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Diamandakis D, Zieminska E, Siwiec M, Tokarski K, Salinska E, Lenart J, Hess G, Lazarewicz JW. Tetrabromobisphenol A-induced depolarization of rat cerebellar granule cells: ex vivo and in vitro studies. CHEMOSPHERE 2019; 223:64-73. [PMID: 30769291 DOI: 10.1016/j.chemosphere.2019.02.032] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2018] [Revised: 02/05/2019] [Accepted: 02/07/2019] [Indexed: 06/09/2023]
Abstract
The brominated flame retardant tetrabromobisphenol A (TBBPA) is toxic to cultured brain neurons, and glutamate receptors partially mediate this effect; consequently, the depolarizing effect of TBBPA on neurons is to be expected, but it is yet to be actually demonstrated. The aim of this study was to detect TBBPA-evoked depolarization and identify the underlying mechanisms. The plasma membrane potential of rat cerebellar granule cells (CGC) in cerebellar slices or in primary cultures was measured using whole-cell current clamp recordings, or the fluorescent probe oxonol VI, respectively. The contribution of NMDA and AMPA receptors, voltage-gated sodium channels and intracellular calcium mobilization was tested using their selective antagonists or inhibitors. Direct interactions of TBBPA with NMDARs were tested by measuring the specific binding of radiolabeled NMDAR ligands to isolated rat cortical membrane fraction. TBBPA (25 μM) strongly depolarized CGC in cerebellar slices, and at ≥ 7.5 μM concentration-dependently depolarized primary CGC cultures. Depolarization of the primary CGC by 25 μM TBBPA was partly reduced when MK-801 was applied alone or in combination with either TTX or CNQX, or where bastadin 12 was applied in combination with ryanodine, whereas depolarization was completely prevented when MK-801, CNQX and TTX where combined. TBBPA had no effect on the specific binding of NMDAR radio-ligands to isolated cortical membranes. These results demonstrate the depolarizing effect of TBBPA on CGC, which is mainly mediated by ionotropic glutamate receptors, while voltage-gated sodium channels are also involved. We found no evidence for the direct activation of NMDARs by TBBPA.
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Affiliation(s)
- Dominik Diamandakis
- Department of Neurochemistry, Mossakowski Medical Research Centre, Polish Academy of Sciences, Pawinskiego 5, 02-106, Warsaw, Poland.
| | - Elzbieta Zieminska
- Department of Neurochemistry, Mossakowski Medical Research Centre, Polish Academy of Sciences, Pawinskiego 5, 02-106, Warsaw, Poland.
| | - Marcin Siwiec
- Department of Physiology, Institute of Pharmacology, Polish Academy of Sciences, Smetna 12, 31-343, Krakow, Poland.
| | - Krzysztof Tokarski
- Department of Physiology, Institute of Pharmacology, Polish Academy of Sciences, Smetna 12, 31-343, Krakow, Poland.
| | - Elzbieta Salinska
- Department of Neurochemistry, Mossakowski Medical Research Centre, Polish Academy of Sciences, Pawinskiego 5, 02-106, Warsaw, Poland.
| | - Jacek Lenart
- Department of Neurochemistry, Mossakowski Medical Research Centre, Polish Academy of Sciences, Pawinskiego 5, 02-106, Warsaw, Poland.
| | - Grzegorz Hess
- Department of Physiology, Institute of Pharmacology, Polish Academy of Sciences, Smetna 12, 31-343, Krakow, Poland.
| | - Jerzy W Lazarewicz
- Department of Neurochemistry, Mossakowski Medical Research Centre, Polish Academy of Sciences, Pawinskiego 5, 02-106, Warsaw, Poland.
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5-HT 1B receptor agonist CGS12066 presynaptically inhibits glutamate release in rat hippocampus. Prog Neuropsychopharmacol Biol Psychiatry 2018; 86:122-130. [PMID: 29803926 DOI: 10.1016/j.pnpbp.2018.05.019] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/16/2018] [Revised: 05/22/2018] [Accepted: 05/23/2018] [Indexed: 11/20/2022]
Abstract
CGS12066, a 5-hydroxytryptamine 1B (5-HT1B) receptor agonist, has been reported to exhibit antidepressant activity. Considering that glutamatergic dysfunction is implicated in depression, the effect of CGS12066 on glutamate release in rat hippocampal nerve terminals and possible underlying mechanism were investigated. We observed that CGS12066 inhibited 4-aminopyridine (4-AP)-evoked glutamate release, and that a 5-HT1B receptor antagonist blocked this inhibition. Western blot analysis and immunocytochemistry confirmed the presence of presynaptic 5-HT1B receptor proteins. CGS12066-mediated inhibition of 4-AP-evoked glutamate release was completely abolished in the synaptosomes pretreated with inhibitors of Gi/Go-protein, adenylate cyclase (AC), and protein kinase A (PKA), namely pertussis toxin, MDL12330A, and H89, respectively. CGS12066 reduced the elevation of 4-AP-evoked intrasynaptosomal Ca2+ and cyclic AMP (cAMP) levels, but did not affect the synaptosomal membrane potential. Furthermore, in the presence of ω-conotoxin MVIIC, a N- and P/Q-type channel blocker, CGS12066-mediated inhibition of 4-AP-evoked glutamate release was markedly reduced; however, the intracellular Ca2+-release inhibitors dantrolene and CGP37157 did not affect the CGS12066 effect. Furthermore, CGS12066 reduced glutamatergic miniature excitatory postsynaptic current (mEPSC) frequency but did not affect mEPSC amplitude or glutamate-activated currents in hippocampal slices. Our data are the first to suggest that CGS12066 reduces AC/cAMP/PKA activation, through the activation of Gi/Go protein-coupled 5-HT1B receptors present on hippocampal nerve terminals, subsequently reducing Ca2+ entry through voltage-dependent Ca2+ channels and reducing 4-AP-evoked glutamate release. This investigation into the role of 5-HT1B receptors in glutamate release provides crucial information regarding the potential therapeutic role of 5-HT1B receptors for treating depression.
