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Ashton MK, Rueda AVL, Ho AM, Noor Aizin NABM, Sharma H, Dodd PR, Stadlin A, Camarini R. Sex differences in GABA A receptor subunit transcript expression are mediated by genotype in subjects with alcohol-related cirrhosis of the liver. GENES, BRAIN, AND BEHAVIOR 2022; 21:e12785. [PMID: 35301805 PMCID: PMC9744570 DOI: 10.1111/gbb.12785] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Revised: 11/17/2021] [Accepted: 11/18/2021] [Indexed: 11/29/2022]
Abstract
Male and female human subjects show contrasting propensities to misuse drugs of addiction, including alcohol. These differences lead to different psychological and neurological consequences, such as the likelihood of developing dependence. The pattern and extent of brain damage in alcohol-use disorder cases also varies with comorbid disease. To explore mechanisms that might underlie these outcomes, we used autopsy tissue to determine mRNA transcript expression in relation to genotype for two GABAA receptor subunit genes. We used quantitative Real-Time PCR to measure GABRA6 and GABRA2 mRNA concentrations in dorsolateral prefrontal and primary motor cortices of alcohol-use disorder subjects and controls of both sexes with and without liver disease who had been genotyped for these GABAA receptor subunit genes. Cirrhotic alcohol-use disorder cases had significantly higher expression of GABRA6 and GABRA2 transcripts than either controls or non-cirrhotic alcohol-use disorder cases. Differences were observed between sexes, genotypes and brain regions. We show that sex differences in subjects with GABRA6 and GABRA2 variants may contribute to differences in susceptibility to alcohol-use disorder and alcohol-induced cirrhosis.
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Affiliation(s)
- Madeline K. Ashton
- School of Chemistry and Molecular BiosciencesThe University of QueenslandBrisbaneQueenslandAustralia
| | - André V. L. Rueda
- School of Chemistry and Molecular BiosciencesThe University of QueenslandBrisbaneQueenslandAustralia
- Departamento de Farmacologia, ICBUniversidade de São PauloSão PauloBrazil
| | - Ada M.‐C. Ho
- School of Chemistry and Molecular BiosciencesThe University of QueenslandBrisbaneQueenslandAustralia
- Department of Psychiatry and PsychologyMayo ClinicRochesterMinnesotaUSA
| | - Noradibah Arina Binte M. Noor Aizin
- School of Chemistry and Molecular BiosciencesThe University of QueenslandBrisbaneQueenslandAustralia
- Vela Research Singapore Pte LtdThe KendallSingapore
| | - Hansa Sharma
- School of Chemistry and Molecular BiosciencesThe University of QueenslandBrisbaneQueenslandAustralia
| | - Peter R. Dodd
- School of Chemistry and Molecular BiosciencesThe University of QueenslandBrisbaneQueenslandAustralia
| | | | - Rosana Camarini
- Departamento de Farmacologia, ICBUniversidade de São PauloSão PauloBrazil
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2
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Miguel-Hidalgo JJ. Astroglia in the Vulnerability and Maintenance of Alcohol Use Disorders. ADVANCES IN NEUROBIOLOGY 2021; 26:255-279. [PMID: 34888838 DOI: 10.1007/978-3-030-77375-5_11] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Changes induced in the morphology and the multiplicity of functional roles played by astrocytes in brain regions critical to the establishment and maintenance of alcohol abuse suggest that they make an important contribution to the vulnerability to alcohol use disorders. The understanding of the relevant mechanisms accounting for that contribution is complicated by the fact that alcohol itself acts directly on astrocytes altering their metabolism, gene expression, and plasticity, so that the ultimate result is a complex interaction of various cellular pathways, including intracellular calcium regulation, neuroimmune responses, and regulation of neurotransmitter and gliotransmitter release and uptake. The recent years have seen a steady increase in the characterization of several of the relevant mechanisms, but much remains to be done for a full understanding of the astrocytes' contribution to the vulnerability to alcohol dependence and abuse and for using that knowledge in designing effective therapies for AUDs.
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Affiliation(s)
- José Javier Miguel-Hidalgo
- Department of Psychiatry and Human Behavior, University of Mississippi Medical Center, Jackson, MS, USA.
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3
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Role of glutamatergic system and mesocorticolimbic circuits in alcohol dependence. Prog Neurobiol 2018; 171:32-49. [PMID: 30316901 DOI: 10.1016/j.pneurobio.2018.10.001] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2018] [Revised: 09/08/2018] [Accepted: 10/08/2018] [Indexed: 02/06/2023]
Abstract
Emerging evidence demonstrates that alcohol dependence is associated with dysregulation of several neurotransmitters. Alterations in dopamine, glutamate and gamma-aminobutyric acid release are linked to chronic alcohol exposure. The effects of alcohol on the glutamatergic system in the mesocorticolimbic areas have been investigated extensively. Several studies have demonstrated dysregulation in the glutamatergic systems in animal models exposed to alcohol. Alcohol exposure can lead to an increase in extracellular glutamate concentrations in mesocorticolimbic brain regions. In addition, alcohol exposure affects the expression and functions of several glutamate receptors and glutamate transporters in these brain regions. In this review, we discussed the effects of alcohol exposure on glutamate receptors, glutamate transporters and glutamate homeostasis in each area of the mesocorticolimbic system. In addition, we discussed the genetic aspect of alcohol associated with glutamate and reward circuitry. We also discussed the potential therapeutic role of glutamate receptors and glutamate transporters in each brain region for the treatment of alcohol dependence. Finally, we provided some limitations on targeting the glutamatergic system for potential therapeutic options for the treatment alcohol use disorders.
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Silva CP, Horton WJ, Caruso MJ, Sebastian A, Klein LC, Albert I, Kamens HM. The influence of adolescent nicotine exposure on ethanol intake and brain gene expression. PLoS One 2018; 13:e0198935. [PMID: 29912970 PMCID: PMC6005571 DOI: 10.1371/journal.pone.0198935] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2018] [Accepted: 05/29/2018] [Indexed: 01/14/2023] Open
Abstract
Nicotine and alcohol are often co-abused. Adolescence is a vulnerable period for the initiation of both nicotine and alcohol use, which can lead to subsequent neurodevelopmental and behavioral alterations. It is possible that during this vulnerable period, use of one drug leads to neurobiological alterations that affect subsequent consumption of the other drug. The aim of the present study was to determine the effect of nicotine exposure during adolescence on ethanol intake, and the effect of these substances on brain gene expression. Forty-three adolescent female C57BL/6J mice were assigned to four groups. In the first phase of the experiment, adolescent mice (PND 36-41 days) were exposed to three bottles filled with water or nicotine (200 μg/ml) for 22 h a day and a single bottle of water 2 h a day for six days. In the second phase (PND 42-45 days), the 4-day Drinking-in-the-Dark paradigm consisting of access to 20% v/v ethanol or water for 2h or 4h (the last day) was overlaid during the time when the mice did not have nicotine available. Ethanol consumption (g/kg) and blood ethanol concentrations (BEC, mg %) were measured on the final day and whole brains including the cerebellum, were dissected for RNA sequencing. Differentially expressed genes (DEG) were detected with CuffDiff and gene networks were built using WGCNA. Prior nicotine exposure increased ethanol consumption and resulting BEC. Significant DEG and biological pathways found in the group exposed to both nicotine and ethanol included genes important in stress-related neuropeptide signaling, hypothalamic-pituitary-adrenal (HPA) axis activity, glutamate release, GABA signaling, and dopamine release. These results replicate our earlier findings that nicotine exposure during adolescence increases ethanol consumption and extends this work by examining gene expression differences which could mediate these behavioral effects.
