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Sebastião AM, Ribeiro JA. Adjusting the brakes to adjust neuronal activity: Adenosinergic modulation of GABAergic transmission. Neuropharmacology 2023; 236:109600. [PMID: 37225084 DOI: 10.1016/j.neuropharm.2023.109600] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Revised: 04/20/2023] [Accepted: 05/16/2023] [Indexed: 05/26/2023]
Abstract
About 50 years elapsed from the publication of the first full paper on the neuromodulatory action of adenosine at a 'simple' synapse model, the neuromuscular junction (Ginsborg and Hirst, 1972). In that study adenosine was used as a tool to increase cyclic AMP and for the great surprise, it decreased rather than increased neurotransmitter release, and for a further surprise, its action was prevented by theophylline, at the time only known as inhibitor of phosphodiesterases. These intriguing observations opened the curiosity for immediate studies relating the action of adenine nucleotides, known to be released together with neurotransmitters, to that of adenosine (Ribeiro and Walker, 1973, 1975). Our understanding on the ways adenosine uses to modulate synapses, circuits, and brain activity, vastly expanded since then. However, except for A2A receptors, whose actions upon GABAergic neurons of the striatum are well known, most of the attention given to the neuromodulatory action of adenosine has been focusing upon excitatory synapses. Evidence is growing that GABAergic transmission is also a target for adenosinergic neuromodulation through A1 and A2A receptors. Some o these actions have specific time windows during brain development, and others are selective for specific GABAergic neurons. Both tonic and phasic GABAergic transmission can be affected, and either neurons or astrocytes can be targeted. In some cases, those effects result from a concerted action with other neuromodulators. Implications of these actions in the control of neuronal function/dysfunction will be the focus of this review.
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Affiliation(s)
- Ana M Sebastião
- Instituto de Farmacologia e Neurociências, Faculdade de Medicina, Universidade de Lisboa, Portugal; Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Portugal.
| | - Joaquim Alexandre Ribeiro
- Instituto de Farmacologia e Neurociências, Faculdade de Medicina, Universidade de Lisboa, Portugal; Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Portugal
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Weerasinghe-Mudiyanselage PD, Kang S, Kim JS, Moon C. Therapeutic Approaches to Non-Motor Symptoms of Parkinson's Disease: A Current Update on Preclinical Evidence. Curr Neuropharmacol 2023; 21:560-577. [PMID: 36200159 PMCID: PMC10207906 DOI: 10.2174/1570159x20666221005090126] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2022] [Revised: 08/30/2022] [Accepted: 09/02/2022] [Indexed: 11/22/2022] Open
Abstract
Despite being classified as a movement disorder, Parkinson's disease (PD) is characterized by a wide range of non-motor symptoms that significantly affect the patients' quality of life. However, clear evidence-based therapy recommendations for non-motor symptoms of PD are uncommon. Animal models of PD have previously been shown to be useful for advancing the knowledge and treatment of motor symptoms. However, these models may provide insight into and assess therapies for non-motor symptoms in PD. This paper highlights non-motor symptoms in preclinical models of PD and the current position regarding preclinical therapeutic approaches for these non-motor symptoms. This information may be relevant for designing future preclinical investigations of therapies for nonmotor symptoms in PD.