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3
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Lu CW, Hung CF, Jean WH, Lin TY, Huang SK, Wang SJ. Lycopene depresses glutamate release through inhibition of voltage-dependent Ca 2+ entry and protein kinase C in rat cerebrocortical nerve terminals. Can J Physiol Pharmacol 2017; 96:479-484. [PMID: 29216442 DOI: 10.1139/cjpp-2017-0520] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Lycopene is a natural dietary carotenoid that was reported to exhibit a neuroprotective profile. Considering that excitotoxicity and cell death induced by glutamate are involved in many brain disorders, the effect of lycopene on glutamate release in rat cerebrocortical nerve terminals and the possible mechanism involved in such effect was investigated. We observed here that lycopene inhibited 4-aminopyridine (4-AP)-evoked glutamate release and intrasynaptosomal Ca2+ concentration elevation. The inhibitory effect of lycopene on 4-AP-evoked glutamate release was markedly reduced in the presence of the Cav2.2 (N-type) and Cav2.1 (P/Q-type) channel blocker ω-conotoxin MVIIC, but was insensitive to the intracellular Ca2+-release inhibitors dantrolene and CGP37157. Furthermore, in the presence of the protein kinase C inhibitors GF109203X and Go6976, the action of lycopene on evoked glutamate release was prevented. These results are the first to suggest that lycopene inhibits glutamate release from rat cortical synaptosomes by suppressing presynaptic Ca2+ entry and protein kinase C activity.
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Affiliation(s)
- Cheng-Wei Lu
- a Department of Anesthesiology, Far-Eastern Memorial Hospital, New Taipei City 220, Taiwan.,b Department of Mechanical Engineering, Yuan Ze University, Taoyuan City 320, Taiwan
| | - Chi-Feng Hung
- c School of Medicine, Fu Jen Catholic University, New Taipei City 24205, Taiwan.,d Department of Fragrance and Cosmetic Science, Kaohsiung Medical University, Kaohsiung, 80708, Taiwan
| | - Wei-Horng Jean
- a Department of Anesthesiology, Far-Eastern Memorial Hospital, New Taipei City 220, Taiwan
| | - Tzu-Yu Lin
- a Department of Anesthesiology, Far-Eastern Memorial Hospital, New Taipei City 220, Taiwan.,b Department of Mechanical Engineering, Yuan Ze University, Taoyuan City 320, Taiwan
| | - Shu-Kuei Huang
- a Department of Anesthesiology, Far-Eastern Memorial Hospital, New Taipei City 220, Taiwan
| | - Su-Jane Wang
- c School of Medicine, Fu Jen Catholic University, New Taipei City 24205, Taiwan.,e Research Center for Chinese Herbal Medicine, College of Human Ecology, Chang Gung University of Science and Technology, Taoyuan City 33303, Taiwan
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Lu CW, Lin TY, Huang SK, Wang SJ. Echinacoside Inhibits Glutamate Release by Suppressing Voltage-Dependent Ca(2+) Entry and Protein Kinase C in Rat Cerebrocortical Nerve Terminals. Int J Mol Sci 2016; 17:ijms17071006. [PMID: 27347934 PMCID: PMC4964382 DOI: 10.3390/ijms17071006] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2016] [Revised: 06/16/2016] [Accepted: 06/20/2016] [Indexed: 02/07/2023] Open
Abstract
The glutamatergic system may be involved in the effects of neuroprotectant therapies. Echinacoside, a phenylethanoid glycoside extracted from the medicinal Chinese herb HerbaCistanche, has neuroprotective effects. This study investigated the effects of echinacoside on 4-aminopyridine-evoked glutamate release in rat cerebrocortical nerve terminals (synaptosomes). Echinacoside inhibited Ca2+-dependent, but not Ca2+-independent, 4-aminopyridine-evoked glutamate release in a concentration-dependent manner. Echinacoside also reduced the 4-aminopyridine-evoked increase in cytoplasmic free Ca2+ concentration but did not alter the synaptosomal membrane potential. The inhibitory effect of echinacoside on 4-aminopyridine-evoked glutamate release was prevented by ω-conotoxin MVIIC, a wide-spectrum blocker of Cav2.2 (N-type) and Cav2.1 (P/Q-type) channels, but was insensitive to the intracellular Ca2+ release-inhibitors dantrolene and 7-chloro-5-(2-chloropheny)-1,5-dihydro-4,1-benzothiazepin-2(3H)-one (CGP37157). Furthermore, echinacoside decreased the 4-aminopyridine-induced phosphorylation of protein kinase C, and protein kinase C inhibitors abolished the effect of echinacoside on glutamate release. According to these results, we suggest that the inhibitory effect of echinacoside on evoked glutamate release is associated with reduced voltage-dependent Ca2+ entry and subsequent suppression of protein kinase C activity.
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Affiliation(s)
- Cheng Wei Lu
- Department of Anesthesiology, Far-Eastern Memorial Hospital, Pan-Chiao District, New Taipei City 22060, Taiwan.
- Department of Mechanical Engineering, Yuan Ze University, Taoyuan 32003, Taiwan.
| | - Tzu Yu Lin
- Department of Anesthesiology, Far-Eastern Memorial Hospital, Pan-Chiao District, New Taipei City 22060, Taiwan.
- Department of Mechanical Engineering, Yuan Ze University, Taoyuan 32003, Taiwan.
| | - Shu Kuei Huang
- Department of Anesthesiology, Far-Eastern Memorial Hospital, Pan-Chiao District, New Taipei City 22060, Taiwan.
| | - Su Jane Wang
- School of Medicine, Fu Jen Catholic University, No. 510, Zhongzheng Rd., Xinzhuang Dist., New Taipei 24205, Taiwan.
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Lan YL, Zhao J, Li S. Estrogen receptors' neuroprotective effect against glutamate-induced neurotoxicity. Neurol Sci 2014; 35:1657-62. [PMID: 25228013 DOI: 10.1007/s10072-014-1937-8] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2014] [Accepted: 08/29/2014] [Indexed: 01/28/2023]
Abstract
Glutamate is the most abundant excitatory brain neurotransmitter that has important functional significance with respect to neurodegenerative conditions. Glutamate-mediated excitotoxicity and neurodegeneration in Alzheimer's disease (AD) has been gradually becoming elucidated recently. Excessive release of glutamate induces an increase in intracellular Ca(2+) levels, thus triggers a cascade of cellular responses, ultimately leading to neuronal cell death. This type of neuronal damage induced by over-excitation has been proposed to be involved in a number of neuropathological conditions, ranging from acute insults to chronic neurodegenerative disorders. Estrogen could be effective in modulating glutamate-induced neurotoxicity and the protective responsivenesses are mostly estrogen receptors (ERs)-dependent. However, the mechanism underlying estrogen's neuroprotective effect is not fully clarified and is complicated by the presence of several distinct ER types. So a deeper research into the neuroprotection of ERs might be informative about the positive effect that estrogen might have on ageing-related cognitive changes. Extensive studies have indicated the neuroprotective effects of ERs against glutamate-induced neurotoxicity. The purpose of this review is to elucidate ERs' neuroprotective effects against glutamate-induced cytotoxicity and explore new ways to prevent and cure neurotoxicity-associated neurodegenerative disorders.
