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Arora I, Mal P, Arora P, Paul A, Kumar M. GABAergic implications in anxiety and related disorders. Biochem Biophys Res Commun 2024; 724:150218. [PMID: 38865810 DOI: 10.1016/j.bbrc.2024.150218] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2024] [Revised: 05/05/2024] [Accepted: 06/02/2024] [Indexed: 06/14/2024]
Abstract
Evidence indicates that anxiety disorders arise from an imbalance in the functioning of brain circuits that govern the modulation of emotional responses to possibly threatening stimuli. The circuits under consideration in this context include the amygdala's bottom-up activity, which signifies the existence of stimuli that may be seen as dangerous. Moreover, these circuits encompass top-down regulatory processes that originate in the prefrontal cortex, facilitating the communication of the emotional significance associated with the inputs. Diverse databases (e.g., Pubmed, ScienceDirect, Web of Science, Google Scholar) were searched for literature using a combination of different terms e.g., "anxiety", "stress", "neuroanatomy", and "neural circuits", etc. A decrease in GABAergic activity is present in both anxiety disorders and severe depression. Research on cerebral functional imaging in depressive individuals has shown reduced levels of GABA within the cortical regions. Additionally, animal studies demonstrated that a reduction in the expression of GABAA/B receptors results in a behavioral pattern resembling anxiety. The amygdala consists of inhibitory networks composed of GABAergic interneurons, responsible for modulating anxiety responses in both normal and pathological conditions. The GABAA receptor has allosteric sites (e.g., α/γ, γ/β, and α/β) which enable regulation of neuronal inhibition in the amygdala. These sites serve as molecular targets for anxiolytic medications such as benzodiazepine and barbiturates. Alterations in the levels of naturally occurring regulators of these allosteric sites, along with alterations to the composition of the GABAA receptor subunits, could potentially act as mechanisms via which the extent of neuronal inhibition is diminished in pathological anxiety disorders.
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Affiliation(s)
- Indu Arora
- Chitkara College of Pharmacy, Chitkara University, Punjab, India
| | - Pankaj Mal
- Chitkara College of Pharmacy, Chitkara University, Punjab, India
| | - Poonam Arora
- Chitkara College of Pharmacy, Chitkara University, Punjab, India
| | - Anushka Paul
- Chitkara College of Pharmacy, Chitkara University, Punjab, India
| | - Manish Kumar
- Chitkara College of Pharmacy, Chitkara University, Punjab, India.
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Daack CW, Yeh D, Busch M, Kliethermes CL. GABAergic regulation of locomotion before and during an ethanol exposure in Drosophila melanogaster. Behav Brain Res 2021; 410:113369. [PMID: 34015397 DOI: 10.1016/j.bbr.2021.113369] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2021] [Revised: 04/30/2021] [Accepted: 05/14/2021] [Indexed: 11/17/2022]
Abstract
Ethanol at low doses induces a locomotor stimulant response across a range of phylogenetically diverse species. In rodents, this response is commonly used as an index of ethanol's disinhibitory, anxiolytic, or reinforcing effects, and its expression is regulated by signaling through a number of conserved neurotransmitter systems. In the current experiments, we asked whether ethanol-induced locomotor stimulation in the fruit fly Drosophila melanogaster might be mediated by ionotropic GABA receptors. We measured basal and ethanol-stimulated locomotion in flies expressing RNAi directed against three known subunits of ionotropic GABA receptors, and also examined the effects of picrotoxin feeding on these behaviors. We found that RNAi-mediated knockdown of a subunit of fly ionotropic GABA receptors, RDL, in all neurons resulted in an increased ethanol-induced locomotor stimulant response, while knockdown of two other subunits, LCCH3 and GRD, did not affect the responses. The effect of pan neuronal RDL knockdown was recapitulated with selective RDL knockdown in cholinergic neurons, and increased ethanol-induced locomotor stimulation was also seen by feeding the GABAA antagonist picrotoxin to flies prior to behavioral testing. However, the increase in ethanol-stimulated locomotion in each of these experiments was largely accounted for by decreased baseline activity. Our results indicate that ionotropic GABA receptors might be a conserved mediator of the locomotor stimulant effects of ethanol, but that alternative experimental approaches will be necessary to disentangle effects of GABAergic manipulations on baseline and ethanol-stimulated locomotion in flies.
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Affiliation(s)
- Calvin W Daack
- Drake University, 318 Olin Hall, 1344 27thStreet, Des Moines, IA, 50311, United States
| | - Derek Yeh
- Drake University, 318 Olin Hall, 1344 27thStreet, Des Moines, IA, 50311, United States
| | - Marc Busch
- Drake University, 318 Olin Hall, 1344 27thStreet, Des Moines, IA, 50311, United States
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Garbusow M, Sebold M, Beck A, Heinz A. Too difficult to stop: mechanisms facilitating relapse in alcohol dependence. Neuropsychobiology 2015; 70:103-10. [PMID: 25359490 DOI: 10.1159/000362838] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/30/2013] [Accepted: 04/13/2013] [Indexed: 11/19/2022]
Abstract
BACKGROUND In alcohol and other substance dependencies, patients often suffer relapse despite better knowledge and their intention to remain abstinent. A variety of neurotransmitter systems and their respective alterations due to the chronic drug intake are involved in mechanisms that facilitate relapse. It has been postulated that these neurotransmitter systems are related to changes in motivational and learning mechanisms, and engender a shift from goal-directed to habitual behavior in dependent patients that facilitates drug-seeking behavior. METHODS We review learning mechanisms facilitating relapse, as identified and tested to date. We focus on studies examining the interaction between alcohol-related changes in monoaminergic neurotransmission and their respective effects on pavlovian and operant learning mechanisms in alcohol dependence. RESULTS Animal experiments and first human studies suggest that chronic alcohol intake impairs goal-directed behavior and facilitates habitual drug intake. Key symptoms of alcohol dependence such as tolerance development, withdrawal, craving and reduced control of alcohol intake can be explained by alcohol-induced alteration of dopaminergic neurotransmission and its GABAergic and glutamatergic modulation and their respective effects on pavlovian and operant conditioning as well as pavlovian-to-instrumental transfer. CONCLUSION Chronic alcohol intake impairs neurotransmitter systems that regulate prefrontal-striatal circuits and interfere with goal-directed decision-making and the acquisition of new, non-drug-related behavior patterns. Alcohol craving induced by pavlovian conditioned cues can facilitate habitual drug intake. Such learning mechanisms and their alterations by chronic alcohol intake might be targeted by specific interventions.
