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Neel AI, Wang Y, Sun H, Liontis KE, McCormack MC, Mayer JC, Cervera Juanes RP, Davenport AT, Grant KA, Daunais JD, Chen R. Differential regulation of G protein-coupled receptor-associated proteins in the caudate and the putamen of cynomolgus macaques following chronic ethanol drinking. J Neurochem 2024. [PMID: 38783749 DOI: 10.1111/jnc.16134] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2024] [Revised: 04/16/2024] [Accepted: 05/08/2024] [Indexed: 05/25/2024]
Abstract
The dorsal striatum is composed of the caudate nucleus and the putamen in human and non-human primates. These two regions receive different cortical projections and are functionally distinct. The caudate is involved in the control of goal-directed behaviors, while the putamen is implicated in habit learning and formation. Previous reports indicate that ethanol differentially influences neurotransmission in these two regions. Because neurotransmitters primarily signal through G protein-coupled receptors (GPCRs) to modulate neuronal activity, the present study aimed to determine whether ethanol had a region-dependent impact on the expression of proteins that are involved in the trafficking and function of GPCRs, including G protein subunits and their effectors, protein kinases, and elements of the cytoskeleton. Western blotting was performed to examine protein levels in the caudate and the putamen of male cynomolgus macaques that self-administered ethanol for 1 year under free access conditions, along with control animals that self-administered an isocaloric sweetened solution under identical operant conditions. Among the 18 proteins studied, we found that the levels of one protein (PKCβ) were increased, and 13 proteins (Gαi1/3, Gαi2, Gαo, Gβ1γ, PKCα, PKCε, CaMKII, GSK3β, β-actin, cofilin, α-tubulin, and tubulin polymerization promoting protein) were reduced in the caudate of alcohol-drinking macaques. However, ethanol did not alter the expression of any proteins examined in the putamen. These observations underscore the unique vulnerability of the caudate nucleus to changes in protein expression induced by chronic ethanol exposure. Whether these alterations are associated with ethanol-induced dysregulation of GPCR function and neurotransmission warrants future investigation.
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Affiliation(s)
- Anna I Neel
- Department of Translational Neuroscience, Wake Forest University School of Medicine, Winston Salem, North Carolina, USA
| | - Yutong Wang
- Department of Translational Neuroscience, Wake Forest University School of Medicine, Winston Salem, North Carolina, USA
| | - Haiguo Sun
- Department of Translational Neuroscience, Wake Forest University School of Medicine, Winston Salem, North Carolina, USA
| | - Katherine E Liontis
- Department of Translational Neuroscience, Wake Forest University School of Medicine, Winston Salem, North Carolina, USA
| | - Mary C McCormack
- Department of Translational Neuroscience, Wake Forest University School of Medicine, Winston Salem, North Carolina, USA
| | - Jonathan C Mayer
- Department of Translational Neuroscience, Wake Forest University School of Medicine, Winston Salem, North Carolina, USA
| | - Rita P Cervera Juanes
- Department of Translational Neuroscience, Wake Forest University School of Medicine, Winston Salem, North Carolina, USA
| | - April T Davenport
- Department of Translational Neuroscience, Wake Forest University School of Medicine, Winston Salem, North Carolina, USA
| | - Kathleen A Grant
- Division of Neuroscience Oregon National Primate Research Center, Oregon Health & Science University, Portland, Oregon, USA
| | - James D Daunais
- Department of Translational Neuroscience, Wake Forest University School of Medicine, Winston Salem, North Carolina, USA
| | - Rong Chen
- Department of Translational Neuroscience, Wake Forest University School of Medicine, Winston Salem, North Carolina, USA
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2
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Vizuete AFK, Mussulini BH, Zenki KC, Baggio S, Pasqualotto A, Rosemberg DB, Bogo MR, de Oliveira DL, Rico EP. Prolonged ethanol exposure alters glutamate uptake leading to astrogliosis and neuroinflammation in adult zebrafish brain. Neurotoxicology 2021; 88:57-64. [PMID: 34728274 DOI: 10.1016/j.neuro.2021.10.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Revised: 10/04/2021] [Accepted: 10/28/2021] [Indexed: 10/19/2022]
Abstract
High ethanol (EtOH) consumption is a serious condition that induces tremors, alcoholic psychosis, and delirium, being considered a public health problem worldwide. Prolonged EtOH exposure promotes neurodegeneration, affecting several neurotransmitter systems and transduction signaling pathways. Glutamate is the major excitatory amino acid in the central nervous system (CNS) and the extracellular glutamatergic tonus is controlled by glutamate transporters mostly located in astrocytes. Here, we explore the effects of prolonged EtOH exposure on the glutamatergic uptake system and its relationship with astroglial markers (GFAP and S100B), neuroinflammation (IL-1β and TNF-α), and brain derived neurotrophic factor (BDNF) levels in the CNS of adult zebrafish. Animals were exposed to 0.5% EtOH for 7, 14, and 28 days continuously. Glutamate uptake was significantly decreased after 7 and 14 days of EtOH exposure, returning to baseline levels after 28 days of exposure. No alterations were observed in crucial enzymatic activities linked to glutamate uptake, like Na,K-ATPase or glutamine synthetase. Prolonged EtOH exposure increased GFAP, S100B, and TNF-α levels after 14 days. Additionally, increased BDNF mRNA levels were observed after 14 and 28 days of EtOH exposure, while BDNF protein levels increased only after 28 days. Collectively, our data show markedly brain astroglial, neuroinflammatory and neurotrofic responses after an initial impairment of glutamate uptake following prolonged EtOH exposure. This neuroplasticity event could play a key role in the modulatory effect of EtOH on glutamate uptake after 28 days of continuous exposure.
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Affiliation(s)
- Adriana Fernanda Kuckartz Vizuete
- Programa de Pós-Graduação em Ciências Biológicas: Bioquímica, Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul. Rua Ramiro Barcelos 2600-Anexo, 90035-003, Porto Alegre, RS, Brazil
| | - Ben Hur Mussulini
- Programa de Pós-Graduação em Ciências Biológicas: Bioquímica, Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul. Rua Ramiro Barcelos 2600-Anexo, 90035-003, Porto Alegre, RS, Brazil
| | - Kamila Cagliari Zenki
- Programa de Pós-Graduação em Ciências Biológicas: Bioquímica, Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul. Rua Ramiro Barcelos 2600-Anexo, 90035-003, Porto Alegre, RS, Brazil
| | - Suelen Baggio
- Programa de Pós-Graduação em Ciências Biológicas: Bioquímica, Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul. Rua Ramiro Barcelos 2600-Anexo, 90035-003, Porto Alegre, RS, Brazil
| | - Amanda Pasqualotto
- Programa de Pós-Graduação em Ciências Biológicas: Bioquímica, Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul. Rua Ramiro Barcelos 2600-Anexo, 90035-003, Porto Alegre, RS, Brazil
| | - Denis Broock Rosemberg
- Programa de Pós-Graduação em Bioquímica Toxicológica, Departamento de Bioquímica e Biologia Molecular, Centro de Ciências Naturais e Exatas, Universidade Federal de Santa Maria, RS, 97105-900, Santa Maria, RS, Brazil; The International Zebrafish Neuroscience Research Consortium (ZNRC), 309 Palmer Court, Slidell, LA, 70458, USA
| | - Maurício Reis Bogo
- Programa de Pós-Graduação em Biologia Celular e Molecular, Laboratório de Neuroquímica e Psicofarmacologia, Pontifícia Universidade Católica do Rio Grande do Sul, Brazil
| | - Diogo Lösch de Oliveira
- Programa de Pós-Graduação em Ciências Biológicas: Bioquímica, Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul. Rua Ramiro Barcelos 2600-Anexo, 90035-003, Porto Alegre, RS, Brazil; The International Zebrafish Neuroscience Research Consortium (ZNRC), 309 Palmer Court, Slidell, LA, 70458, USA
| | - Eduardo Pacheco Rico
- Translational Psychiatry Laboratory, Graduate Program in Health Sciences, University of Extreme Southern Catarinense (UNESC), Criciúma, SC, Brazil.
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3
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Cuzon Carlson VC. GABA and Glutamate Synaptic Coadaptations to Chronic Ethanol in the Striatum. Handb Exp Pharmacol 2018; 248:79-112. [PMID: 29460153 DOI: 10.1007/164_2018_98] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Alcohol (ethanol) is a widely used and abused drug with approximately 90% of adults over the age of 18 consuming alcohol at some point in their lifetime. Alcohol exerts its actions through multiple neurotransmitter systems within the brain, most notably the GABAergic and glutamatergic systems. Alcohol's actions on GABAergic and glutamatergic neurotransmission have been suggested to underlie the acute behavioral effects of ethanol. The striatum is the primary input nucleus of the basal ganglia that plays a role in motor and reward systems. The effect of ethanol on GABAergic and glutamatergic neurotransmission within striatal circuitry has been thought to underlie ethanol taking, seeking, withdrawal and relapse. This chapter reviews the effects of ethanol on GABAergic and glutamatergic transmission, highlighting the dynamic changes in striatal circuitry from acute to chronic exposure and withdrawal.