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Affiliation(s)
- Yu-Long Lan
- Department of Physiology, Dalian Medical University, Dalian, 116044, China
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Lin TY, Lu CW, Wang CC, Huang SK, Wang SJ. Cyclooxygenase 2 inhibitor celecoxib inhibits glutamate release by attenuating the PGE2/EP2 pathway in rat cerebral cortex endings. J Pharmacol Exp Ther 2014; 351:134-45. [PMID: 25047516 DOI: 10.1124/jpet.114.217372] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The excitotoxicity caused by excessive glutamate is a critical element in the neuropathology of acute and chronic brain disorders. Therefore, inhibition of glutamate release is a potentially valuable therapeutic strategy for treating these diseases. In this study, we investigated the effect of celecoxib, a selective cyclooxygenase-2 (COX-2) inhibitor that reduces the level of prostaglandin E2 (PGE2), on endogenous glutamate release in rat cerebral cortex nerve terminals (synaptosomes). Celecoxib substantially inhibited the release of glutamate induced by the K(+) channel blocker 4-aminopyridine (4-AP), and this phenomenon was prevented by chelating the extracellular Ca(2+) ions and by the vesicular transporter inhibitor bafilomycin A1. Celecoxib inhibited a 4-AP-induced increase in cytosolic-free Ca(2+) concentration, and the celecoxib-mediated inhibition of glutamate release was prevented by the Cav2.2 (N-type) and Cav2.1 (P/Q-type) channel blocker ω-conotoxin MVIIC. However, celecoxib did not alter 4-AP-mediated depolarization and Na(+) influx. In addition, this glutamate release-inhibiting effect of celecoxib was mediated through the PGE2 subtype 2 receptor (EP2) because it was not observed in the presence of butaprost (an EP2 agonist) or PF04418948 [1-(4-fluorobenzoyl)-3-[[6-methoxy-2-naphthalenyl)methyl]-3-azetidinecarboxylic acid; an EP2 antagonist]. The celecoxib effect on 4-AP-induced glutamate release was prevented by the inhibition or activation of protein kinase A (PKA), and celecoxib decreased the 4-AP-induced phosphorylation of PKA. We also determined that COX-2 and the EP2 receptor are present in presynaptic terminals because they are colocalized with synaptophysin, a presynaptic marker. These results collectively indicate that celecoxib inhibits glutamate release from nerve terminals by reducing voltage-dependent Ca(2+) entry through a signaling cascade involving EP2 and PKA.
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Affiliation(s)
- Tzu-Yu Lin
- Department of Anesthesiology, Far-Eastern Memorial Hospital, New Taipei, Taiwan (T.-Y.L., C.-W.L., S.K.H.); Department of Mechanical Engineering, Yuan Ze University, Taoyuan, Taiwan (T.-Y.L., C.-W.L.); and Graduate Institute of Basic Medicine (S.-J.W.) and School of Medicine (C.-C.W., S.-J.W.), Fu Jen Catholic University, New Taipei, Taiwan
| | - Cheng-Wei Lu
- Department of Anesthesiology, Far-Eastern Memorial Hospital, New Taipei, Taiwan (T.-Y.L., C.-W.L., S.K.H.); Department of Mechanical Engineering, Yuan Ze University, Taoyuan, Taiwan (T.-Y.L., C.-W.L.); and Graduate Institute of Basic Medicine (S.-J.W.) and School of Medicine (C.-C.W., S.-J.W.), Fu Jen Catholic University, New Taipei, Taiwan
| | - Chia-Chuan Wang
- Department of Anesthesiology, Far-Eastern Memorial Hospital, New Taipei, Taiwan (T.-Y.L., C.-W.L., S.K.H.); Department of Mechanical Engineering, Yuan Ze University, Taoyuan, Taiwan (T.-Y.L., C.-W.L.); and Graduate Institute of Basic Medicine (S.-J.W.) and School of Medicine (C.-C.W., S.-J.W.), Fu Jen Catholic University, New Taipei, Taiwan
| | - Shu Kuei Huang
- Department of Anesthesiology, Far-Eastern Memorial Hospital, New Taipei, Taiwan (T.-Y.L., C.-W.L., S.K.H.); Department of Mechanical Engineering, Yuan Ze University, Taoyuan, Taiwan (T.-Y.L., C.-W.L.); and Graduate Institute of Basic Medicine (S.-J.W.) and School of Medicine (C.-C.W., S.-J.W.), Fu Jen Catholic University, New Taipei, Taiwan
| | - Su-Jane Wang
- Department of Anesthesiology, Far-Eastern Memorial Hospital, New Taipei, Taiwan (T.-Y.L., C.-W.L., S.K.H.); Department of Mechanical Engineering, Yuan Ze University, Taoyuan, Taiwan (T.-Y.L., C.-W.L.); and Graduate Institute of Basic Medicine (S.-J.W.) and School of Medicine (C.-C.W., S.-J.W.), Fu Jen Catholic University, New Taipei, Taiwan
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7
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Wang CC, Kuo JR, Wang SJ. Dimebon, an antihistamine drug, inhibits glutamate release in rat cerebrocortical nerve terminals. Eur J Pharmacol 2014; 734:67-76. [PMID: 24726847 DOI: 10.1016/j.ejphar.2014.03.052] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2013] [Revised: 03/05/2014] [Accepted: 03/26/2014] [Indexed: 10/25/2022]
Abstract
The excessive release of glutamate is a critical element in the neuropathology of acute and chronic brain disorders. The purpose of the present study was to investigate the effect and possible mechanism of dimebon, an antihistamine with a neuroprotective profile, on endogenous glutamate release in the nerve terminals (synaptosomes) of the rat cerebral cortex. Dimebon inhibited the release of glutamate that was evoked by exposing the synaptosomes to the K(+) channel blocker 4-aminopyridine, and this effect was prevented by chelating extracellular Ca(2+) ions, and the vesicular transporter inhibitor bafilomycin A1. Dimebon inhibited depolarization-evoked increase in cytosolic free Ca(2+) concentration, and the dimebon-mediated inhibition of glutamate release was prevented by the Cav2.2 (N-type) and Cav2.1 (P/Q-type) channel blocker ω-conotoxin MVIIC. The inhibitory action of dimebon on glutamate release was not due to its decreasing synaptosomal excitability, because dimebon did not alter the resting synaptosomal membrane potential or 4-aminopyridine-mediated depolarization. Furthemore, the dimebon effect on 4-aminopyridine-evoked glutamate release was prevented by the protein kinase C inhibitor, and dimebon substantially reduced the 4-AP-induced phosphorylation of protein kinase C. However, the dimebon-mediated inhibition of glutamate release was unaffected by the N-methyl-d-aspartate receptor agonist or antagonist. These results suggest that dimebon inhibits glutamate release from rat cortical synaptosomes by suppressing presynaptic voltage-dependent Ca(2+) entry and protein kinase C activity. This implies that the inhibition of glutamate release is an additional pharmacological activity of dimebon that may play a critical role in the apparent clinical efficacy of this compound.