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Affiliation(s)
- Maria Garbusow
- Department of Psychiatry and Psychotherapy, Campus Charité Mitte, Charité Universitätsmedizin Berlin, Berlin, Germany
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Blednov YA, Benavidez JM, Black M, Mayfield J, Harris RA. Role of interleukin-1 receptor signaling in the behavioral effects of ethanol and benzodiazepines. Neuropharmacology 2015; 95:309-20. [PMID: 25839897 DOI: 10.1016/j.neuropharm.2015.03.015] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2014] [Revised: 02/10/2015] [Accepted: 03/16/2015] [Indexed: 12/20/2022]
Abstract
Gene expression studies identified the interleukin-1 receptor type I (IL-1R1) as part of a pathway associated with a genetic predisposition to high alcohol consumption, and lack of the endogenous IL-1 receptor antagonist (IL-1ra) strongly reduced ethanol intake in mice. Here, we compared ethanol-mediated behaviors in mice lacking Il1rn or Il1r1. Deletion of Il1rn (the gene encoding IL-1ra) increases sensitivity to the sedative/hypnotic effects of ethanol and flurazepam and reduces severity of acute ethanol withdrawal. Conversely, deletion of Il1r1 (the gene encoding the IL-1 receptor type I, IL-1R1) reduces sensitivity to the sedative effects of ethanol and flurazepam and increases the severity of acute ethanol withdrawal. The sedative effects of ketamine and pentobarbital were not altered in the knockout (KO) strains. Ethanol intake and preference were not changed in mice lacking Il1r1 in three different tests of ethanol consumption. Recovery from ethanol-induced motor incoordination was only altered in female mice lacking Il1r1. Mice lacking Il1rn (but not Il1r1) showed increased ethanol clearance and decreased ethanol-induced conditioned taste aversion. The increased ethanol- and flurazepam-induced sedation in Il1rn KO mice was decreased by administration of IL-1ra (Kineret), and pre-treatment with Kineret also restored the severity of acute ethanol withdrawal. Ethanol-induced sedation and withdrawal severity were changed in opposite directions in the null mutants, indicating that these responses are likely regulated by IL-1R1 signaling, whereas ethanol intake and preference do not appear to be solely regulated by this pathway.
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Affiliation(s)
- Yuri A Blednov
- Waggoner Center for Alcohol and Addiction Research, The University of Texas at Austin, Austin, TX 78712, USA
| | - Jillian M Benavidez
- Waggoner Center for Alcohol and Addiction Research, The University of Texas at Austin, Austin, TX 78712, USA
| | - Mendy Black
- Waggoner Center for Alcohol and Addiction Research, The University of Texas at Austin, Austin, TX 78712, USA
| | - Jody Mayfield
- Waggoner Center for Alcohol and Addiction Research, The University of Texas at Austin, Austin, TX 78712, USA
| | - R Adron Harris
- Waggoner Center for Alcohol and Addiction Research, The University of Texas at Austin, Austin, TX 78712, USA.
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Wang S, Luo Y, Feng A, Li T, Yang X, Nofech-Mozes R, Yu M, Wang C, Li Z, Yi F, Liu C, Lu WY. Ethanol induced impairment of glucose metabolism involves alterations of GABAergic signaling in pancreatic β-cells. Toxicology 2014; 326:44-52. [PMID: 25456265 DOI: 10.1016/j.tox.2014.10.005] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2014] [Revised: 10/09/2014] [Accepted: 10/10/2014] [Indexed: 01/02/2023]
Abstract
Alcohol overindulgence is a risk factor of type 2 diabetes mellitus. However, the mechanisms by which alcohol overindulgence damages glucose metabolism remain unclear. Pancreatic islet β-cells are endowed with type-A γ-aminobutyric acid receptor (GABAAR) mediated autocrine signaling mechanism, which regulates insulin secretion and fine-tunes glucose metabolism. In neurons GABAAR is one of the major targets for alcohol. This study investigated whether ethanol alters glucose metabolism by affecting GABAAR signaling in pancreatic β-cells. Blood glucose level of test mice was measured using a blood glucose meter. Insulin secretion by the pancreatic β-cell line INS-1 cells was examined using a specific insulin ELISA kit. Whole-cell patch-clamp recording was used to evaluate GABA-elicited current in INS-1 cells. Western blot and immunostaining were used to measure the expression of GABAAR subunits in mouse pancreatic tissues or in INS-1 cells. Intraperitoneal (i.p.) administration of ethanol (3.0g/kg body weight) to mice altered glucose metabolism, which was associated with decreased expression of GABAAR α1- and δ- subunits on the surface of pancreatic β-cells. Acute treatment of cultured INS-1cells with ethanol (60mM) decreased the GABA-induced current and reduced insulin secretion. In contrast, treating INS-1 cells with GABA (100μM) largely prevented the ethanol-induced reduction of insulin release. Importantly, pre-treating mice with GABA (i.p., 1.5mg/kg body weight) partially reversed ethanol-induced impairment of glucose homeostasis in mice. Our data suggest a novel role of pancreatic GABA signaling in protecting pancreatic islet β-cells from ethanol-induced dysfunction.