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Affiliation(s)
- Constanza P. Silva
- Biobehavioral Health Department, Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - William J. Horton
- Department of Animal Science, Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Michael J. Caruso
- Biobehavioral Health Department, Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Aswathy Sebastian
- Biochemistry and Molecular Biology, Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Laura C. Klein
- Biobehavioral Health Department, Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Istvan Albert
- Biochemistry and Molecular Biology, Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Helen M. Kamens
- Biobehavioral Health Department, Pennsylvania State University, University Park, Pennsylvania, United States of America
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5
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Miguel-Hidalgo JJ. Molecular Neuropathology of Astrocytes and Oligodendrocytes in Alcohol Use Disorders. Front Mol Neurosci 2018; 11:78. [PMID: 29615864 PMCID: PMC5869926 DOI: 10.3389/fnmol.2018.00078] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2017] [Accepted: 02/28/2018] [Indexed: 12/16/2022] Open
Abstract
Postmortem studies reveal structural and molecular alterations of astrocytes and oligodendrocytes in both the gray and white matter (GM and WM) of the prefrontal cortex (PFC) in human subjects with chronic alcohol abuse or dependence. These glial cellular changes appear to parallel and may largely explain structural and functional alterations detected using neuroimaging techniques in subjects with alcohol use disorders (AUDs). Moreover, due to the crucial roles of astrocytes and oligodendrocytes in neurotransmission and signal conduction, these cells are very likely major players in the molecular mechanisms underpinning alcoholism-related connectivity disturbances between the PFC and relevant interconnecting brain regions. The glia-mediated etiology of alcohol-related brain damage is likely multifactorial since metabolic, hormonal, hepatic and hemodynamic factors as well as direct actions of ethanol or its metabolites have the potential to disrupt distinct aspects of glial neurobiology. Studies in animal models of alcoholism and postmortem human brains have identified astrocyte markers altered in response to significant exposures to ethanol or during alcohol withdrawal, such as gap-junction proteins, glutamate transporters or enzymes related to glutamate and gamma-aminobutyric acid (GABA) metabolism. Changes in these proteins and their regulatory pathways would not only cause GM neuronal dysfunction, but also disturbances in the ability of WM axons to convey impulses. In addition, alcoholism alters the expression of astrocyte and myelin proteins and of oligodendrocyte transcription factors important for the maintenance and plasticity of myelin sheaths in WM and GM. These changes are concomitant with epigenetic DNA and histone modifications as well as alterations in regulatory microRNAs (miRNAs) that likely cause profound disturbances of gene expression and protein translation. Knowledge is also available about interactions between astrocytes and oligodendrocytes not only at the Nodes of Ranvier (NR), but also in gap junction-based astrocyte-oligodendrocyte contacts and other forms of cell-to-cell communication now understood to be critical for the maintenance and formation of myelin. Close interactions between astrocytes and oligodendrocytes also suggest that therapies for alcoholism based on a specific glial cell type pathology will require a better understanding of molecular interactions between different cell types, as well as considering the possibility of using combined molecular approaches for more effective therapies.
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Affiliation(s)
- José J Miguel-Hidalgo
- Department of Psychiatry and Human Behavior, University of Mississippi Medical Center, Jackson, MS, United States
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6
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Chen J, Ma Y, Fan R, Yang Z, Li MD. Implication of Genes for the N-Methyl-D-Aspartate (NMDA) Receptor in Substance Addictions. Mol Neurobiol 2018; 55:7567-7578. [PMID: 29429049 DOI: 10.1007/s12035-018-0877-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2017] [Accepted: 01/07/2018] [Indexed: 12/17/2022]
Abstract
Drug dependence is a chronic brain disease with harmful consequences for both individual users and society. Glutamate is a primary excitatory neurotransmitter in the brain, and both in vivo and in vitro experiments have implicated N-methyl-D-aspartate (NMDA) receptor, a glutamate receptor, as an element in various types of addiction. Recent findings from genetics-based approaches such as genome-wide linkage, candidate gene association, genome-wide association (GWA), and next-generation sequencing have demonstrated the significant association of NMDA receptor subunit genes such as GluN3A, GluN2B, and GluN2A with various addiction-related phenotypes. Of these genes, GluN3A has been the most studied, and it has been revealed to play crucial roles in the etiology of addictions. In this communication, we provide an updated view of the genetic effects of NMDA receptor subunit genes and their functions in the etiology of addictions based on the findings from investigation of both common and rare variants as well as SNP-SNP interactions. To better understand the molecular mechanisms underlying addiction-related behaviors and to promote the development of specific medicines for the prevention and treatment of addictions, current efforts aim not only to identify more causal variants in NMDA receptor subunits by using large independent samples but also to reveal the molecular functions of these variants in addictions.
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Affiliation(s)
- Jiali Chen
- State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Zhejiang University School of Medicine, Hangzhou, China
| | - Yunlong Ma
- State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Zhejiang University School of Medicine, Hangzhou, China
| | - Rongli Fan
- State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Zhejiang University School of Medicine, Hangzhou, China
| | - Zhongli Yang
- State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Zhejiang University School of Medicine, Hangzhou, China.
| | - Ming D Li
- State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Zhejiang University School of Medicine, Hangzhou, China. .,Research Center for Air Pollution and Health, Zhejiang University, Hangzhou, China. .,Institute of NeuroImmune Pharmacology, Seton Hall University, South Orange, NJ, USA.
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7
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Sun Y, Zhan L, Cheng X, Zhang L, Hu J, Gao Z. The Regulation of GluN2A by Endogenous and Exogenous Regulators in the Central Nervous System. Cell Mol Neurobiol 2016; 37:389-403. [PMID: 27255970 DOI: 10.1007/s10571-016-0388-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2016] [Accepted: 05/25/2016] [Indexed: 12/25/2022]
Abstract
The NMDA receptor is the most widely studied ionotropic glutamate receptor, and it is central to many physiological and pathophysiological processes in the central nervous system. GluN2A is one of the two main types of GluN2 NMDA receptor subunits in the forebrain. The proper activity of GluN2A is important to brain function, as the abnormal regulation of GluN2A may induce some neuropsychiatric disorders. This review will examine the regulation of GluN2A by endogenous and exogenous regulators in the central nervous system.
