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Oka M, Yoshino R, Kitanaka N, Hall FS, Uhl GR, Kitanaka J. Role of glycogen synthase kinase-3β in dependence and abuse liability of alcohol. Alcohol Alcohol 2024; 59:agad086. [PMID: 38145944 DOI: 10.1093/alcalc/agad086] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2023] [Revised: 11/25/2023] [Accepted: 11/28/2023] [Indexed: 12/27/2023] Open
Abstract
BACKGROUND Alcohol is a major abused drug worldwide that contributes substantially to health and social problems. These problems result from acute alcohol overuse as well as chronic use, leading to alcohol use disorder (AUD). A major goal of this field is to establish a treatment for alcohol abuse and dependence in patients with AUD. The central molecular mechanisms of acute alcohol actions have been extensively investigated in rodent models. AIMS One of the central mechanisms that may be involved is glycogen synthase kinase-3β (GSK-3β) activity, a key enzyme involved in glycogen metabolism but which has crucial roles in numerous cellular processes. Although the exact mechanisms leading from acute alcohol actions to these chronic changes in GSK-3β function are not yet clear, GSK-3β nonetheless constitutes a potential therapeutic target for AUD by reducing its function using GSK-3β inhibitors. This review is focused on the correlation between GSK-3β activity and the degree of alcohol consumption. METHODS Research articles regarding investigation of effect of GSK-3β on alcohol consumption in rodents were searched on PubMed, Embase, and Scopus databases using keywords "glycogen synthase kinase," "alcohol (or ethanol)," "intake (or consumption)," and evaluated by changes in ratios of pGSK-3βSer9/pGSK-3β. RESULTS In animal experiments, GSK-3β activity decreases in the brain under forced and voluntary alcohol consumption while GSK-3β activity increases under alcohol-seeking behavior. CONCLUSIONS Several pieces of evidence suggest that alterations in GSK-3β function are important mediators of chronic ethanol actions, including those related to alcohol dependence and the adverse effects of chronic ethanol exposure.
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Affiliation(s)
- Masahiro Oka
- Laboratory of Drug Addiction and Experimental Therapeutics, Department of Pharmacy, School of Pharmacy, Hyogo Medical University, 1-3-6 Minatojima, Chuo-ku, Kobe, Hyogo 650-8530, Japan
| | - Rui Yoshino
- Laboratory of Drug Addiction and Experimental Therapeutics, Department of Pharmacy, School of Pharmacy, Hyogo Medical University, 1-3-6 Minatojima, Chuo-ku, Kobe, Hyogo 650-8530, Japan
| | - Nobue Kitanaka
- Department of Pharmacology, School of Medicine, Hyogo Medical University, Nishinomiya, Hyogo 663-8501, Japan
| | - F Scott Hall
- Department of Pharmacology and Experimental Therapeutics, College of Pharmacy and Pharmaceutical Sciences, University of Toledo, Frederic and Mary Wolfe Center HEB 282D, Mail Stop 1015, 3000 Arlington Avenue,Toledo, OH 43614, United States
| | - George R Uhl
- Neurology Service, VA Maryland Healthcare System, 10 North Greene Street, Baltimore, MD 21201, United States
- Departments of Neurology and Pharmacology, University of Maryland School of Medicine, 655 W. Baltimore Street, Baltimore, MD 21201, United States
| | - Junichi Kitanaka
- Laboratory of Drug Addiction and Experimental Therapeutics, Department of Pharmacy, School of Pharmacy, Hyogo Medical University, 1-3-6 Minatojima, Chuo-ku, Kobe, Hyogo 650-8530, Japan
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Sayson LV, Lee HJ, Ortiz DM, Kim M, Custodio RJP, Lee CH, Lee YS, Cheong JH, Kim HJ. The differential vulnerabilities of Per2 knockout mice to the addictive properties of methamphetamine and cocaine. Prog Neuropsychopharmacol Biol Psychiatry 2023; 126:110782. [PMID: 37141987 DOI: 10.1016/j.pnpbp.2023.110782] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Revised: 04/18/2023] [Accepted: 04/30/2023] [Indexed: 05/06/2023]
Abstract
With the pervasive occurrence of substance abuse worldwide, unraveling the neuropharmacology of drugs of abuse, such as psychostimulants, is undeniably essential. Mice lacking Period 2 (Per2), a gene associated with the biological time-regulating system or circadian rhythm, have been proposed as a potential animal model for drug abuse vulnerability, demonstrating a greater preference for methamphetamine (METH) reward than wild-type (WT) mice. However, the responses of Per2 knockout (KO) mice to the reinforcing effects of METH or other psychostimulants are yet to be established. In this study, the responses of WT and Per2 KO mice to various psychostimulants via intravenous self-administration were determined, along with their behaviors in METH- or cocaine (COC)-induced conditioned place preference and spontaneous locomotion in the open-field test. Per2 KO mice exhibited greater addiction-like responses to METH and 5-EAPB (1-(1-benzofuran-5-yl)-N-ethylpropan-2-amine), but their responses to COC and dimethocaine were comparable to WT mice, indicating a divergent influence of Per2 deficiency on abuse susceptibility to specific psychostimulants. To potentially define the underlying mechanism for this phenotype, 19 differentially expressed genes were identified, through RNA sequencing, which might respond specifically to repeated METH, but not COC, administration in the mouse striatum and were narrowed down to those previously associated with immediate early genes or synaptic plasticity. The correlation between locomotor activity and mRNA expression levels revealed a moderate correlation between METH-induced behavior and Arc or Junb expression in Per2 KO mice only, suggesting their essential role that may lead to the higher vulnerability of Per2 KO mice to METH, but not COC. These findings indicate a potentially unique effect of Per2 expression level on the involvement of Arc and Junb in determining specific vulnerabilities to drugs, and possibly including abuse potential.
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Affiliation(s)
- Leandro Val Sayson
- Uimyung Research Institute for Neuroscience, Department of Pharmacy, Sahmyook University, 815 Hwarang-ro, Nowon-gu, Seoul 01795, Republic of Korea
| | - Hyun Jun Lee
- Uimyung Research Institute for Neuroscience, Department of Pharmacy, Sahmyook University, 815 Hwarang-ro, Nowon-gu, Seoul 01795, Republic of Korea
| | - Darlene Mae Ortiz
- Uimyung Research Institute for Neuroscience, Department of Pharmacy, Sahmyook University, 815 Hwarang-ro, Nowon-gu, Seoul 01795, Republic of Korea
| | - Mikyung Kim
- Department of Chemistry & Life Science, Sahmyook University, 815 Hwarang-ro, Nowon-gu, Seoul 01795, Republic of Korea
| | - Raly James Perez Custodio
- Department of Ergonomics, Leibniz Research Centre for Working Environment and Human Factors - IfADo, Ardeystr. 67, 44139 Dortmund, Germany
| | - Chae Hyeon Lee
- Medicinal Chemistry Laboratory, Department of Fundamental Pharmaceutical Sciences, College of Pharmacy, Kyung Hee University, Seoul 02447, Republic of Korea
| | - Yong Sup Lee
- Medicinal Chemistry Laboratory, Department of Fundamental Pharmaceutical Sciences, College of Pharmacy, Kyung Hee University, Seoul 02447, Republic of Korea
| | - Jae Hoon Cheong
- Institute for New Drug Development, School of Pharmacy, Jeonbuk National University, 567 Baekje-daero, Deokjin-gu, Jeonju-si, Jeollabuk-do 54896, Republic of Korea.
| | - Hee Jin Kim
- Uimyung Research Institute for Neuroscience, Department of Pharmacy, Sahmyook University, 815 Hwarang-ro, Nowon-gu, Seoul 01795, Republic of Korea.
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Turcato FC, Wegman E, Lu T, Ferguson N, Luo Y. Dopaminergic neurons are not a major Sonic hedgehog ligand source for striatal cholinergic or PV interneurons. iScience 2022; 25:105278. [PMID: 36281454 PMCID: PMC9587326 DOI: 10.1016/j.isci.2022.105278] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2022] [Revised: 08/05/2022] [Accepted: 09/30/2022] [Indexed: 11/16/2022] Open
Abstract
A model was previously proposed that DA neurons provide SHH ligand to striatal interneurons, which in turn support the survival of DA neurons through the release of trophic factors such as Glial cell-derived neurotrophic factor (GDNF). However, some key clinical observations do not support this proposed model, and a recent independent study shows that striatal cholinergic neuron survival does not rely on intact DA neuron projections. To resolve this discrepancy, we generated several independent mouse lines to examine the exact role of DA neuron-derived Shh signaling in the maintenance of the basal ganglia circuit and to identify the Shh-producing cells in the adult brain. Our data suggest that the deletion of Shh in DA neurons does not affect DA neuron survival or locomotive function in cKO mice during aging, nor does it affect the long-term survival of cholinergic or FS PV + interneurons in the striatum (STR).
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Affiliation(s)
- Flavia Correa Turcato
- Department of Molecular Genetics, Biochemistry and Microbiology, College of Medicine, University of Cincinnati, Cincinnati, OH 45267, USA
| | - Elliot Wegman
- Department of Molecular Genetics, Biochemistry and Microbiology, College of Medicine, University of Cincinnati, Cincinnati, OH 45267, USA
| | - Tao Lu
- Department of Molecular Genetics, Biochemistry and Microbiology, College of Medicine, University of Cincinnati, Cincinnati, OH 45267, USA
| | - Nathan Ferguson
- Department of Molecular Genetics, Biochemistry and Microbiology, College of Medicine, University of Cincinnati, Cincinnati, OH 45267, USA
| | - Yu Luo
- Department of Molecular Genetics, Biochemistry and Microbiology, College of Medicine, University of Cincinnati, Cincinnati, OH 45267, USA
- Neuroscience Graduate Program, University of Cincinnati, Cincinnati, OH 45267, USA
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Bowen MT, George O, Muskiewicz DE, Hall FS. FACTORS CONTRIBUTING TO THE ESCALATION OF ALCOHOL CONSUMPTION. Neurosci Biobehav Rev 2022; 132:730-756. [PMID: 34839930 PMCID: PMC8892842 DOI: 10.1016/j.neubiorev.2021.11.017] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Revised: 11/05/2021] [Accepted: 11/12/2021] [Indexed: 01/03/2023]
Abstract
Understanding factors that contribute to the escalation of alcohol consumption is key to understanding how an individual transitions from non/social drinking to AUD and to providing better treatment. In this review, we discuss how the way ethanol is consumed as well as individual and environmental factors contribute to the escalation of ethanol consumption from intermittent low levels to consistently high levels. Moreover, we discuss how these factors are modelled in animals. It is clear a vast array of complex, interacting factors influence changes in alcohol consumption. Some of these factors act early in the acquisition of ethanol consumption and initial escalation, while others contribute to escalation of ethanol consumption at a later stage and are involved in the development of alcohol dependence. There is considerable need for more studies examining escalation associated with the formation of dependence and other hallmark features of AUD, especially studies examining mechanisms, as it is of considerable relevance to understanding and treating AUD.