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Affiliation(s)
- Poornima D.E. Weerasinghe-Mudiyanselage
- Department of Veterinary Anatomy and Animal Behavior, College of Veterinary Medicine and BK21 FOUR Program, Chonnam National University, Gwangju 61186, South Korea
| | - Sohi Kang
- Department of Veterinary Anatomy and Animal Behavior, College of Veterinary Medicine and BK21 FOUR Program, Chonnam National University, Gwangju 61186, South Korea
| | - Joong-Sun Kim
- Department of Veterinary Anatomy and Animal Behavior, College of Veterinary Medicine and BK21 FOUR Program, Chonnam National University, Gwangju 61186, South Korea
| | - Changjong Moon
- Department of Veterinary Anatomy and Animal Behavior, College of Veterinary Medicine and BK21 FOUR Program, Chonnam National University, Gwangju 61186, South Korea
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Kubrusly RCC, da Rosa Valli T, Ferreira MNMR, de Moura P, Borges-Martins VPP, Martins RS, Ferreira DDP, Sathler MF, de Melo Reis RA, Ferreira GC, Manhães AC, Dos Santos Pereira M. Caffeine Improves GABA Transport in the Striatum of Spontaneously Hypertensive Rats (SHR). Neurotox Res 2021; 39:1946-1958. [PMID: 34637050 DOI: 10.1007/s12640-021-00423-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Revised: 09/25/2021] [Accepted: 09/27/2021] [Indexed: 11/28/2022]
Abstract
The spontaneously hypertensive rat (SHR) is an excellent animal model that mimics the behavioral and neurochemical phenotype of attention-deficit/hyperactivity disorder (ADHD). Here, we characterized the striatal GABA transport of SHR and investigated whether caffeine, a non-selective antagonist of adenosine receptors, could influence GABAergic circuitry. For this purpose, ex vivo striatal slices of SHR and Wistar (control strain) on the 35th postnatal day were dissected and incubated with [3H]-GABA to quantify the basal levels of uptake and release. SHR exhibited a reduced [3H]-GABA uptake and release, suggesting a defective striatal GABAergic transport system. GAT-1 appears to be the primary transporter for [3H]-GABA uptake in SHR striatum, as GAT-1 selective blocker, NO-711, completely abolished it. We also verified that acute exposure of striatal slices to caffeine improved [3H]-GABA uptake and release in SHR, whereas Wistar rats were not affected. GABA-uptake increase and cAMP accumulation promoted by caffeine was reverted by A1R activation with N6-cyclohexyl adenosine (CHA). As expected, the pharmacological blockade of cAMP-PKA signaling by H-89 also prevented caffeine-mediated [3H]-GABA uptake increment. Interestingly, a single caffeine exposure did not affect GAT-1 or A1R protein density in SHR, which was not different from Wistar protein levels, suggesting that the GAT-1-dependent transport in SHR has a defective functional activity rather than lower protein expression. The current data support that caffeine regulates GAT-1 function and improves striatal GABA transport via A1R-cAMP-PKA signaling, specifically in SHR. These results reinforce that caffeine may have therapeutic use in disorders where the GABA transport system is impaired.
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Affiliation(s)
| | | | | | - Pâmella de Moura
- Laboratório de Neurofarmacologia, Instituto Biomédico, Niterói, RJ, Brazil
| | | | - Robertta Silva Martins
- Laboratório de Neurofarmacologia, Instituto Biomédico, Niterói, RJ, Brazil
- Laboratório de Neurobiologia Celular E Molecular, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal Do Rio de Janeiro, Rio de Janeiro, Brazil
| | | | | | - Ricardo Augusto de Melo Reis
- Laboratório de Neuroquímica, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal Do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Gustavo Costa Ferreira
- Laboratório de Neuroenergética E Erros Inatos Do Metabolismo, Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal Do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Alex Christian Manhães
- Laboratório de Neurofisiologia, Instituto de Biologia, Universidade Do Estado Do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Maurício Dos Santos Pereira
- Laboratório de Neurofarmacologia, Instituto Biomédico, Niterói, RJ, Brazil.
- Laboratório de Neurofisiologia Molecular, Departamento de Biologia Básica E Oral, Faculdade de Odontologia de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, Brazil.