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Hsieh YJ, Wu LC, Ke CC, Chang CW, Kuo JW, Huang WS, Chen FD, Yang BH, Tai HT, Chen SCJ, Liu RS. Effects of the Acute and Chronic Ethanol Intoxication on Acetate Metabolism and Kinetics in the Rat Brain. Alcohol Clin Exp Res 2017; 42:329-337. [PMID: 29205407 DOI: 10.1111/acer.13573] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Accepted: 11/20/2017] [Indexed: 10/18/2022]
Abstract
BACKGROUND Ethanol (EtOH) intoxication inhibits glucose transport and decreases overall brain glucose metabolism; however, humans with long-term EtOH consumption were found to have a significant increase in [1-11 C]-acetate uptake in the brain. The relationship between the cause and effect of [1-11 C]-acetate kinetics and acute/chronic EtOH intoxication, however, is still unclear. METHODS [1-11 C]-acetate positron emission tomography (PET) with dynamic measurement of K1 and k2 rate constants was used to investigate the changes in acetate metabolism in different brain regions of rats with acute or chronic EtOH intoxication. RESULTS PET imaging demonstrated decreased [1-11 C]-acetate uptake in rat brain with acute EtOH intoxication, but this increased with chronic EtOH intoxication. Tracer uptake rate constant K1 and clearance rate constant k2 were decreased in acutely intoxicated rats. No significant change was noted in K1 and k2 in chronic EtOH intoxication, although 6 of 7 brain regions showed slightly higher k2 than baseline. These results indicate that acute EtOH intoxication accelerated acetate transport and metabolism in the rat brain, whereas chronic EtOH intoxication status showed no significant effect. CONCLUSIONS In vivo PET study confirmed the modulatory role of EtOH, administered acutely or chronically, in [1-11 C]-acetate kinetics and metabolism in the rat brain. Acute EtOH intoxication may inhibit the transport and metabolism of acetate in the brain, whereas chronic EtOH exposure may lead to the adaptation of the rat brain to EtOH in acetate utilization. [1-11 C]-acetate PET imaging is a feasible approach to study the effect of EtOH on acetate metabolism in rat brain.
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Affiliation(s)
- Ya-Ju Hsieh
- Department of Medical Imaging and Radiological Sciences, Kaohsiung Medical University, Kaohsiung, Taiwan.,Department of Medical Research, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan
| | - Liang-Chih Wu
- National PET/Cyclotron Center, Department of Nuclear Medicine, Taipei Veterans General Hospital, Taipei, Taiwan
| | - Chien-Chih Ke
- Biomedical Imaging Research Center, National Yang-Ming University, Taipei, Taiwan.,Molecular and Genetic Imaging Core/Taiwan Mouse Clinic, National Comprehensive Mouse Phenotyping and Drug Testing Center, Taipei, Taiwan
| | - Chi-Wei Chang
- National PET/Cyclotron Center, Department of Nuclear Medicine, Taipei Veterans General Hospital, Taipei, Taiwan
| | - Jung-Wen Kuo
- Biomedical Imaging Research Center, National Yang-Ming University, Taipei, Taiwan.,Molecular and Genetic Imaging Core/Taiwan Mouse Clinic, National Comprehensive Mouse Phenotyping and Drug Testing Center, Taipei, Taiwan
| | - Wen-Sheng Huang
- National PET/Cyclotron Center, Department of Nuclear Medicine, Taipei Veterans General Hospital, Taipei, Taiwan
| | - Fu-Du Chen
- Biomedical Imaging Research Center, National Yang-Ming University, Taipei, Taiwan.,Department of Biomedical Imaging and Radiological Sciences, National Yang-Ming University, Taipei, Taiwan
| | - Bang-Hung Yang
- National PET/Cyclotron Center, Department of Nuclear Medicine, Taipei Veterans General Hospital, Taipei, Taiwan.,Department of Biomedical Imaging and Radiological Sciences, National Yang-Ming University, Taipei, Taiwan
| | - Hsiao-Ting Tai
- Department of Medical Research, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan
| | - Sharon Chia-Ju Chen
- Department of Medical Imaging and Radiological Sciences, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - Ren-Shyan Liu
- National PET/Cyclotron Center, Department of Nuclear Medicine, Taipei Veterans General Hospital, Taipei, Taiwan.,Biomedical Imaging Research Center, National Yang-Ming University, Taipei, Taiwan.,Molecular and Genetic Imaging Core/Taiwan Mouse Clinic, National Comprehensive Mouse Phenotyping and Drug Testing Center, Taipei, Taiwan.,Department of Biomedical Imaging and Radiological Sciences, National Yang-Ming University, Taipei, Taiwan.,Institute of Clinical Medicine, National Yang-Ming University, Taipei, Taiwan.,Biophotonic and Molecular Imaging Research Center, National Yang-Ming University, Taipei, Taiwan.,Department of Nuclear Medicine, Cheng-Hsin General Hospital, Taipei, Taiwan
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5
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Bell RL, Hauser S, Rodd ZA, Liang T, Sari Y, McClintick J, Rahman S, Engleman EA. A Genetic Animal Model of Alcoholism for Screening Medications to Treat Addiction. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2016; 126:179-261. [PMID: 27055615 PMCID: PMC4851471 DOI: 10.1016/bs.irn.2016.02.017] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The purpose of this review is to present up-to-date pharmacological, genetic, and behavioral findings from the alcohol-preferring P rat and summarize similar past work. Behaviorally, the focus will be on how the P rat meets criteria put forth for a valid animal model of alcoholism with a highlight on its use as an animal model of polysubstance abuse, including alcohol, nicotine, and psychostimulants. Pharmacologically and genetically, the focus will be on the neurotransmitter and neuropeptide systems that have received the most attention: cholinergic, dopaminergic, GABAergic, glutamatergic, serotonergic, noradrenergic, corticotrophin releasing hormone, opioid, and neuropeptide Y. Herein, we sought to place the P rat's behavioral and neurochemical phenotypes, and to some extent its genotype, in the context of the clinical literature. After reviewing the findings thus far, this chapter discusses future directions for expanding the use of this genetic animal model of alcoholism to identify molecular targets for treating drug addiction in general.
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Affiliation(s)
- R L Bell
- Institute of Psychiatric Research, Indiana University School of Medicine, Indianapolis, IN, United States.
| | - S Hauser
- Institute of Psychiatric Research, Indiana University School of Medicine, Indianapolis, IN, United States
| | - Z A Rodd
- Institute of Psychiatric Research, Indiana University School of Medicine, Indianapolis, IN, United States
| | - T Liang
- Indiana University School of Medicine, Indianapolis, IN, United States
| | - Y Sari
- University of Toledo, Toledo, OH, United States
| | - J McClintick
- Center for Medical Genomics, Indiana University School of Medicine, Indianapolis, IN, United States
| | - S Rahman
- Department of Pharmaceutical Sciences, South Dakota State University, Brookings, SD, United States
| | - E A Engleman
- Institute of Psychiatric Research, Indiana University School of Medicine, Indianapolis, IN, United States
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6
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Mishra D, Harrison NR, Gonzales CB, Schilström B, Konradsson-Geuken Å. Effects of age and acute ethanol on glutamatergic neurotransmission in the medial prefrontal cortex of freely moving rats using enzyme-based microelectrode amperometry. PLoS One 2015; 10:e0125567. [PMID: 25927237 PMCID: PMC4416039 DOI: 10.1371/journal.pone.0125567] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2014] [Accepted: 03/24/2015] [Indexed: 01/04/2023] Open
Abstract
Ethanol abuse during adolescence may significantly alter development of the prefrontal cortex which continues to undergo structural remodeling into adulthood. Glutamatergic neurotransmission plays an important role during these brain maturation processes and is modulated by ethanol. In this study, we investigated glutamate dynamics in the medial prefrontal cortex of freely moving rats, using enzyme-based microelectrode amperometry. We analyzed the effects of an intraperitoneal ethanol injection (1 g/kg) on cortical glutamate levels in adolescent and adult rats. Notably, basal glutamate levels decreased with age and these levels were found to be significantly different between postnatal day (PND) 28-38 vs PND 44-55 (p<0.05) and PND 28-38 vs adult animals (p<0.001). We also observed spontaneous glutamate release (transients) throughout the recordings. The frequency of transients (per hour) was significantly higher in adolescent rats (PND 28-38 and PND 44-55) compared to those of adults. In adolescent rats, post-ethanol injection, the frequency of glutamate transients decreased within the first hour (p<0.05), it recovered slowly and in the third hour there was a significant rebound increase of the frequency (p<0.05). Our data demonstrate age-dependent differences in extracellular glutamate levels in the medial prefrontal cortex and suggest that acute ethanol injections have both inhibitory and excitatory effects in adolescent rats. These effects of ethanol on the prefrontal cortex may disturb its maturation and possibly limiting individuals´ control over addictive behaviors.