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Affiliation(s)
- Che-Chuan Wang
- Department of Neurology, Chi Mei Medical Center, Tainan, Taiwan; Biotechnology, Southern Taiwan University of Science and Technology, Tainan, Taiwan
| | - Jinn-Rung Kuo
- Department of Neurology, Chi Mei Medical Center, Tainan, Taiwan; Biotechnology, Southern Taiwan University of Science and Technology, Tainan, Taiwan
| | - Su-Jane Wang
- Graduate Institute of Basic Medicine, Fu Jen Catholic University, No.510, Zhongzheng Rd., Xinzhuang District, New Taipei 24205, Taiwan; School of Medicine, Fu Jen Catholic University, No.510, Zhongzheng Rd., Xinzhuang District, New Taipei 24205, Taiwan.
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8
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Annapurna M, Vishnuvardhan Reddy P, Singh SP, Kantam ML. Heck cross-coupling of vinyl heteroaromatic compounds with aryl and heteroaryl halides using Pd(II) complex under phosphine-free conditions. Tetrahedron 2013. [DOI: 10.1016/j.tet.2013.10.078] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Hovelsø N, Sotty F, Montezinho LP, Pinheiro PS, Herrik KF, Mørk A. Therapeutic potential of metabotropic glutamate receptor modulators. Curr Neuropharmacol 2012; 10:12-48. [PMID: 22942876 PMCID: PMC3286844 DOI: 10.2174/157015912799362805] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2010] [Revised: 01/10/2011] [Accepted: 03/04/2011] [Indexed: 12/21/2022] Open
Abstract
Glutamate is the main excitatory neurotransmitter in the central nervous system (CNS) and is a major player in complex brain functions. Glutamatergic transmission is primarily mediated by ionotropic glutamate receptors, which include NMDA, AMPA and kainate receptors. However, glutamate exerts modulatory actions through a family of metabotropic G-protein-coupled glutamate receptors (mGluRs). Dysfunctions of glutamatergic neurotransmission have been implicated in the etiology of several diseases. Therefore, pharmacological modulation of ionotropic glutamate receptors has been widely investigated as a potential therapeutic strategy for the treatment of several disorders associated with glutamatergic dysfunction. However, blockade of ionotropic glutamate receptors might be accompanied by severe side effects due to their vital role in many important physiological functions. A different strategy aimed at pharmacologically interfering with mGluR function has recently gained interest. Many subtype selective agonists and antagonists have been identified and widely used in preclinical studies as an attempt to elucidate the role of specific mGluRs subtypes in glutamatergic transmission. These studies have allowed linkage between specific subtypes and various physiological functions and more importantly to pathological states. This article reviews the currently available knowledge regarding the therapeutic potential of targeting mGluRs in the treatment of several CNS disorders, including schizophrenia, addiction, major depressive disorder and anxiety, Fragile X Syndrome, Parkinson’s disease, Alzheimer’s disease and pain.
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Affiliation(s)
- N Hovelsø
- Department of Neurophysiology, H. Lundbeck A/S, Ottiliavej 9, 2500 Copenhagen-Valby, Denmark
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Giribaldi F, Milanese M, Bonifacino T, Anna Rossi PI, Di Prisco S, Pittaluga A, Tacchetti C, Puliti A, Usai C, Bonanno G. Group I metabotropic glutamate autoreceptors induce abnormal glutamate exocytosis in a mouse model of amyotrophic lateral sclerosis. Neuropharmacology 2012; 66:253-63. [PMID: 22634363 DOI: 10.1016/j.neuropharm.2012.05.018] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2012] [Revised: 04/26/2012] [Accepted: 05/13/2012] [Indexed: 10/28/2022]
Abstract
Glutamate-mediated excitotoxicity plays a major role in ALS and reduced astrocytic glutamate transport was suggested as a cause. Based on previous work we have proposed that abnormal release may represent another source of excessive glutamate. In this line, here we studied the modulation of glutamate release in ALS by Group I metabotropic glutamate (mGlu) receptors, that comprise mGlu1 and mGlu5 members. Synaptosomes from the lumbar spinal cord of SOD1/G93A mice, a widely used murine model for human ALS, and controls were used in release, confocal or electron microscopy and Western blot experiments. Concentrations of the mGlu1/5 receptor agonist 3,5-DHPG >0.3 μM stimulated the release of [(3)H]d- aspartate, used to label the releasing pools of glutamate, both in control and SOD1/G93A mice. At variance, ≤0.3 μM 3,5-DHPG increased [(3)H]d-aspartate release in SOD1/G93A mice only. Experiments with selective antagonists indicated the involvement of both mGlu1 and mGlu5 receptors, mGlu5 being preferentially involved in the high potency effects of 3,5-DHPG. High 3,5-DHPG concentrations increased IP3 formation in both mouse strains, whereas low 3,5-DHPG did it in SOD1/G93A mice only. Release experiments confirmed that 3,5-DHPG elicited [(3)H]d-aspartate exocytosis involving intra-terminal Ca(2+) release through IP3-sensitive channels. Confocal microscopy indicated the co-existence of both receptors presynaptically in the same glutamatergic nerve terminal in SOD1/G93A mice. To conclude, activation of mGlu1/5 receptors produced abnormal glutamate release in SOD1/G93A mice, suggesting that these receptors are implicated in ALS and that selective antagonists may be predicted for new therapeutic approaches. This article is part of a Special Issue entitled 'Metabotropic Glutamate Receptors'.