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Affiliation(s)
- Michael T. Bowen
- The University of Sydney, Brain and Mind Centre, Sydney, NSW, 2050, Australia,The University of Sydney, Faculty of Science, School of Psychology, Sydney, NSW, 2006, Australia,Corresponding Author: Michael T. Bowen, Brain and Mind Centre, The University of Sydney, 94 Mallett Street, Camperdown, Sydney, NSW, 2050, Australia,
| | - Olivier George
- Department of Psychology, University of California, San Diego, School of Medicine, La Jolla, CA, 92093, USA
| | - Dawn E. Muskiewicz
- Department of Pharmacology & Experimental Therapeutics, College of Pharmacology and Pharmacological Science, University of Toledo, OH, USA
| | - F. Scott Hall
- Department of Pharmacology & Experimental Therapeutics, College of Pharmacology and Pharmacological Science, University of Toledo, OH, USA
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5
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Salesse C, Charest J, Doucet-Beaupré H, Castonguay AM, Labrecque S, De Koninck P, Lévesque M. Opposite Control of Excitatory and Inhibitory Synapse Formation by Slitrk2 and Slitrk5 on Dopamine Neurons Modulates Hyperactivity Behavior. Cell Rep 2021; 30:2374-2386.e5. [PMID: 32075770 DOI: 10.1016/j.celrep.2020.01.084] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2018] [Revised: 12/03/2019] [Accepted: 01/24/2020] [Indexed: 11/26/2022] Open
Abstract
The neurodevelopmental origin of hyperactivity disorder has been suggested to involve the dopaminergic system, but the underlying mechanisms are still unknown. Here, transcription factors Lmx1a and Lmx1b are shown to be essential for midbrain dopaminergic (mDA) neuron excitatory synaptic inputs and dendritic development. Strikingly, conditional knockout (cKO) of Lmx1a/b in postmitotic mDA neurons results in marked hyperactivity. In seeking Lmx1a/b target genes, we identify positively regulated Slitrk2 and negatively regulated Slitrk5. These two synaptic adhesion proteins promote excitatory and inhibitory synapses on mDA neurons, respectively. Knocking down Slitrk2 reproduces some of the Lmx1a/b cKO cellular and behavioral phenotypes, whereas Slitrk5 knockdown has opposite effects. The hyperactivity caused by this imbalance in excitatory/inhibitory synaptic inputs on dopamine neurons is reproduced by chronically inhibiting the ventral tegmental area during development using pharmacogenetics. Our study shows that alterations in developing dopaminergic circuits strongly impact locomotor activity, shedding light on mechanisms causing hyperactivity behaviors.
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Affiliation(s)
- Charleen Salesse
- CERVO Brain Research Centre, 2601 de la Canardière, Québec, QC G1J 2G3, Canada
| | - Julien Charest
- CERVO Brain Research Centre, 2601 de la Canardière, Québec, QC G1J 2G3, Canada
| | | | | | - Simon Labrecque
- CERVO Brain Research Centre, 2601 de la Canardière, Québec, QC G1J 2G3, Canada
| | - Paul De Koninck
- CERVO Brain Research Centre, 2601 de la Canardière, Québec, QC G1J 2G3, Canada; Department of Biochemistry, Microbiology and Bioinformatics, Faculty of Science and Engineering, Université Laval, Québec, QC G1V 0A6, Canada
| | - Martin Lévesque
- CERVO Brain Research Centre, 2601 de la Canardière, Québec, QC G1J 2G3, Canada; Department of Psychiatry and Neuroscience, Faculty of Medicine, Université Laval, Québec, QC G1V 0A6, Canada.
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Tschumi CW, Daszkowski AW, Sharpe AL, Trzeciak M, Beckstead MJ. A history of ethanol drinking increases locomotor stimulation and blunts enhancement of dendritic dopamine transmission by methamphetamine. Addict Biol 2020; 25:e12763. [PMID: 31062485 DOI: 10.1111/adb.12763] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2018] [Revised: 02/15/2019] [Accepted: 03/22/2019] [Indexed: 12/19/2022]
Abstract
Ethanol and psychostimulant use disorders exhibit comorbidity in humans and cross-sensitization in animal models, but the neurobiological underpinnings of this are not well understood. Ethanol acutely increases dopamine neuron excitability, and psychostimulants such as cocaine or methamphetamine increase extracellular dopamine through inhibition of uptake through the dopamine transporter (DAT) and/or vesicular monoamine transporter 2 (VMAT2). Psychostimulants also depress dopamine neuron activity by enhancing dendritic dopamine neurotransmission. Here, we show that mice with a previous history of ethanol drinking are more sensitive to the locomotor-stimulating effects of a high dose (5 mg/kg), but not lower doses (1 and 3 mg/kg) of methamphetamine or any tested dose of cocaine (3, 10, and 18 mg/kg), compared with water-drinking controls. We next investigated the impact of a history of ethanol drinking, in a separate group of mice, on methamphetamine- or cocaine-induced enhancement of dendritic dopamine transmission using whole-cell voltage clamp electrophysiology in mouse brain slices. Methamphetamine, applied at a concentration (10 μM) that affects both DAT and VMAT2, enhanced D2 receptor-mediated inhibitory postsynaptic currents (D2-IPSCs) in both groups, but this effect was blunted in mice with a history of ethanol drinking. As methamphetamine action at VMAT2 disrupts dopamine neurotransmission, these results may suggest enhanced action of methamphetamine at VMAT2. Furthermore, there were no differences in low-dose methamphetamine or cocaine-induced enhancement of D2-IPSCs, suggesting intact DAT function. Disruption of methamphetamine-induced enhancement of dendritic dopamine transmission would result in decreased inhibition of dopamine neurons, ultimately increasing downstream release and the behavioral effects of methamphetamine.
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Affiliation(s)
- Christopher W. Tschumi
- Aging and Metabolism Research Program Oklahoma Medical Research Foundation Oklahoma City Oklahoma USA
- Department of Cellular and Integrative Physiology University of Texas Health Science Center at San Antonio San Antonio Texas USA
| | - Anna W. Daszkowski
- Department of Cellular and Integrative Physiology University of Texas Health Science Center at San Antonio San Antonio Texas USA
| | - Amanda L. Sharpe
- Department of Pharmaceutical Sciences University of Oklahoma Health Sciences Center Oklahoma City Oklahoma USA
| | - Marta Trzeciak
- Aging and Metabolism Research Program Oklahoma Medical Research Foundation Oklahoma City Oklahoma USA
| | - Michael J. Beckstead
- Aging and Metabolism Research Program Oklahoma Medical Research Foundation Oklahoma City Oklahoma USA
- Department of Cellular and Integrative Physiology University of Texas Health Science Center at San Antonio San Antonio Texas USA
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Bahi A. Dopamine transporter gene expression within the nucleus accumbens plays important role in the acquisition and reinstatement of ethanol-seeking behavior in mice. Behav Brain Res 2020; 381:112475. [PMID: 31923430 DOI: 10.1016/j.bbr.2020.112475] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2019] [Revised: 12/15/2019] [Accepted: 01/06/2020] [Indexed: 11/26/2022]
Abstract
Alcoholism and alcohol use disorders are chronically relapsing conditions which is a major problem in treating alcohol addiction. In a previous study we showed that the dopamine transporter (DAT) is implicated in voluntary intake and preference. However, its role in modulating ethanol-associated contextual memory remains largely unknown. In this study we have investigated the role of DAT in ethanol-induced conditioned place preference (EtOH-CPP) acquisition and reinstatement in adult male C57BL/6 mice. For this purpose, we used both loss- and gain-of-function approaches to test the effects of central DAT manipulation on EtOH-CPP. We developed a lentiviral-mediated gene transfer approach to examine whether DAT knockdown (shDAT) or overexpression in the nucleus accumbens (Nacc) is enough to impair EtOH-CPP acquisition and reinstatement. In the first experiment, results showed that DAT knockdown blocked, whereas DAT overexpression, exacerbated the acquisition of EtOH-CPP. In the second experiment and after the EtOH-CPP expression, the mice were subjected to a 14-day extinction trials before drug-induced EtOH-CPP reinstatement was induced by a priming injection of 1 g/kg EtOH. Results indicated that reinstatement of EtOH-CPP was considerably decreased after accumbal shDAT injection. However, DAT overexpression significantly increased EtOH-CPP reinstatement. Finally, and following DAT mRNA quantification using RT-PCR, Pearson's correlation showed a strong positive relationship between accumbal DAT mRNA and EtOH-CPP acquisition and reinstatement. These results suggest that DAT expression in the Nacc is involved in the acquisition and retrieval of EtOH contextual memory and that blockade of this transporter can decrease the rewarding properties of EtOH.
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Affiliation(s)
- Amine Bahi
- College of Medicine, Ajman University, Ajman, UAE; Department of Anatomy, College of Medicine & Health Sciences, United Arab Emirates University, Al Ain, UAE.
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8
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Abstract
The human dopamine transporter gene SLC6A3 is involved in substance use disorders (SUDs) among many other common neuropsychiatric illnesses but allelic association results including those with its classic genetic markers 3'VNTR or Int8VNTR remain mixed and unexplainable. To better understand the genetics for reproducible association signals, we report the presence of recombination hotspots based on sequencing of the entire 5' promoter regions in two small SUDs cohorts, 30 African Americans (AAs) and 30 European Americans (EAs). Recombination rate was the highest near the transcription start site (TSS) in both cohorts. In addition, each cohort carried 57 different promoter haplotypes out of 60 and no haplotypes were shared between the two ethnicities. A quarter of the haplotypes evolved in an ethnicity-specific manner. Finally, analysis of five hundred subjects of European ancestry, from the 1000 Genome Project, confirmed the promoter recombination hotspots and also revealed several additional ones in non-coding regions only. These findings provide an explanation for the mixed results as well as guidance for selection of effective markers to be used in next generation association validation (NGAV), facilitating the delineation of pathogenic variation in this critical neuropsychiatric gene.