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Affiliation(s)
- Devesh Mishra
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
| | - Nicholas R. Harrison
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
| | - Carolina B. Gonzales
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
| | - Björn Schilström
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
- Department of Neuroscience and Physiology, Section of Neuropsychiatry, Gothenburg University, Gothenburg, Sweden
| | - Åsa Konradsson-Geuken
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
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7
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Odeon MM, Andreu M, Yamauchi L, Grosman M, Acosta GB. Chronic postnatal stress induces voluntary alcohol intake and modifies glutamate transporters in adolescent rats. Stress 2015; 18:427-34. [PMID: 26037264 DOI: 10.3109/10253890.2015.1041909] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Postnatal stress alters stress responses for life, with serious consequences on the central nervous system (CNS), involving glutamatergic neurotransmission and development of voluntary alcohol intake. Several drugs of abuse, including alcohol and cocaine, alter glutamate transport (GluT). Here, we evaluated effects of chronic postnatal stress (CPS) on alcohol intake and brain glutamate uptake and transporters in male adolescent Wistar rats. For CPS from postnatal day (PD) 7, pups were separated from their mothers and exposed to cold stress (4 °C) for 1 h daily for 20 days; controls remained with their mothers. Then they were exposed to either voluntary ethanol (6%) or dextrose (1%) intake for 7 days (5-7 rats per group), then killed. CPS: (1) increased voluntary ethanol intake, (2) did not affect body weight gain or produce signs of toxicity with alcohol exposure, (3) increased glutamate uptake by hippocampal synaptosomes in vitro and (4) reduced protein levels (Western measurements) in hippocampus and frontal cortex of glial glutamate transporter-1 (GLT-1) and excitatory amino-acid transporter-3 (EAAT-3) but increased glutamate aspartate transporter (GLAST) levels. We propose that CPS-induced decrements in GLT-1 and EAAT-3 expression levels are opposed by activation of a compensatory mechanism to prevent excitotoxicity. A greater role for GLAST in total glutamate uptake to prevent enlarged extracellular glutamate levels is inferred. Although CPS strongly increased intake of ethanol, this had little impact on effects of CPS on brain glutamate uptake or transporters. However, the impact of early life adverse events on glutamatergic neurotransmission may underlie increased alcohol consumption in adulthood.
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Affiliation(s)
- María Mercedes Odeon
- a Institute of Pharmacological Research (ININFA), National Scientific and Technologic Research Council (CONICET), School of Pharmacy and Biochemistry, University of Buenos Aires , Buenos Aires , Argentina and
| | - Marcela Andreu
- b Laboratorio Bioquímica Médica SRL , Buenos Aires , Argentina
| | - Laura Yamauchi
- b Laboratorio Bioquímica Médica SRL , Buenos Aires , Argentina
| | | | - Gabriela Beatriz Acosta
- a Institute of Pharmacological Research (ININFA), National Scientific and Technologic Research Council (CONICET), School of Pharmacy and Biochemistry, University of Buenos Aires , Buenos Aires , Argentina and
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8
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Alhaddad H, Kim NT, Aal-Aaboda M, Althobaiti YS, Leighton J, Boddu SHS, Wei Y, Sari Y. Effects of MS-153 on chronic ethanol consumption and GLT1 modulation of glutamate levels in male alcohol-preferring rats. Front Behav Neurosci 2014; 8:366. [PMID: 25400560 PMCID: PMC4214358 DOI: 10.3389/fnbeh.2014.00366] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2014] [Accepted: 10/05/2014] [Indexed: 12/26/2022] Open
Abstract
We have recently shown that upregulation of glutamate transporter 1 (GLT1) in the brain is associated in part with reduction in ethanol intake in alcohol-preferring (P) male rats. In this study, we investigated the effects of a synthetic compound, (R)-(−)-5-methyl-1-nicotinoyl-2-pyrazoline (MS-153), known to activate GLT1 on ethanol consumption as well as GLT1 expression and certain signaling pathways in P rats. P rats were given 24-h concurrent access to 15 and 30% ethanol, water and food for 5 weeks. On week 6, P rats received MS-153 at a dose of 50 mg/kg (i.p.) or a vehicle (i.p.) for 5 consecutive days. We also tested the effect of MS-153 on daily sucrose (10%) intake. Our studies revealed a significant decrease in ethanol intake at the dose of 50 mg/kg MS-153 from Day 1 through 14. In addition, MS-153 at dose of 50 mg/kg did not induce any significant effect on sucrose intake. Importantly, we found that MS-153 upregulated the GLT1 level in the nucleus accumbens (NAc) but not in the prefrontal cortex (PFC). In accordance, we found upregulation of nuclear NFkB-65 level in NAc in MS-153-treated group, however, IkBα was downregulated in MS-153-treated group in NAc. We did not find any changes in NFkB-65 and IkBα levels in PFC. Interestingly, we revealed that p-Akt was downregulated in ethanol vehicle treated groups in the NAc; this downregulation was reversed by MS-153 treatment. We did not observe any significant differences in glutamate aspartate transporter (GLAST) expression among all groups. These findings reveal MS-153 as a GLT1 modulator that may have potential as a therapeutic drug for the treatment of alcohol dependence.
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Affiliation(s)
- Hasan Alhaddad
- Department of Pharmacology, College of Pharmacy and Pharmaceutical Sciences, University of Toledo Toledo, OH, USA
| | - Nathaniel T Kim
- Department of Chemistry, Columbia University New York, NY, USA
| | - Munaf Aal-Aaboda
- Department of Pharmacology, College of Pharmacy and Pharmaceutical Sciences, University of Toledo Toledo, OH, USA
| | - Yusuf S Althobaiti
- Department of Pharmacology, College of Pharmacy and Pharmaceutical Sciences, University of Toledo Toledo, OH, USA
| | - James Leighton
- Department of Chemistry, Columbia University New York, NY, USA
| | - Sai H S Boddu
- Department of Pharmacy Practice, College of Pharmacy and Pharmaceutical Sciences, University of Toledo Toledo, OH, USA
| | - Yangjie Wei
- Department of Pharmacy Practice, College of Pharmacy and Pharmaceutical Sciences, University of Toledo Toledo, OH, USA
| | - Youssef Sari
- Department of Pharmacology, College of Pharmacy and Pharmaceutical Sciences, University of Toledo Toledo, OH, USA
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9
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Sari Y. Role of glutamate transporter 1 in the attenuation of alcohol intake. Front Neurosci 2014; 8:200. [PMID: 25100932 PMCID: PMC4101336 DOI: 10.3389/fnins.2014.00200] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2014] [Accepted: 06/26/2014] [Indexed: 01/07/2023] Open
Affiliation(s)
- Youssef Sari
- Department of Pharmacology, College of Pharmacy and Pharmaceutical Sciences, University of Toledo Toledo, OH, USA
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10
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Clark PJ, Ghasem PR, Mika A, Day HE, Herrera JJ, Greenwood BN, Fleshner M. Wheel running alters patterns of uncontrollable stress-induced cfos mRNA expression in rat dorsal striatum direct and indirect pathways: A possible role for plasticity in adenosine receptors. Behav Brain Res 2014; 272:252-63. [PMID: 25017571 DOI: 10.1016/j.bbr.2014.07.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2014] [Revised: 05/22/2014] [Accepted: 07/03/2014] [Indexed: 01/22/2023]
Abstract
Emerging evidence indicates that adenosine is a major regulator of striatum activity, in part, through the antagonistic modulation of dopaminergic function. Exercise can influence adenosine and dopamine activity, which may subsequently promote plasticity in striatum adenosine and dopamine systems. Such changes could alter activity of medium spiny neurons and impact striatum function. The purpose of this study was twofold. The first was to characterize the effect of long-term wheel running on adenosine 1 (A1R), adenosine 2A (A2AR), dopamine 1 (D1R), and dopamine 2 (D2R) receptor mRNA expression in adult rat dorsal and ventral striatum structures using in situ hybridization. The second was to determine if changes to adenosine and dopamine receptor mRNA from running are associated with altered cfos mRNA induction in dynorphin- (direct pathway) and enkephalin- (indirect pathway) expressing neurons of the dorsal striatum following stress exposure. We report that chronic running, as well as acute uncontrollable stress, reduced A1R and A2AR mRNA levels in the dorsal and ventral striatum. Running also modestly elevated D2R mRNA levels in striatum regions. Finally, stress-induced cfos was potentiated in dynorphin and attenuated in enkephalin expressing neurons of running rats. These data suggest striatum adenosine and dopamine systems are targets for neuroplasticity from exercise, which may contribute to changes in direct and indirect pathway activity. These findings may have implications for striatum mediated motor and cognitive processes, as well as exercise facilitated stress-resistance.