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Affiliation(s)
- Francesco Giribaldi
- Department of Experimental Medicine Pharmacology and Toxicology Unit, University of Genoa, Genoa, Italy
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Lu CW, Lin TY, Wang CC, Wang SJ. σ-1 Receptor agonist SKF10047 inhibits glutamate release in rat cerebral cortex nerve endings. J Pharmacol Exp Ther 2012; 341:532-42. [PMID: 22357973 DOI: 10.1124/jpet.111.191189] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2023] Open
Abstract
σ-1 Receptors are expressed in the brain, and their activation has been shown to prevent neuronal death associated with glutamate toxicity. This study investigates the possible mechanism and effect of [2S-(2α,6α,11R*]-1,2,3,4,5,6-hexahydro-6,11-dimethyl-3-(2-propenyl)-2,6-methano-3-benzazocin-8-ol (SKF10047), a σ-1 receptor agonist, on endogenous glutamate release in the nerve terminals of rat cerebral cortex. Results show that SKF10047 inhibited the release of glutamate evoked by the K⁺ channel blocker 4-aminopyridine (4-AP), and the σ-1 receptor antagonist N-[2-(3,4-dichlorophenyl)ethyl]-N-methyl-2-(dimethylamino)ethylamine (BD1047) blocked this phenomenon. The effects of SKF10047 on the evoked glutamate release were prevented by the chelating extracellular Ca²⁺ions and the vesicular transporter inhibitor bafilomycin A1. However, the glutamate transporter inhibitor DL-threo-β-benzyl-oxyaspartate did not have any effect on the action of SKF10047. SKF10047 decreased the depolarization-induced increase in the cytosolic free Ca²⁺ concentration ([Ca²⁺](C)), but did not alter 4-AP-mediated depolarization. Furthermore, the effects of SKF10047 on evoked glutamate release were prevented by blocking the Ca(v)2.2 (N-type) and Ca(v)2.1 (P/Q-type) channels, but not by blocking the ryanodine receptors or the mitochondrial Na⁺/Ca²⁺ exchange. In addition, conventional protein kinase C (PKC) inhibitors abolished the SKF10047 effect on 4-AP-evoked glutamate release. Western blot analyses showed that SKF10047 decreased the 4-AP-induced phosphorylation of PKC and PKCα. These results show that σ-1 receptor activation inhibits glutamate release from rat cortical nerve terminals. This effect is linked to a decrease in [Ca²⁺](C) caused by Ca²⁺ entry through presynaptic voltage-dependent Ca²⁺ channels and the suppression of the PKC signaling cascade.
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Affiliation(s)
- Cheng-Wei Lu
- Department of Anesthesiology, Far-Eastern Memorial Hospital, New Taipei, Taiwan
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12
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Tamoxifen depresses glutamate release through inhibition of voltage-dependent Ca2+ entry and protein kinase Cα in rat cerebral cortex nerve terminals. Neurochem Int 2012; 60:105-14. [DOI: 10.1016/j.neuint.2011.11.014] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2011] [Revised: 11/17/2011] [Accepted: 11/21/2011] [Indexed: 12/30/2022]
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13
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Cellular mechanisms of acute decrease of glutamate release induced by raloxifene in rat cerebral cortex. Neuropharmacology 2011; 61:293-304. [DOI: 10.1016/j.neuropharm.2011.04.016] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2011] [Revised: 03/29/2011] [Accepted: 04/12/2011] [Indexed: 11/24/2022]
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14
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Chang Y, Lin YW, Wang SJ. Idebenone inhibition of glutamate release from rat cerebral cortex nerve endings by suppression of voltage-dependent calcium influx and protein kinase A. NAUNYN-SCHMIEDEBERG'S ARCHIVES OF PHARMACOLOGY 2011; 384:59-70. [PMID: 21541760 DOI: 10.1007/s00210-011-0630-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2011] [Accepted: 03/25/2011] [Indexed: 11/29/2022]
Abstract
The present study was aimed at investigating the effect and the possible mechanism of idebenone on endogenous glutamate release in nerve terminals of rat cerebral cortex (synaptosomes). Idebenone inhibited the release of glutamate that was evoked by exposing synaptosomes to the K(+) channel blocker 4-aminopyridine (4-AP), and this phenomenon was concentration dependent. Inhibition of glutamate release by idebenone was prevented by chelating extracellular Ca(2+), or by the vesicular transporter inhibitor bafilomycin A1, but was insensitive to DL-threo-beta-benzyl-oxyaspartate, a glutamate transporter inhibitor. Idebenone decreased the depolarization-induced increase in the cytosolic free Ca(2+) concentration ([Ca(2+)](C)),whereas it did not alter the resting synaptosomal membrane potential or 4-AP-mediated depolarization. The inhibitory effect of idebenone on evoked glutamate release was prevented by blocking the Ca(v)2.2 (N-type) and Ca(v)2.1 (P/Q-type) channels, but not by blocking intracellular Ca(2+) release or Na(+)/Ca(2+) exchange. Furthermore, the idebenone effect on 4-AP-evoked Ca(2+) influx and glutamate release was completely abolished by the protein kinase A (PKA) inhibitors, H89 and KT5720. On the basis of these results, it was concluded that idebenone inhibits glutamate release from rat cortical synaptosomes and this effect is linked to a decrease in [Ca(2+)](C) contributed by Ca(2+) entry through presynaptic voltage-dependent Ca(2+) channels and to the suppression of PKA signaling cascade.
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Affiliation(s)
- Yi Chang
- Department of Anesthesiology, Shin Kong Wu Ho-Su Memorial Hospital, Taipei, Taiwan
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Chang Y, Wang SJ. Hypericin, the active component of St. John's wort, inhibits glutamate release in the rat cerebrocortical synaptosomes via a mitogen-activated protein kinase-dependent pathway. Eur J Pharmacol 2010; 634:53-61. [DOI: 10.1016/j.ejphar.2010.02.035] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2009] [Revised: 01/14/2010] [Accepted: 02/15/2010] [Indexed: 10/19/2022]
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Grilli M, Neri E, Zappettini S, Massa F, Bisio A, Romussi G, Marchi M, Pittaluga A. Salvinorin A exerts opposite presynaptic controls on neurotransmitter exocytosis from mouse brain nerve terminals. Neuropharmacology 2009; 57:523-30. [DOI: 10.1016/j.neuropharm.2009.07.023] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2009] [Revised: 07/13/2009] [Accepted: 07/15/2009] [Indexed: 10/20/2022]
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Yang TT, Wang SJ. Pyridoxine Inhibits Depolarization-Evoked Glutamate Release in Nerve Terminals from Rat Cerebral Cortex: a Possible Neuroprotective Mechanism? J Pharmacol Exp Ther 2009; 331:244-54. [DOI: 10.1124/jpet.109.155176] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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2-Methyl-6-phenylethynyl-pyridine (MPEP), a non-competitive mGluR5 antagonist, differentially affects the anticonvulsant activity of four conventional antiepileptic drugs against amygdala-kindled seizures in rats. Pharmacol Rep 2009; 61:621-30. [DOI: 10.1016/s1734-1140(09)70114-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2008] [Revised: 06/09/2009] [Indexed: 11/24/2022]
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Mazars C, Bourque S, Mithöfer A, Pugin A, Ranjeva R. Calcium homeostasis in plant cell nuclei. THE NEW PHYTOLOGIST 2009; 181:261-274. [PMID: 19130634 DOI: 10.1111/j.1469-8137.2008.02680.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
In plant cells, calcium-based signaling pathways are involved in a large array of biological processes, including cell division, polarity, growth, development and adaptation to changing biotic and abiotic environmental conditions. Free calcium changes are known to proceed in a nonstereotypical manner and produce a specific signature, which mirrors the nature, strength and frequency of a stimulus. The temporal aspects of calcium signatures are well documented, but their vectorial aspects also have a profound influence on biological output. Here, we will focus on the regulation of calcium homeostasis in the nucleus. We will discuss data and present hypotheses suggesting that, while interacting with other organelles, the nucleus has the potential to generate and regulate calcium signals on its own.