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No effect of sex on ethanol intake and preference after dopamine transporter (DAT) knockdown in adult mice. Psychopharmacology (Berl) 2019; 236:1349-1365. [PMID: 30539268 DOI: 10.1007/s00213-018-5144-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/20/2018] [Accepted: 12/03/2018] [Indexed: 10/27/2022]
Abstract
RATIONALE Dopamine levels are controlled in part by transport across the cell membrane by the dopamine transporter (DAT), and recent evidence showed that a polymorphism in the gene encoding DAT is associated with alcoholism. However, research in animal models using DAT knockout mice has yielded conflicting results. OBJECTIVES The present study was planned to evaluate the effects of DAT knockdown in the nucleus accumbens (Nacc) on voluntary ethanol consumption and preference in male and female C57BL/6J mice. METHODS For this purpose, animals were stereotaxically injected with DAT siRNA-expressing lentiviral vectors in the Nacc, and using a voluntary, continuous access two-bottle choice model of alcohol, we investigated the importance of accumbal DAT expression in voluntary alcohol intake and preference. We also investigated the effects of DAT knockdown on saccharin and quinine consumption and ethanol metabolism. RESULTS We show that females consumed more alcohol than males. Interestingly, DAT knockdown in the Nacc significantly decreased alcohol intake and preference in both groups, but no significant sex by group interaction was observed. Also, DAT knockdown did not alter total fluid consumption, saccharin or quinine consumption, or blood ethanol concentrations. Using Pearson correlation, results indicated a strong positive relationship between DAT mRNA expression and ethanol consumption and preference. CONCLUSIONS Taken together, these data provide further evidence that DAT plays an important role in controlling ethanol intake and that accumbal DAT contributes in the modulation of the reinforcing effects of ethanol. Overall, the results suggest that DAT inhibitors may be valuable in the pharmacotherapy of alcoholism.
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Lohoff FW, Carr GV, Brookshire B, Ferraro TN, Lucki I. Deletion of the vesicular monoamine transporter 1 (vmat1/slc18a1) gene affects dopamine signaling. Brain Res 2019; 1712:151-157. [PMID: 30685272 DOI: 10.1016/j.brainres.2019.01.029] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Revised: 01/18/2019] [Accepted: 01/23/2019] [Indexed: 10/27/2022]
Abstract
The vesicular monoamine transporter is involved in presynaptic catecholamine storage and neurotransmission. Two isoforms of the transporter exist, VMAT1 and VMAT2, and both are expressed in the brain, though VMAT2 expression is more robust and has been more widely studied. In this study we investigated the role of VMAT1 KO on markers of dopaminergic function and neurotransmission, and dopamine-related behaviors. Null-mutant VMAT1 mice were studied behaviorally using the tail suspension test, elevated zero maze and locomotor activity assessments. Tissue monoamines were measured both ex vivo and by using in vivo microdialysis. Protein expression of tyrosine hydroxylase and D2 dopamine receptors was measured using western blot analysis. Results show that VMAT1 KO mice have decreased dopamine levels in the frontal cortex, increased postsynaptic D2 expression, and lower frontal cortex tyrosine hydroxylase expression compared to WT mice. VMAT1 KO mice also show an exaggerated behavioral locomotor response to acute amphetamine treatment. We conclude that dopaminergic signaling is robustly altered in the frontal cortex of VMAT1 null-mutant mice and suggest that VMAT1 may be relevant to the pathogenesis and/or treatment of psychiatric illnesses including schizophrenia and bipolar disease.
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Affiliation(s)
- Falk W Lohoff
- Section on Clinical Genomics and Experimental Therapeutics, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD, USA.
| | - Gregory V Carr
- Lieber Institute for Brain Development, Baltimore, MD, USA; Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Bethany Brookshire
- Center for Neurobiology and Behavior, Department of Psychiatry, University of Pennsylvania School of Medicine Translational Research Laboratories, Philadelphia, PA, USA
| | - Thomas N Ferraro
- Department of Biomedical Sciences, Rowan University, Camden, NJ, USA
| | - Irwin Lucki
- Department of Pharmacology, Uniformed Services University, Bethesda, MD, USA
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A Dopamine Pathway Gene Risk Score for Cognitive Recovery Following Traumatic Brain Injury: Methodological Considerations, Preliminary Findings, and Interactions With Sex. J Head Trauma Rehabil 2018; 31:E15-29. [PMID: 26580694 DOI: 10.1097/htr.0000000000000199] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
OBJECTIVES With evidence of sexual dimorphism involving the dopamine (DA)-pathway, and the importance of DA pathways in traumatic brain injury (TBI) recovery, we hypothesized that sex × DA-gene interactions may influence cognition post-TBI. PARTICIPANTS Adult survivors of severe TBI (n = 193) consecutively recruited from a level 1 trauma center. DESIGN Risk allele assignments were made for multiple DA pathway genes using a sex-specific stratified approach. Genetic risk alleles, and their impacts on cognition, were assessed at 6 and 12 months postinjury using unweighted, semiweighted, and weighted gene risk score (GRS) approaches. MAIN MEASURES A cognitive composite score generated from 8 standardized neuropsychological tests targeting multiple cognitive domains. RESULTS A significant sex × gene interaction was observed at 6 and 12 months for ANKK1 rs1800497 (6M: P = .002, 12M: P = .001) and COMT rs4680 (6M: P = .048; 12M: P = .004); DRD2 rs6279 (P = .001) and VMAT rs363226 (P = .043) genotypes were independently associated with cognition at 6 months, with trends for a sex × gene interaction at 12 months. All GRS methods were significant predictors of cognitive performance in multivariable models. Weighted GRS multivariate models captured the greatest variance in cognition: R = 0.344 (6 months); R = 0.441 (12 months), significantly increasing the variance captured from the base prediction models. CONCLUSIONS A sex-specific DA-pathway GRS may be a valuable tool when predicting cognitive recovery post-TBI. Future work should validate these findings and explore how DA-pathway genetics may guide therapeutic intervention.
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12
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Sheng Y, Filichia E, Shick E, Preston KL, Phillips KA, Cooperman L, Lin Z, Tesar P, Hoffer B, Luo Y. Using iPSC-derived human DA neurons from opioid-dependent subjects to study dopamine dynamics. Brain Behav 2016; 6:e00491. [PMID: 27547496 PMCID: PMC4884574 DOI: 10.1002/brb3.491] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/27/2016] [Revised: 04/09/2016] [Accepted: 04/13/2016] [Indexed: 12/23/2022] Open
Abstract
INTRODUCTION The dopaminergic (DA) system plays important roles in addiction. However, human DA neurons from drug-dependent subjects were not available for study until recent development in inducible pluripotent stem cells (iPSCs) technology. METHODS In this study, we produced DA neurons differentiated using iPSCs derived from opioid-dependent and control subjects carrying different 3' VNTR (variable number tandem repeat) polymorphism in the human dopamine transporter (DAT or SLC6A3). In addition, the effects of valproic acid (VPA) exposures on iPSC-derived human DA neurons are also examined. RESULTS We present the first evidence suggesting that the 3' VNTR polymorphism in the hDAT gene affects DAT expression level in iPSC-derived human DA neurons. In human DA neurons, which provide an appropriate cellular milieu, VPA treatment alters the expression of several genes important for dopaminergic neuron function including DAT, Nurr1, and TH; this might partly explain its action in regulating addictive behaviors. VPA treatment also significantly increased DA D2 receptor (Drd2) expression, especially in the opioid-dependent iPSC cell lines. CONCLUSIONS Our data suggest that human iPSC-derived DA neurons may be useful in in vitro experimental model to examine the effects of genetic variation in gene regulation, to examine the underlying mechanisms in neurological disorders including drug addiction, and to serve as a platform for therapeutic development.
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Affiliation(s)
- Yang Sheng
- Department of Neurological Surgery Case Western Reserve University Cleveland Ohio 44106
| | - Emily Filichia
- Department of Neurological Surgery Case Western Reserve University Cleveland Ohio 44106
| | - Elizabeth Shick
- Department of Genetics Case Western Reserve University Cleveland Ohio 44106
| | - Kenzie L Preston
- National Institute on Drug Abuse Intramural Research Program Baltimore Maryland 21224
| | - Karran A Phillips
- National Institute on Drug Abuse Intramural Research Program Baltimore Maryland 21224
| | - Leslie Cooperman
- Department of Genetics Case Western Reserve University Cleveland Ohio 44106
| | - Zhicheng Lin
- Department of Psychiatry Mclean Hospital Harvard University Belmont Massachusetts 02478
| | - Paul Tesar
- Department of Genetics Case Western Reserve University Cleveland Ohio 44106
| | - Barry Hoffer
- Department of Neurological Surgery Case Western Reserve University Cleveland Ohio 44106
| | - Yu Luo
- Department of Neurological Surgery Case Western Reserve University Cleveland Ohio 44106
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Mayfield J, Arends MA, Harris RA, Blednov YA. Genes and Alcohol Consumption: Studies with Mutant Mice. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2016; 126:293-355. [PMID: 27055617 PMCID: PMC5302130 DOI: 10.1016/bs.irn.2016.02.014] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
In this chapter, we review the effects of global null mutant and overexpressing transgenic mouse lines on voluntary self-administration of alcohol. We examine approximately 200 publications pertaining to the effects of 155 mouse genes on alcohol consumption in different drinking models. The targeted genes vary in function and include neurotransmitter, ion channel, neuroimmune, and neuropeptide signaling systems. The alcohol self-administration models include operant conditioning, two- and four-bottle choice continuous and intermittent access, drinking in the dark limited access, chronic intermittent ethanol, and scheduled high alcohol consumption tests. Comparisons of different drinking models using the same mutant mice are potentially the most informative, and we will highlight those examples. More mutants have been tested for continuous two-bottle choice consumption than any other test; of the 137 mouse genes examined using this model, 97 (72%) altered drinking in at least one sex. Overall, the effects of genetic manipulations on alcohol drinking often depend on the sex of the mice, alcohol concentration and time of access, genetic background, as well as the drinking test.