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Affiliation(s)
- Peter J Clark
- Integrative Physiology, University of Colorado Boulder, 354 UCB, Boulder, CO 80309, United States.
| | - Parsa R Ghasem
- Integrative Physiology, University of Colorado Boulder, 354 UCB, Boulder, CO 80309, United States
| | - Agnieszka Mika
- Integrative Physiology, University of Colorado Boulder, 354 UCB, Boulder, CO 80309, United States
| | - Heidi E Day
- Integrative Physiology, University of Colorado Boulder, 354 UCB, Boulder, CO 80309, United States; Department of Psychology & Neuroscience, University of Colorado Boulder, Muenzinger D244, 345 UCB, Boulder, CO 80309, United States
| | - Jonathan J Herrera
- Integrative Physiology, University of Colorado Boulder, 354 UCB, Boulder, CO 80309, United States
| | - Benjamin N Greenwood
- Integrative Physiology, University of Colorado Boulder, 354 UCB, Boulder, CO 80309, United States
| | - Monika Fleshner
- Integrative Physiology, University of Colorado Boulder, 354 UCB, Boulder, CO 80309, United States
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11
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Adenosine and glutamate in neuroglial interaction: implications for circadian disorders and alcoholism. ADVANCES IN NEUROBIOLOGY 2014; 11:103-19. [PMID: 25236726 DOI: 10.1007/978-3-319-08894-5_6] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Recent studies have demonstrated that the function of glia is not restricted to the support of neuronal function. In fact, astrocytes are essential for neuronal activity in the brain and play an important role in the regulation of complex behavior. Astrocytes actively participate in synapse formation and brain information processing by releasing and uptaking glutamate, D-serine, adenosine 5'-triphosphate (ATP), and adenosine. In the central nervous system, adenosine-mediated neuronal activity modulates the actions of other neurotransmitter systems. Adenosinergic fine-tuning of the glutamate system in particular has been shown to regulate circadian rhythmicity and sleep, as well as alcohol-related behavior and drinking. Adenosine gates both photic (light-induced) glutamatergic and nonphotic (alerting) input to the circadian clock located in the suprachiasmatic nucleus of the hypothalamus. Astrocytic, SNARE-mediated ATP release provides the extracellular adenosine that drives homeostatic sleep. Acute ethanol increases extracellular adenosine, which mediates the ataxic and hypnotic/sedative effects of alcohol, while chronic ethanol leads to downregulated adenosine signaling that underlies insomnia, a major predictor of relapse. Studies using mice lacking the equilibrative nucleoside transporter 1 have illuminated how adenosine functions through neuroglial interactions involving glutamate uptake transporter GLT-1 [referred to as excitatory amino acid transporter 2 (EAAT2) in human] and possibly water channel aquaporin 4 to regulate ethanol sensitivity, reward-related motivational processes, and alcohol intake.
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Sari Y, Sreemantula SN, Lee MR, Choi DS. Ceftriaxone treatment affects the levels of GLT1 and ENT1 as well as ethanol intake in alcohol-preferring rats. J Mol Neurosci 2013; 51:779-87. [PMID: 23893122 DOI: 10.1007/s12031-013-0064-y] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2013] [Accepted: 06/27/2013] [Indexed: 12/14/2022]
Abstract
Studies have demonstrated that deletion of equilibrative nucleoside transporter 1 (ENT1) is associated with reduced glutamate transporter 1 (GLT1) level, and consequently increased ethanol intake. In this study, we measured changes in GLT1 and ENT1 levels in prefrontal cortex (PFC), and nucleus accumbens (NAc) core and shell associated with alcohol drinking in alcohol-preferring (P) rats. We examined, then, whether ceftriaxone (CEF) would affect both GLT1 and ENT1 levels in these brain regions. P rats were given 24-h concurrent access to 15 and 30% ethanol, water, and food for 5 weeks. On Week 6, P rats received 100 mg/kg CEF (i.p.) or a saline vehicle for five consecutive days. Ethanol intake was measured daily for 8 days starting on the first day of injections. We found a significant reduction in daily ethanol intake in CEF-treated group, starting on Day 2 of injections. Western blot for GLT1 and binding assay for ENT1 revealed downregulation of GLT1 level, whereas ENT1 levels were increased in the NAc core and NAc shell, respectively, but not in the PFC in saline vehicle group. Importantly, CEF treatment reversed these effects in both NAc core and shell. These findings provide evidence for potential regulatory effects of CEF on both GLT1 and ENT1 expression in reducing ethanol intake.
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Affiliation(s)
- Youssef Sari
- Department of Pharmacology, College of Pharmacy and Pharmaceutical Sciences, University of Toledo, Toledo, OH, 43614, USA,
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Rao PSS, Sari Y. Glutamate transporter 1: target for the treatment of alcohol dependence. Curr Med Chem 2013; 19:5148-56. [PMID: 22680643 DOI: 10.2174/092986712803530511] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2012] [Revised: 05/04/2012] [Accepted: 05/07/2012] [Indexed: 12/19/2022]
Abstract
Emerging evidence indicates that many aspects of alcohol and drug dependence involve changes in glutamate transmission. A number of studies have reported that drugs of abuse, including alcohol and cocaine, alter glutamate transport. Extracellular glutamate is regulated by a number of glutamate transporters in various brain regions. Of these transporters, glutamate transporter (GLT1) is a key player in the removal of most of the extracellular glutamate. Similar to neurodegenerative disease models, in which there is dysfunction of the glutamatergic excitatory system, the role of GLT1 has been tested in drug dependence models that show dysfunction of glutamate transmission. We and others have recently found that ceftriaxone, an FDA-approved drug known to elevate GLT1 expression, attenuates cue-induced cocaine relapse. Moreover, we recently found that alcohol-preferring rats treated with ceftriaxone showed a significant dosedependent reduction in alcohol consumption. We also demonstrated that ceftriaxone-induced upregulation of GLT1 expression was associated with increases in glutamate uptake in Huntington's disease mouse model. Importantly, ceftriaxone is currently in clinical trials for the treatment of amyotrophic lateral sclerosis. This review provides information about the potential therapeutic role of GLT1 for the treatment of alcohol abuse and dependence.
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Affiliation(s)
- P S S Rao
- University of Toledo, College of Pharmacy and Pharmaceutical Sciences, Department of Pharmacology, Health Science Campus, 3000 Arlington Avenue, Toledo, OH 43614, USA
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Ding ZM, Rodd ZA, Engleman EA, Bailey JA, Lahiri DK, McBride WJ. Alcohol drinking and deprivation alter basal extracellular glutamate concentrations and clearance in the mesolimbic system of alcohol-preferring (P) rats. Addict Biol 2013; 18:297-306. [PMID: 23240885 PMCID: PMC3584204 DOI: 10.1111/adb.12018] [Citation(s) in RCA: 71] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The present study determined the effects of voluntary ethanol drinking and deprivation on basal extracellular glutamate concentrations and clearance in the mesolimbic system and tested the hypothesis that chronic ethanol drinking would persistently increase basal glutamate neurotransmission. Three groups of alcohol-preferring (P) rats were used: 'water group (WG),' 'ethanol maintenance group (MG; 24-hour free choice water versus 15% ethanol)' and 'ethanol deprivation group (DG; 2 weeks of deprivation).' Quantitative microdialysis and Western blots were conducted to measure basal extracellular glutamate concentrations, clearance and proteins associated with glutamate clearance. Chronic alcohol drinking produced a 70-100% increase of basal extracellular glutamate concentrations in the posterior ventral tegmental area (4.0 versus 7.0 μM) and nucleus accumbens shell (3.0 versus 6.0 μM). Glutamate clearances were reduced by 30-40% in both regions of MG rats compared with WG rats. In addition, Western blots revealed a 40-45% decrease of excitatory amino transporter 1 (EAAT1) protein, but no significant changes in the levels of EAAT2 or cystine-glutamate antiporter in these regions of MG versus WG rats. The enhanced glutamate concentrations returned to control levels, accompanied by a recovery of glutamate clearance following deprivation. These results indicated that chronic alcohol drinking enhanced extracellular glutamate concentrations in the mesolimbic system, as a result, in part, of reduced clearance, suggesting that enhanced glutamate neurotransmission may contribute to the maintenance of alcohol drinking. However, because the increased glutamate levels returned to normal after deprivation, elevated glutamate neurotransmission may not contribute to the initiation of relapse drinking.
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Affiliation(s)
- Zheng-Ming Ding
- Institute of Psychiatric Research, Department of Psychiatry, Indiana University School of Medicine, Indianapolis, IN 46202-4887, USA.