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Affiliation(s)
- Christian Mazars
- UMR CNRS 5546/Université de Toulouse, Surfaces Cellulaires et Signalisation chez les Végétaux, Pôle de Biotechnologie Végétale, BP 42617 Auzeville, 31326 Castanet-Tolosan cédex, France;UMR INRA 1088/CNRS 5184/Université de Bourgogne Plante-Microbe-Environnement, 17 Rue Sully, BP 86510, 21065 Dijon cédex, France;Max Planck Institute for Chemical Ecology, Department Bioorganic Chemistry, Hans-Knöll-Str. 8, 07745 Jena, Germany;GDR CNRS Calcium et Régulation des Gènes, 118 route de Narbonne, 31062 Toulouse cédex, France
| | - Stéphane Bourque
- UMR CNRS 5546/Université de Toulouse, Surfaces Cellulaires et Signalisation chez les Végétaux, Pôle de Biotechnologie Végétale, BP 42617 Auzeville, 31326 Castanet-Tolosan cédex, France;UMR INRA 1088/CNRS 5184/Université de Bourgogne Plante-Microbe-Environnement, 17 Rue Sully, BP 86510, 21065 Dijon cédex, France;Max Planck Institute for Chemical Ecology, Department Bioorganic Chemistry, Hans-Knöll-Str. 8, 07745 Jena, Germany;GDR CNRS Calcium et Régulation des Gènes, 118 route de Narbonne, 31062 Toulouse cédex, France
| | - Axel Mithöfer
- UMR CNRS 5546/Université de Toulouse, Surfaces Cellulaires et Signalisation chez les Végétaux, Pôle de Biotechnologie Végétale, BP 42617 Auzeville, 31326 Castanet-Tolosan cédex, France;UMR INRA 1088/CNRS 5184/Université de Bourgogne Plante-Microbe-Environnement, 17 Rue Sully, BP 86510, 21065 Dijon cédex, France;Max Planck Institute for Chemical Ecology, Department Bioorganic Chemistry, Hans-Knöll-Str. 8, 07745 Jena, Germany;GDR CNRS Calcium et Régulation des Gènes, 118 route de Narbonne, 31062 Toulouse cédex, France
| | - Alain Pugin
- UMR CNRS 5546/Université de Toulouse, Surfaces Cellulaires et Signalisation chez les Végétaux, Pôle de Biotechnologie Végétale, BP 42617 Auzeville, 31326 Castanet-Tolosan cédex, France;UMR INRA 1088/CNRS 5184/Université de Bourgogne Plante-Microbe-Environnement, 17 Rue Sully, BP 86510, 21065 Dijon cédex, France;Max Planck Institute for Chemical Ecology, Department Bioorganic Chemistry, Hans-Knöll-Str. 8, 07745 Jena, Germany;GDR CNRS Calcium et Régulation des Gènes, 118 route de Narbonne, 31062 Toulouse cédex, France
| | - Raoul Ranjeva
- UMR CNRS 5546/Université de Toulouse, Surfaces Cellulaires et Signalisation chez les Végétaux, Pôle de Biotechnologie Végétale, BP 42617 Auzeville, 31326 Castanet-Tolosan cédex, France;UMR INRA 1088/CNRS 5184/Université de Bourgogne Plante-Microbe-Environnement, 17 Rue Sully, BP 86510, 21065 Dijon cédex, France;Max Planck Institute for Chemical Ecology, Department Bioorganic Chemistry, Hans-Knöll-Str. 8, 07745 Jena, Germany;GDR CNRS Calcium et Régulation des Gènes, 118 route de Narbonne, 31062 Toulouse cédex, France
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Musante V, Neri E, Feligioni M, Puliti A, Pedrazzi M, Conti V, Usai C, Diaspro A, Ravazzolo R, Henley JM, Battaglia G, Pittaluga A. Presynaptic mGlu1 and mGlu5 autoreceptors facilitate glutamate exocytosis from mouse cortical nerve endings. Neuropharmacology 2008; 55:474-82. [PMID: 18625255 PMCID: PMC3310906 DOI: 10.1016/j.neuropharm.2008.06.056] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2008] [Revised: 06/16/2008] [Accepted: 06/18/2008] [Indexed: 11/19/2022]
Abstract
The effects of mGlu1 and mGlu5 receptor activation on the depolarization-evoked release of [3H]d-aspartate ([3H]D-ASP) from mouse cortical synaptosomes were investigated. The mGlu1/5 receptor agonist 3,5-DHPG (0.1-100microM) potentiated the K+(12mM)-evoked [3H]D-ASP overflow. The potentiation occurred in a concentration-dependent manner showing a biphasic pattern. The agonist potentiated [3H]D-ASP exocytosis when applied at 0.3microM; the efficacy of 3,5-DHPG then rapidly declined and reappeared at 30-100microM. The fall of efficacy of agonist at intermediate concentration may be consistent with 3,5-DHPG-induced receptor desensitization. Facilitation of [3H]D-ASP exocytosis caused by 0.3microM 3,5-DHPG was prevented by the selective mGlu5 receptor antagonist MPEP, but was insensitive to the selective mGlu1 receptor antagonist CPCCOEt. In contrast, CPCCOEt prevented the potentiation by 50microM 3,5-DHPG, while MPEP had minimal effect. Unexpectedly, LY 367385 antagonized both the 3,5-DHPG-induced effects. A total of 0.3microM 3,5-DHPG failed to facilitate the K+-evoked [3H]D-ASP overflow from mGlu5 receptor knockout (mGlu5-/-) cortical synaptosomes, but not from nerve terminals prepared from the cortex of animals lacking the mGlu1 receptors, the crv4/crv4 mice. On the contrary, 50microM 3,5-DHPG failed to affect the [3H]D-ASP exocytosis from cortical synaptosomes obtained from crv4/crv4 and mGlu5-/-mice. Western blot analyses in subsynaptic fractions support the existence of both mGlu1 and mGlu5 autoreceptors located presynaptically, while immunocytochemistry revealed their presence at glutamatergic terminals. We propose that mGlu1 and mGlu5 autoreceptors exist on mouse glutamatergic cortical terminals; mGlu5 receptors may represent the "high affinity" binding sites for 3,5-DHPG, while mGlu1 autoreceptors represent the "low affinity" binding sites.