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Affiliation(s)
- J Mayfield
- Waggoner Center for Alcohol and Addiction Research, The University of Texas at Austin, Austin, TX, United States
| | - M A Arends
- Committee on the Neurobiology of Addictive Disorders, The Scripps Research Institute, La Jolla, CA, United States
| | - R A Harris
- Waggoner Center for Alcohol and Addiction Research, The University of Texas at Austin, Austin, TX, United States.
| | - Y A Blednov
- Waggoner Center for Alcohol and Addiction Research, The University of Texas at Austin, Austin, TX, United States
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Delis F, Rombola C, Bellezza R, Rosko L, Grandy DK, Volkow ND, Thanos PK. Regulation of ethanol intake under chronic mild stress: roles of dopamine receptors and transporters. Front Behav Neurosci 2015; 9:118. [PMID: 26029066 PMCID: PMC4428139 DOI: 10.3389/fnbeh.2015.00118] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2015] [Accepted: 04/24/2015] [Indexed: 01/24/2023] Open
Abstract
Studies have shown that exposure to chronic mild stress decreases ethanol intake and preference in dopamine D2 receptor wild-type mice (Drd2 (+/+)), while it increases intake in heterozygous (Drd2 (+/-)) and knockout (Drd2 (-/-)) mice. Dopaminergic neurotransmission in the basal forebrain plays a major role in the reinforcing actions of ethanol as well as in brain responses to stress. In order to identify neurochemical changes associated with the regulation of ethanol intake, we used in vitro receptor autoradiography to measure the levels and distribution of dopamine D1 and D2 receptors and dopamine transporters (DAT). Receptor levels were measured in the basal forebrain of Drd2 (+/+), Drd2 (+/-), and Drd2 (-/-) mice belonging to one of four groups: control (C), ethanol intake (E), chronic mild stress exposure (S), and ethanol intake under chronic mild stress (ES). D2 receptor levels were higher in the lateral and medial striatum of Drd2 (+/+) ES mice, compared with Drd2 (+/+) E mice. Ethanol intake in Drd2 (+/+) mice was negatively correlated with striatal D2 receptor levels. D2 receptor levels in Drd2(+/-) mice were the same among the four treatment groups. DAT levels were lower in Drd2(+/-) C and Drd2 (-/-) C mice, compared with Drd2 (+/+) C mice. Among Drd2(+/-) mice, S and ES groups had higher DAT levels compared with C and E groups in most regions examined. In Drd2(-/-) mice, ethanol intake was positively correlated with DAT levels in all regions studied. D1 receptor levels were lower in Drd2(+/-) and Drd2(-/-) mice, compared with Drd2(+/+), in all regions examined and remained unaffected by all treatments. The results suggest that in normal mice, ethanol intake is associated with D2 receptor-mediated neurotransmission, which exerts a protective effect against ethanol overconsumption under stress. In mice with low Drd2 expression, where DRD2 levels are not further modulated, ethanol intake is associated with DAT function which is upregulated under stress leading to ethanol overconsumption.
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Affiliation(s)
- Foteini Delis
- Department of Psychology, State University of New York at Stony Brook Stony Brook, NY, USA
| | - Christina Rombola
- Department of Psychology, State University of New York at Stony Brook Stony Brook, NY, USA
| | - Robert Bellezza
- Department of Psychology, State University of New York at Stony Brook Stony Brook, NY, USA
| | - Lauren Rosko
- Department of Psychology, State University of New York at Stony Brook Stony Brook, NY, USA
| | - David K Grandy
- Department of Physiology & Pharmacology, School of Medicine, Oregon Health & Science University Portland, OR, USA
| | - Nora D Volkow
- Laboratory of Neuroimaging, National Institute on Alcohol Abuse and Alcoholism Bethesda, MD, USA
| | - Panayotis K Thanos
- Department of Psychology, State University of New York at Stony Brook Stony Brook, NY, USA
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15
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Ford MM. Applications of schedule-induced polydipsia in rodents for the study of an excessive ethanol intake phenotype. Alcohol 2014; 48:265-76. [PMID: 24680665 DOI: 10.1016/j.alcohol.2014.01.005] [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: 05/28/2013] [Revised: 11/27/2013] [Accepted: 01/23/2014] [Indexed: 01/12/2023]
Abstract
Schedule-induced polydipsia (SIP) is generated by subjecting a highly motivated animal to a sub-optimal rate of food reinforcement while also providing access to a fluid. SIP is one of several adjunctive (or displacement) behaviors that are expressed in an exaggerated form that is deemed 'excessive.' This feature makes SIP an attractive model for studying an excessive ethanol drinking phenotype in rodents. Multiple experimental variables are crucial for the full manifestation of adjunctive drinking, including the degree of food deprivation, the inter-pellet interval selected, and the size of the food reward offered. Although these variables were extensively studied and optimized for water polydipsia in rats, a similarly customized approach to ethanol SIP and application of the procedure in mice have largely been curtailed in favor of the default variable values historically used for water SIP in rats. Further, ethanol SIP also requires careful consideration of variables such as taste and ethanol concentration. Investigation of the stress axis and neurochemical systems such as dopamine and serotonin in mediating adjunctive drinking stemmed from two leading hypotheses regarding the underlying mechanisms of SIP generation: 1) SIP as a coping strategy to mitigate stress associated with the aversive environmental condition, and 2) SIP as a displacement of reward in a highly motivated animal. Ethanol SIP is a powerful model of excessive intake because it can generate an ethanol-dependent state and sustain frequent and intoxicating levels of blood ethanol with voluntary oral consumption. The required food deprivation and the loss of the excessive drinking phenotype following removal of the generator schedule are the two main limitations of the model. Future utility of ethanol SIP will be enhanced by more fully dissecting the underlying hormonal and neurochemical mechanisms and optimizing experimental variables for ethanol SIP on a per species and strain basis.
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Abstract
Alcohol abuse and alcoholism incur a heavy socioeconomic cost in many countries. Both genetic and environmental factors contribute to variation in the inebriating effects of alcohol and alcohol addiction among individuals within and across populations. From a genetics perspective, alcohol sensitivity is a quantitative trait determined by the cumulative effects of multiple segregating genes and their interactions with the environment. This review summarizes insights from model organisms as well as human populations that represent our current understanding of the genetic and genomic underpinnings that govern alcohol metabolism and the sedative and addictive effects of alcohol on the nervous system.
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McCall NM, Sprow GM, Delpire E, Thiele TE, Kash TL, Pleil KE. Effects of sex and deletion of neuropeptide Y2 receptors from GABAergic neurons on affective and alcohol drinking behaviors in mice. Front Integr Neurosci 2013; 7:100. [PMID: 24399943 PMCID: PMC3872329 DOI: 10.3389/fnint.2013.00100] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2013] [Accepted: 12/08/2013] [Indexed: 12/13/2022] Open
Abstract
A large literature has demonstrated that neuropeptide Y (NPY) regulates many emotional and reward-related behaviors via its primary receptors, Y1R and Y2R. Classically, NPY actions at postsynaptic Y1R decrease anxiety, depression, and alcohol drinking, while its actions at presynaptic Y2R produce the opposite behavioral phenotypes. However, emerging evidence suggests that activation of Y2R can also produce anxiolysis in a brain region and neurotransmitter system-dependent fashion. Further, numerous human and rodent studies have reported that females display higher levels of anxiety, depression, and alcohol drinking. In this study, we evaluated sex differences and the role of Y2R on GABAergic transmission in these behaviors using a novel transgenic mouse that lacks Y2R specifically in VGAT-expressing neurons (VGAT-Y2R knockout). First, we confirmed our genetic manipulation by demonstrating that Y2R protein expression was decreased and that a Y2R agonist could not alter GABAergic transmission in the extended amygdala, a limbic brain region critically implicated in the regulation of anxiety and alcohol drinking behaviors, using immunofluorescence and slice electrophysiology. Then, we tested male and female VGAT-Y2R knockout mice on a series of behavioral assays for anxiety, depression, fear, anhedonia, and alcohol drinking. We found that females displayed greater basal anxiety, higher levels of ethanol consumption, and faster fear conditioning than males, and that knockout mice exhibited enhanced depressive-like behavior in the forced swim test. Together, these results confirm previous studies that demonstrate higher expression of negative affective and alcohol drinking behaviors in females than males, and they highlight the importance of Y2R function in GABAergic systems in the expression of depressive-like behavior.
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Affiliation(s)
- Nora M McCall
- Bowles Center for Alcohol Studies, University of North Carolina School of Medicine Chapel Hill, NC, USA ; Department of Pharmacology, University of North Carolina School of Medicine Chapel Hill, NC, USA
| | - Gretchen M Sprow
- Bowles Center for Alcohol Studies, University of North Carolina School of Medicine Chapel Hill, NC, USA ; Department of Psychology, University of North Carolina at Chapel Hill Chapel Hill, NC, USA
| | - Eric Delpire
- Department of Anesthesiology, Vanderbilt University Nashville, TN, USA ; Department of Molecular Physiology and Biophysics, Vanderbilt University Nashville, TN, USA
| | - Todd E Thiele
- Bowles Center for Alcohol Studies, University of North Carolina School of Medicine Chapel Hill, NC, USA ; Department of Psychology, University of North Carolina at Chapel Hill Chapel Hill, NC, USA
| | - Thomas L Kash
- Bowles Center for Alcohol Studies, University of North Carolina School of Medicine Chapel Hill, NC, USA ; Department of Pharmacology, University of North Carolina School of Medicine Chapel Hill, NC, USA
| | - Kristen E Pleil
- Bowles Center for Alcohol Studies, University of North Carolina School of Medicine Chapel Hill, NC, USA ; Department of Pharmacology, University of North Carolina School of Medicine Chapel Hill, NC, USA
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18
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Darlington TM, McCarthy RD, Cox RJ, Ehringer MA. Mesolimbic transcriptional response to hedonic substitution of voluntary exercise and voluntary ethanol consumption. Behav Brain Res 2013; 259:313-20. [PMID: 24239693 DOI: 10.1016/j.bbr.2013.11.011] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2013] [Revised: 10/17/2013] [Accepted: 11/06/2013] [Indexed: 12/14/2022]
Abstract
The mesolimbic dopaminergic pathway has been implicated in many rewarding behaviors, including the consumption of ethanol and voluntary exercise. It has become apparent that different rewarding stimuli activate this pathway, and therefore it is possible for these behaviors to influence each other, i.e. hedonic substitution. Using adult female C57BL/6J mice, we demonstrate that voluntary access to a running wheel substantially reduces the consumption and preference of ethanol. Furthermore, we examined gene expression of several genes involved in regulating the mesolimbic dopaminergic pathway, which we hypothesized to be the main pathway involved in hedonic substitution. In the striatum, we observed a reduction in mRNA expression of Drd1a due to exercise. Hippocampal Bdnf mRNA increased in response to exercise and decreased in response to ethanol. Furthermore, there was an interaction effect of exercise and ethanol on the expression of Slc18a2 in the midbrain. These data suggest an important role for this pathway, and especially for Bdnf and Slc18a2 in regulating hedonic substitution.