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Sari Y, Sreemantula SN. Neuroimmunophilin GPI-1046 reduces ethanol consumption in part through activation of GLT1 in alcohol-preferring rats. Neuroscience 2012; 227:327-35. [PMID: 23059796 PMCID: PMC3505992 DOI: 10.1016/j.neuroscience.2012.10.007] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2012] [Revised: 10/01/2012] [Accepted: 10/02/2012] [Indexed: 01/13/2023]
Abstract
We have previously shown that ceftriaxone, β-lactam antibiotic known to upregulate glutamate transporter 1 (GLT1), reduced ethanol intake in alcohol-preferring (P) rats. GLT1 is a glial glutamate transporter that regulates the majority of extracellular glutamate uptake. We tested in this study the effects of neuroimmunophilin GPI-1046 (3-(3-pyridyl)-1-propyl (2S)-1-(3,3-dimethyl-1,2-dioxopentyl)-2-pyrrolidinecarboxylate), known also to upregulate GLT1 expression, in ethanol intake in P rats. Male P rats had concurrent access to free choice of 15% and 30% ethanol, water, and food for five weeks. On Week 6, P rats continued in this drinking and food regimen and they were administered either 10 or 20mg/kg GPI-1046 (i.p.), or a vehicle for five consecutive days. Body weight, ethanol intake, and water consumption were measured daily for 8 days starting on Day 1 of GPI-1046 or vehicle i.p. injections. We have also tested the effect of GPI-1046 (20mg/kg) on daily sucrose (10%) intake. The data revealed significant dose-dependent effects in the reduction of ethanol intake starting 48 h after the first treatment with GPI-1046 throughout treatment and post-treatment periods. There were also dose-dependent increases in water intake. However, GPI-1046 treatment did not affect the body weight of all animals nor sucrose intake. Importantly, GPI-1046 (20mg/kg) increased GLT1 level compared to all groups in nucleus accumbens core (NAc-core). Alternatively, GPI-1046 (10mg/kg) upregulated GLT1 level in NAc-core compared to vehicle (ethanol naïve) group. Moreover, both doses of GPI-1046 increased significantly GLT1 level in the prefrontal cortex (PFC) compared to ethanol naïve vehicle group. GPI-1046 (20mg/kg) increased GLT1 level in PFC compared to naïve control group that was exposed to water and food only. These findings demonstrated that neuroimmunophilin GPI-1046 attenuates ethanol intake in part through the upregulation of GLT1 in PFC and NAc-core.
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Affiliation(s)
- Y Sari
- University of Toledo, College of Pharmacy and Pharmaceutical Sciences, Department of Pharmacology, Toledo, OH 43614, United States.
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Franke H, Verkhratsky A, Burnstock G, Illes P. Pathophysiology of astroglial purinergic signalling. Purinergic Signal 2012; 8:629-57. [PMID: 22544529 DOI: 10.1007/s11302-012-9300-0] [Citation(s) in RCA: 147] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2011] [Accepted: 02/01/2012] [Indexed: 12/13/2022] Open
Abstract
Astrocytes are fundamental for central nervous system (CNS) physiology and are the fulcrum of neurological diseases. Astroglial cells control development of the nervous system, regulate synaptogenesis, maturation, maintenance and plasticity of synapses and are central for nervous system homeostasis. Astroglial reactions determine progression and outcome of many neuropathologies and are critical for regeneration and remodelling of neural circuits following trauma, stroke, ischaemia or neurodegenerative disorders. They secrete multiple neurotransmitters and neurohormones to communicate with neurones, microglia and the vascular walls of capillaries. Signalling through release of ATP is the most widespread mean of communication between astrocytes and other types of neural cells. ATP serves as a fast excitatory neurotransmitter and has pronounced long-term (trophic) roles in cell proliferation, growth, and development. During pathology, ATP is released from damaged cells and acts both as a cytotoxic factor and a proinflammatory mediator, being a universal "danger" signal. In this review, we summarise contemporary knowledge on the role of purinergic receptors (P2Rs) in a variety of diseases in relation to changes of astrocytic functions and nucleotide signalling. We have focussed on the role of the ionotropic P2X and metabotropic P2YRs working alone or in concert to modify the release of neurotransmitters, to activate signalling cascades and to change the expression levels of ion channels and protein kinases. All these effects are of great importance for the initiation, progression and maintenance of astrogliosis-the conserved and ubiquitous glial defensive reaction to CNS pathologies. We highlighted specific aspects of reactive astrogliosis, especially with respect to the involvement of the P2X(7) and P2Y(1)R subtypes. Reactive astrogliosis exerts both beneficial and detrimental effects in a context-specific manner determined by distinct molecular signalling cascades. Understanding the role of purinergic signalling in astrocytes is critical to identifying new therapeutic principles to treat acute and chronic neurological diseases.
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Affiliation(s)
- Heike Franke
- Rudolf Boehm Institute of Pharmacology and Toxicology, University of Leipzig, Härtelstrasse 16-18, 04107, Leipzig, Germany.
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Nam HW, McIver SR, Hinton DJ, Thakkar MM, Sari Y, Parkinson FE, Haydon PG, Choi DS. Adenosine and glutamate signaling in neuron-glial interactions: implications in alcoholism and sleep disorders. Alcohol Clin Exp Res 2012; 36:1117-25. [PMID: 22309182 DOI: 10.1111/j.1530-0277.2011.01722.x] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2011] [Accepted: 11/03/2011] [Indexed: 12/27/2022]
Abstract
Recent studies have demonstrated that the function of glia is not restricted to the support of neuronal function. Especially, astrocytes are essential for neuronal activity in the brain. Astrocytes actively participate in synapse formation and brain information processing by releasing or uptaking gliotransmitters such as glutamate, d-serine, adenosine 5'-triphosphate (ATP), and adenosine. In the central nervous system, adenosine plays an important role in regulating neuronal activity as well as in controlling other neurotransmitter systems such as GABA, glutamate, and dopamine. Ethanol (EtOH) increases extracellular adenosine levels, which regulates the ataxic and hypnotic/sedative (somnogenic) effects of EtOH. Adenosine signaling is also involved in the homeostasis of major inhibitory/excitatory neurotransmission (i.e., GABA or glutamate) through neuron-glial interactions, which regulates the effect of EtOH and sleep. Adenosine transporters or astrocytic SNARE-mediated transmitter release regulates extracellular or synaptic adenosine levels. Adenosine then exerts its function through several adenosine receptors and regulates glutamate levels in the brain. This review presents novel findings on how neuron-glial interactions, particularly adenosinergic signaling and glutamate uptake activity involving glutamate transporter 1 (GLT1), are implicated in alcoholism and sleep disorders.
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Affiliation(s)
- Hyung W Nam
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic College of Medicine, Rochester, MN 55905, USA
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Coller JK, Hutchinson MR. Implications of central immune signaling caused by drugs of abuse: mechanisms, mediators and new therapeutic approaches for prediction and treatment of drug dependence. Pharmacol Ther 2012; 134:219-45. [PMID: 22316499 DOI: 10.1016/j.pharmthera.2012.01.008] [Citation(s) in RCA: 137] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2012] [Accepted: 01/17/2012] [Indexed: 01/12/2023]
Abstract
In the past two decades a trickle of manuscripts examining the non-neuronal central nervous system immune consequences of the drugs of abuse has now swollen to a significant body of work. Initially, these studies reported associative evidence of central nervous system proinflammation resulting from exposure to the drugs of abuse demonstrating key implications for neurotoxicity and disease progression associated with, for example, HIV infection. However, more recently this drug-induced activation of central immune signaling is now understood to contribute substantially to the pharmacodynamic actions of the drugs of abuse, by enhancing the engagement of classical mesolimbic dopamine reward pathways and withdrawal centers. This review will highlight the key in vivo animal, human, biological and molecular evidence of these central immune signaling actions of opioids, alcohol, cocaine, methamphetamine, and 3,4-methylenedioxymethamphetamine (MDMA). Excitingly, this new appreciation of central immune signaling activity of drugs of abuse provides novel therapeutic interventions and opportunities to identify 'at risk' individuals through the use of immunogenetics. Discussion will also cover the evidence of modulation of this signaling by existing clinical and pre-clinical drug candidates, and novel pharmacological targets. Finally, following examination of the breadth of central immune signaling actions of the drugs of abuse highlighted here, the current known common immune signaling components will be outlined and their impact on established addiction neurocircuitry discussed, thereby synthesizing a common neuroimmune hypothesis of addiction.
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Affiliation(s)
- Janet K Coller
- Discipline of Pharmacology, School of Medical Sciences, University of Adelaide, South Australia 5005, Australia.
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Ethanol enhances neurosteroidogenesis in hippocampal pyramidal neurons by paradoxical NMDA receptor activation. J Neurosci 2011; 31:9905-9. [PMID: 21734282 DOI: 10.1523/jneurosci.1660-11.2011] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Using an antibody against 5α-reduced neurosteroids, predominantly allopregnanolone, we found that immunostaining in the CA1 region of rat hippocampal slices was confined to pyramidal neurons. This neurosteroid staining was increased following 15 min administration of 60 mm but not 20 mm ethanol, and the enhancement was blocked by finasteride and dutasteride, selective inhibitors of 5α-reductase, a key enzyme required for allopregnanolone synthesis. Consistent with a prior report indicating that N-methyl-D-aspartate (NMDA) receptor (NMDAR) activation can promote steroid production, we observed that D-2-amino-5-phosphonovalerate (APV), a competitive NMDAR antagonist, blocked the effects of 60 mm ethanol on staining. We previously reported that 60 mm ethanol inhibits the induction of long-term potentiation (LTP), a cellular model for memory formation, in the CA1 region. In the present study, LTP inhibition by 60 mm ethanol was also overcome by both the 5α-reductase inhibitors and by APV. Furthermore, the effects of ethanol on neurosteroid production and LTP were mimicked by a low concentration of NMDA (1 μm), and the ability of NMDA to inhibit LTP and to enhance neurosteroid staining was reversed by finasteride and dutasteride, as well as by APV. These results indicate that ethanol paradoxically enhances GABAergic neurosteroid production by activation of unblocked NMDARs and that acute LTP inhibition by ethanol represents a form of NMDAR-mediated metaplasticity.