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Diao HL, Xue Y, Han XH, Wang SY, Liu C, Chen WF, Chen L. Adenosine A 2A Receptor Modulates the Activity of Globus Pallidus Neurons in Rats. Front Physiol 2017; 8:897. [PMID: 29163226 PMCID: PMC5682020 DOI: 10.3389/fphys.2017.00897] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2017] [Accepted: 10/24/2017] [Indexed: 12/23/2022] Open
Abstract
The globus pallidus is a central nucleus in the basal ganglia motor control circuit. Morphological studies have revealed the expression of adenosine A2A receptors in the globus pallidus. To determine the modulation of adenosine A2A receptors on the activity of pallidal neurons in both normal and parkinsonian rats, in vivo electrophysiological and behavioral tests were performed in the present study. The extracellular single unit recordings showed that micro-pressure administration of adenosine A2A receptor agonist, CGS21680, regulated the pallidal firing activity. GABAergic neurotransmission was involved in CGS21680-induced modulation of pallidal neurons via a PKA pathway. Furthermore, application of two adenosine A2A receptor antagonists, KW6002 or SCH442416, mainly increased the spontaneous firing of pallidal neurons, suggesting that endogenous adenosine system modulates the activity of pallidal neurons through adenosine A2A receptors. Finally, elevated body swing test (EBST) showed that intrapallidal microinjection of adenosine A2A receptor agonist/antagonist induced ipsilateral/contralateral-biased swing, respectively. In addition, the electrophysiological and behavioral findings also revealed that activation of dopamine D2 receptors by quinpirole strengthened KW6002/SCH442416-induced excitation of pallidal activity. Co-application of quinpirole with KW6002 or SCH442416 alleviated biased swing in hemi-parkinsonian rats. Based on the present findings, we concluded that pallidal adenosine A2A receptors may be potentially useful in the treatment of Parkinson's disease.
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Affiliation(s)
- Hui-Ling Diao
- Department of Physiology, Qingdao University, Qingdao, China.,Department of Physiology, Binzhou Medical University, Yantai, China
| | - Yan Xue
- Department of Physiology, Qingdao University, Qingdao, China
| | - Xiao-Hua Han
- Department of Physiology, Qingdao University, Qingdao, China
| | - Shuang-Yan Wang
- Department of Physiology, Qingdao University, Qingdao, China.,Department of Anatomy, Qingdao University, Qingdao, China
| | - Cui Liu
- Department of Physiology, Qingdao University, Qingdao, China
| | - Wen-Fang Chen
- Department of Physiology, Qingdao University, Qingdao, China
| | - Lei Chen
- Department of Physiology, Qingdao University, Qingdao, China
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Danielsson J, Zaidi S, Kim B, Funayama H, Yim PD, Xu D, Worgall TS, Gallos G, Emala CW. Airway Epithelial Cell Release of GABA is Regulated by Protein Kinase A. Lung 2016; 194:401-8. [PMID: 26989055 DOI: 10.1007/s00408-016-9867-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2015] [Accepted: 03/09/2016] [Indexed: 01/05/2023]
Abstract
INTRODUCTION γ-amino butyric acid (GABA) is not only the major inhibitory neurotransmitter in the central nervous system (CNS), but it also plays an important role in the lung, mediating airway smooth muscle relaxation and mucus production. As kinases such as protein kinase A (PKA) are known to regulate the release and reuptake of GABA in the CNS by GABA transporters, we hypothesized that β-agonists would affect GABA release from airway epithelial cells through activation of PKA. METHODS C57/BL6 mice received a pretreatment of a β-agonist or vehicle (PBS), followed by methacholine or PBS. Bronchoalveolar lavage (BAL) was collected and the amount of GABA was quantified using HPLC mass spectrometry. For in vitro studies, cultured BEAS-2B human airway epithelial cells were loaded with (3)H-GABA. (3)H-GABA released was measured during activation and inhibition of PKA and tyrosine kinase signaling pathways. RESULTS β-agonist pretreatment prior to methacholine challenge attenuated in vivo GABA release in mouse BAL and (3)H-GABA release from depolarized BEAS-2B cells. GABA release was also decreased in BEAS-2B cells by increases in cAMP but not by Epac or tyrosine kinase activation. CONCLUSION β-agonists decrease GABA release from airway epithelium through the activation of cAMP and PKA. This has important therapeutic implications as β-agonists and GABA are important mediators of both mucus production and airway smooth muscle tone.