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Affiliation(s)
- Veronica Musante
- Department of Experimental Medicine, Section of Pharmacology and Toxicology, University of Genoa, Genoa, Italy
| | - Elisa Neri
- Department of Experimental Medicine, Section of Pharmacology and Toxicology, University of Genoa, Genoa, Italy
| | - Marco Feligioni
- MRC Centre for Synaptic Plasticity, Department of Anatomy, School of Medical Sciences, University of Bristol, Bristol BS8 1TD, UK
| | - Aldamaria Puliti
- Center of Excellence for Biomedical Research, University of Genoa, Genoa, Italy
- Laboratory of Molecular Genetics and Cytogenetics, G. Gaslini Institute, Genoa, Italy
- Department of Pediatric Sciences, University of Genoa, Genoa, Italy
| | - Marco Pedrazzi
- Department of Pediatric Sciences, University of Genoa, Genoa, Italy
- Department of Experimental Medicine, Section of Biochemistry, University of Genoa, Genoa, Italy
| | - Valerio Conti
- Laboratory of Molecular Genetics and Cytogenetics, G. Gaslini Institute, Genoa, Italy
- Renal Child Foundation, G. Gaslini Institute, Genoa, Italy
| | - Cesare Usai
- Institute of Biophysics, National Research Council, Genoa, Italy
| | | | - Roberto Ravazzolo
- Center of Excellence for Biomedical Research, University of Genoa, Genoa, Italy
- Laboratory of Molecular Genetics and Cytogenetics, G. Gaslini Institute, Genoa, Italy
- Department of Pediatric Sciences, University of Genoa, Genoa, Italy
| | - Jeremy M. Henley
- MRC Centre for Synaptic Plasticity, Department of Anatomy, School of Medical Sciences, University of Bristol, Bristol BS8 1TD, UK
| | | | - Anna Pittaluga
- Department of Experimental Medicine, Section of Pharmacology and Toxicology, University of Genoa, Genoa, Italy
- Center of Excellence for Biomedical Research, University of Genoa, Genoa, Italy
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Li M, Hua R. Palladium-catalyzed Heck coupling of 2-vinylpyridine with aryl chlorides. Appl Organomet Chem 2008. [DOI: 10.1002/aoc.1414] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Abstract
Glutamate and GABA, the two most abundant neurotransmitters in the mammalian central nervous system, can act on metabotropic receptors that are structurally quite dissimilar from those targeted by most other neurotransmitters/modulators. Accordingly, metabotropic glutamate receptors (mGluRs) and GABA(B) receptors (GABA(B)Rs) are classified as members of family 3 (or family C) of G protein-coupled receptors. On the other hand, mGluRs and GABA(B)Rs exhibit pronounced and partly unresolved differences between each other. The most intriguing difference is that mGluRs exist as multiple pharmacologically as well as structurally distinct subtypes, whereas, in the case of GABA(B)Rs, molecular biologists have so far identified only one structurally distinct heterodimeric complex whose few variants seem unable to explain the pharmacological heterogeneity of GABA(B)Rs observed in many functional studies. Both mGluRs and GABA(B)Rs can be localized on axon terminals of different neuronal systems as presynaptic autoreceptors and heteroreceptors modulating the exocytosis of various transmitters.
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Affiliation(s)
- M Raiteri
- Department of Experimental Medicine, Pharmacology and Toxicology Section, University of Genoa, 16148 Genoa, Italy.
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Abstract
Kainate receptors (KARs), together with NMDA and alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate receptors (AMPA), are typically described as ionotropic glutamate receptors. Although ionotropic functions for KARs are beginning to be characterized in multiple brain regions, both, in the pre- and post-synaptic compartments of the synapse, there is accumulating evidence that KARs mediate some of their effects without invoking ion-fluxes. Thus, since 1998, when the first metabotropic action of KARs was described in the modulation of GABA release in hippocampal interneurons, there have been increasing reports that some of the functions of KARs involve the participation of intracellular signalling cascades and depend on G protein activation. These surprising observations, attesting metabotropic actions of KARs, akin to those usually attributed to seven transmembrane region G protein-coupled receptors, make the physiological classification and description of glutamate receptors more complex. In the present review, we describe the metabotropic roles of KARs in the CNS and discuss the intriguing properties of this receptor which, structurally shows all the facets of a typical ionotropic receptor, but appears to express a metabotropic remit at some key synapses.
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Affiliation(s)
- Antonio Rodríguez-Moreno
- Departamento de Fisiología, Anatomía y Biología Celular, Universidad Pablo de Olavide, Sevilla, Spain.
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Wang SJ, Wang KY, Wang WC, Sihra TS. Unexpected inhibitory regulation of glutamate release from rat cerebrocortical nerve terminals by presynaptic 5-hydroxytryptamine-2A receptors. J Neurosci Res 2007; 84:1528-42. [PMID: 17016851 DOI: 10.1002/jnr.21060] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Presynaptic 5-HT(2A) receptor modulation of glutamate release from rat cerebrocortical nerve terminals (synaptosomes) was investigated by using the 5-HT(2A/2C) receptor agonist (+/-)-1-[2,5-dimethoxy-4-iodophenyl]-2-aminopropane (DOI). DOI potently inhibited 4-aminopyridine (4AP)-evoked glutamate release. Involvement of presynaptic 5-HT(2A) receptors in this modulation of 4AP-evoked release was confirmed by blockade of the DOI-mediated inhibition by the 5-HT(2A) receptor antagonist ketanserin but not by the 5-HT(2C) receptor antagonist RS102221. Inhibition of glutamate release by DOI was associated with a reduction of 4AP-evoked depolarization and downstream elevation of cytoplasmic free calcium concentration ([Ca(2+)](C)) mediated via P/Q- and N-type voltage-dependent Ca(2+) channels (VDCCs). In contrast to the DOI effect on 4AP-evoked release, the agonist had no effect on high external [K(+)] (30 mM)-induced (KCl) stimulation of VDCCs or glutamate release. Likewise, release mediated by direct Ca(2+) entry with Ca(2+) ionophore (ionomycin) or by hypertonic sucrose was unaffected by DOI. Mechanistically, DOI modulation of 4AP-evoked glutamate release appeared to involve a phospholipase C/protein kinase C signaling cascade, insofar as pretreatment of synaptosomes with the phospholipase C inhibitor U73122 or protein kinase C inhibitors Ro320432 or GF109203X all effectively occluded the inhibitory effect of the agonist. Together, these results suggest that presynaptic 5-HT(2A) receptors present on glutamatergic terminals effect an unexpected depression of glutamate release by negatively modulating nerve terminal excitability and downstream VDCC activation through a signaling cascade involving phospholipase C/protein kinase C. These observations invoke presynaptic inhibitory 5-HT(2A) receptor function as a potential target for drugs to mitigate the effects of excessive glutamatergic transmission.