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Affiliation(s)
- Shuanglian Wang
- Department of Physiology, Shandong University School of Medicine, Jinan, Shandong, PR China
| | - Yan Luo
- Department of Physiology and Pharmacology, University of Western Ontario, London, ON, Canada
| | - Allen Feng
- Department of Physiology and Pharmacology, University of Western Ontario, London, ON, Canada; Robarts Research Institute, University of Western Ontario, London, ON, Canada
| | - Tao Li
- Department of Physiology, Shandong University School of Medicine, Jinan, Shandong, PR China
| | - Xupeng Yang
- Department of Physiology, Shandong University School of Medicine, Jinan, Shandong, PR China
| | - Roy Nofech-Mozes
- Department of Physiology and Pharmacology, University of Western Ontario, London, ON, Canada; Robarts Research Institute, University of Western Ontario, London, ON, Canada
| | - Meng Yu
- Department of Physiology, Shandong University School of Medicine, Jinan, Shandong, PR China
| | - Changhui Wang
- Department of Physiology, Shandong University School of Medicine, Jinan, Shandong, PR China
| | - Ziwei Li
- Department of Physiology, Shandong University School of Medicine, Jinan, Shandong, PR China
| | - Fan Yi
- Department of Pharmacology, Shandong University School of Medicine, Jinan, Shandong, PR China
| | - Chuanyong Liu
- Department of Physiology, Shandong University School of Medicine, Jinan, Shandong, PR China.
| | - Wei-Yang Lu
- Department of Physiology and Pharmacology, University of Western Ontario, London, ON, Canada; Robarts Research Institute, University of Western Ontario, London, ON, Canada.
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Silveri MM. GABAergic contributions to alcohol responsivity during adolescence: insights from preclinical and clinical studies. Pharmacol Ther 2014; 143:197-216. [PMID: 24631274 DOI: 10.1016/j.pharmthera.2014.03.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2014] [Accepted: 02/28/2014] [Indexed: 01/04/2023]
Abstract
There is a considerable body of literature demonstrating that adolescence is a unique age period, which includes rapid and dramatic maturation of behavioral, cognitive, hormonal and neurobiological systems. Most notably, adolescence is also a period of unique responsiveness to alcohol effects, with both hyposensitivity and hypersensitivity observed to the various effects of alcohol. Multiple neurotransmitter systems are undergoing fine-tuning during this critical period of brain development, including those that contribute to the rewarding effects of drugs of abuse. The role of developmental maturation of the γ-amino-butyric acid (GABA) system, however, has received less attention in contributing to age-specific alcohol sensitivities. This review integrates GABA findings from human magnetic resonance spectroscopy studies as they may translate to understanding adolescent-specific responsiveness to alcohol effects. Better understanding of the vulnerability of the GABA system both during adolescent development, and in psychiatric conditions that include alcohol dependence, could point to a putative mechanism, boosting brain GABA, that may have increased effectiveness for treating alcohol use disorders.
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Affiliation(s)
- Marisa M Silveri
- Neurodevelopmental Laboratory on Addictions and Mental Health, McLean Hospital, Belmont, MA, USA; Department of Psychiatry, Harvard Medical School, Boston, MA, USA.
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Howard RJ, Trudell JR, Harris RA. Seeking structural specificity: direct modulation of pentameric ligand-gated ion channels by alcohols and general anesthetics. Pharmacol Rev 2014; 66:396-412. [PMID: 24515646 PMCID: PMC3973611 DOI: 10.1124/pr.113.007468] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Alcohols and other anesthetic agents dramatically alter neurologic function in a wide range of organisms, yet their molecular sites of action remain poorly characterized. Pentameric ligand-gated ion channels, long implicated in important direct effects of alcohol and anesthetic binding, have recently been illuminated in renewed detail thanks to the determination of atomic-resolution structures of several family members from lower organisms. These structures provide valuable models for understanding and developing anesthetic agents and for allosteric modulation in general. This review surveys progress in this field from function to structure and back again, outlining early evidence for relevant modulation of pentameric ligand-gated ion channels and the development of early structural models for ion channel function and modulation. We highlight insights and challenges provided by recent crystal structures and resulting simulations, as well as opportunities for translation of these newly detailed models back to behavior and therapy.
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Affiliation(s)
- Rebecca J Howard
- Department of Chemistry, Skidmore College, Saratoga Springs, NY 12866.
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Dostalova Z, Zhou X, Liu A, Zhang X, Zhang Y, Desai R, Forman SA, Miller KW. Human α1β3γ2L gamma-aminobutyric acid type A receptors: High-level production and purification in a functional state. Protein Sci 2013; 23:157-66. [PMID: 24288268 DOI: 10.1002/pro.2401] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2013] [Revised: 11/25/2013] [Accepted: 11/26/2013] [Indexed: 02/01/2023]
Abstract
Gamma-aminobutyric acid type A receptors (GABA(A)Rs) are the most important inhibitory chloride ion channels in the central nervous system and are major targets for a wide variety of drugs. The subunit compositions of GABA(A)Rs determine their function and pharmacological profile. GABAA Rs are heteropentamers of subunits, and (α1)2 (β3)2 (γ2L)1 is a common subtype. Biochemical and biophysical studies of GABA(A)Rs require larger quantities of receptors of defined subunit composition than are currently available. We previously reported high-level production of active human α1β3 GABA(A)R using tetracycline-inducible stable HEK293 cells. Here we extend the strategy to receptors containing three different subunits. We constructed a stable tetracycline-inducible HEK293-TetR cell line expressing human (N)-FLAG-α1β3γ2L-(C)-(GGS)3 GK-1D4 GABA(A)R. These cells achieved expression levels of 70-90 pmol [(3)H]muscimol binding sites/15-cm plate at a specific activity of 15-30 pmol/mg of membrane protein. Incorporation of the γ2 subunit was confirmed by the ratio of [(3)H]flunitrazepam to [(3)H]muscimol binding sites and sensitivity of GABA-induced currents to benzodiazepines and zinc. The α1β3γ2L GABA(A)Rs were solubilized in dodecyl-D-maltoside, purified by anti-FLAG affinity chromatography and reconstituted in CHAPS/asolectin at an overall yield of ∼ 30%. Typical purifications yielded 1.0-1.5 nmoles of [(3)H]muscimol binding sites/60 plates. Receptors with similar properties could be purified by 1D4 affinity chromatography with lower overall yield. The composition of the purified, reconstituted receptors was confirmed by ligand binding, Western blot, and proteomics. Allosteric interactions between etomidate and [(3)H]muscimol binding were maintained in the purified state.