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Affiliation(s)
- Jennifer Danielsson
- Department of Anesthesiology, Columbia University, 630 W 168th St., P&S Box 46, New York, NY, 10032, USA.
| | - Sarah Zaidi
- Department of Pediatrics, Columbia University, New York, NY, 10032, USA
| | - Benjamin Kim
- Department of Pathology and Cell Biology, Columbia University, New York, NY, 10032, USA
| | - Hiromi Funayama
- Department of Anesthesiology, Columbia University, 630 W 168th St., P&S Box 46, New York, NY, 10032, USA
- Department of Pediatric Dentistry, Tsurumi University School of Dental Medicine, Yokohama, Japan
| | - Peter D Yim
- Department of Anesthesiology, Columbia University, 630 W 168th St., P&S Box 46, New York, NY, 10032, USA
| | - Dingbang Xu
- Department of Anesthesiology, Columbia University, 630 W 168th St., P&S Box 46, New York, NY, 10032, USA
| | - Tilla S Worgall
- Department of Pathology and Cell Biology, Columbia University, New York, NY, 10032, USA
| | - George Gallos
- Department of Anesthesiology, Columbia University, 630 W 168th St., P&S Box 46, New York, NY, 10032, USA
| | - Charles W Emala
- Department of Anesthesiology, Columbia University, 630 W 168th St., P&S Box 46, New York, NY, 10032, USA
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Muñoz-Arenas G, Paz-Bermúdez F, Báez-Cordero A, Caballero-Florán R, González-Hernández B, Florán B, Daniel Limón I. Cannabinoid CB1 receptors activation and coactivation with D2 receptors modulate GABAergic neurotransmission in the globus pallidus and increase motor asymmetry. Synapse 2014; 69:103-14. [DOI: 10.1002/syn.21796] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2014] [Revised: 11/29/2014] [Accepted: 12/03/2014] [Indexed: 11/11/2022]
Affiliation(s)
- Guadalupe Muñoz-Arenas
- Laboratorio de Neurofarmacología; Facultad de Ciencias Químicas; and Posgrado en Ciencias Químicas; Benemérita Universidad Autónoma de Puebla; Puebla 72570 México
| | - Francisco Paz-Bermúdez
- Departamento de Fisiología; Biofísica y Neurociencias; Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional; México
| | - Ana Báez-Cordero
- Laboratorio de Neurofarmacología; Facultad de Ciencias Químicas; and Posgrado en Ciencias Químicas; Benemérita Universidad Autónoma de Puebla; Puebla 72570 México
| | - René Caballero-Florán
- Departamento de Fisiología; Biofísica y Neurociencias; Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional; México
| | | | - Benjamín Florán
- Departamento de Fisiología; Biofísica y Neurociencias; Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional; México
| | - I. Daniel Limón
- Laboratorio de Neurofarmacología; Facultad de Ciencias Químicas; and Posgrado en Ciencias Químicas; Benemérita Universidad Autónoma de Puebla; Puebla 72570 México
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Jin XT, Paré JF, Smith Y. GABA transporter subtype 1 and GABA transporter subtype 3 modulate glutamatergic transmission via activation of presynaptic GABA(B) receptors in the rat globus pallidus. Eur J Neurosci 2012; 36:2482-92. [PMID: 22616751 DOI: 10.1111/j.1460-9568.2012.08147.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The intra-pallidal application of γ-aminobutyric acid (GABA) transporter subtype 1 (GAT-1) or GABA transporter subtype 3 (GAT-3) transporter blockers [1-(4,4-diphenyl-3-butenyl)-3-piperidinecarboxylic acid hydrochloride (SKF 89976A) or 1-[2-[tris(4-methoxyphenyl)methoxy]ethyl]-(S)-3-piperidinecarboxylic acid (SNAP 5114)] reduces the activity of pallidal neurons in monkey. This effect could be mediated through the activation of presynaptic GABA(B) heteroreceptors in glutamatergic terminals by