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Affiliation(s)
- Todd M Darlington
- Institute for Behavioral Genetics, Department of Integrative Physiology, University of Colorado, Boulder, Boulder, CO 80303, USA
| | - Riley D McCarthy
- Institute for Behavioral Genetics, Department of Integrative Physiology, University of Colorado, Boulder, Boulder, CO 80303, USA
| | - Ryan J Cox
- Institute for Behavioral Genetics, Department of Integrative Physiology, University of Colorado, Boulder, Boulder, CO 80303, USA
| | - Marissa A Ehringer
- Institute for Behavioral Genetics, Department of Integrative Physiology, University of Colorado, Boulder, Boulder, CO 80303, USA.
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19
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Fehr C, Sommerlad D, Sander T, Anghelescu I, Dahmen N, Szegedi A, Mueller C, Zill P, Soyka M, Preuss UW. Association of VMAT2 gene polymorphisms with alcohol dependence. J Neural Transm (Vienna) 2013; 120:1161-9. [PMID: 23504072 DOI: 10.1007/s00702-013-0996-y] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2012] [Accepted: 02/09/2013] [Indexed: 10/27/2022]
Abstract
Alcohol-related diseases cause significant harm in the western world. Up to 65 % of the phenotypic variance is genetically determined. Few candidate genes have been identified, comprising ADH4, ALDH2, COMT, CRHR1, DAT (SLC6A3), GABRA2 and MAOA. While abnormalities in the dopaminergic mesolimbic reward system are considered important mediators of alcoholism, studies analyzing variants of dopamine receptors showed conflicting results. Other modulators of the reward system are synaptosomal genes. Among candidate genes, polygenic variants of the Vesicular Monamine Transporter 2 (VMAT2) gene locus associated with alterations of drinking behavior were published. These variants comprise single nucleotide polymorphisms (SNPs) within the promoter region and the open reading frame. In this study, we confirm the association of VMAT2 SNP rs363387 (allelic association: p = 0.015) with alcohol dependence. This SNP defines several haplotypes including up to four SNPs (minimal p = 0.0045). In addition, numeric effects in the subgroups of males and patients with positive family history were found. We suggest that several rs363387 T-allele containing haplotypes increase the risk of alcohol dependence (OR 1.53), whereas G-allele containing haplotypes confer protection against alcohol dependence. Taken together, there is supporting evidence for a contribution of VMAT2 gene variants to phenotypes of alcohol dependence.
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Affiliation(s)
- Christoph Fehr
- Department of Psychiatry and Psychotherapy, University of Mainz, Untere Zahlbacher Str. 8, 55131, Mainz, Germany
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20
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Ohara A, Kasahara Y, Yamamoto H, Hata H, Kobayashi H, Numachi Y, Miyoshi I, Hall FS, Uhl GR, Ikeda K, Sora I. Exclusive expression of VMAT2 in noradrenergic neurons increases viability of homozygous VMAT2 knockout mice. Biochem Biophys Res Commun 2013; 432:526-32. [PMID: 23410751 DOI: 10.1016/j.bbrc.2013.02.014] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2013] [Accepted: 02/04/2013] [Indexed: 11/26/2022]
Abstract
The vesicular monoamine transporter 2 (VMAT2) translocates monoamine neurotransmitters from the neuronal cytoplasm into synaptic vesicles. Since VMAT2-/- mice die within a few days of birth, it is difficult to analyze the detailed VMAT2 functions using these mice. In this study, we generated human VMAT2 transgenic mice that expressed VMAT2 in noradrenergic neurons with the aim to rescue the lethality of VMAT2 deletion. The expression of human VMAT2 in noradrenergic neurons extended the life of VMAT2-/- mice for up to three weeks, and these mice showed severe growth deficiency compared with VMAT2+/+ mice. These results may indicate that VMAT2 expressed in noradrenergic neurons has crucial roles in survival during the first several weeks after birth, and VMAT2 functions in other monoaminergic systems could be required for further extended survival. Although VMAT2 rescue in noradrenergic neurons did not eliminate the increased morbidity and lethality associated with VMAT2 deletion, the extension of the lifespan in VMAT2 transgenic mice will enable behavioral, pharmacological and pathophysiological studies of VMAT2 function.
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Affiliation(s)
- Arihisa Ohara
- Department of Biological Psychiatry, Tohoku University Graduate School of Medicine, Sendai, Japan
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21
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Multani PK, Hodge R, Estévez MA, Abel T, Kung H, Alter M, Brookshire B, Lucki I, Nall AH, Talbot K, Doyle GA, Lohoff FW. VMAT1 deletion causes neuronal loss in the hippocampus and neurocognitive deficits in spatial discrimination. Neuroscience 2012. [PMID: 23201251 DOI: 10.1016/j.neuroscience.2012.11.023] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Vesicular monoamine transporters (VMAT) are involved in presynaptic storage and release of neurotransmitters. While it was thought initially that only VMAT2 is brain expressed and VMAT1 is present only in the periphery, recent data have challenged the exclusive expression of VMAT2 in the brain. To further elucidate the role of VMAT1 brain expression and its potential role in neuropsychiatric disorders, we have investigated mice lacking VMAT1. Comparison of wildtype and knock-out (KO) mice using qPCR and immunohistochemistry documents the expression of VMAT1 in the brain. Deletion of VMAT1 leads to increased hippocampal apoptosis and reduced neurogenesis as assessed by caspase-3-labeling and 5-bromo-deoxy-uridine-labeling. Behavioral data show that mice lacking VMAT1 have neurocognitive deficits. VMAT2 expression is not altered in VMAT1 KO mice, suggesting a distinct role of VMAT1. Our data support VMAT1 brain expression and suggest that VMAT1 plays a key role in survival of hippocampal neurons and thus might contribute to neurocognitive deficits observed in neuropsychiatric disorders.
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Affiliation(s)
- P K Multani
- Center for Neurobiology and Behavior, Department of Psychiatry, University of Pennsylvania School of Medicine, Translational Research Laboratories, Philadelphia, PA, USA
| | - R Hodge
- Center for Neurobiology and Behavior, Department of Psychiatry, University of Pennsylvania School of Medicine, Translational Research Laboratories, Philadelphia, PA, USA
| | - M A Estévez
- Department of Biology, University of Pennsylvania, Philadelphia, PA, USA
| | - T Abel
- Center for Neurobiology and Behavior, Department of Psychiatry, University of Pennsylvania School of Medicine, Translational Research Laboratories, Philadelphia, PA, USA; Department of Biology, University of Pennsylvania, Philadelphia, PA, USA
| | - H Kung
- Department of Radiology, University of Pennsylvania School of Medicine, Philadelphia, PA, USA
| | - M Alter
- Center for Neurobiology and Behavior, Department of Psychiatry, University of Pennsylvania School of Medicine, Translational Research Laboratories, Philadelphia, PA, USA
| | - B Brookshire
- Center for Neurobiology and Behavior, Department of Psychiatry, University of Pennsylvania School of Medicine, Translational Research Laboratories, Philadelphia, PA, USA
| | - I Lucki
- Center for Neurobiology and Behavior, Department of Psychiatry, University of Pennsylvania School of Medicine, Translational Research Laboratories, Philadelphia, PA, USA; Department of Pharmacology, University of Pennsylvania School of Medicine, Philadelphia, PA, USA
| | - A H Nall
- Center for Neurobiology and Behavior, Department of Psychiatry, University of Pennsylvania School of Medicine, Translational Research Laboratories, Philadelphia, PA, USA
| | - K Talbot
- Center for Neurobiology and Behavior, Department of Psychiatry, University of Pennsylvania School of Medicine, Translational Research Laboratories, Philadelphia, PA, USA
| | - G A Doyle
- Center for Neurobiology and Behavior, Department of Psychiatry, University of Pennsylvania School of Medicine, Translational Research Laboratories, Philadelphia, PA, USA
| | - F W Lohoff
- Center for Neurobiology and Behavior, Department of Psychiatry, University of Pennsylvania School of Medicine, Translational Research Laboratories, Philadelphia, PA, USA.
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22
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Zhao Y, Zhou Y, Xiong N, Lin Z. Identification of an intronic cis-acting element in the human dopamine transporter gene. Mol Biol Rep 2011; 39:5393-9. [PMID: 22160470 DOI: 10.1007/s11033-011-1339-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2011] [Accepted: 12/03/2011] [Indexed: 10/14/2022]
Abstract
The human dopamine transporter gene (hDAT) encodes the dopamine transporter in dopamine (DA) neurons to regulate DA transmission. hDAT expression varies significantly from neuron to neuron, and from individual to individual so that dysregulation of hDAT is related to many neuropsychiatric disorders. It is critical to identify hDAT-specific cis-acting elements that regulate the hDAT expression. Previous studies showed that hDAT Intron 1 displayed inhibitory activity for reporter gene expression. Here we report that the hDAT Intron 1 contains a 121-bp fragment that down-regulated both SV40 and hDAT promoter activities by 80% in vitro. Subfragments of 121-bp still down-regulated the SV40 promoter but not the hDAT promoter, as supported by nuclear protein-binding activities. Collectively, 121-bp is a silencer in vitro that might coordinate with transcriptional activities both inside and outside 121-bp in regulation of hDAT.
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Affiliation(s)
- Ying Zhao
- Department of Psychiatry, Harvard Medical School, Boston, MA 02478, USA
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23
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Eiden LE, Weihe E. VMAT2: a dynamic regulator of brain monoaminergic neuronal function interacting with drugs of abuse. Ann N Y Acad Sci 2011; 1216:86-98. [PMID: 21272013 DOI: 10.1111/j.1749-6632.2010.05906.x] [Citation(s) in RCA: 114] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The monoaminergic neuron, in particular the dopaminergic neuron, is central to mediating the hedonic and addictive properties of drugs of abuse. The effects of amphetamine (AMPH) and cocaine (COC), for example, depend on the ability to increase dopamine in the synapse, by effects on either the plasma membrane transporter DAT or the vesicular transporter for monoamine storage, VMAT2. The potential role of DAT as a target for AMPH and COC has been reviewed extensively. Here, we present VMAT2 as a target that enables the rewarding and addictive actions of these drugs, based on imaging, neurochemical, biochemical, cell biological, genetic, and immunohistochemical evidence. The presence of VMAT2 in noradrenergic, serotoninergic, histaminergic, and potentially trace aminergic neurons invites consideration of a wider role for aminergic neurotransmission in AMPH and COC abuse and addiction.