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Affiliation(s)
- Zuzana Dostalova
- Department of Anesthesia and Critical Care, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, 02114; Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts, 02115
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Kaminski BJ, Van Linn ML, Cook JM, Yin W, Weerts EM. Effects of the benzodiazepine GABAA α1-preferring ligand, 3-propoxy-β-carboline hydrochloride (3-PBC), on alcohol seeking and self-administration in baboons. Psychopharmacology (Berl) 2013; 227:127-36. [PMID: 23271191 PMCID: PMC3624026 DOI: 10.1007/s00213-012-2946-z] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/04/2012] [Accepted: 12/01/2012] [Indexed: 12/18/2022]
Abstract
RATIONALE The various α subtypes of GABAA receptors have been strongly implicated in alcohol reinforcement and consumption. OBJECTIVES The effects of the GABAA α1-preferring ligand, 3-propoxy-β-carboline hydrochloride (3-PBC), on seeking and self-administration responses were evaluated in two groups of baboons trained under a 3-component chained schedule of reinforcement (CSR). METHODS Alcohol (4 % w/v; n = 5; alcohol group) or a preferred nonalcoholic beverage (n = 4; control group) was available for self-administration only in component 3 of the CSR. Responses in component 2 provided indices of motivation to drink (seeking). 3-PBC (1.0-30.0 mg/kg) and saline were administered before drinking sessions under both acute and 5-day dosing conditions. RESULTS Repeated, and not acute, doses of 3-PBC significantly decreased total self-administration responses (p < 0.05), volume consumed (p < 0.05), and gram per kilogram of alcohol (p < 0.05) in the alcohol group. In the control group, 5-day administration of 3-PBC significantly decreased total self-administration responses (p < 0.05) but produced nonsignificant decreases in volume consumed. Within-session pattern of drinking was characterized by a high level of drinking in the first 20 min of the session for both groups, which was significantly (p < 0.05) decreased by all doses of 3-PBC (1.0-18.0 mg/kg) only in the alcohol group. In contrast, the first drinking bout in the control group was only reduced at the highest doses of 3-PBC (10.0 and 18.0 mg/kg). CONCLUSIONS The results support the involvement of the GABAA α1 subtype receptor in alcohol reinforcement and consumption.
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Affiliation(s)
- Barbara J. Kaminski
- Division of Behavioral Biology, Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, 5510 Nathan Shock Drive, Baltimore, MD, 21224
| | - Michael L. Van Linn
- Department of Chemistry and Biochemistry, University of Wisconsin-Milwaukee, Milwaukee, WI 53201
| | - James M. Cook
- Department of Chemistry and Biochemistry, University of Wisconsin-Milwaukee, Milwaukee, WI 53201
| | - Wenyuan Yin
- Department of Chemistry and Biochemistry, University of Wisconsin-Milwaukee, Milwaukee, WI 53201
| | - Elise M. Weerts
- Division of Behavioral Biology, Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, 5510 Nathan Shock Drive, Baltimore, MD, 21224
- Corresponding Author: Elise M. Weerts, Ph.D., Johns Hopkins Bayview Campus, Behavioral Biology Research Center, 5510 Nathan Shock Drive, Suite 3000, Baltimore, MD 21224, USA Tel.: 410-550-2781; Fax: 410-550-2780;
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Gubner NR, McKinnon CS, Reed C, Phillips TJ. Accentuating effects of nicotine on ethanol response in mice with high genetic predisposition to ethanol-induced locomotor stimulation. Drug Alcohol Depend 2013; 127:108-14. [PMID: 22795175 PMCID: PMC3505243 DOI: 10.1016/j.drugalcdep.2012.06.015] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/25/2012] [Revised: 06/12/2012] [Accepted: 06/14/2012] [Indexed: 01/12/2023]
Abstract
BACKGROUND Co-morbid use of nicotine-containing tobacco products and alcohol is prevalent in alcohol dependent individuals. Common genetic factors could influence initial sensitivity to the independent or interactive effects of these drugs and play a role in their co-abuse. METHODS Locomotor sensitivity to nicotine and ethanol, alone and in combination, was assessed in mice bred for high (FAST) and low (SLOW) sensitivity to the locomotor stimulant effects of ethanol and in an inbred strain of mouse (DBA/2J) that has been shown to have extreme sensitivity to ethanol-induced stimulation in comparison to other strains. RESULTS The effects of nicotine and ethanol, alone and in combination, were dependent on genotype. In FAST and DBA/2J mice that show high sensitivity to ethanol-induced stimulation, nicotine accentuated the locomotor stimulant response to ethanol. This effect was not found in SLOW mice that are not stimulated by ethanol alone. CONCLUSIONS These data indicate that genes underlying differential sensitivity to the stimulant effects of ethanol alone also influence sensitivity to nicotine in combination with ethanol. Sensitivity to the stimulant effects of nicotine alone does not appear to predict the response to the drug combination, as FAST mice are sensitive to nicotine-induced stimulation, whereas SLOW and DBA/2J mice are not. The combination of nicotine and ethanol may have genotype-dependent effects that could impact co-abuse liability.