GABA spillover following GABA transporter (GAT) blockade. To test this hypothesis, we applied the whole-cell recording technique to study the effects of SKF 89976A and SNAP 5114 on evoked excitatory postsynaptic currents (eEPSCs) in the presence of gabazine, a GABA(A) receptor antagonist, in rat globus pallidus slice preparations. Under the condition of postsynaptic GABA(B) receptor blockade by the intra-cellular application of N-(2,6-dimethylphenylcarbamoylmethyl)-triethylammonium bromide (OX314), bath application of SKF 89976A (10 μM) or SNAP 5114 (10 μM) decreased the amplitude of eEPSCs, without a significant effect on its holding current and whole cell input resistance. The inhibitory effect of GAT blockade on eEPSCs was blocked by (2S)-3-[[(1S)-1-(3,4-dichlorophenyl)ethyl]amino-2-hydroxypropyl](phenylmethyl)phosphinic acid, a GABA(B) receptor antagonist. The paired-pulse ratio of eEPSCs was increased, whereas the frequency, but not the amplitude, of miniature excitatory postsynaptic currents was reduced in the presence of either GAT blocker, demonstrating a presynaptic effect. These results suggest that synaptically released GABA can inhibit glutamatergic transmission through the activation of presynaptic GABA(B) heteroreceptors following GAT-1 or GAT-3 blockade. In conclusion, our findings demonstrate that presynaptic GABA(B) heteroreceptors in putative glutamatergic subthalamic afferents to the globus pallidus are sensitive to increases in extracellular GABA induced by GAT inactivation, thereby suggesting that GAT blockade represents a potential mechanism by which overactive subthalamopallidal activity may be reduced in parkinsonism.
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Affiliation(s)
- Xiao-Tao Jin
- Division of Neuroscience, Yerkes National Primate Research Center, Emory University, 954 Gatewood Road NE, Atlanta, GA 30329, USA
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Jin XT, Galvan A, Wichmann T, Smith Y. Localization and Function of GABA Transporters GAT-1 and GAT-3 in the Basal Ganglia. Front Syst Neurosci 2011; 5:63. [PMID: 21847373 PMCID: PMC3148782 DOI: 10.3389/fnsys.2011.00063] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2011] [Accepted: 07/13/2011] [Indexed: 02/04/2023] Open
Abstract
GABA transporter type 1 and 3 (GAT-1 and GAT-3, respectively) are the two main subtypes of GATs responsible for the regulation of extracellular GABA levels in the central nervous system. These transporters are widely expressed in neuronal (mainly GAT-1) and glial (mainly GAT-3) elements throughout the brain, but most data obtained so far relate to their role in the regulation of GABA(A) receptor-mediated postsynaptic tonic and phasic inhibition in the hippocampus, cerebral cortex and cerebellum. Taking into consideration the key role of GABAergic transmission within basal ganglia networks, and the importance for these systems to be properly balanced to mediate normal basal ganglia function, we analyzed in detail the localization and function of GAT-1 and GAT-3 in the globus pallidus of normal and Parkinsonian animals, in order to further understand the substrate and possible mechanisms by which GABA transporters may regulate basal ganglia outflow, and may become relevant targets for new therapeutic approaches for the treatment of basal ganglia-related disorders. In this review, we describe the general features of GATs in the basal ganglia, and give a detailed account of recent evidence that GAT-1 and GAT-3 regulation can have a major impact on the firing rate and pattern of basal ganglia neurons through pre- and post-synaptic GABA(A)- and GABA(B)-receptor-mediated effects.