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Affiliation(s)
- Lee E Eiden
- Section on Molecular Neuroscience, Laboratory of Cellular and Molecular Regulation, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland, USA.
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24
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Dopamine dynamics associated with, and resulting from, schedule-induced alcohol self-administration: analyses in dopamine transporter knockout mice. Alcohol 2011; 45:325-39. [PMID: 21354763 DOI: 10.1016/j.alcohol.2010.12.006] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2010] [Revised: 11/23/2010] [Accepted: 12/16/2010] [Indexed: 11/21/2022]
Abstract
Preclinical and clinical evidence suggest an association between alcoholism and the primary regulator of extracellular dopamine concentrations, the dopamine transporter (DAT). However, the nature of this association is unclear. We determined if 10 days of voluntary alcohol self-administration followed by withdrawal could directly alter DAT function, or if genetically mediated changes in DAT function and/or availability could influence vulnerability to alcohol abuse. Heterozygous (DAT+/-) and homozygous mutant (DAT-/-) and wild-type (DAT+/+) mice were allowed to consume 5% alcohol in a schedule-induced polydipsia (SIP) task. In vivo fixed potential amperometry in anesthetized mice was used to (1) identify functional characteristics of mesoaccumbens dopamine neurons related to genotype, including dopamine autoreceptor (DAR) sensitivity, DAT efficiency, and DAT capacity, (2) determine if any of these characteristics correlated with alcohol drinking observed in DAT+/+ and DAT+/- animals, and (3) determine if SIP-alcohol self-administration altered DAR sensitivity, DAT efficiency, and DAT capacity by comparing these characteristics in wild-type (DAT+/+) mice that were SIP-alcohol naïve, with those that had undergone SIP-alcohol testing. DAT-/- mice consumed significantly less alcohol during testing and this behavioral difference was related to significant differences in DAR sensitivity, DAT efficiency, and DAT capacity. These functional characteristics were correlated to varying degrees with g/kg alcohol consumption in DAT+/+ and DAT+/- mice. DAR sensitivity was consistently reduced and DAT efficiency was enhanced in SIP-alcohol-experienced DAT+/+ mice when compared with naïve animals. These results indicate that DAR sensitivity is reduced by SIP-alcohol consumption and that DAT efficiency is modified by genotype and SIP-alcohol exposure. DAT capacity appeared to be strictly associated with SIP-alcohol consumption.
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25
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Haenisch B, Bönisch H. Depression and antidepressants: Insights from knockout of dopamine, serotonin or noradrenaline re-uptake transporters. Pharmacol Ther 2011; 129:352-68. [DOI: 10.1016/j.pharmthera.2010.12.002] [Citation(s) in RCA: 143] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2010] [Accepted: 11/29/2010] [Indexed: 12/15/2022]
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26
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Lin Z, Canales JJ, Björgvinsson T, Thomsen MM, Qu H, Liu QR, Torres GE, Caine SB. Monoamine transporters: vulnerable and vital doorkeepers. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2011; 98:1-46. [PMID: 21199769 PMCID: PMC3321928 DOI: 10.1016/b978-0-12-385506-0.00001-6] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Transporters of dopamine, serotonin, and norepinephrine have been empirically used as medication targets for several mental illnesses in the last decades. These protein-targeted medications are effective only for subpopulations of patients with transporter-related brain disorders. Since the cDNA clonings in early 1990s, molecular studies of these transporters have revealed a wealth of information about the transporters' structure-activity relationship (SAR), neuropharmacology, cell biology, biochemistry, pharmacogenetics, and the diseases related to the human genes encoding these transporters among related regulators. Such new information creates a unique opportunity to develop transporter-specific medications based on SAR, mRNA, DNA, and perhaps transporter trafficking regulation for a number of highly relevant diseases including substance abuse, depression, schizophrenia, and Parkinson's disease.
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Affiliation(s)
- Zhicheng Lin
- Department of Psychiatry, Harvard Medical School and Division of Alcohol and Drug Abuse, McLean Hospital, Belmont, MA 02478, USA
| | - Juan J. Canales
- Department of Psychology, Behavioural Neuroscience, University of Canterbury, Private Bag 4800, Christchurch, New Zealand
| | - Thröstur Björgvinsson
- Behavioral Health Partial Hospital and Psychology Internship Programs, McLean Hospital/Harvard Medical School, Belmont, MA 02478, USA
| | - Morgane M. Thomsen
- Department of Psychiatry, Harvard Medical School and Division of Alcohol and Drug Abuse, McLean Hospital, Belmont, MA 02478, USA
| | - Hong Qu
- Center for Bioinformatics, National Laboratory of Protein Engineering and Plant Genetic Engineering, College of Life Sciences, Peking University. Beijing, 100871 China
| | - Qing-Rong Liu
- Behavioral Neuroscience Branch, Intramural Research Program, National Institute on Drug Abuse, NIH/DHHS, 251 Bayview Boulevard, Baltimore, MD 21224, USA
| | - Gonzalo E. Torres
- Department of Neurobiology, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | - S. Barak Caine
- Department of Psychiatry, Harvard Medical School and Division of Alcohol and Drug Abuse, McLean Hospital, Belmont, MA 02478, USA
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27
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O'Tuathaigh CMP, Desbonnet L, Moran PM, Waddington JL. Susceptibility genes for schizophrenia: mutant models, endophenotypes and psychobiology. Curr Top Behav Neurosci 2011; 12:209-50. [PMID: 22367925 DOI: 10.1007/7854_2011_194] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Schizophrenia is characterised by a multifactorial aetiology that involves genetic liability interacting with epigenetic and environmental factors to increase risk for developing the disorder. A consensus view is that the genetic component involves several common risk alleles of small effect and/or rare but penetrant copy number variations. Furthermore, there is increasing evidence for broader, overlapping genetic-phenotypic relationships in psychosis; for example, the same susceptibility genes also confer risk for bipolar disorder. Phenotypic characterisation of genetic models of candidate risk genes and/or putative pathophysiological processes implicated in schizophrenia, as well as examination of epidemiologically relevant gene × environment interactions in these models, can illuminate molecular and pathobiological mechanisms involved in schizophrenia. The present chapter outlines both the evidence from phenotypic studies in mutant mouse models related to schizophrenia and recently described mutant models addressing such gene × environment interactions. Emphasis is placed on evaluating the extent to which mutant phenotypes recapitulate the totality of the disease phenotype or model selective endophenotypes. We also discuss new developments and trends in relation to the functional genomics of psychosis which might help to inform on the construct validity of mutant models of schizophrenia and highlight methodological challenges in phenotypic evaluation that relate to such models.
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Affiliation(s)
- Colm M P O'Tuathaigh
- Molecular and Cellular Therapeutics, Royal College of Surgeons in Ireland, Dublin 2, Ireland,
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Tammimäki A, Männistö PT. Effect of genetic modifications in the synaptic dopamine clearance systems on addiction-like behaviour in mice. Basic Clin Pharmacol Toxicol 2010; 108:2-8. [PMID: 21118356 DOI: 10.1111/j.1742-7843.2010.00647.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
During the last 15 years, genetically modified mouse lines have proved to be a valuable research tool. This review summarizes research that studied addiction-like behaviour in mice that had a targeted mutation in the genes of the synaptic dopamine removal systems, i.e. in the dopamine transporter (DAT), a vesicular monoamine transporter 2 (VMAT2) or two dopamine-metabolizing enzymes (monoamine oxidase, MAO, mainly MAO-A isoenzyme, and catechol-O-methyltransferase, COMT). Majority of the mice are knockouts but also some knock-in and knock down mouse lines are included. Most studies have explored DAT, and it has been shown to be the critical target in addiction to psychostimulants. Its role in the development of addiction-like behaviour to nicotine, opioids or ethanol is less clear. VMAT2 also seems to be linked to psychostimulant addiction. MAO-A and COMT have a minor role in addiction-like behaviour that is further complicated by a sexual dimorphism.
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Affiliation(s)
- Anne Tammimäki
- Division of Pharmacology and Toxicology, Faculty of Pharmacy, University of Helsinki, Finland.
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Lin Z, Zhao Y, Chung CY, Zhou Y, Xiong N, Glatt CE, Isacson O. High regulatability favors genetic selection in SLC18A2, a vesicular monoamine transporter essential for life. FASEB J 2010; 24:2191-200. [PMID: 20181938 DOI: 10.1096/fj.09-140368] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
SLC18A2 encodes the vesicular monoamine transporter 2 protein that regulates neurotransmission and reduces cytosolic toxicity of monoamines. Deletion of this gene causes lethality in mice, and DNA sequence variation in this gene is associated with alcoholism and Parkinson's disease, among other disorders. The Caucasian SLC18A2 promoter has at least 20 haplotypes (A-T), with A representing two-thirds of 1460 chromosomes. It is not known why A is selected in the human lineage. To understand the selection, here we took a functional approach by investigating the regulations of 4 representative haplotypes (A, C, G, and T) by 17 agents. We show that 76.5% of the agents were able to regulate A but only 11.8-23.5% of them regulated the 3 other infrequent ones, observing a positive correlation between haplotype frequency and regulatability. Pathway and molecular analyses revealed five signaling hubs that regulate the four haplotypes differentially, probably through targeting the polymorphic core promoter region. These findings suggest that greater diversity of transcriptional regulations is the driving force for the haplotype selection in SLC18A2.
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Affiliation(s)
- Zhicheng Lin
- Department of Psychiatry, Harvard Medical School, Boston, Massachusetts, USA.