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Affiliation(s)
- N R Gubner
- Department of Behavioral Neuroscience and Portland Alcohol Research Center, Oregon Health & Science University, Portland, OR, USA
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11
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Carta MG, Bhat KM, Preti A. GABAergic neuroactive steroids: a new frontier in bipolar disorders? Behav Brain Funct 2012; 8:61. [PMID: 23253178 PMCID: PMC3573983 DOI: 10.1186/1744-9081-8-61] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2012] [Accepted: 11/30/2012] [Indexed: 01/27/2023] Open
Abstract
Neurosteroids are synthesized in the brain and modulate brain excitability. There is increasing evidence of their sedative, anesthetic and antiseizure properties, as well as their influence on mood. Currently neurosteroids are classified as pregnane neurosteroids (allopregnanolone and allotetrahydrodeoxycorticosterone), androstane neurosteroids (androstanediol and etiocholanone) or sulfated neurosteroids (pregnenolone sulfate and dehydroepiandrosterone sulfate). Both preclinical and clinical findings indicate that progesterone derivative neurosteroids such as allopregnanolone and allotetrahydrodeoxycorticosterone play a role in mood disorders. Clozapine and olanzapine, which were shown to be effective in stabilizing bipolar disorder, elevate pregnenolone levels in rat hippocampus, cerebral cortex, and serum. In lithium-treated mice, the blood levels of allopregnanolone and pregnenolone were elevated compared to control levels. Women diagnosed with bipolar disorder typically show symptomatic exacerbation in relation to the menstrual cycle, and show vulnerability to the onset or recurrence of mood disorders immediately after giving birth, when the levels of neurosteroid derivatives of progesterone drop. Whereas in women who had recovered from bipolar disorder, the plasma concentration of allopregnanolone was elevated compared to either healthy controls or women with major depressive disorder during the premenstrual period. During depressive episodes, blood level of allopregnanolone is low. Treatment with fluoxetine tends to stabilize the levels of neurosteroids in depression. These findings converge to suggest that these steroids have significant mood-stabilizing effect. This hypothesis is consistent with the observation that a number of anticonvulsants are effective therapies for bipolar disorder, a finding also consistent with the antiseizure properties of neurosteroids. Further exploration of action of neuroactive steroids is likely to open new frontiers in the investigation of the etiology and treatment of mood disorders, particularly bipolar disorders.
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Affiliation(s)
- Mauro Giovanni Carta
- Department of Public Health, Clinical and Molecular Medicine, University of Cagliari and Center for Consultation-Liaison Psychiatry and Psychosomatics University Hospital of Cagliari, Cagliari, Italy.
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12
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Taherianfard M, Davazdahemamy M, Shojaeifard M, Sharifi M. Acute and chronic exposure of chick embryo to ethanol alters brain neurosteroid levels. J Physiol Biochem 2012; 69:141-5. [DOI: 10.1007/s13105-012-0198-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2011] [Accepted: 06/28/2012] [Indexed: 12/01/2022]
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13
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Blednov YA, Mayfield RD, Belknap J, Harris RA. Behavioral actions of alcohol: phenotypic relations from multivariate analysis of mutant mouse data. GENES BRAIN AND BEHAVIOR 2012; 11:424-35. [PMID: 22405477 DOI: 10.1111/j.1601-183x.2012.00780.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Behavioral studies on genetically diverse mice have proven powerful for determining relationships between phenotypes and have been widely used in alcohol research. Most of these studies rely on naturally occurring genetic polymorphisms among inbred strains and selected lines. Another approach is to introduce variation by engineering single-gene mutations in mice. We have tested 37 different mutant mice and their wild-type controls for a variety (31) of behaviors and have mined this data set by K-means clustering and analysis of correlations. We found a correlation between a stress-related response (activity in a novel environment) and alcohol consumption and preference for saccharin. We confirmed several relationships detected in earlier genetic studies, including positive correlation of alcohol consumption with saccharin consumption and negative correlations with conditioned taste aversion and alcohol withdrawal severity. Introduction of single-gene mutations either eliminated or greatly diminished these correlations. The three tests of alcohol consumption used (continuous two-bottle choice and two limited access tests: drinking in the dark and sustained high alcohol consumption) share a relationship with saccharin consumption, but differ from each other in their correlation networks. We suggest that alcohol consumption is controlled by multiple physiological systems where single-gene mutations can disrupt the networks of such systems.
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Affiliation(s)
- Y A Blednov
- Waggoner Center for Alcohol and Addiction Research, Section on Neurobiology, Institute for Neuroscience, Institute for Cell and Molecular Biology, University of Texas at Austin, TX 78712, USA
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14
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Wu PH, Schulz KM. Advancing addiction treatment: what can we learn from animal studies? ILAR J 2012; 53:4-13. [PMID: 23520595 DOI: 10.1093/ilar.53.1.4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Substance addiction is a maladaptive behavior characterized by compulsive and uncontrolled self-administration of a substance (drug). Years of research indicate that addictive behavior is the result of complex interactions between the drug, the user, and the environment in which the drug is used; therefore, addiction cannot simply be attributed to the neurobiological actions of a drug. However, despite the obvious complexity of addictive behavior, animal models have both advanced understanding of addiction and contributed importantly to the development of medications to treat this disease. We briefly review recent animal models used to study drug addiction and the contribution of data generated by these animal models for the clinical treatment of addictive disorders.
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Affiliation(s)
- Peter H Wu
- Department of Psychiatry, University of Colorado Anschutz Medical Campus, Research Complex-1 North, Mail Stop 8344, 12800 East 19th Avenue, Aurora, Colorado 80045, USA.
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Blednov YA, Benavidez JM, Homanics GE, Harris RA. Behavioral characterization of knockin mice with mutations M287L and Q266I in the glycine receptor α1 subunit. J Pharmacol Exp Ther 2011; 340:317-29. [PMID: 22037202 DOI: 10.1124/jpet.111.185124] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
We used behavioral pharmacology to characterize heterozygous knockin mice with mutations (Q266I or M287L) in the α1 subunit of the glycine receptor (GlyR) (J Pharmacol Exp Ther 340:304-316, 2012). These mutations were designed to reduce (M287L) or eliminate (Q266I) ethanol potentiation of GlyR function. We asked which behavioral effects of ethanol would be reduced more in the Q266I mutant than the M287L and found rotarod ataxia to be the behavior that fulfilled this criterion. Compared with controls, the mutant mice also differed in ethanol consumption, ethanol-stimulated startle response, signs of acute physical dependence, and duration of loss of righting response produced by ethanol, butanol, ketamine, pentobarbital, and flurazepam. Some of these behavioral changes were mimicked in wild-type mice by acute injections of low, subconvulsive doses of strychnine. Both mutants showed increased acoustic startle response and increased sensitivity to strychnine seizures. Thus, in addition to reducing ethanol action on the GlyRs, these mutations reduced glycinergic inhibition, which may also alter sensitivity to GABAergic drugs.