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Affiliation(s)
- Yongjun Sun
- Department of Pharmacy, Hebei University of Science and Technology, Yuhua East Road 70, Shijiazhuang, 050018, People's Republic of China.,Hebei Research Center of Pharmaceutical and Chemical Engineering, Hebei University of Science and Technology, Shijiazhuang, 050018, People's Republic of China
| | - Liying Zhan
- Department of Pharmacy, Hebei University of Science and Technology, Yuhua East Road 70, Shijiazhuang, 050018, People's Republic of China
| | - Xiaokun Cheng
- North China Pharmaceutical Group New Drug Research and Development Co., Ltd, Shijiazhuang, 050015, People's Republic of China
| | - Linan Zhang
- Department of Pathophysiology, Hebei Medical University, Shijiazhuang, 050017, People's Republic of China
| | - Jie Hu
- School of Nursing, Hebei Medical University, Shijiazhuang, 050017, People's Republic of China
| | - Zibin Gao
- Department of Pharmacy, Hebei University of Science and Technology, Yuhua East Road 70, Shijiazhuang, 050018, People's Republic of China. .,Hebei Research Center of Pharmaceutical and Chemical Engineering, Hebei University of Science and Technology, Shijiazhuang, 050018, People's Republic of China. .,State Key Laboratory Breeding Base-Hebei Province Key Laboratory of Molecular Chemistry for Drug, Shijiazhuang, 050018, People's Republic of China.
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8
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Xiang Y, Kim KY, Gelernter J, Park IH, Zhang H. Ethanol upregulates NMDA receptor subunit gene expression in human embryonic stem cell-derived cortical neurons. PLoS One 2015; 10:e0134907. [PMID: 26266540 PMCID: PMC4534442 DOI: 10.1371/journal.pone.0134907] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2015] [Accepted: 07/16/2015] [Indexed: 01/16/2023] Open
Abstract
Chronic alcohol consumption may result in sustained gene expression alterations in the brain, leading to alcohol abuse or dependence. Because of ethical concerns of using live human brain cells in research, this hypothesis cannot be tested directly in live human brains. In the present study, we used human embryonic stem cell (hESC)-derived cortical neurons as in vitro cellular models to investigate alcohol-induced expression changes of genes involved in alcohol metabolism (ALDH2), anti-apoptosis (BCL2 and CCND2), neurotransmission (NMDA receptor subunit genes: GRIN1, GRIN2A, GRIN2B, and GRIN2D), calcium channel activity (ITPR2), or transcriptional repression (JARID2). hESCs were differentiated into cortical neurons, which were characterized by immunostaining using antibodies against cortical neuron-specific biomarkers. Ethanol-induced gene expression changes were determined by reverse-transcription quantitative polymerase chain reaction (RT-qPCR). After a 7-day ethanol (50 mM) exposure followed by a 24-hour ethanol withdrawal treatment, five of the above nine genes (including all four NMDA receptor subunit genes) were highly upregulated (GRIN1: 1.93-fold, P = 0.003; GRIN2A: 1.40-fold, P = 0.003; GRIN2B: 1.75-fold, P = 0.002; GRIN2D: 1.86-fold, P = 0.048; BCL2: 1.34-fold, P = 0.031), and the results of GRIN1, GRIN2A, and GRIN2B survived multiple comparison correction. Our findings suggest that alcohol responsive genes, particularly NMDA receptor genes, play an important role in regulating neuronal function and mediating chronic alcohol consumption-induced neuroadaptations.
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Affiliation(s)
- Yangfei Xiang
- Department of Genetics, Yale University School of Medicine, New Haven, CT, United States of America
| | - Kun-Yong Kim
- Department of Genetics, Yale University School of Medicine, New Haven, CT, United States of America
| | - Joel Gelernter
- Department of Genetics, Yale University School of Medicine, New Haven, CT, United States of America
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT, United States of America
- Department of Neurobiology, Yale University School of Medicine, New Haven, CT, United States of America
- VA Medical Center, VA Connecticut Healthcare System, West Haven, CT, United States of America
| | - In-Hyun Park
- Department of Genetics, Yale University School of Medicine, New Haven, CT, United States of America
- * E-mail: (HZ); (IHP)
| | - Huiping Zhang
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT, United States of America
- VA Medical Center, VA Connecticut Healthcare System, West Haven, CT, United States of America
- * E-mail: (HZ); (IHP)
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9
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Nair SS, Prathibha P, Syam Das S, Kavitha S, Indira M. All trans retinoic acid (ATRA) mediated modulation of N-methyl D-aspartate receptor (NMDAR) and Kruppel like factor 11 (KLF11) expressions in the mitigation of ethanol induced alterations in the brain. Neurochem Int 2015; 83-84:41-7. [PMID: 25754253 DOI: 10.1016/j.neuint.2015.02.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2015] [Revised: 02/19/2015] [Accepted: 02/28/2015] [Indexed: 10/23/2022]
Abstract
BACKGROUND Damaging effects that chronic ethanol exposure causes to the brain and the neurons are well documented. Ethanol and its toxic metabolites increase the oxidative stress in brain. Chronic exposure to ethanol leads to upregulation of N-methyl D-aspartate receptors (NMDAR) and also activates Kruppel like factor 11 (KLF11) mediated death cascade and thereby neurodegeneration. OBJECTIVE Ethanol depletes vitamin A stores. But supplementation of vitamin A exacerbates ethanol induced toxicity since alcohol and its metabolites are competitive inhibitors of the enzymes involved in the metabolism of vitamin A. Hence, in this study we investigated the impact of co-administration of ethanol and all trans retinoic acid (ATRA), active metabolite of vitamin A, on ethanol induced alterations to the brain. MATERIALS AND METHODS Male Sprague Dawley rats, adolescent, were grouped as follows and maintained for 90 days. I - Control, II - Ethanol (4 g/kg b.w.), III - ATRA (100 µg/kg b.w.), IV - Ethanol (4 g/kg b.w.), +ATRA (100 µg/kg b.w.). Oxidative stress and the mRNA expression of various receptors for the neurotransmitter involved in glutamergic, serotonergic and gabaergic pathways were studied in the brain homogenate. RESULTS Ethanol treatment was shown to decrease brain weight and it was increased on ATRA treatment. Increase in oxidative stress due to ethanol treatment was also brought down on ATRA administration. Ethanol induced upregulation of NMDAR and KLF11 was also downregulated on ATRA supplementation. The alterations in the levels of neurotransmitters and the expression of their receptors due to ethanol treatment also were ameliorated on ATRA supplementation. CONCLUSION Our results show that ATRA supplementation mitigates the ethanol induced alterations in the brain by reducing oxidative stress in the brain with concurrent suppression of NMDAR and KLF11 expression leading to enhanced catabolism of neurotransmitters.
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Affiliation(s)
- Saritha S Nair
- Department of Biochemistry, University of Kerala, Kariavattom, Thiruvananthapuram-695 581, Kerala, India
| | - P Prathibha
- Department of Biochemistry, University of Kerala, Kariavattom, Thiruvananthapuram-695 581, Kerala, India
| | - S Syam Das
- Department of Biochemistry, University of Kerala, Kariavattom, Thiruvananthapuram-695 581, Kerala, India
| | - S Kavitha
- Department of Biochemistry, University of Kerala, Kariavattom, Thiruvananthapuram-695 581, Kerala, India
| | - M Indira
- Department of Biochemistry, University of Kerala, Kariavattom, Thiruvananthapuram-695 581, Kerala, India.