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Affiliation(s)
- Su-Jane Wang
- School of Medicine, Fu Jen Catholic University, Taipei Hsien, Taiwan
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Hainsworth AH, Nelson RM, Lambert DG, Green AR, Webb TE. Glutamate receptor-mediated inhibition of L-glutamate efflux from cerebral cortex in vitro. Brain Res 2006; 1114:36-40. [PMID: 16904087 DOI: 10.1016/j.brainres.2006.07.038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2005] [Revised: 07/05/2006] [Accepted: 07/13/2006] [Indexed: 11/30/2022]
Abstract
We tested whether glutamate receptor ligands affect oxygen-glucose deprivation-evoked L-glutamate efflux from adult rat cerebrocortical prisms. The uncompetitive NMDA antagonist AR-R15896AR inhibited efflux (IC50 34 microM, 87% maximal inhibition). AMPA/kainate receptor blockade (NBQX, 100 microM) or Group II metabotropic glutamate receptor activation (DCG-IV, 10 microM) inhibited efflux (41%, 67% respectively) but Group I mGluR blockade (CPCCOEt/MPEP, 10 microM) was without effect. These data support a modulatory effect of glutamate receptors on L-glutamate efflux.
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Affiliation(s)
- Atticus H Hainsworth
- Pharmacology Research Group, Leicester School of Pharmacy, De Montfort University, Leicester, LE1 9BH, UK.
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Tebano MT, Martire A, Pepponi R, Domenici MR, Popoli P. Is the functional interaction between adenosine A(2A) receptors and metabotropic glutamate 5 receptors a general mechanism in the brain? Differences and similarities between the striatum and the hippocampus. Purinergic Signal 2006; 2:619-25. [PMID: 18404464 PMCID: PMC2096652 DOI: 10.1007/s11302-006-9026-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2005] [Revised: 03/30/2006] [Accepted: 04/20/2006] [Indexed: 12/20/2022] Open
Abstract
The aim of the present paper was to examine, in a comparative way, the occurrence and the mechanisms of the interactions between adenosine A2A receptors (A2ARs) and metabotropic glutamate 5 receptors (mGlu5Rs) in the hippocampus and the striatum. In rat hippocampal and corticostriatal slices, combined ineffective doses of the mGlu5R agonist 2-chloro-5-hydroxyphenylglycine (CHPG) and the A2AR agonist CGS 21680 synergistically reduced the slope of excitatory postsynaptic field potentials (fEPSPs) recorded in CA1 and the amplitude of field potentials (FPs) recorded in the dorsomedial striatum. The cyclic adenosine monophosphate (cAMP)/protein kinase A (PKA) pathway appeared to be involved in the effects of CGS 21680 in corticostriatal but not in hippocampal slices. In both areas, a postsynaptic locus of interaction appeared more likely. N-methyl-D-aspartate (NMDA) reduced the fEPSP slope and FP amplitude in hippocampal and corticostriatal slices, respectively. Such an effect was significantly potentiated by CHPG in both areas. Interestingly, the A2AR antagonist ZM 241385 significantly reduced the NMDA-potentiating effect of CHPG. In primary cultures of rat hippocampal and striatal neurons (ED 17, DIV 14), CHPG significantly potentiated NMDA-induced lactate dehydrogenase (LDH) release. Again, such an effect was prevented by ZM 241385. Our results show that A2A and mGlu5 receptors functionally interact both in the hippocampus and in the striatum, even though different mechanisms seem to be involved in the two areas. The ability of A2ARs to control mGlu5R-dependent effects may thus be a general feature of A2ARs in different brain regions (irrespective of their density) and may represent an additional target for the development of therapeutic strategies against neurological disorders.
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Affiliation(s)
- M T Tebano
- Department of Drug Research and Evaluation, Istituto Superiore di Sanità, Viale Regina Elena, Rome, 299 00161, Italy,
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Tebano MT, Martire A, Rebola N, Pepponi R, Domenici MR, Grò MC, Schwarzschild MA, Chen JF, Cunha RA, Popoli P. Adenosine A2A receptors and metabotropic glutamate 5 receptors are co-localized and functionally interact in the hippocampus: a possible key mechanism in the modulation of N-methyl-d-aspartate effects. J Neurochem 2005; 95:1188-200. [PMID: 16271052 DOI: 10.1111/j.1471-4159.2005.03455.x] [Citation(s) in RCA: 93] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Hippocampal metabotropic glutamate 5 receptors (mGlu5Rs) regulate both physiological and pathological responses to glutamate. Because mGlu5R activation enhances NMDA-mediated effects, and given the role played by NMDA receptors in synaptic plasticity and excitotoxicity, modulating mGlu5R may influence both the physiological and the pathological effects elicited by NMDA receptor stimulation. We evaluated whether adenosine A2A receptors (A(2A)Rs) modulated mGlu5R-dependent effects in the hippocampus, as they do in the striatum. Co-application of the A(2A)R agonist CGS 21680 with the mGlu5R agonist (RS)-2-chloro-s-hydroxyphenylglycine(CHPG) synergistically reduced field excitatory postsynaptic potentials in the CA1 area of rat hippocampal slices. Endogenous tone at A(2A)Rs seemed to be required to enable mGlu5R-mediated effects, as the ability of CHPG to potentiate NMDA effects was antagonized by the selective A(2A)R antagonist ZM 241385 in rat hippocampal slices and cultured hippocampal neurons, and abolished in the hippocampus of A(2A)R knockout mice. Evidence for the interaction between A(2A)Rs and mGlu5Rs was further strengthened by demonstrating their co-localization in hippocampal synapses. This is the first evidence showing that hippocampal A(2A)Rs and mGlu5Rs are co-located and act synergistically, and that A(2A)Rs play a permissive role in mGlu5R receptor-mediated potentiation of NMDA effects in the hippocampus.
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Affiliation(s)
- M T Tebano
- Department of Drug Research and Evaluation, Istituto Superiore di Sanità, Rome, Italy
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