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Affiliation(s)
- Yuri A Blednov
- Waggoner Center for Alcohol and Addiction Research, University of Texas, Austin, TX 78712-0159, USA
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16
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Dickerson D, Pittman B, Ralevski E, Perrino A, Limoncelli D, Edgecombe J, Acampora G, Krystal JH, Petrakis I. Ethanol-like effects of thiopental and ketamine in healthy humans. J Psychopharmacol 2010; 24:203-11. [PMID: 19028835 PMCID: PMC4484757 DOI: 10.1177/0269881108098612] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The gamma-aminobutyric acid-A (GABA(A)) and N-methyl-D-aspartate (NMDA) receptors mediate aspects of the behavioural effects of alcohol. Prior studies reported drugs that block NMDA receptors or facilitate GABA(A) receptor function produce ethanol-like effects in humans. The purpose of this study was to compare the ethanol-related effects of two pharmacological agents with known NMDA and GABA(A) receptor activity. As part of an ongoing, larger study, 28 subjects (age, 21-30) with no personal or family histories of alcoholism were administered subanesthetic doses of the GABA(A) receptor agonist thiopental, the NMDA receptor antagonist, ketamine and placebo on three separate test days. Various ethanol-related measures were administered. At doses of thiopental and ketamine that produced similar levels of sedation and cognitive effects, both agents produced significant ethanol-like effects and subjective intoxication. However, the intensity of the ethanol-like effects of ketamine was greater than that of thiopental. In addition, ketamine produced alterations in perception that were not produced by thiopental. These data provide further support for a model where GABA(A) receptor facilitation may contribute significantly to ethanol effects associated with social drinking, whereas NMDA receptor antagonism may contribute to relatively greater extent to features of ethanol 'intoxication'.
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Affiliation(s)
- D Dickerson
- UCLA Integrated Substance Abuse Programs, Los Angeles, CA, USA
| | - B Pittman
- NIAAA Center for the Translational Neuroscience of Alcoholism and Department of Psychiatry, Yale University School of Medicine, New Haven, CT, USA
| | - E Ralevski
- NIAAA Center for the Translational Neuroscience of Alcoholism and Department of Psychiatry, Yale University School of Medicine, New Haven, Connecticut, USA; Department of Veterans Affairs Alcohol Research Center, VA Connecticut Healthcare System (116-A), West Haven, CT, USA
| | - A Perrino
- NIAAA Center for the Translational Neuroscience of Alcoholism and Department of Anesthesiology, Yale University School of Medicine, New Haven, CT, USA; Department of Veterans Affairs Alcohol Research Center, VA Connecticut Healthcare System (116-A), West Haven, CT, USA
| | - D Limoncelli
- NIAAA Center for the Translational Neuroscience of Alcoholism and Department of Psychiatry, Yale University School of Medicine, New Haven, CT, USA; Department of Veterans Affairs Alcohol Research Center, VA Connecticut Healthcare System (116-A), West Haven, CT, USA
| | - J Edgecombe
- NIAAA Center for the Translational Neuroscience of Alcoholism and Department of Psychiatry, Yale University School of Medicine, New Haven, CT, USA; Department of Veterans Affairs Alcohol Research Center, VA Connecticut Healthcare System (116-A), West Haven, CT, USA
| | - G Acampora
- NIAAA Center for the Translational Neuroscience of Alcoholism and Department of Psychiatry, Yale University School of Medicine, New Haven, CT, USA; Department of Veterans Affairs Alcohol Research Center, VA Connecticut Healthcare System (116-A), West Haven, CT, USA
| | - JH Krystal
- NIAAA Center for the Translational Neuroscience of Alcoholism and Department of Psychiatry, Yale University School of Medicine, New Haven, CT, USA; Department of Veterans Affairs Alcohol Research Center, VA Connecticut Healthcare System (116-A), West Haven, CT, USA; Clinical Neuroscience Research Unit, Abraham Ribicoff Research Facilities, New Haven, CT, USA
| | - I Petrakis
- NIAAA Center for the Translational Neuroscience of Alcoholism and Department of Psychiatry, Yale University School of Medicine, New Haven, CT, USA; Department of Veterans Affairs Alcohol Research Center, VA Connecticut Healthcare System (116-A), West Haven, CT, USA
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17
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The physiological properties and therapeutic potential of alpha5-GABAA receptors. Biochem Soc Trans 2010; 37:1334-7. [PMID: 19909271 DOI: 10.1042/bst0371334] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The notion that drug treatments can improve memory performance has moved from the realm of science fiction to that of serious investigation. A popular working hypothesis is that cognition can be improved by altering the balance between excitatory and inhibitory neurotransmission. This review focuses on the unique physiological and pharmacological properties of GABA(A)Rs [GABA (gamma-aminobutyric acid) subtype A receptors] that contain the alpha(5) subunit (alpha(5)-GABA(A)R), as these receptors serve as candidate targets for memory-enhancing drugs.