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10
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Barker JM, Taylor JR. Habitual alcohol seeking: modeling the transition from casual drinking to addiction. Neurosci Biobehav Rev 2014; 47:281-94. [PMID: 25193245 PMCID: PMC4258136 DOI: 10.1016/j.neubiorev.2014.08.012] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2014] [Revised: 07/17/2014] [Accepted: 08/25/2014] [Indexed: 12/29/2022]
Abstract
The transition from goal-directed actions to habitual ethanol seeking models the development of addictive behavior that characterizes alcohol use disorders. The progression to habitual ethanol-seeking behavior occurs more rapidly than for natural rewards, suggesting that ethanol may act on habit circuit to drive the loss of behavioral flexibility. This review will highlight recent research that has focused on the formation and expression of habitual ethanol seeking, and the commonalities and distinctions between ethanol and natural reward-seeking habits, with the goal of highlighting important, understudied research areas that we believe will lead toward the development of novel treatment and prevention strategies for uncontrolled drinking.
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Affiliation(s)
- Jacqueline M Barker
- Department of Psychiatry, Yale University School of Medicine, Ribicoff Labs, New Haven, CT, USA; Interdepartmental Neuroscience Program, Yale University School of Medicine, New Haven, CT, USA
| | - Jane R Taylor
- Interdepartmental Neuroscience Program, Yale University School of Medicine, New Haven, CT, USA.
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11
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Jin Z, Bhandage AK, Bazov I, Kononenko O, Bakalkin G, Korpi ER, Birnir B. Expression of specific ionotropic glutamate and GABA-A receptor subunits is decreased in central amygdala of alcoholics. Front Cell Neurosci 2014; 8:288. [PMID: 25278838 PMCID: PMC4165314 DOI: 10.3389/fncel.2014.00288] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2014] [Accepted: 08/29/2014] [Indexed: 01/20/2023] Open
Abstract
The central amygdala (CeA) has a role for mediating fear and anxiety responses. It is also involved in emotional imbalance caused by alcohol abuse and dependence and in regulating relapse to alcohol abuse. Growing evidences suggest that excitatory glutamatergic and inhibitory γ-aminobutyric acid-ergic (GABAergic) transmissions in the CeA are affected by chronic alcohol exposure. Human post-mortem CeA samples from male alcoholics (n = 9) and matched controls (n = 9) were assayed for the expression level of ionotropic glutamate and GABA-A receptors subunit mRNAs using quantitative real-time reverse transcription-PCR (RT-qPCR). Our data revealed that out of the 16 ionotropic glutamate receptor subunits, mRNAs encoding two AMPA [2-amino-3-(3-hydroxy-5-methyl-isoxazol-4-yl)propanoic acid] receptor subunits GluA1 and GluA4; one kainate receptor subunit GluK2; one NMDA (N-methyl-D-aspartate) receptor subunit GluN2D and one delta receptor subunit GluD2 were significantly decreased in the CeA of alcoholics. In contrast, of the 19 GABA-A receptor subunits, only the mRNA encoding the α2 subunit was significantly down-regulated in the CeA of the alcoholics as compared with control subjects. Our findings imply that the down-regulation of specific ionotropic glutamate and GABA-A receptor subunits in the CeA of alcoholics may represent one of the molecular substrates underlying the new balance between excitatory and inhibitory neurotransmission in alcohol dependence.
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Affiliation(s)
- Zhe Jin
- Molecular Physiology and Neuroscience Unit, Neuroscience, Biomedical Center, Uppsala University Uppsala, Sweden
| | - Amol K Bhandage
- Molecular Physiology and Neuroscience Unit, Neuroscience, Biomedical Center, Uppsala University Uppsala, Sweden
| | - Igor Bazov
- Division of Biological Research on Drug Dependence, Department of Pharmaceutical Biosciences, Uppsala University Uppsala, Sweden
| | - Olga Kononenko
- Division of Biological Research on Drug Dependence, Department of Pharmaceutical Biosciences, Uppsala University Uppsala, Sweden
| | - Georgy Bakalkin
- Division of Biological Research on Drug Dependence, Department of Pharmaceutical Biosciences, Uppsala University Uppsala, Sweden
| | - Esa R Korpi
- Pharmacology, Institute of Biomedicine, University of Helsinki Helsinki, Finland
| | - Bryndis Birnir
- Molecular Physiology and Neuroscience Unit, Neuroscience, Biomedical Center, Uppsala University Uppsala, Sweden
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12
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Janeczek P, MacKay RK, Lea RA, Dodd PR, Lewohl JM. Reduced expression of α-synuclein in alcoholic brain: influence of SNCA-Rep1 genotype. Addict Biol 2014; 19:509-15. [PMID: 22974310 DOI: 10.1111/j.1369-1600.2012.00495.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
α-Synuclein has recently been implicated in the pathophysiology of alcohol abuse due to its role in dopaminergic neurotransmission. In these studies, genetic variability in the α-synuclein gene influences its expression which may contribute to susceptibility to chronic alcohol abuse. Real-time PCR was used to quantify α-synuclein mRNA expression in autopsy samples of human dorsolateral prefrontal cortex. Because of the association between length of the α-synuclein-repeat 1 microsatellite marker and expression levels of the gene, this marker was genotyped in a Caucasian sample of 126 controls and 117 alcoholics using capillary gel electrophoresis. The allele and genotype frequencies of α-synuclein-repeat 1 marker differed significantly between alcoholics and controls. Alcoholics had greater frequencies of the shortest allele found (267 bp). The shortest allele of the α-synuclein-repeat 1 marker was associated with decreased expression of α-synuclein in prefrontal cortex. Individuals with at least one copy of the 267 bp allele were more likely to exhibit an alcohol abuse phenotype. These results suggest that individuals with the 267 bp allele may be at increased risk of developing alcoholism and that genetic variation at the α-synuclein-repeat 1 locus may influence α-synuclein expression in the prefrontal cortex.