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Zink M, Ferbert T, Frank ST, Seufert P, Gebicke-Haerter PJ, Spanagel R. Perinatal exposure to alcohol disturbs spatial learning and glutamate transmission-related gene expression in the adult hippocampus. Eur J Neurosci 2011; 34:457-68. [DOI: 10.1111/j.1460-9568.2011.07776.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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Ruby CL, Adams CA, Knight EJ, Nam HW, Choi DS. An essential role for adenosine signaling in alcohol abuse. ACTA ACUST UNITED AC 2011; 3:163-74. [PMID: 21054262 DOI: 10.2174/1874473711003030163] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2010] [Accepted: 09/20/2010] [Indexed: 12/16/2022]
Abstract
In the central nervous system (CNS), adenosine plays an important role in regulating neuronal activity and modulates signaling by other neurotransmitters, including GABA, glutamate, and dopamine. Adenosine suppresses neurotransmitter release, reduces neuronal excitability, and regulates ion channel function through activation of four classes of G protein-coupled receptors, A(1), A(2A), A(2B), and A(3). Central adenosine are largely controlled by nucleoside transporters, which transport adenosine levels across the plasma membrane. Adenosine has been shown to modulate cortical glutamate signaling and ventral-tegmental dopaminergic signaling, which are involved in several aspects of alcohol use disorders. Acute ethanol elevates extracellular adenosine levels by selectively inhibiting the type 1 equilibrative nucleoside transporter, ENT1. Raised adenosine levels mediate the ataxic and sedative/hypnotic effects of ethanol through activation of A(1) receptors in the cerebellum, striatum, and cerebral cortex. Recently, we have shown that pharmacological inhibition or genetic deletion of ENT1 reduces the expression of excitatory amino acid transporter 2 (EAAT2), the primary regulator of extracellular glutamate, in astrocytes. These lines of evidence support a central role for adenosine-mediated glutamate signaling and the involvement of astrocytes in regulating ethanol intoxication and preference. In this paper, we discuss recent findings on the implication of adenosine signaling in alcohol use disorders.
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Affiliation(s)
- Christina L Ruby
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic College of Medicine, 200 First Street SW, Rochester, Minnesota 55905, USA
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Sari Y, Sakai M, Weedman JM, Rebec GV, Bell RL. Ceftriaxone, a beta-lactam antibiotic, reduces ethanol consumption in alcohol-preferring rats. Alcohol Alcohol 2011; 46:239-46. [PMID: 21422004 DOI: 10.1093/alcalc/agr023] [Citation(s) in RCA: 114] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
AIMS Changes in glutamatergic transmission affect many aspects of neuroplasticity associated with ethanol and drug addiction. For instance, ethanol- and drug-seeking behavior is promoted by increased glutamate transmission in key regions of the motive circuit. We hypothesized that because glutamate transporter 1 (GLT1) is responsible for the removal of most extracellular glutamate, up-regulation or activation of GLT1 would attenuate ethanol consumption. METHODS Alcohol-preferring (P) rats were given 24 h/day concurrent access to 15 and 30% ethanol, water and food for 7 weeks. During Week 6, P rats received either 25, 50, 100 or 200 mg/kg ceftriaxone (CEF, i.p.), a β-lactam antibiotic known to elevate GLT1 expression, or a saline vehicle for five consecutive days. Water intake, ethanol consumption and body weight were measured daily for 15 days starting on Day 1 of injections. We also tested the effects of CEF (100 and 200 mg/kg, i.p.) on daily sucrose (10%) consumption as a control for motivated behavioral drinking. RESULTS Statistical analyses revealed a significant reduction in daily ethanol, but not sucrose, consumption following CEF treatment. During the post treatment period, there was a recovery of ethanol intake across days. Dose-dependent increases in water intake were manifest concurrent with the CEF-induced decreases in ethanol intake. Nevertheless, CEF did not affect body weight. An examination of a subset of the CEF-treated ethanol-drinking rats, on the third day post CEF treatment, revealed increases in GTL1 expression levels within the prefrontal cortex and nucleus accumbens. CONCLUSIONS These results indicate that CEF effectively reduces ethanol intake, possibly through activation of GLT1, and may be a potential therapeutic drug for alcohol addiction treatment.
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Affiliation(s)
- Youssef Sari
- Department of Pharmacology, College of Pharmacy and Pharmaceutical Sciences, University of Toledo, Health Science Campus, 3000 Arlington Avenue, Toledo, OH 43614, USA.
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Sivaswamy S, Neafsey EJ, Collins MA. Neuroprotective preconditioning of rat brain cultures with ethanol: potential transduction by PKC isoforms and focal adhesion kinase upstream of increases in effector heat shock proteins. Eur J Neurosci 2010; 32:1800-12. [DOI: 10.1111/j.1460-9568.2010.07451.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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Wu J, Lee MR, Choi S, Kim T, Choi DS. ENT1 regulates ethanol-sensitive EAAT2 expression and function in astrocytes. Alcohol Clin Exp Res 2010; 34:1110-7. [PMID: 20374202 DOI: 10.1111/j.1530-0277.2010.01187.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
BACKGROUND Equilibrative nucleoside transporter 1 (ENT1) and excitatory amino acid transporter 2 (EAAT2) are predominantly expressed in astrocytes where they are thought to regulate synaptic adenosine and glutamate levels. Because mice lacking ENT1 display increased glutamate levels in the ventral striatum, we investigated whether ENT1 regulates the expression and function of EAAT2 in astrocytes, which could contribute to altered glutamate levels in the striatum. METHODS We examined the effect of ENT1 inhibition and overexpression on the expression of EAAT2 using quantitative real-time PCR and measured glutamate uptake activity in cultured astrocytes. We also examined the effect of 0 to 200 mM ethanol doses for 0 to 24 hours of ethanol exposure on EAAT2 expression and glutamate uptake activity. We further examined the effect of ENT1 knockdown by a specific siRNA on ethanol-induced EAAT2 expression. RESULTS An ENT1-specific antagonist and siRNA treatments significantly reduced both EAAT2 expression and glutamate uptake activity while ENT1 overexpression up-regulated EAAT2 mRNA expression. Interestingly, 100 or 200 mM ethanol exposure increased EAAT2 mRNA expression as well as glutamate uptake activity. Moreover, we found that ENT1 knockdown inhibited the ethanol-induced EAAT2 up-regulation. CONCLUSIONS Our results suggest that ENT1 regulates glutamate uptake activity by altering EAAT2 expression and function, which might be implicated in ethanol intoxication and preference.
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Affiliation(s)
- Jinhua Wu
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic College of Medicine, Rochester, Minnesota 55905, USA
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Mulholland PJ, Carpenter-Hyland EP, Woodward JJ, Chandler LJ. Ethanol disrupts NMDA receptor and astroglial EAAT2 modulation of Kv2.1 potassium channels in hippocampus. Alcohol 2009; 43:45-50. [PMID: 19185209 DOI: 10.1016/j.alcohol.2008.10.001] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2008] [Revised: 09/24/2008] [Accepted: 10/02/2008] [Indexed: 11/24/2022]
Abstract
Delayed-rectifier Kv2.1 channels are the principal component of voltage-sensitive K+ currents (I(K)) in hippocampal neurons and are critical regulators of somatodendritic excitability. In a recent study, we demonstrated that surface trafficking and phosphorylation of Kv2.1 channels is modulated by NMDA-type glutamate receptors and that astroglial excitatory amino acid transporters 2 (EAAT2) regulate the coupling of NMDA receptors and Kv2.1 channels. Because ethanol is known to acutely inhibit NMDA receptors, we sought to determine if NMDA receptor and astroglial EAAT2 modulation of Kv2.1 channels is impaired by ethanol in the rodent hippocampus. As expected, bath application of NMDA to hippocampal cultures reduced the size of Kv2.1 clusters and produced a hyperpolarizing shift in the voltage-dependent activation of I(K) that was associated with dephosphorylated Kv2.1 channels. Ethanol, applied acutely, prevented the hyperpolarizing shift in activation of I(K) induced by NMDA and restored Kv2.1 clustering and phosphorylation to near control levels. Ethanol also attenuated the dephosphorylation of Kv2.1 channels produced by the EAAT2 selective inhibitor dihydrokainic acid. These data demonstrate that acute ethanol disrupts changes in Kv2.1 channels that follow NMDA receptor activation and impairs astroglial regulation of the functional coupling between NMDA receptors and Kv2.1 channels.