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Affiliation(s)
- Xiao-Tao Jin
- Division of Neuroscience, Yerkes National Primate Research Center and Department of Neurology, Emory UniversityAtlanta, GA, USA
| | - Adriana Galvan
- Division of Neuroscience, Yerkes National Primate Research Center and Department of Neurology, Emory UniversityAtlanta, GA, USA
| | - Thomas Wichmann
- Division of Neuroscience, Yerkes National Primate Research Center and Department of Neurology, Emory UniversityAtlanta, GA, USA
| | - Yoland Smith
- Division of Neuroscience, Yerkes National Primate Research Center and Department of Neurology, Emory UniversityAtlanta, GA, USA
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9
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Jin XT, Paré JF, Smith Y. Differential localization and function of GABA transporters, GAT-1 and GAT-3, in the rat globus pallidus. Eur J Neurosci 2011; 33:1504-18. [PMID: 21410779 DOI: 10.1111/j.1460-9568.2011.07636.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
GABA transporter subtype 1 (GAT-1) and GABA transporter subtype 3 (GAT-3) are the main transporters that regulate inhibitory GABAergic transmission in the mammalian brain through GABA reuptake. In this study, we characterized the ultrastructural localizations and determined the respective roles of these transporters in regulating evoked inhibitory postsynaptic currents (eIPSCs) in globus pallidus (GP) neurons after striatal stimulation. In the young and adult rat GP, GAT-1 was preferentially expressed in unmyelinated axons, whereas GAT-3 was almost exclusively found in glial processes. Except for rare instances of GAT-1 localization, neither of the two transporters was significantly expressed in GABAergic terminals in the rat GP. 1-(4,4-Diphenyl-3-butenyl)-3-piperidinecarboxylic acid hydrochloride (SKF 89976A) (10 μm), a GAT-1 inhibitor, significantly prolonged the decay time, but did not affect the amplitude, of eIPSCs induced by striatal stimulation (15-20 V). On the other hand, the semi-selective GAT-3 inhibitor 1-(2-[tris(4-methoxyphenyl)methoxy]ethyl)-(S)-3-piperidinecarboxylic acid (SNAP 5114) (10 μm) increased the amplitude and prolonged the decay time of eIPSCs. The effects of transporter blockade on the decay time and amplitude of eIPSCs were further increased when both inhibitors were applied together. Furthermore, SKF 89976A or SNAP 5114 blockade also increased the amplitude and frequency of spontaneous IPSCs, but did not affect miniature IPSCs. Significant GABA(A) receptor-mediated tonic currents were induced in the presence of high concentrations of both SKF 89976A (30 μm) and SNAP 5114 (30 μm). In conclusion, these data indicate that GAT-1 and GAT-3 represent different target sites through which GABA reuptake may subserve complementary regulation of GABAergic transmission in the rat GP.
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Affiliation(s)
- Xiao-Tao Jin
- Yerkes National Primate Research Center, Emory University, Atlanta, GA 30329, USA.
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Cristóvão-Ferreira S, Vaz SH, Ribeiro JA, Sebastião AM. Adenosine A2A receptors enhance GABA transport into nerve terminals by restraining PKC inhibition of GAT-1. J Neurochem 2009; 109:336-47. [DOI: 10.1111/j.1471-4159.2009.05963.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Gonzalez B, Paz F, Florán L, Aceves J, Erlij D, Florán B. Cannabinoid agonists stimulate [3H]GABA release in the globus pallidus of the rat when G(i) protein-receptor coupling is restricted: role of dopamine D2 receptors. J Pharmacol Exp Ther 2008; 328:822-8. [PMID: 19106171 DOI: 10.1124/jpet.108.145425] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The motor effects of cannabinoids in the globus pallidus appear to be caused by increases in interstitial GABA. To elucidate the mechanism of this response, we investigated the effect of the selective cannabinoid type 1 receptor (CB1) cannabinoid agonist arachidonyl-2-chloroethylamide (ACEA) on [(3)H]GABA release in slices of the rat globus pallidus. ACEA had two effects: concentrations between 10(-8) and 10(-6) M stimulated release, whereas higher concentrations (IC(50) approximately 10(-6) M) inhibited it. Another cannabinoid agonist, WIN-55,212-2, also had bimodal effects on release. Studies of cAMP production indicate that under conditions of low G(i/o), availability the coupling of CB1 receptors with G(i/o) proteins can be changed into CB1:G(s/olf) coupling; therefore, we determined the effects of conditions that limit G(i/o) availability on [(3)H]GABA release. Blockers of G(i/o) protein interactions, pertussis toxin and N-ethylmaleimide, transformed the inhibitory effects of ACEA on GABA release into stimulation. It also has been suggested that stimulation of D2 receptors can reduce G(i/o) availability. Blocking D2 receptors with sulpiride [(S)-5-aminosulfonyl-N-[(1-ethyl-2-pyrrolidinyl)methyl]-2-methoxybenzamidersqb] or depleting dopamine with reserpine inhibited the ACEA-induced stimulation of release. Thus, the D2 dependence of stimulation is consistent with the proposal that D2 receptors reduce G(i/o) proteins available for binding to the CB1 receptor. In summary, CB1 receptor activation has dual effects on GABA release in the globus pallidus. Low concentrations stimulate release through a process that depends on activation of dopamine D2 receptors that may limit G(i/o) protein availability. Higher concentrations of cannabinoid inhibit GABA release through mechanisms that are independent of D2 receptor activation.