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van der Zwaluw CS, Engels RCME, Buitelaar J, Verkes RJ, Franke B, Scholte RHJ. Polymorphisms in the dopamine transporter gene (SLC6A3/DAT1) and alcohol dependence in humans: a systematic review. Pharmacogenomics 2009; 10:853-66. [DOI: 10.2217/pgs.09.24] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Dopamine neurotransmission has been a key player in attempts to identify genetic factors involved in alcohol dependence. The dopamine transporter terminates dopaminergic neurotransmission, making the gene encoding the transporter (SLC6A3/DAT1) an attractive candidate in clinical studies on alcohol dependence. We conducted a systematic review of 18 studies examining associations between polymorphisms in DAT1 and alcohol dependence. The DAT1 variable number tandem repeat, the most frequent studied polymorphism in DAT1, did not show a direct association with alcohol dependence in general. Several, but not all, studies found that the DAT1 variable number tandem repeat (9-repeat allele) was associated with alcohol-withdrawal symptoms, such as seizures and delirium tremens. We discuss shortcomings, such as lack of power and disregarding moderating variables, as well as future challenges of gene association studies.
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Affiliation(s)
- Carmen S van der Zwaluw
- Behavioural Science Institute, Radboud University Nijmegen, PO Box 9104, 6500 HE Nijmegen, The Netherlands
| | - Rutger CME Engels
- Behavioural Science Institute, Radboud University Nijmegen, PO Box 9104, 6500 HE Nijmegen, The Netherlands
| | - Jan Buitelaar
- Behavioural Science Institute, Radboud University Nijmegen, PO Box 9104, 6500 HE Nijmegen, The Netherlands
| | - Robbert J Verkes
- Behavioural Science Institute, Radboud University Nijmegen, PO Box 9104, 6500 HE Nijmegen, The Netherlands
| | - Barbara Franke
- Behavioural Science Institute, Radboud University Nijmegen, PO Box 9104, 6500 HE Nijmegen, The Netherlands
| | - Ron HJ Scholte
- Behavioural Science Institute, Radboud University Nijmegen, PO Box 9104, 6500 HE Nijmegen, The Netherlands
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Itzhak Y, Anderson KL. Ethanol-induced behavioral sensitization in adolescent and adult mice: role of the nNOS gene. Alcohol Clin Exp Res 2008; 32:1839-48. [PMID: 18652592 DOI: 10.1111/j.1530-0277.2008.00766.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
BACKGROUND In the brain, nitric oxide (NO) produced by neuronal nitric oxide synthase (nNOS) has a role in synaptic plasticity. Recent evidence suggests the role of NO in a variety of effects produced by alcohol in the central nervous system. The current study investigated the role of the nNOS gene in the development of behavioral sensitization to ethanol in adolescent and adult mice. METHODS Adolescent and adult wild type (WT; B6;129SF2) and nNOS knockout (KO; B6;129S4-Nos1) mice of both sexes received saline or ethanol (1.5 g/kg; intraperitoneally) for 5 consecutive days, and locomotor activity was recorded daily. The locomotor response to challenge ethanol and saline injections was investigated at various time points following withdrawal from ethanol. RESULTS Adolescent WT but not nNOS KO mice developed a long-lasting sensitized response to ethanol as well as context-dependent hyperlocomotion (in response to saline) from adolescence through adulthood; sex-dependent differences were not observed. Compared to adolescent WT mice, adult WT males developed a short-term sensitized response to ethanol and context-dependent hyperlocomotion; adult WT females showed only short-term context-dependent hyperlocomotion. Adult nNOS KO males (like their adolescent counterparts) did not develop behavioral sensitization; no significant differences between adult nNOS KO and WT females were observed. Blood ethanol concentrations did not show genotype- or sex-dependent differences. CONCLUSIONS (1) The nNOS gene is required for the development of behavioral sensitization to ethanol in adolescent male and female mice. (2) Adolescent exposure to ethanol results in long-lasting behavioral sensitization through adulthood, while adult exposure to ethanol results in a shorter behavioral sensitization. (3) Sex-dependent differences are observed when ethanol exposure begins in adulthood but not in adolescence. (4) Ethanol-induced behavioral sensitization in adulthood is nNOS-dependent in males but not in females. Taken together, results suggest genotype-, ontogeny-, and sex-dependent differences in the development of behavioral sensitization to ethanol.
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Affiliation(s)
- Yossef Itzhak
- Department of Psychiatry & Behavioral Sciences, University of Miami Miller School of Medicine, Miami, Florida 33136, USA.
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32
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Tammimäki A, Forsberg MM, Karayiorgou M, Gogos JA, Männistö PT. Increase in free choice oral ethanol self-administration in catechol-o-methyltransferase gene-disrupted male mice. Basic Clin Pharmacol Toxicol 2008; 103:297-304. [PMID: 18684228 DOI: 10.1111/j.1742-7843.2008.00267.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The effect of catechol-O-methyltransferase (Comt) gene disruption on the voluntary oral consumption of water, ethanol (2.5-20%, v/v) and cocaine (0.1-0.8 mg/ml) was studied in the free-choice, two-bottle paradigm in male and female mice. Solutions containing ethanol or cocaine, or tap water were available ad libitum from drinking burettes for 4 weeks. Catechol-O-methyltransferase-deficient male mice consumed significantly more ethanol than their wild-type male littermates. In contrast, female mice did not show genotype differences in the consumption of ethanol solutions. During the cocaine experiment, male mice developed either a side preference or an aversion that obscured cocaine consumption. This pattern of drinking was not dependent on Comt genotype. In female mice, Comt genotype was not associated with cocaine consumption. In conclusion, disruption of Comt gene influenced ethanol consumption in a gender-dependent manner in mice, supporting the hypothesis that low catechol-O-methyltransferase activity is one of the predisposing factors for high alcohol consumption in males.
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Affiliation(s)
- Anne Tammimäki
- Division of Pharmacology and Toxicology, Faculty of Pharmacy, University of Helsinki, Helsinki, Finland.
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33
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Fei H, Grygoruk A, Brooks ES, Chen A, Krantz DE. Trafficking of vesicular neurotransmitter transporters. Traffic 2008; 9:1425-36. [PMID: 18507811 DOI: 10.1111/j.1600-0854.2008.00771.x] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Vesicular neurotransmitter transporters are required for the storage of all classical and amino acid neurotransmitters in secretory vesicles. Transporter expression can influence neurotransmitter storage and release, and trafficking targets the transporters to different types of secretory vesicles. Vesicular transporters traffic to synaptic vesicles (SVs) as well as large dense core vesicles and are recycled to SVs at the nerve terminal. Some of the intrinsic signals for these trafficking events have been defined and include a dileucine motif present in multiple transporter subtypes, an acidic cluster in the neural isoform of the vesicular monoamine transporter (VMAT) 2 and a polyproline motif in the vesicular glutamate transporter (VGLUT) 1. The sorting of VMAT2 and the vesicular acetylcholine transporter to secretory vesicles is regulated by phosphorylation. In addition, VGLUT1 uses alternative endocytic pathways for recycling back to SVs following exocytosis. Regulation of these sorting events has the potential to influence synaptic transmission and behavior.
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Affiliation(s)
- Hao Fei
- Departments of Psychiatry and Neurobiology, Gonda Goldschmied Neuroscience and Genetics Research Center, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095-1761, USA
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34
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Dopamine transporter mutant mice in experimental neuropharmacology. Naunyn Schmiedebergs Arch Pharmacol 2007; 377:301-13. [PMID: 18057916 DOI: 10.1007/s00210-007-0216-0] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2007] [Accepted: 11/02/2007] [Indexed: 12/27/2022]
Abstract
An opportunity to perform targeted genetic manipulations in mice has provided another dimension for modern pharmacological research. Genetically modified mice have become important tools to investigate functions of previously unexplored proteins, define mechanism of action of new and known pharmacological drugs, and validate novel targets for treatment of human disorders. One of the best examples of such use of genetic models in experimental pharmacology represents investigations involving mice deficient in the gene encoding the dopamine transporter (DAT). The dopamine transporter tightly regulates the extracellular dynamics of dopamine by recapturing released neurotransmitter into the presynaptic terminals, and genetic deletion of this protein results in profound alterations in both the presynaptic homeostasis and the extracellular dynamics of dopamine. By using this model of severe dopaminergic dysregulation, significant progress has been made in defining the major target of psychotropic drugs, understanding the mechanisms of their action, unraveling novel signaling events relevant for dopaminergic transmission, and mapping neuronal pathways involved in dopamine-related behaviors. Furthermore, DAT mutant mice provided an opportunity to model in vivo conditions of extreme dopaminergic dysfunction that could be relevant for human disorders such as ADHD, schizophrenia, and Parkinson's disease and, thus, could serve as test systems for developing novel treatments for these and related disorders.
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35
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Harris PE, Ferrara C, Barba P, Polito T, Freeby M, Maffei A. VMAT2 gene expression and function as it applies to imaging beta-cell mass. J Mol Med (Berl) 2007; 86:5-16. [PMID: 17665159 DOI: 10.1007/s00109-007-0242-x] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2007] [Revised: 06/06/2007] [Accepted: 06/27/2007] [Indexed: 12/14/2022]
Abstract
Diabetes mellitus is a metabolic disorder characterized by hyperglycemia. The two main forms of the disease are distinguished by different pathogenesis, natural histories, and population distributions and indicated as either type 1 (T1DM) or type 2 diabetes mellitus (T2DM). It is well established that T1DM is an autoimmune disease whereby beta-cells of pancreatic islets are destroyed leading to loss of endogenous insulin production. Albeit less dramatic, beta-cell mass (BCM) also drops in T2DM. Therefore, it is realistic to expect that noninvasive measures of BCM might provide useful information in the diabetes-care field. Preclinical studies have demonstrated that BCM measurements by positron emission tomography scanning, using the vesicular monoamine transporter type 2 (VMAT2) as a tissue-specific surrogate marker of insulin production and [11C] Dihydrotetrabenazine (DTBZ) as the radioligand specific for this molecule, is feasible in animal models. Unfortunately, the mechanisms underlying beta-cell-specific expression of VMAT2 are still largely unexplored, and a much better understanding of the regulation of VMAT2 gene expression and of its function in beta-cells will be required before the full utility of this technique in the prediction and treatment of individuals with diabetes can be understood. In this review, we summarize much of what is understood about the regulation of VMAT2 and identify questions whose answers may help in understanding what measurements of VMAT2 density mean in the context of diabetes.
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Affiliation(s)
- Paul E Harris
- Institute of Genetics and Biophysics Adriano Buzzati-Traverso, CNR, Naples, Italy.
