a greater effect on pattern than rate. A probabilistic algorithm for the random insertion of spikes into the firing pattern produces a good approximation to the pattern changes induced by increasing the AMPA conductance, but not by blocking the SK current, consistent with a differential modulation in the latter case. Furthermore, blocking SK produced a longer burst with a greater intra-burst frequency in response to a simulated meaningful input, suggesting that reduction of this current may augment reward-related responses.
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Affiliation(s)
- C C Canavier
- Neuroscience Center of Excellence, LSU Health Sciences Center, 2020 Gravier St., Suite D, New Orleans, LA 70112, USA.
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28
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Sekizawa SI, Bonham AC. Group I Metabotropic Glutamate Receptors on Second-Order Baroreceptor Neurons Are Tonically Activated and Induce a Na+–Ca2+Exchange Current. J Neurophysiol 2006; 95:882-92. [PMID: 16192328 DOI: 10.1152/jn.00772.2005] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
The nucleus tractus solitarius (NTS) is essential for coordinating baroreflex control of blood pressure. The baroreceptor sensory fibers make glutamatergic synapses onto second-order NTS neurons. Glutamate spillover activates Group II and III presynaptic metabotropic glutamate receptors (mGluRs) on the baroreceptor central terminals to inhibit synaptic transmission, but the role of postsynaptic mGluRs is less understood. We used whole cell patch-clamping in anatomically identified second-order baroreceptor neurons in a brain stem slice to test whether Group I, II, and III mGluRs had postsynaptic effects at this first central synapse in the baroreceptor afferent pathway. The Group I agonist DHPG induced a depolarization and spiking that was mimicked by endogenous glutamate. Group I mGluR blockade prevented the depolarization and slightly hyperpolarized the neurons, suggesting a small tonic Group I mGluR activation. The DHPG-induced inward current consisted of voltage-dependent and -independent components; the former was blocked by TEA and the latter was blocked by replacing extracellular NaCl with LiCl or Tris-HCl. The DHPG current was potentiated in a Ca2+-free external solution and was diminished by intracellular dialysis with BAPTA and by perfusion with Na+–Ca2+exchanger blockers, KB-R7943 or 3′,4′-dichlorobenzamil. Intracellular dialysis with GDPβS or heparin and perfusion with the PLC inhibitor U-73122 or the Ca2+-calmodulin inhibitor W-7 significantly decreased the DHPG current. The data suggest that Group I mGluRs on baroreceptor neurons are functional; are activated by endogenous glutamate; and activate a Na+–Ca2+exchanger through G-protein, PLC, IP3, and Ca2+-calmodulin mechanisms to excite the cell, thus providing postsynaptic mechanisms to enhance or prolong baroreceptor signal transmission.
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Affiliation(s)
- Shin-ichi Sekizawa
- Department of Pharmacology, School of Medicine, University of California, Davis, CA 95817, USA
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Marinelli S, Pascucci T, Bernardi G, Puglisi-Allegra S, Mercuri NB. Activation of TRPV1 in the VTA excites dopaminergic neurons and increases chemical- and noxious-induced dopamine release in the nucleus accumbens. Neuropsychopharmacology 2005; 30:864-70. [PMID: 15562294 DOI: 10.1038/sj.npp.1300615] [Citation(s) in RCA: 102] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Dopamine (DA)-containing neurons of the ventral tegmental area (VTA) provide dopaminergic input to the nucleus accumbens and to the prefrontal cortex within the mesolimbic pathway. In the present study, we combined electrophysiological recordings and microdialysis techniques to investigate the function of transient receptor potential vanilloid 1 (TRPV1) channel in the VTA. In brain slices, application of the TRPV1 receptor agonist capsaicin increased the firing rate of rat dopamine neurons and in a proportion of tested cells (44%) it also induced a bursting behavior. The effects of capsaicin were concentration dependent. The increase in neuronal firing was dependent on enhanced glutamatergic transmission since it was blocked by the superfusion of the ionotropic glutamate antagonists, CNQX and AP5. Interestingly, microinjection of capsaicin into the VTA and noxious tail stimulation transiently enhanced dopamine release into the nucleus accumbens. Both the in vitro and in vivo effects were mediated by TRPV1 activation in the VTA since they were reduced by co-perfusion of the selective TRPV1 receptor antagonist iodoresineferatoxin. Our data suggest a novel role for TRPV1 channels in the mesencephalon of rat, namely activation of the DA system following a peripheral noxious stimulation.
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Affiliation(s)
- Silvia Marinelli
- Laboratorio di Neurologia Sperimentale, IRCCS Fondazione Santa Lucia, Italy.