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Affiliation(s)
- Brenda Gonzalez
- Departamento de Fisiología, Biofísica y Neurociencias, Centro de Investigación y de Estudios Avanzados del InstitutoPolitécnico Nacional, Mexico
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Simola N, Fenu S, Baraldi PG, Tabrizi MA, Morelli M. Blockade of globus pallidus adenosine A(2A) receptors displays antiparkinsonian activity in 6-hydroxydopamine-lesioned rats treated with D(1) or D(2) dopamine receptor agonists. Synapse 2008; 62:345-51. [PMID: 18297692 DOI: 10.1002/syn.20504] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
We have recently demonstrated how antagonism of adenosine A(2A) receptors within the globus pallidus (GP) ipsilateral to dopaminergic denervation potentiates contralateral rotational behavior induced by the dopamine precursor L-DOPA in 6-hydroxydopamine-lesioned hemiparkinsonian rats. To further characterize the influence of pallidal A(2A) receptor blockade on the motor stimulant effects elicited by dopamine receptor activation, hemiparkinsonian rats were infused with the water-soluble A(2A) antagonist SCH BT2 in the GP, alone or in combination with systemic administration of either SKF 38393 or quinpirole, to stimulate dopamine D(1) or D(2) receptors, respectively. SCH BT2 alone (5 mug/1 mul) neither altered motor behavior nor produced postural asymmetry. In contrast, the contralateral rotations elicited by SKF 38393 (1.5 mg/kg) as well as quinpirole (0.05 mg/kg) were potentiated by the concomitant intrapallidal infusion of SCH BT2. The results of this study demonstrate that blockade of pallidal A(2A) receptors exerts a facilitatory influence on the motor effects produced by the selective stimulation of either D(1) or D(2) dopamine receptors in hemiparkinsonian rats and suggest an involvement of GP in the antiparkinsonian activity of A(2A) receptor antagonists.
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Affiliation(s)
- Nicola Simola
- Department of Toxicology, University of Cagliari, 09124 Cagliari, Italy
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Galvan A, Kuwajima M, Smith Y. Glutamate and GABA receptors and transporters in the basal ganglia: what does their subsynaptic localization reveal about their function? Neuroscience 2006; 143:351-75. [PMID: 17059868 PMCID: PMC2039707 DOI: 10.1016/j.neuroscience.2006.09.019] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2006] [Revised: 09/10/2006] [Accepted: 09/13/2006] [Indexed: 01/29/2023]
Abstract
GABA and glutamate, the main transmitters in the basal ganglia, exert their effects through ionotropic and metabotropic receptors. The dynamic activation of these receptors in response to released neurotransmitter depends, among other factors, on their precise localization in relation to corresponding synapses. The use of high resolution quantitative electron microscope immunocytochemical techniques has provided in-depth description of the subcellular and subsynaptic localization of these receptors in the CNS. In this article, we review recent findings on the ultrastructural localization of GABA and glutamate receptors and transporters in monkey and rat basal ganglia, at synaptic, extrasynaptic and presynaptic sites. The anatomical evidence supports numerous potential locations for receptor-neurotransmitter interactions, and raises important questions regarding mechanisms of activation and function of synaptic versus extrasynaptic receptors in the basal ganglia.
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Affiliation(s)
- A Galvan
- Yerkes National Primate Research Center, Emory University, Atlanta, GA 30322, USA.
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