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Yoo SY, Kim JH, Do SH, Zuo Z. Inhibition of the Activity of Excitatory Amino Acid Transporter 4 Expressed inXenopusOocytes After Chronic Exposure to Ethanol. Alcohol Clin Exp Res 2008; 32:1292-8. [DOI: 10.1111/j.1530-0277.2008.00697.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Park HY, Kim JH, Zuo Z, Do SH. Ethanol increases the activity of rat excitatory amino acid transporter type 4 expressed in Xenopus oocytes: role of protein kinase C and phosphatidylinositol 3-kinase. Alcohol Clin Exp Res 2008; 32:348-54. [PMID: 18226120 DOI: 10.1111/j.1530-0277.2007.00577.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
BACKGROUND Glutamate is the major excitatory neurotransmitter in the central nervous system and is critical for essentially all physiological processes, such as learning, memory, central pain transduction, and control of motor function. Excitatory amino acid transporters (EAATs) play a key role in regulating glutamate neurotransmission by uptake of glutamate into cells. EAAT4 is the major EAAT in the cerebellar Purkinje cells. The authors investigated the effects of ethanol on EAAT4 and the mediatory effects of protein kinase C (PKC) and phosphatidylinositol 3-kinase (PI3K) in this context. METHODS Excitatory amino acid transporter 4 was expressed in Xenopus oocytes by injecting EAAT4 mRNA. l-aspartate-induced membrane currents were measured using a two-electrode voltage clamp. Responses were quantified by integrating current traces and are represented in microCoulombs (microC). RESULTS Ethanol increased EAAT4 activity in a dose-dependent manner. At ethanol concentrations of 25, 50, 100, and 200 mM, the responses were significantly higher than untreated control values. Ethanol (25 mM) significantly increased the V(max) (1.5 +/- 0.1 microC for control vs. 2.0 +/- 0.1 microC for ethanol, p < 0.05), but did not affect K(m) (2.3 +/- 0.6 microM for control vs. 1.7 +/- 0.7 microM for ethanol, p > 0.05) of EAAT4 for l-aspartate. Preincubation of oocytes with phorbol-12-myristate-13-acetate (PMA, a PKC activator) significantly increased EAAT4 activity. However, combinations of PMA and ethanol versus PMA or ethanol alone did not increase responses further. Two PKC inhibitors, chelerythrine and staurosporine did not reduce basal EAAT4 activity but abolished ethanol-enhanced EAAT4 activity. Pretreatment with wortmannin (a PI3K inhibitor) also abolished ethanol-enhanced EAAT4 activity. CONCLUSIONS These results demonstrate that acute ethanol exposure increases EAAT4 activity at clinically relevant concentrations and that PKC and PI3K may mediate this. The effects of ethanol on EAAT4 may play a role in the cerebellar dysfunction caused by ethanol intoxication.
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Affiliation(s)
- Hee-Yeon Park
- Department of Anesthesiology & Pain Medicine, Seoul National University Bundang Hospital, Gyeonggi-do, Korea
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Gass JT, Olive MF. Glutamatergic substrates of drug addiction and alcoholism. Biochem Pharmacol 2008; 75:218-65. [PMID: 17706608 PMCID: PMC2239014 DOI: 10.1016/j.bcp.2007.06.039] [Citation(s) in RCA: 355] [Impact Index Per Article: 22.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2007] [Revised: 06/22/2007] [Accepted: 06/26/2007] [Indexed: 12/20/2022]
Abstract
The past two decades have witnessed a dramatic accumulation of evidence indicating that the excitatory amino acid glutamate plays an important role in drug addiction and alcoholism. The purpose of this review is to summarize findings on glutamatergic substrates of addiction, surveying data from both human and animal studies. The effects of various drugs of abuse on glutamatergic neurotransmission are discussed, as are the effects of pharmacological or genetic manipulation of various components of glutamate transmission on drug reinforcement, conditioned reward, extinction, and relapse-like behavior. In addition, glutamatergic agents that are currently in use or are undergoing testing in clinical trials for the treatment of addiction are discussed, including acamprosate, N-acetylcysteine, modafinil, topiramate, lamotrigine, gabapentin and memantine. All drugs of abuse appear to modulate glutamatergic transmission, albeit by different mechanisms, and this modulation of glutamate transmission is believed to result in long-lasting neuroplastic changes in the brain that may contribute to the perseveration of drug-seeking behavior and drug-associated memories. In general, attenuation of glutamatergic transmission reduces drug reward, reinforcement, and relapse-like behavior. On the other hand, potentiation of glutamatergic transmission appears to facilitate the extinction of drug-seeking behavior. However, attempts at identifying genetic polymorphisms in components of glutamate transmission in humans have yielded only a limited number of candidate genes that may serve as risk factors for the development of addiction. Nonetheless, manipulation of glutamatergic neurotransmission appears to be a promising avenue of research in developing improved therapeutic agents for the treatment of drug addiction and alcoholism.
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Affiliation(s)
- Justin T Gass
- Center for Drug and Alcohol Programs, Department of Psychiatry and Behavioral Sciences, Medical University of South Carolina, Charleston, SC 29425, USA
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Kim JH, Do SH, Kim YL, Zuo Z. Effects of chronic exposure to ethanol on glutamate transporter EAAT3 expressed in Xenopus oocytes: evidence for protein kinase C involvement. Alcohol Clin Exp Res 2006; 29:2046-52. [PMID: 16340463 DOI: 10.1097/01.alc.0000187594.92476.07] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND Glutamate transporters (excitatory amino acid transporters, EAAT) regulate extracellular concentrations of glutamate, a major excitatory neurotransmitter. We reported that acute ethanol exposure increases the activity of a major neuronal EAAT, EAAT3. This effect is consistent with the general inhibitory effect of acute alcohol toxicity in the central nervous system (CNS). However, chronic ethanol exposure has CNS presentations different from acute alcohol toxicity. We hypothesize that chronic ethanol exposure will affect the EAAT3 activity differently from acute ethanol exposure. METHODS EAAT3 was expressed in Xenopus oocytes by injection of EAAT3 mRNA. Oocytes were incubated with diluted ethanol for 24-96 hr. Using two-electrode voltage clamp, membrane currents were recorded after the application of L-glutamate. Responses were quantified by integration of the current trace and reported as microCoulombs (microC). RESULTS Ethanol (10-100 mM) reduced EAAT3 activity in a time-dependent and reversible manner. After a 96 hr-incubation, the activity was significantly decreased compared to the control values at any concentrations tested in this study. Kinetic study demonstrated that a 96 hr-exposure to 50 mM ethanol significantly decreased Vmax (3.6 +/- 0.3 for control versus 2.6 +/- 0.3 microC for ethanol, n = 20, p < 0.05) but had no effect on Km (57.6 +/- 12.8 for control versus 51.8 +/- 16.3 microM for ethanol, n = 20, p > 0.05) of EAAT3 for glutamate. When ethanol (50 mM for 96 hr)-treated oocytes were incubated with phorbol-12-myrisate-13-acetate (50 or 100 nM for 10 min), ethanol-induced decrease in EAAT3 activity was abolished. Preincubation of the oocytes with 100 microM chelerythrine significantly decreased EAAT3 activity (1.00 +/- 0.08 for control versus 0.51 +/- 0.09 microC for chelerythrine group, n = 18-20, p < 0.05). However, there was no statistical difference among the chelerythrine, ethanol, or chelerythrine plus ethanol groups. Likewise, staurosporine (2 microM for 1 hr) significantly decreased EAAT3 activity and there was no statistical difference among the staurosporine, ethanol, or staurosporine plus ethanol groups. CONCLUSIONS Our results show that chronic ethanol exposure decreases EAAT3 activity at clinically relevant concentrations and that this effect may be protein kinase C-dependent. Such an effect could be a neuroadaptive mechanism to overcome the inhibitory effect of ethanol on the excitatory neurotransmission.
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Affiliation(s)
- Jin-Hee Kim
- Department of Anesthesiology, Seoul National University College of Medicine, Seoul, Korea
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Adermark L, Lovinger DM. Ethanol effects on electrophysiological properties of astrocytes in striatal brain slices. Neuropharmacology 2006; 51:1099-108. [PMID: 16938316 DOI: 10.1016/j.neuropharm.2006.05.035] [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] [Received: 03/08/2006] [Revised: 05/02/2006] [Accepted: 05/25/2006] [Indexed: 11/24/2022]
Abstract
Ethanol (EtOH) is known to alter neuronal physiology, but much less is known about the actions of this drug on glial function. To this end, we examined acute effects of ethanol on resting and voltage-activated membrane currents in striatal astrocytes using rat brain slices. Ten minutes exposure to 50mM EtOH reduced slope conductance by 20%, increased input resistance by 25% and decreased capacitance by 38% but did not affect resting membrane potential. Current generated by a hyperpolarizing pulse was inhibited in a concentration dependent manner in passive astrocytes, while no significant EtOH effect was observed in complex astrocytes or neurons. The EtOH effect was blocked when intracellular KCl was replaced with CsCl, but not during chelation of intracellular calcium with BAPTA. During blockage of gap junction coupling with high intracellular CaCl(2) or extracellular carbenoxolone the EtOH effect persisted but was reduced. Interestingly, EtOH effects were largely irreversible when gap junctions were open, but were fully reversible when gap junctions were closed. Ethanol also reduced the spread to other cells of Lucifer Yellow dye from individual glia filled via the patch pipette. These data suggest that EtOH inhibits a calcium-insensitive potassium channel, most likely a passive potassium channel, but also affects gap junction coupling in a way that is sustained after ethanol withdrawal. Astrocytes play a critical role in brain potassium homeostasis, and therefore EtOH effects on astrocytic function could influence neuronal activity.