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Blednov YA, Walker DL, Iyer SV, Homanics G, Harris AR. Mice lacking Gad2 show altered behavioral effects of ethanol, flurazepam and gabaxadol. Addict Biol 2010; 15:45-61. [PMID: 20002022 PMCID: PMC3038569 DOI: 10.1111/j.1369-1600.2009.00186.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Gamma-aminobutyric acid (GABA) is synthesized in brain by two isoforms of glutamic acid decarboxylase (Gad), Gad1 and Gad2. Gad1 provides most of the GABA in brain, but Gad2 can be rapidly activated in times of high GABA demand. Mice lacking Gad2 are viable whereas deletion of Gad1 is lethal. We produced null mutant mice for Gad2 on three different genetic backgrounds: predominantly C57BL/6J and one or two generations of backcrossing to 129S1/SvimJ (129N1, 129N2). We used these mice to determine if actions of alcohol are regulated by synthesis of GABA from this isoform. We also studied behavioral responses to a benzodiazepine (flurazepam) and a GABAA receptor agonist (gabaxadol). Deletion of Gad2 increased ethanol palatability and intake and slightly reduced the severity of ethanol-induced withdrawal, but these effects depended strongly on genetic background. Mutant mice on the 129N2 background showed the above three ethanol behavioral phenotypes, but the C57BL/6J inbred background did not show any of these phenotypes. Effects on ethanol consumption also depended on the test as the mutation did not alter consumption in limited access models. Deletion of Gad2 reduced the effect of flurazepam on motor incoordination and increased the effect of extrasynaptic GABAA receptor agonist gabaxadol without changing the duration of loss of righting reflex produced by these drugs. These results are consistent with earlier proposals that deletion of Gad2 (on 129N2 background) reduces synaptic GABA but also suggest changes in extrasynaptic receptor function.
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Affiliation(s)
- Yuri A. Blednov
- University of Texas, Waggoner Center for Alcohol and Addiction Research, USA
| | - Danielle L. Walker
- University of Texas, Waggoner Center for Alcohol and Addiction Research, USA
| | - Sangeetha V. Iyer
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, USA
| | - Gregg Homanics
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, USA,Department of Anesthesiology, University of Pittsburgh, USA
| | - Adron R. Harris
- University of Texas, Waggoner Center for Alcohol and Addiction Research, USA
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Pohl‐Guimarães F, Calaza KDC, Yamasaki EN, Kubrusly RCC, Melo Reis RA. Ethanol increases GABA release in the embryonic avian retina. Int J Dev Neurosci 2009; 28:189-94. [DOI: 10.1016/j.ijdevneu.2009.11.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2009] [Revised: 10/15/2009] [Accepted: 11/05/2009] [Indexed: 12/24/2022] Open
Affiliation(s)
- Fernanda Pohl‐Guimarães
- Laboratory of Neurochemistry, Program in Neurobiology, Biophysics Institute Carlos Chagas FilhoUFRJRio de JaneiroBrazil
| | - Karin da Costa Calaza
- Laboratory of Neurobiology of the Retina, Program in Neurosciences, Biology Institute, UFF24020140NiteróiRJBrazil
| | - Edna Nanami Yamasaki
- Laboratory of Neurobiology of the Retina, Program in Neurobiology, Biophysics Institute Carlos Chagas FilhoUFRJRio de JaneiroBrazil
| | - Regina Célia Cussa Kubrusly
- Laboratory of Neuropharmacology, Program in NeurosciencesDepartment of Physiology and PharmacologyUFFNiteróiRJBrazil
| | - Ricardo Augusto Melo Reis
- Laboratory of Neurochemistry, Program in Neurobiology, Biophysics Institute Carlos Chagas FilhoUFRJRio de JaneiroBrazil
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Kumar S, Porcu P, Werner DF, Matthews DB, Diaz-Granados JL, Helfand RS, Morrow AL. The role of GABA(A) receptors in the acute and chronic effects of ethanol: a decade of progress. Psychopharmacology (Berl) 2009; 205:529-64. [PMID: 19455309 PMCID: PMC2814770 DOI: 10.1007/s00213-009-1562-z] [Citation(s) in RCA: 342] [Impact Index Per Article: 22.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/17/2008] [Accepted: 04/30/2009] [Indexed: 12/12/2022]
Abstract
The past decade has brought many advances in our understanding of GABA(A) receptor-mediated ethanol action in the central nervous system. We now know that specific GABA(A) receptor subtypes are sensitive to ethanol at doses attained during social drinking while other subtypes respond to ethanol at doses attained by severe intoxication. Furthermore, ethanol increases GABAergic neurotransmission through indirect effects, including the elevation of endogenous GABAergic neuroactive steroids, presynaptic release of GABA, and dephosphorylation of GABA(A) receptors promoting increases in GABA sensitivity. Ethanol's effects on intracellular signaling also influence GABAergic transmission in multiple ways that vary across brain regions and cell types. The effects of chronic ethanol administration are influenced by adaptations in GABA(A) receptor function, expression, trafficking, and subcellular localization that contribute to ethanol tolerance, dependence, and withdrawal hyperexcitability. Adolescents exhibit altered sensitivity to ethanol actions, the tendency for higher drinking and longer lasting GABAergic adaptations to chronic ethanol administration. The elucidation of the mechanisms that underlie adaptations to ethanol exposure are leading to a better understanding of the regulation of inhibitory transmission and new targets for therapies to support recovery from ethanol withdrawal and alcoholism.