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Affiliation(s)
- Paulina Janeczek
- Griffith Health Institute, School of Medical Sciences; Griffith University; Australia
| | - Rachel K. MacKay
- Griffith Health Institute, School of Medical Sciences; Griffith University; Australia
| | - Rodney A. Lea
- Griffith Health Institute, School of Medical Sciences; Griffith University; Australia
| | - Peter R. Dodd
- School of Chemistry and Molecular Biosciences; University of Queensland; Australia
| | - Joanne M. Lewohl
- Griffith Health Institute, School of Medical Sciences; Griffith University; Australia
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13
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Kim A, Zamora-Martinez ER, Edwards S, Mandyam CD. Structural reorganization of pyramidal neurons in the medial prefrontal cortex of alcohol dependent rats is associated with altered glial plasticity. Brain Struct Funct 2014; 220:1705-20. [PMID: 24667898 PMCID: PMC4177030 DOI: 10.1007/s00429-014-0755-3] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2013] [Accepted: 03/10/2014] [Indexed: 12/22/2022]
Abstract
In rodents, chronic intermittent ethanol vapor exposure (CIE) produces alcohol dependence, alters the activity of pyramidal neurons and decreases the number of glial progenitors in the medial prefrontal cortex (mPFC). Adult male Wistar rats were exposed to CIE and were injected with mitotic markers to label and phenotype proliferating cells to test the hypothesis that CIE produces concurrent alterations in the structure of pyramidal neurons and the cell cycle kinetics and developmental stages of glial progenitors in the mPFC. Medial prefrontal cortical tissue was processed for Golgi-Cox staining, immunohistochemistry and Western blotting analysis. CIE increased dendritic arborization and spine densities within basal and apical dendrites of pyramidal neurons via aberrant reorganization of actin cytoskeleton-associated molecules. CIE concomitantly increased the expression of total NR2B subunits without affecting phosphorylation of NR2B at Tyr-1472 or levels of PSD-95. CIE reduced the length of S-phase of the cell cycle of glial progenitors and reduced proliferation and differentiation of progenitors into bHLH transcription factor Olig2-expressing premyelinating oligodendrocyte progenitor cells (OPCs). CIE also produced a corresponding hyperphosphorylation of Olig2, and reduced expression of myelin basic protein. Our findings demonstrate that CIE-induced alterations in OPCs and myelin-related proteins are associated with profound alterations in the structure of pyramidal neurons. In sum, our results not only provide evidence that alcohol dependence leads to pathological changes in the mPFC, which may in part define a cellular basis for cognitive impairments associated with alcoholism, but also show dependence-associated morphological changes in the PFC at the single neuron level.
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Affiliation(s)
- Airee Kim
- Committee on the Neurobiology of Addictive Disorders, The Scripps Research Institute, La Jolla, CA, USA
| | - Eva R. Zamora-Martinez
- Committee on the Neurobiology of Addictive Disorders, The Scripps Research Institute, La Jolla, CA, USA
| | - Scott Edwards
- Department of Physiology, Alcohol & Drug Abuse Center of Excellence, LSU Health Sciences Center, New Orleans, LA, USA
| | - Chitra D. Mandyam
- Committee on the Neurobiology of Addictive Disorders, The Scripps Research Institute, La Jolla, CA, USA
- Skaggs School of Pharmaceutical Sciences, University of California San Diego, La Jolla, CA, USA
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14
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Abstract
RATIONALE An increasingly compelling literature points to a major role for the glutamate system in mediating the effects of alcohol on behavior and the pathophysiology of alcoholism. Preclinical studies indicate that glutamate signaling mediates certain aspects of ethanol's intoxicating and rewarding effects, and undergoes adaptations following chronic alcohol exposure that may contribute to the withdrawal, craving and compulsive drug-seeking that drive alcohol abuse and alcoholism. OBJECTIVES We discuss the potential for targeting the glutamate system as a novel pharmacotherapeutic approach to treating alcohol use disorders, focusing on five major components of the glutamate system: the N-methyl-D-aspartate (NMDA) receptor and specific NMDA subunits, the glycineB site on the NMDA receptors (NMDAR), L-alpha-amino-3-hydroxy-5-methyl-isoxazole-4-propionic acid ionotropic (AMPA) and kainate (KAR) receptors, metabotropic receptors (mGluR), and glutamate transporters. RESULTS Chronic alcohol abuse produces a hyperglutamatergic state, characterized by elevated extracellular glutamate and altered glutamate receptors and transporters. Pharmacologically manipulating glutamatergic neurotransmission alters alcohol-related behaviors including intoxication, withdrawal, and alcohol-seeking, in rodents and human subjects. Blocking NMDA and AMPA receptors reduces alcohol consumption in rodents, but side-effects may limit this as a therapeutic approach. Selectively targeting NMDA and AMPA receptor subunits (e.g., GluN2B, GluA3), or the NMDAR glycineB site offers an alternative approach. Blocking mGluR5 potently affects various alcohol-related behaviors in rodents, and mGluR2/3 agonism also suppresses alcohol consumption. Finally, glutamate transporter upregulation may mitigate behavioral and neurotoxic sequelae of excess glutamate caused by alcohol. CONCLUSIONS Despite the many challenges that remain, targeting the glutamate system offers genuine promise for developing new treatments for alcoholism.
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15
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Janeczek P, Lewohl JM. The role of α-synuclein in the pathophysiology of alcoholism. Neurochem Int 2013; 63:154-62. [PMID: 23791711 DOI: 10.1016/j.neuint.2013.06.007] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2013] [Revised: 06/06/2013] [Accepted: 06/08/2013] [Indexed: 12/14/2022]
Abstract
Alcoholism has complex etiology and there is evidence for both genetic and environmental factors in its pathophysiology. Chronic, long-term alcohol abuse and alcohol dependence are associated with neuronal loss with the prefrontal cortex being particularly susceptible to neurotoxic damage. This brain region is involved in the development and persistence of alcohol addiction and neurotoxic damage is likely to exacerbate the reinforcing effects of alcohol and may hinder treatment. Understanding the mechanism of alcohol's neurotoxic effects on the brain and the genetic risk factors associated with alcohol abuse are the focus of current research. Because of its well-established role in neurodegenerative and neuropsychological disorders, and its emerging role in the pathophysiology of addiction, here we review the genetic and epigenetic factors involved in regulating α-synuclein expression and its potential role in the pathophysiology of chronic alcohol abuse. Elucidation of the mechanisms of α-synuclein regulation may prove beneficial in understanding the role of this key synaptic protein in disease and its potential for therapeutic modulation in the treatment of substance use disorders as well as other neurodegenerative diseases.
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Affiliation(s)
- Paulina Janeczek
- Griffith Health Institute, School of Medical Sciences, Griffith University, Gold Coast Campus, Southport, Australia
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16
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Predominance of D2 receptors in mediating dopamine's effects in brain metabolism: effects of alcoholism. J Neurosci 2013; 33:4527-35. [PMID: 23467368 DOI: 10.1523/jneurosci.5261-12.2013] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Dopamine signals through D1-like and D2-like receptors, which can stimulate or inhibit, respectively, neuronal activity. Here we assessed the balance between D1 or D2 receptor signaling in the human brain and how it is affected in alcoholism. Using PET, we measured the relationship between changes in dopamine and brain glucose metabolism induced by methylphenidate in controls and alcoholics. We show that methylphenidate induced significant DA increases in striatum, amygdala, and medial orbitofrontal cortex, whereas it decreased metabolism in these brain regions. Methylphenidate-induced dopamine increases were greater in controls than in alcoholics, whereas methylphenidate-induced metabolic decreases were greater in alcoholics. For both groups, methylphenidate-induced dopamine increases were associated with decreases in regional brain metabolism, and the correlations were strongest in subthalamic nuclei, anterior cingulate, and medial orbitofrontal cortex. These correlations were more extensive and robust and the slopes steeper in alcoholics than in controls despite their attenuated dopamine responses to methylphenidate, which suggests an impaired modulation of dopamine signals in the brain of alcoholic subjects. These findings are consistent with a predominant inhibitory effect of dopamine in the human brain that is likely mediated by the prominence of dopamine D2/D3 receptors.