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36
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Savelieva KV, Caudle WM, Miller GW. Altered ethanol-associated behaviors in vesicular monoamine transporter heterozygote knockout mice. Alcohol 2006; 40:87-94. [PMID: 17307644 DOI: 10.1016/j.alcohol.2006.09.030] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2005] [Revised: 09/21/2006] [Accepted: 09/21/2006] [Indexed: 11/16/2022]
Abstract
The purpose of this study was to examine the effects of the genetic reduction of vesicular monoamine transporter 2 (VMAT2) on voluntary ethanol consumption and conditioned place preference (CPP) using VMAT2 heterozygote knockout mice [VMAT2(+/-)]. Ethanol preference and consumption were assessed in a two-bottle choice procedure, and rewarding properties of ethanol were determined using a CPP paradigm. In the two-bottle choice VMAT2(+/-) male mice exhibited a decreased preference for and consumption of ethanol at all concentrations tested, as compared to their wild-type littermates. While female mice consumed more ethanol than male mice, there was no difference between the wild type and VMAT2(+/-). In the CPP experiment, wild-type mice exhibited place preference for the ethanol-paired environment while neither male or female VMAT2(+/-) mice developed place preference. Wild type and VMAT2(+/-) mice did not differ in blood ethanol metabolism and sensitivity to the depressant effects of ethanol. These data demonstrate that a reduction of VMAT2 expression reduces ethanol consumption in male mice and eliminates place preference in heterozygote mice of both sexes and suggests that altered VMAT2 expression may contribute to the rewarding properties of ethanol.
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Affiliation(s)
- Katerina V Savelieva
- Division of Pharmacology and Toxicology, College of Pharmacy, University of Texas, Waggoner Center for Alcohol and Addiction Research, Austin, Texas 78712, USA
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37
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Bäckman CM, Malik N, Zhang Y, Shan L, Grinberg A, Hoffer BJ, Westphal H, Tomac AC. Characterization of a mouse strain expressing Cre recombinase from the 3' untranslated region of the dopamine transporter locus. Genesis 2006; 44:383-90. [PMID: 16865686 DOI: 10.1002/dvg.20228] [Citation(s) in RCA: 293] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Dopamine (DA) neurotransmission has been implicated in several neurological and psychiatric disorders. The dopamine transporter (DAT) is highly expressed in dopaminergic neurons of the ventral mesencephalon and regulates neurotransmission by transporting DA back into the presynaptic terminals. To mediate restricted DNA recombination events into DA neurons using the Cre/loxP technology, we have generated a knockin mouse expressing Cre recombinase under the transcriptional control of the endogenous DAT promoter. To minimize interference with DAT function by preservation of both DAT alleles, Cre recombinase expression was driven from the 3' untranslated region (3'UTR) of the endogenous DAT gene by means of an internal ribosomal entry sequence. Crossing this murine line with a LacZ reporter showed colocalization of DAT immunocytochemistry and beta-galactosidase staining in all regions analyzed. This knockin mouse can be used for generating tissue specific knockouts in mice carrying genes flanked by loxP sites, and will facilitate the analysis of gene function in dopaminergic neurons.
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Affiliation(s)
- Cristina M Bäckman
- Cellular Neurobiology Branch, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD 21224, USA.
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38
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Schwab SG, Franke PE, Hoefgen B, Guttenthaler V, Lichtermann D, Trixler M, Knapp M, Maier W, Wildenauer DB. Association of DNA polymorphisms in the synaptic vesicular amine transporter gene (SLC18A2) with alcohol and nicotine dependence. Neuropsychopharmacology 2005; 30:2263-8. [PMID: 15988470 DOI: 10.1038/sj.npp.1300809] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The brain synaptic vesicular amine transporter SLCA18A2 is a key component for the uptake of monoamines like dopamine or serotonin into vesicles. We have analyzed seven DNA polymorphisms located in the genomic region of SLC18A2 for association with alcohol- and nicotine dependence, using a family-based design. Our sample comprised 131 families with alcohol-dependent offspring and 96 families with at least one nicotine-dependent offspring. For the alcohol-dependent sample, we found statistical significant association for two single markers (rs363387, P=0.03; rs363333, P=0.0066) as well as for several haplotypes (minimal P=0.0038). When the sample with alcohol dependence was stratified according to gender, we observed increased association for the male subgroup (rs363387, P=0.0011). None of the markers showed association in the sample of families with nicotine dependence. However, analysis of a combined sample of alcohol and nicotine-dependent families resulted in single markers as well as several haplotypes showing statistical significant association with substance dependence (minimal P=0.0044). We conclude that DNA polymorphisms located in SLC18A2 might contribute to the development of substance dependence.
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Affiliation(s)
- Sibylle G Schwab
- School of Psychiatry and Clinical Neurosciences, University of Western Australia, Perth, WA, Australia.
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Cowen MS, Adams C, Kraehenbuehl T, Vengeliene V, Lawrence AJ. The acute anti-craving effect of acamprosate in alcohol-preferring rats is associated with modulation of the mesolimbic dopamine system. Addict Biol 2005; 10:233-42. [PMID: 16109584 DOI: 10.1080/13556210500223132] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Acamprosate (Campral) is a drug used clinically for the treatment of alcoholism. In order to examine further the time-course and mechanism of action of acamprosate, the effect of acute and repeated acamprosate administration was examined on (i) operant ethanol self-administration and (ii) voluntary home cage ethanol consumption by alcohol-preferring Fawn-Hooded, iP and Alko Alcohol (AA) rats. Acutely, acamprosate was shown to cause a significant decrease in operant ethanol self-administration by Fawn-Hooded and alcohol-preferring iP rats in part by decreasing the motivational relevance of a specific ethanol cue; however, repeated injection of acamprosate led to tolerance to this effect. Voluntary alcohol consumption in the home cage in Fawn-Hooded and AA rats was also reduced by an acute acamprosate injection; however, again tolerance developed to repeated injections. In a separate experiment, the effect of acamprosate on markers of the dopaminergic system was examined. Interestingly, acute acamprosate was also shown to cause increased dopamine transporter density and decreased dopamine D2-like receptor density within the nucleus accumbens but not in the caudate-putamen, suggesting a link between the decreased motivational salience of the ethanol cue and altered dopaminergic signalling within the nucleus accumbens. With repeated injections of acamprosate, markers of the dopaminergic system returned to steady state levels with a similar temporal profile to the development of tolerance in the behavioural studies. Along with previous studies, our findings indicate that acamprosate modulates the mesolimbic dopaminergic system and may thereby decrease ethanol reinforcement processes; however, these effects undergo tolerance in alcohol-preferring rats and may in part explain the fact why some subjects are non-responders to chronic acamprosate treatment.
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Lin Z, Walther D, Yu XY, Li S, Drgon T, Uhl GR. SLC18A2 promoter haplotypes and identification of a novel protective factor against alcoholism. Hum Mol Genet 2005; 14:1393-404. [PMID: 15829504 DOI: 10.1093/hmg/ddi148] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The vesicular monoamine transporter 2 (VMAT2, SLC18A2) takes up cytosolic monoamines into intracellular secretory vesicles, preventing their neurotoxicity in the cytosol and discharging them into extracellular space by exocytosis. It has been shown that one-copy deletion of the VMAT2 gene increases locomotion activity significantly in response to drug treatments and dopamine neuron death rate in response to neurotoxin treatments in knockout mice. Little is known about promoter polymorphisms and their influence on SLC18A2 promoter activity. We have re-sequenced a 17.4 kb DNA in the SLC18A2 promoter region for Caucasians and revealed 47 polymorphisms that confer 13 haplotypes. One of the haplotypes reaches a frequency as high as 65%, likely due to positive selection. In vitro analysis showed a 20% difference in promoter activity between two frequent haplotypes and identified some of the polymorphisms that influence promoter activity. Four haplotype-defining single nucleotide polymorphisms (hdSNPs) can define the frequent haplotypes and by genotyping these hdSNPs, we find that haplotypes with -14234G and -2504C of SLC18A2 promoter region represent a protective factor against alcoholism (P = 0.0038 by Fisher's exact tests). Therefore, SLC18A2 promoter haplotypes defined here create a foundation for transcriptional characterization of individuality and for association study on monoamine-related human diseases.
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Affiliation(s)
- Zhicheng Lin
- Molecular Neurobiology Branch, Baltimore, MD 21224, USA.
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41
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Dunnett SB. Chapter V Motor function(s) of the nigrostriatal dopamine system: Studies of lesions and behavior. ACTA ACUST UNITED AC 2005. [DOI: 10.1016/s0924-8196(05)80009-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/25/2023]
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Zhuang X, Masson J, Gingrich JA, Rayport S, Hen R. Targeted gene expression in dopamine and serotonin neurons of the mouse brain. J Neurosci Methods 2004; 143:27-32. [PMID: 15763133 DOI: 10.1016/j.jneumeth.2004.09.020] [Citation(s) in RCA: 219] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
We used a knock-in strategy to generate two lines of mice expressing Cre recombinase under the transcriptional control of the dopamine transporter promoter (DAT-cre mice) or the serotonin transporter promoter (SERT-cre mice). In DAT-cre mice, immunocytochemical staining of adult brains for the dopamine-synthetic enzyme tyrosine hydroxylase and for Cre recombinase revealed that virtually all dopaminergic neurons in the ventral midbrain expressed Cre. Crossing DAT-cre mice with ROSA26-stop-lacZ or ROSA26-stop-YFP reporter mice revealed a near perfect correlation between staining for tyrosine hydroxylase and beta-galactosidase or YFP. YFP-labeled fluorescent dopaminergic neurons could be readily identified in live slices. Crossing SERT-cre mice with the ROSA26-stop-lacZ or ROSA26-stop-YFP reporter mice similarly revealed a near perfect correlation between staining for serotonin-synthetic enzyme tryptophan hydroxylase and beta-galactosidase or YFP. Additional Cre expression in the thalamus and cortex was observed, reflecting the known pattern of transient SERT expression during early postnatal development. These findings suggest a general strategy of using neurotransmitter transporter promoters to drive selective Cre expression and thus control mutations in specific neurotransmitter systems. Crossed with fluorescent-gene reporters, this strategy tags neurons by neurotransmitter status, providing new tools for electrophysiology and imaging.
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Affiliation(s)
- Xiaoxi Zhuang
- Department of Neurobiology, Pharmacology and Physiology, The University of Chicago, 924 East 57th Street, Knapp Center, R214, Chicago, IL 60637, USA.
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