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Melis M, Spiga S, Diana M. The dopamine hypothesis of drug addiction: hypodopaminergic state. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2005; 63:101-54. [PMID: 15797467 DOI: 10.1016/s0074-7742(05)63005-x] [Citation(s) in RCA: 182] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Affiliation(s)
- Miriam Melis
- B.B. Brodie Department of Neuroscience, University of Cagliari, 09042 Monserrato, Italy
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31
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Lee B, Platt DM, Rowlett JK, Adewale AS, Spealman RD. Attenuation of behavioral effects of cocaine by the Metabotropic Glutamate Receptor 5 Antagonist 2-Methyl-6-(phenylethynyl)-pyridine in squirrel monkeys: comparison with dizocilpine. J Pharmacol Exp Ther 2004; 312:1232-40. [PMID: 15550570 DOI: 10.1124/jpet.104.078733] [Citation(s) in RCA: 111] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Growing evidence suggests a role for metabotropic glutamate receptors (mGluRs) in the behavioral effects of cocaine related to its abuse. The mGluR5 subtype, in particular, has come under scrutiny due to its distribution in brain regions associated with drug addiction. This study investigated interactions between the selective mGluR5 antagonist 2-methyl-6-(phenylethynyl)-pyridine (MPEP) and cocaine in squirrel monkeys whose lever-pressing behavior was 1) maintained under a second-order schedule of cocaine self-administration, 2) extinguished and then reinstated by cocaine priming, and 3) controlled by the discriminative stimulus (DS) effects of cocaine. Additional studies determined the effects of MPEP on unconditioned behaviors, coordination, and muscle resistance. In each experiment, the effects of MPEP were compared with those of the N-methyl-d-aspartate antagonist dizocilpine. MPEP attenuated cocaine self-administration, cocaine-induced reinstatement of drug seeking, and the DS effects of cocaine at doses that did not markedly impair motor function or operant behavior in the context of drug discrimination. Dizocilpine also attenuated cocaine self-administration, but it did not significantly alter cocaine-induced reinstatement of drug seeking, and it enhanced rather than attenuated the DS effects of cocaine. The findings point to a significant contribution of mGluR5 mechanisms in the behavioral effects of cocaine related to its abuse and suggest that MPEP has properties of a functional cocaine antagonist, which are not secondary to antagonism at NMDA receptors. The contrasting interactions of MPEP and dizocilpine with cocaine imply that glutamate acting through different metabotropic and ionotropic receptors may modulate the behavioral effects of cocaine in qualitatively different ways.
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Affiliation(s)
- Buyean Lee
- Harvard Medical School, New England Primate Research Center, P.O. Box 9102, Southborough, MA 01772-9102, USA
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Caputi L, Bengtson CP, Guatteo E, Bernardi G, Mercuri NB. D-tubocurarine reduces GABA responses in rat substantia nigra dopamine neurons. Synapse 2003; 47:236-9. [PMID: 12494406 DOI: 10.1002/syn.10164] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Luigi Caputi
- IRCCS - Fondazione Santa Lucia, Via Ardeatina 306, 00179, Rome, Italy
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Katayama J, Akaike N, Nabekura J. Characterization of pre- and post-synaptic metabotropic glutamate receptor-mediated inhibitory responses in substantia nigra dopamine neurons. Neurosci Res 2003; 45:101-15. [PMID: 12507729 DOI: 10.1016/s0168-0102(02)00202-x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Two inhibitory responses mediated by both pre- and post-synaptic metabotropic glutamate receptors (mGluRs) were investigated in dopamine neurons of the substantia nigra using whole-cell patch recordings. (2R,4R)-APDC, a group II mGluR agonist, and L-2-amino-4-phosphonobutyrate (L-AP4), a group III mGluR agonist, reversibly suppressed the amplitude of excitatory postsynaptic currents (EPSCs). However, (S)-3,5-DHPG, a group I mGluR agonist, exhibited less inhibitory action on the EPSCs. LY341495, a highly potent group II mGluR antagonist, antagonized the broad spectrum mGluR agonist, 1S,3R-ACPD-induced suppression of EPSCs. In acutely dissociated dopamine neurons, glutamate (Glu) in the presence of CNQX and AP-5 evoked an outward current accompanied by an increase in K(+) conductance. (S)-3,5-DHPG, but not (2R,4R)-APDC or L-AP4, also induced an outward current. Glu-induced outward current (I(Glu-out)) was partially inhibited by LY367385, a selective mGluR1 antagonist, but not by MPEP, a selective mGluR5 antagonist. Ryanodine and cyclopiazonic acid blocked the I(Glu-out). In the presence of caffeine, Glu failed to induce a current. Charybdotoxin, but not apamin or iberiotoxin, inhibited the I(Glu-out). Taken together, both group II and III mGluRs are mainly involved in the presynaptic inhibition of Glu release to dopamine neurons, while group I mGluRs, including at least mGluR1, participate in the hyperpolarization of dopamine neurons mediated by the opening of charybdotoxin-sensitive Ca(2+)-activated K(+) channels.
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Affiliation(s)
- Jiro Katayama
- Cellular and System Physiology, Graduate School of Medical Science, Kyushu University, 3-1-1 Maidashi Higashi-ku, Fukuoka 812-8582, Japan
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