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17
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Lieberman R, Levine ES, Kranzler HR, Abreu C, Covault J. Pilot study of iPS-derived neural cells to examine biologic effects of alcohol on human neurons in vitro. Alcohol Clin Exp Res 2012; 36:1678-87. [PMID: 22486492 DOI: 10.1111/j.1530-0277.2012.01792.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2011] [Accepted: 01/31/2012] [Indexed: 01/06/2023]
Abstract
BACKGROUND Studies of the effects of alcohol on N-methyl-d-aspartate (NMDA) receptor function and gene expression have depended on rodent or postmortem human brain models. Ideally, the effects of alcohol might better be examined in living neural tissue derived from human subjects. In this study, we used new technologies to reprogram human subject-specific tissue into pluripotent cell colonies and generate human neural cultures as a model system to examine the molecular actions of alcohol. METHODS Induced pluripotent stem (iPS) cells were generated from skin biopsies taken from 7 individuals, 4 alcohol-dependent subjects, and 3 social drinkers. We differentiated the iPS cells into neural cultures and characterized them by immunocytochemistry using antibodies for the neuronal marker beta-III tubulin, glial marker s100β, and synaptic marker synpasin-1. Electrophysiology was performed to characterize the iPS-derived neurons and to measure the effects of acute alcohol exposure on the NMDA receptor response in chronically alcohol exposed and nonexposed neural cultures from 1 nonalcoholic. Finally, we examined changes in mRNA expression of the NMDA receptor subunit genes GRIN1, GRIN2A, GRIN2B, and GRIN2D after 7 days of alcohol exposure and after 24-hour withdrawal from chronic alcohol exposure. RESULTS Immunocytochemistry revealed positive staining for neuronal, glial, and synaptic markers. iPS-derived neurons displayed spontaneous electrical properties and functional ionotropic receptors. Acute alcohol exposure significantly attenuated the NMDA response, an effect that was not observed after 7 days of chronic alcohol exposure. After 7 days of chronic alcohol exposure, there were significant increases in mRNA expression of GRIN1, GRIN2A, and GRIN2D in cultures derived from alcoholic subjects but not in cultures derived from nonalcoholics. CONCLUSIONS These findings support the potential utility of human iPS-derived neural cultures as in vitro models to examine the molecular actions of alcohol on human neural cells.
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Affiliation(s)
- Richard Lieberman
- Graduate Program in Neuroscience, University of Connecticut Health Center, Farmington, CT 06030-1410, USA
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18
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Gilpin NW, Roberto M. Neuropeptide modulation of central amygdala neuroplasticity is a key mediator of alcohol dependence. Neurosci Biobehav Rev 2012; 36:873-88. [PMID: 22101113 PMCID: PMC3325612 DOI: 10.1016/j.neubiorev.2011.11.002] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2011] [Revised: 11/01/2011] [Accepted: 11/05/2011] [Indexed: 01/08/2023]
Abstract
Alcohol use disorders are characterized by compulsive drug-seeking and drug-taking, loss of control in limiting intake, and withdrawal syndrome in the absence of drug. The central amygdala (CeA) and neighboring regions (extended amygdala) mediate alcohol-related behaviors and chronic alcohol-induced plasticity. Acute alcohol suppresses excitatory (glutamatergic) transmission whereas chronic alcohol enhances glutamatergic transmission in CeA. Acute alcohol facilitates inhibitory (GABAergic) transmission in CeA, and chronic alcohol increases GABAergic transmission. Electrophysiology techniques are used to explore the effects of neuropeptides/neuromodulators (CRF, NPY, nociceptin, dynorphin, endocannabinoids, galanin) on inhibitory transmission in CeA. In general, pro-anxiety peptides increase, and anti-anxiety peptides decrease CeA GABAergic transmission. These neuropeptides facilitate or block the action of acute alcohol in CeA, and chronic alcohol produces plasticity in neuropeptide systems, possibly reflecting recruitment of negative reinforcement mechanisms during the transition to alcohol dependence. A disinhibition model of CeA output is discussed in the context of alcohol dependence- and anxiety-related behaviors.
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Affiliation(s)
- Nicholas W Gilpin
- Department of Physiology, Louisiana State University Health Sciences Center, 1901 Perdido Street, New Orleans, LA 70112, USA.
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19
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Ali SF, Onaivi ES, Dodd PR, Cadet JL, Schenk S, Kuhar MJ, Koob GF. Understanding the Global Problem of Drug Addiction is a Challenge for IDARS Scientists. Curr Neuropharmacol 2011; 9:2-7. [PMID: 21886551 PMCID: PMC3137181 DOI: 10.2174/157015911795017245] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2009] [Revised: 04/17/2010] [Accepted: 05/26/2010] [Indexed: 11/22/2022] Open
Abstract
IDARS is an acronym for the International Drug Abuse Research Society. Apart from our scientific and educational purposes, we communicate information to the general and scientific community about substance abuse and addiction science and treatment potential. Members of IDARS are research scientists and clinicians from around the world, with scheduled meetings across the globe. IDARS is developing a vibrant and exciting international mechanism not only for scientific interactions in the domain of addiction between countries but also ultimately as a resource for informing public policy across nations. Nonetheless, a lot more research needs to be done to better understand the neurobiological basis of drug addiction - A challenge for IDARS scientists.
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Affiliation(s)
- S F Ali
- Neurochemistry Laboratory, NCTR/FDA, Jefferson, AR, USA
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20
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Kuo SW, Dodd PR. Electrically evoked synaptosomal amino acid transmitter release in human brain in alcohol misuse. Neurosignals 2011; 19:117-27. [PMID: 21832861 DOI: 10.1159/000326842] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2011] [Accepted: 03/01/2011] [Indexed: 11/19/2022] Open
Abstract
Severe chronic alcohol misuse leads to neuropathological changes in human brain, with the greatest neuronal loss in the dorsolateral prefrontal cortex. In this region, GABA(A) receptors are selectively upregulated, and show altered subunit expression profiles only in alcoholics without comorbid disease, whereas glutamate(NMDA) subunit expression profiles are selectively downregulated only in alcoholics with comorbid cirrhosis of the liver. To determine whether these outcomes might be conditional on synaptic transmitter levels, evoked release was studied in well-characterized synaptosome suspensions preloaded with L-[(3)H]glutamate and [(14)C]GABA and stimulated electrically (±10 V contiguous square waves, 0.4 ms, 100 Hz, 1.5 min) with and without Ca(2+). Stimulation elicited brief peaks of both radioisotopes that were larger in the presence of Ca(2+) ions (p < 0.01). A repeat stimulus evoked a second, smaller (p < 0.01) peak. Ca(2+)-dependent L-[(3)H]glutamate release, but not [(14)C]GABA release, was higher overall in alcoholics than in controls (p < 0.05). With comorbid cirrhosis, L-[(3)H]glutamate release showed a graded response, whereas [(14)C]GABA release was lowest in noncirrhotic alcoholics. Release patterns did not differ between cortical regions, or between males and females. Neither age nor postmortem interval was a significant confounder. The released transmitters may differentially alter receptor profiles on postsynaptic cells.