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Affiliation(s)
- Louise Adermark
- Section on Synaptic Pharmacology, Laboratory for Integrative Neuroscience, NIAAA/NIH, 5625 Fishers Lane, TS-13, Bethesda, MD 20892, USA
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Melendez RI, Hicks MP, Cagle SS, Kalivas PW. Ethanol exposure decreases glutamate uptake in the nucleus accumbens. Alcohol Clin Exp Res 2005; 29:326-33. [PMID: 15770106 DOI: 10.1097/01.alc.0000156086.65665.4d] [Citation(s) in RCA: 160] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND An increased level of extracellular glutamate is a key neurochemical feature associated with ethanol exposure and withdrawal. METHODS In the current study, extracellular levels of glutamate and glutamate transport in the nucleus accumbens were assayed 24 hr after repeated ethanol exposure (1 g/kg ip daily for 7 days) with use of in vivo no-net-flux microdialysis and in vitro [(3)H]glutamate uptake, respectively. RESULTS Microdialysis revealed higher extracellular glutamate concentrations in the nucleus accumbens of rats that were given ethanol. The increase in basal extracellular glutamate levels was accounted for in part by a decrease in the in vivo probe recovery of glutamate. Moreover, an in vitro accumbens slice preparation measuring [(3)H]glutamate uptake revealed that Na(+)-dependent [(3)H]glutamate uptake was significantly reduced 24 hr after 7 days of repeated ethanol exposure. The ethanol-induced deficit in glutamate uptake was not associated with decreased total tissue levels of the transporters GLAST or GLT1. The in vivo and in vitro ethanol-induced changes in glutamate levels and uptake returned to control levels 14 days after discontinuing 7 days of repeated ethanol exposure. CONCLUSIONS These results suggest that the previously reported increases in extracellular glutamate induced by ethanol exposure may be due in part to deficits in glutamate transport.
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Affiliation(s)
- Roberto I Melendez
- Department of Physiology and Neuroscience, Medical University of South Carolina, 173 Ashley Avenue, Charleston, SC 29425, USA.
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Zink M, Schmitt A, Vengeliene V, Henn FA, Spanagel R. Ethanol induces expression of the glutamate transporters EAAT1 and EAAT2 in organotypic cortical slice cultures. Alcohol Clin Exp Res 2005; 28:1752-7. [PMID: 15547463 DOI: 10.1097/01.alc.0000145810.12545.b3] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND Exposure of the developing brain to ethanol disposes the fetus to fetal alcohol syndrome and causes a number of changes in several neurochemical systems. In particular, the glutamatergic system is affected by ethanol. Thus, increased sensitivity of glutamate receptors and enhanced transmembrane transport of glutamate were found in primary astrocyte cultures. However, in these in vitro studies, changes in the expression of glutamate transporters were not detected. To further characterize the influence of chronic ethanol exposure on the developing brain, we assessed the transcriptional and translational regulation of glutamate transporters in a less artificial in vitro system. METHODS We exposed postnatal rat cortical organotypic slice cultures to ethanol (100 mM) for 4 and 8 days. Expression of the excitatory amino acid transporters EAAT1 and EAAT2 was analyzed in comparison to untreated controls with semiquantitative reverse transcriptase-polymerase chain reaction. In addition, changes in protein expression were detected by Western blotting. RESULTS In ethanol-exposed cortical slices, we observed more prominent fiber outgrowth and significantly increased gene expression (EAAT1: +35%, p = 0.029; EAAT2: +251%, p = 0.015). These findings could be verified on the protein level, because Western blot analysis revealed significantly higher levels of EAAT1 (+76%; p = 0.008) and EAAT2 (+104%; p = 0.018) in ethanol-treated slices compared with controls. CONCLUSIONS Our results are in concert with earlier studies describing the induction of glutamate transport by ethanol. Enhanced expression of EAAT1 and EAAT2 after ethanol exposure can be viewed as a maladaptive process that disposes the developing brain to fetal alcohol syndrome.
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Affiliation(s)
- Mathias Zink
- Central Institute of Mental Health, P.O. Box 12 21 20, D-68072 Mannheim, Germany.
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Peng L, Huang R, Yu ACH, Fung KY, Rathbone MP, Hertz L. Nucleoside transporter expression and function in cultured mouse astrocytes. Glia 2005; 52:25-35. [PMID: 15892125 DOI: 10.1002/glia.20216] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Uptake of purine and pyrimidine nucleosides in astrocytes is important for several reasons: (1) uptake of nucleosides contributes to nucleic acid synthesis; (2) astrocytes synthesize AMP, ADP, and ATP from adenosine and GTP from guanosine; and (3) adenosine and guanosine function as neuromodulators, whose effects are partly terminated by cellular uptake. It has previously been shown that adenosine is rapidly accumulated by active uptake in astrocytes (Hertz and Matz, Neurochem Res 14:755-760, 1989), but the ratio between active uptake and metabolism-driven uptake of adenosine is unknown, as are uptake characteristics for guanosine. The present study therefore aims at providing detailed information of nucleoside transport and transporters in primary cultures of mouse astrocytes. Reverse transcription-polymerase chain reaction identified the two equilibrative nucleoside transporters, ENT1 and ENT2, together with the concentrative nucleoside transporter CNT2, whereas CNT3 was absent, and CNT1 expression could not be investigated. Uptake studies of tritiated thymidine, formycin B, guanosine, and adenosine (3-s uptakes at 1-4 degrees C to study diffusional uptake and 1-60-min uptakes at 37 degrees C to study concentrative uptake) demonstrated a fast diffusional uptake of all four nucleosides, a small, Na(+)-independent and probably metabolism-driven uptake of thymidine (consistent with DNA synthesis), larger metabolism-driven uptakes of guanosine (consistent with synthesis of DNA, RNA, and GTP) and especially of adenosine (consistent with rapid nucleotide synthesis), and Na(+)-dependent uptakes of adenosine (consistent with its concentrative uptake) and guanosine, rendering neuromodulator uptake independent of nucleoside metabolism. Astrocytes are accordingly well suited for both intense nucleoside metabolism and metabolism-independent uptake to terminate neuromodulator effects of adenosine and guanosine.
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Affiliation(s)
- Liang Peng
- Hong Kong DNA Chips, Ltd., Kowloon, Hong Kong, China
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Kim JH, Lim YJ, Ro YJ, Min SW, Kim CS, Do SH, Kim YL, Zuo Z. Effects of Ethanol on the Rat Glutamate Excitatory Amino Acid Transporter Type 3 Expressed in Xenopus Oocytes: Role of Protein Kinase C and Phosphatidylinositol 3-Kinase. Alcohol Clin Exp Res 2003; 27:1548-53. [PMID: 14574224 DOI: 10.1097/01.alc.0000092061.92393.79] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND Glutamate is a major excitatory neurotransmitter in the central nervous system. Glutamate transporters play a critical role in maintaining extracellular glutamate concentrations. We investigated the effects of ethanol on a neuronal glutamate transporter, excitatory amino acid transporter type 3 (EAAT3), and the role of protein kinase C (PKC) and phosphatidylinositol 3-kinase (PI3 K) in mediating these effects. METHODS EAAT3 was expressed in Xenopus oocytes by injection of EAAT3 messenger RNA. By using a two-electrode voltage clamp, membrane currents were recorded after the application of l-glutamate. Responses were quantified by integration of the current trace and reported as microcoulombs. Data are mean +/- SEM. RESULTS Ethanol enhanced EAAT3 activity in a concentration-dependent manner. At 25, 50, 100, and 200 mM of ethanol, the responses were significantly increased compared with control values. Kinetic study demonstrated that ethanol (50 mM) significantly increased Vmax (3.48 +/- 0.2 microC for control versus 4.16 +/- 0.24 microC for ethanol; n = 19; p < 0.05) without a significant change in the Km (65.6 +/- 11.1 microM for control versus 55.8 +/- 9.6 microM for ethanol; n = 19; p > 0.05) of EAAT3 for glutamate. Preincubation of the oocytes with phorbol-12-myristate-13-acetate (PMA) significantly increased EAAT3 activity (0.98 +/- 0.08 muC for control versus 1.28 +/- 0.09 microC for ethanol; n = 19; p < 0.05). However, there was no statistical difference among the responses of EAAT3 to PMA, ethanol, or PMA plus ethanol. Although the PKC inhibitors chelerythrine and staurosporine did not decrease the basal EAAT3 activity, they abolished the enhancement of EAAT3 activity by ethanol. Pretreatment with wortmannin, a PI3 K inhibitor, also abolished the ethanol-enhanced EAAT3 activity. CONCLUSIONS These results suggest that acute ethanol exposure increases EAAT3 activity at clinically relevant concentrations and that PKC and PI3 K may be involved in mediating these ethanol effects.
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Affiliation(s)
- Jin-Hee Kim
- Department of Anesthesiology, Seoul City Boramae Hospital, Seoul, Korea
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