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Affiliation(s)
- Sheng-Wen Kuo
- School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane, Qld., Australia
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21
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Villegas E, Estruch R, Mengod G, Cortés R. NMDA receptors in frontal cortex and hippocampus of alcohol consumers. Addict Biol 2011; 16:163-5. [PMID: 20192946 DOI: 10.1111/j.1369-1600.2009.00201.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Specific binding of [³H]MK801 to N-methyl-D-aspartate (NMDA) receptors in the frontal cortex and hippocampus (CA1 and gyrus dentatus) was measured by receptor autoradiography in 16 Caucasian chronic alcohol consumers free of clinical manifestations of alcoholism, and compared with 16 Caucasian control subjects. Binding densities were not significantly different between heavy and moderate drinkers, neither between alcohol consumers that were abstinent or non-abstinent before death, nor between ethanol drinkers and controls. Continued alcohol consumption, in the absence of hepatic, neurologic or psychiatric disorders related to alcoholism, does not alter the binding properties of NMDA receptors in the brain areas studied.
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Affiliation(s)
- Eulalia Villegas
- Department of Internal Medicine, Hospital Clínic, Barcelona, Spain.
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22
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Acosta G, Freidman DP, Grant KA, Hemby SE. Alternative splicing of AMPA subunits in prefrontal cortical fields of cynomolgus monkeys following chronic ethanol self-administration. Front Psychiatry 2011; 2:72. [PMID: 22291662 PMCID: PMC3249828 DOI: 10.3389/fpsyt.2011.00072] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/02/2011] [Accepted: 11/26/2011] [Indexed: 01/18/2023] Open
Abstract
Functional impairment of the orbital and medial prefrontal cortex underlies deficits in executive control that characterize addictive disorders, including alcohol addiction. Previous studies indicate that alcohol alters glutamate neurotransmission and one substrate of these effects may be through the reconfiguration of the subunits constituting ionotropic glutamate receptor (iGluR) complexes. Glutamatergic transmission is integral to cortico-cortical and cortico-subcortical communication and alcohol-induced changes in the abundance of the receptor subunits and/or their splice variants may result in critical functional impairments of prefrontal cortex in alcohol dependence. To this end, the effects of chronic ethanol self-administration on glutamate receptor ionotropic AMPA (GRIA) subunit variant and kainate (GRIK) subunit mRNA expression were studied in the orbitofrontal cortex (OFC), dorsolateral prefrontal cortex (DLPFC), and anterior cingulate cortex (ACC) of male cynomolgus monkeys. In DLPFC, total AMPA splice variant expression and total kainate receptor subunit expression were significantly decreased in alcohol drinking monkeys. Expression levels of GRIA3 flip and flop and GRIA4 flop mRNAs in this region were positively correlated with daily ethanol intake and blood ethanol concentrations (BEC) averaged over the 6 months prior to necropsy. In OFC, AMPA subunit splice variant expression was reduced in the alcohol treated group. GRIA2 flop mRNA levels in this region were positively correlated with daily ethanol intake and BEC averaged over the 6 months prior to necropsy. Results from these studies provide further evidence of transcriptional regulation of iGluR subunits in the primate brain following chronic alcohol self-administration. Additional studies examining the cellular localization of such effects in the framework of primate prefrontal cortical circuitry are warranted.
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Affiliation(s)
- Glen Acosta
- Department of Physiology and Pharmacology, Wake Forest University Winston-Salem, NC, USA
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23
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N-methyl-d-aspartic acid receptors are altered by stress and alcohol in Wistar-Kyoto rat brain. Neuroscience 2010; 169:125-31. [PMID: 20466039 DOI: 10.1016/j.neuroscience.2010.05.003] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2009] [Revised: 04/27/2010] [Accepted: 05/01/2010] [Indexed: 11/23/2022]
Abstract
Previous studies have shown that the Wistar-Kyoto (WKY) rat strain is more sensitive to stressors and consumes significant quantities of alcohol under basal as well as stressful conditions when compared to other strains. Given that the glutamate neurotransmitter system has been implicated in depression and addiction, the goals of the present study were to investigate the effects of stress and stress-alcohol interactions on N-methyl-d-aspartate (NMDA) receptors in the rat brain. Thus this study measured the binding of [(3)H] MK-801 to NMDA receptors in the prefrontal cortex (PFC), caudate putamen (CPu), nucleus accumbens (NAc), hippocampus (HIP) and basolateral amygdala (BLA) in WKY rats in comparison to the Wistar (WIS) rat strain. Our results suggested that while voluntary alcohol consumption did not alter NMDA receptors in the PFC, CPu or NAc in either rat strain, it increased NMDA receptors in the HIP and BLA in both strains. In contrast, chronic stress increased NMDA receptors in the PFC, CPu, NAc in WKY rats but not in WIS rats. Chronic stress also decreased NMDA receptors in the HIP and increased NMDA receptors in the BLA in both strains. Alcohol co-treatment with stress increased NMDA receptors in the PFC, CPu and NAc in WKY rats but not in WIS rats. Interestingly, while alcohol co-treatment did not reverse stress induced decreases in NMDA receptors in the HIP, it reduced the binding of NMDA receptors in the BLA to control levels in both strains. Thus it appears that NMDA receptors in the PFC, CPu and NAc may be more sensitive to the effects of stress and could be implicated in the stress-induced alcohol consumption behavior seen in WKY rats. In contrast, NMDA receptors in the HIP and BLA may reflect an adaptive response and may not be responsible for the stress susceptible phenotype of the WKY rat strain.
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Bartolomucci A, Carola V, Pascucci T, Puglisi-Allegra S, Cabib S, Lesch KP, Parmigiani S, Palanza P, Gross C. Increased vulnerability to psychosocial stress in heterozygous serotonin transporter knockout mice. Dis Model Mech 2010; 3:459-70. [PMID: 20371729 DOI: 10.1242/dmm.004614] [Citation(s) in RCA: 88] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Epidemiological evidence links exposure to stressful life events with increased risk for mental illness. However, there is significant individual variability in vulnerability to environmental risk factors, and genetic variation is thought to play a major role in determining who will become ill. Several studies have shown, for example, that individuals carrying the S (short) allele of the serotonin transporter (5-HTT) gene-linked polymorphic region (5-HTTLPR) have an increased risk for major depression following exposure to stress in adulthood. Identifying the molecular mechanisms underlying this gene-by-environment risk factor could help our understanding of the individual differences in resilience to stress. Here, we present a mouse model of the 5-HTT-by-stress risk factor. Wild-type and heterozygous 5-HTT knockout male mice were subjected to three weeks of chronic psychosocial stress. The 5-HTT genotype did not affect the physiological consequences of stress as measured by changes in body temperature, body weight gain and plasma corticosterone. However, when compared with wild-type littermates, heterozygous 5-HTT knockout mice experiencing high levels of stressful life events showed significantly depressed locomotor activity and increased social avoidance toward an unfamiliar male in a novel environment. Heterozygous 5-HTT knockout mice exposed to high stress also showed significantly lower levels of serotonin turnover than wild-type littermates, selectively in the frontal cortex, which is a structure that is known to control fear and avoidance responses, and that is implicated in susceptibility to depression. These data may serve as a useful animal model for better understanding the increased vulnerability to stress reported in individuals carrying the 5-HTTLPR S allele, and suggest that social avoidance represents a behavioral endophenotype of the interaction between 5-HTT and stress.
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Affiliation(s)
- Alessandro Bartolomucci
- Department of Evolutionary and Functional Biology, University of Parma, viale G.P. Usberti 11A, Parma, Italy.
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25
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Acosta G, Hasenkamp W, Daunais JB, Friedman DP, Grant KA, Hemby SE. Ethanol self-administration modulation of NMDA receptor subunit and related synaptic protein mRNA expression in prefrontal cortical fields in cynomolgus monkeys. Brain Res 2010; 1318:144-54. [PMID: 20043891 DOI: 10.1016/j.brainres.2009.12.050] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2009] [Revised: 12/14/2009] [Accepted: 12/16/2009] [Indexed: 01/18/2023]
Abstract
BACKGROUND Functional impairment of the orbital and medial prefrontal cortex underlies deficits in executive control that characterize addictive disorders, including alcohol addiction. Previous studies indicate that alcohol alters glutamate neurotransmission and one substrate of these effects may be through the reconfiguration of the subunits constituting ionotropic glutamate receptor (iGluR) complexes. Glutamatergic transmission is integral to cortico-cortical and cortico-subcortical communication, and alcohol-induced changes in the abundance of the receptor subunits and/or their splice variants may result in critical functional impairments of prefrontal cortex in the alcohol-addicted state. METHODS AND RESULTS The effects of chronic ethanol self-administration on glutamate receptor ionotropic NMDA (GRIN), as well as GRIN1 splice variant mRNA expression was studied in the orbitofrontal cortex (OFC; Area 13), dorsolateral prefrontal cortex (DLPFC; Area 46) and anterior cingulate cortex (ACC; Area 24) of male cynomolgus monkeys. Chronic ethanol self-administration resulted in significant changes in the expression of NMDA subunit mRNA expression in the DLPFC and OFC, but not the ACC. In DLPFC, the overall expression of NMDA subunits was significantly decreased in ethanol treated monkeys. Slight but significant changes were observed for synaptic associated protein 102 kD (SAP102) and neuronal nitric oxide synthase (nNOS) mRNAs. In OFC, the NMDAR1 variant GRIN1-1 was reduced while GRIN1-2 was increased. Furthermore, no significant changes in GFAP protein levels were observed in either the DLPFC or OFC. CONCLUSION Results from these studies provide the first demonstration of posttranscriptional regulation of iGluR subunits in the primate brain following long-term ethanol self-administration. Furthermore, changes in these transcripts do not appear to reflect changes in glial activation or loss. Further studies examining the expression and cellular localization of subunit proteins and receptor pharmacology would shed more light on the findings reported here.
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Affiliation(s)
- Glen Acosta
- Department of Physiology and Pharmacology, Wake Forest University, Winston-Salem, NC 27157, USA
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26
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Abstract
Heritability estimates for alcoholism range from 50% to 60%, pointing out the importance of genetic and environmental factors in its etiology. This review highlights recent advances in translational work investigating genetic influences on alcoholism. We focus on genetic research involving corticotropin-releasing factor, glutamatergic, and opioidergic systems. Variation in the CRF1 receptor gene has been shown to moderate stress-induced alcohol drinking (gene-environment interaction) in animals, and this finding was recently extended to humans. Also, the hyperglutamatergic state, first observed during withdrawal from chronic alcohol exposure in animal models, is associated with aversive and dysphoric states in alcoholics. Pharmacogenetic studies of naltrexone efficacy are in the clinical stages, and recent studies confirmed a differential response dependent on the mu-opioid receptor genotype. Such advances will be essential for the effective treatment of alcoholism in the future.
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Affiliation(s)
- David Stacey
- MRC Social, Genetic, and Developmental Psychiatry Centre, Institute of Psychiatry, King's College, P. O. Box 80, London SE58AF, England
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27
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Ridge JP, Ho AMC, Dodd PR. Sex differences in NMDA receptor expression in human alcoholics. Alcohol Alcohol 2009; 44:594-601. [PMID: 19736238 DOI: 10.1093/alcalc/agp052] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
AIM The aim of this study was to assess whether chronic alcohol misuse affects N-methyl-d-aspartate (NMDA) receptor subunit concentrations in human cases, and whether male and female subjects respond differently. METHODS Real-time RT-PCR normalized to GAPDH was used to assay NR1, NR2A and NR2B subunit mRNA in superior frontal (SFC) and primary motor (PMC) cortex tissue obtained at autopsy from chronic alcoholics with and without comorbid cirrhosis of the liver, and from matched controls. RESULTS The expression of all three subunits was significantly lower in both areas of cirrhotic alcoholics than in either controls or alcoholics without comorbid disease, who did not differ significantly. Values were also influenced by the subject's sex and genotype. The mu-opiate receptor C1031G polymorphism selectively modulated NMDA transcript expression in cirrhotic-alcoholic SFC, an effect that was more marked for NR1 and NR2A than for NR2B subunit transcripts. Contrasting 5HT1B genotypes affected NMDA mRNA expression differently in male and female SFC, but not PMC, in cirrhotic alcoholics. CONCLUSION NMDA receptor subunit expression may differentially influence male and female cirrhotic alcoholics' susceptibility to brain damage.
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Affiliation(s)
- Justin P Ridge
- School of Chemistry and Molecular Biosciences, University of Queensland, St Lucia, Brisbane, Australia
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28
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Ridge JP, Dodd PR. Cortical NMDA receptor expression in human chronic alcoholism: influence of the TaqIA allele of ANKK1. Neurochem Res 2009; 34:1775-82. [PMID: 19283474 DOI: 10.1007/s11064-009-9941-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2008] [Accepted: 02/24/2009] [Indexed: 11/24/2022]
Abstract
Real-time RT-PCR normalized to GAPDH was used to assay N-methyl-D-aspartate (NMDA) receptor NR1, NR2A and NR2B subunit mRNA in human autopsy cortex tissue from chronic alcoholics with and without comorbid cirrhosis of the liver and matched controls. Subunit expression was influenced by the subject's genotype. The TaqIA polymorphism selectively modulated NMDA receptor mean transcript expression in cirrhotic-alcoholic superior frontal cortex, in diametrically opposite ways in male and female subjects. Genetic make-up may differentially influence vulnerability to brain damage by altering the excitation: inhibition balance, particularly in alcoholics with comorbid cirrhosis of the liver. The TaqIA polymorphism occurs within the poorly characterised ankyrin-repeat containing kinase 1 (ANKK1) gene. Using PCR, ANKK1 mRNA transcript was detected in inferior temporal, occipital, superior frontal and primary motor cortex of control human brain. ANKK1 expression may mediate the influence of the TaqIA polymorphism on phenotype.
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Affiliation(s)
- Justin P Ridge
- School of Chemistry and Molecular Biosciences, University of Queensland, St. Lucia, Building #76, Brisbane, QLD 4072, Australia
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