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Affiliation(s)
- Sandeep Kumar
- Department of Psychiatry, Bowles Center for Alcohol Studies, University of North Carolina School of Medicine, 3027 Thurston-Bowles Building, CB #7178, Chapel Hill, NC 27599-7178, USA
| | - Patrizia Porcu
- Department of Psychiatry, Bowles Center for Alcohol Studies, University of North Carolina School of Medicine, 3027 Thurston-Bowles Building, CB #7178, Chapel Hill, NC 27599-7178, USA
| | - David F. Werner
- Department of Psychiatry, Bowles Center for Alcohol Studies, University of North Carolina School of Medicine, 3027 Thurston-Bowles Building, CB #7178, Chapel Hill, NC 27599-7178, USA
| | | | | | - Rebecca S. Helfand
- Department of Psychology and Neuroscience, Baylor University, Waco, TX, USA
| | - A. Leslie Morrow
- Department of Psychiatry, Bowles Center for Alcohol Studies, University of North Carolina School of Medicine, 3027 Thurston-Bowles Building, CB #7178, Chapel Hill, NC 27599-7178, USA, Department of Pharmacology, Bowles Center for Alcohol Studies, University of North Carolina School of Medicine, 3027 Thurston-Bowles Building, CB #7178, Chapel Hill, NC 27599-7178, USA
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21
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Molnár T, Antal K, Nyitrai G, Emri Z. gamma-Hydroxybutyrate (GHB) induces GABA(B) receptor independent intracellular Ca2+ transients in astrocytes, but has no effect on GHB or GABA(B) receptors of medium spiny neurons in the nucleus accumbens. Neuroscience 2009; 162:268-81. [PMID: 19446011 DOI: 10.1016/j.neuroscience.2009.05.017] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2009] [Revised: 04/27/2009] [Accepted: 05/08/2009] [Indexed: 02/07/2023]
Abstract
We report on cellular actions of the illicit recreational drug gamma-hydroxybutyrate (GHB) in the brain reward area nucleus accumbens. First, we compared the effects of GHB and the GABA(B) receptor agonist baclofen. Neither of them affected the membrane currents of medium spiny neurons in rat nucleus accumbens slices. GABAergic and glutamatergic synaptic potentials of medium spiny neurons, however, were reduced by baclofen but not GHB. These results indicate the lack of GHB as well as postsynaptic GABA(B) receptors, and the presence of GHB insensitive presynaptic GABA(B) receptors in medium spiny neurons. In astrocytes GHB induced intracellular Ca(2+) transients, preserved in slices from GABA(B) receptor type 1 subunit knockout mice. The effects of tetrodotoxin, zero added Ca(2+) with/without intracellular Ca(2+) store depletor cyclopiazonic acid or vacuolar H-ATPase inhibitor bafilomycin A1 indicate that GHB-evoked Ca(2+) transients depend on external Ca(2+) and intracellular Ca(2+) stores, but not on vesicular transmitter release. GHB-induced astrocytic Ca(2+) transients were not affected by the GHB receptor-specific antagonist NCS-382, suggesting the presence of a novel NCS-382-insensitive target for GHB in astrocytes. The activation of astrocytes by GHB implies their involvement in physiological actions of GHB. Our findings disclose a novel profile of GHB action in the nucleus accumbens. Here, unlike in other brain areas, GHB does not act on GABA(B) receptors, but activates an NCS-382 insensitive GHB-specific target in a subpopulation of astrocytes. The lack of either post- or presynaptic effects on medium spiny neurons in the nucleus accumbens distinguishes GHB from many drugs and natural rewards with addictive properties and might explain why GHB has only a weak reinforcing capacity.
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Affiliation(s)
- T Molnár
- Department of Neurochemistry, Institute of Biomolecular Chemistry, Chemical Research Center, Hungarian Academy of Sciences, Pusztaszeri út 59-67.1025, Budapest, Hungary
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22
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Berry RB, Chandra D, Diaz-Granados JL, Homanics GE, Matthews DB. Investigation of ethanol-induced impairment of spatial memory in gamma2 heterozygous knockout mice. Neurosci Lett 2009; 455:84-7. [PMID: 19368851 DOI: 10.1016/j.neulet.2009.03.046] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2009] [Revised: 03/03/2009] [Accepted: 03/04/2009] [Indexed: 11/19/2022]
Abstract
GABA(A) receptors, the major inhibitory receptors in the mammalian central nervous system, are affected by a number of drug compounds, including ethanol. The pharmacological effects of certain drugs have been shown to be dependent upon specific GABA(A) receptor subunits. Because benzodiazepines and ethanol have similar effect signatures, it has been hypothesized that these drugs share the gamma2-containing GABA(A) receptors as a mechanism of action. To probe the involvement of the gamma2 subunit in ethanol's actions, spatial memory for the Morris water maze task was tested in gamma2 heterozygous knockout mice and wild type littermate controls following ethanol administration at the following doses: 0.0, 1.25, 1.75, and 2.25 g/kg. While baseline learning and memory were unaffected by reduction of gamma2 containing GABA(A) receptors, ethanol dose-dependently impaired spatial memory equally in gamma2 heterozygous knockouts and wild type littermate controls.
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Affiliation(s)
- Raymond B Berry
- Department of Psychology, The University of Memphis, Memphis, TN 38152, USA
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23
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Alvarez-Jaimes L, Polis I, Parsons LH. Regional Influence of Cannabinoid CB 1 Receptors in the Regulation of Ethanol Self-Administration by Wistar Rats. THE OPEN NEUROPSYCHOPHARMACOLOGY JOURNAL 2009; 2:77-85. [PMID: 27974944 PMCID: PMC5152943 DOI: 10.2174/1876523800902020077] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Substantial evidence suggests a facilitatory influence of cannabinoid CB1 receptors in the modulation of ethanol consumption by rodents. Studies performed in rats selectively bred for high alcohol preference point to an involvement of CB1 receptors in the nucleus accumbens (NAC), ventral tegmental area (VTA) and medial prefrontal cortex (mPFC) in the modulation ethanol self-administration. However, the neural mechanisms through which CB1 receptors regulate ethanol intake in out-bred Wistar rats have not been investigated. The present study evaluated alterations in ethanol self-administration induced by localized infusions of the CB1 receptor antagonist SR141716A (0, 1 and 3 μg/side) into the NAC, anterior and posterior VTA and mPFC. Separate groups of Wistar rats were trained to operantly respond for an oral ethanol solution and prepared with bilateral injection cannulae aimed at each brain region. Results revealed significant decreases in ethanol intake following intra-NAC SR141716A administration, consistent with our prior observation of ethanol-induced increases extracellular 2-arachidonoyl glycerol (2-AG) in this brain region. We also observed a significant dose-dependent reduction in ethanol intake following SR141716A administration into the posterior, but not anterior VTA, consistent with evidence of a specific involvement of the posterior VTA in the regulation of ethanol intake. Ethanol consumption was unaltered following intra-mPFC SR141716A administration and ethanol self-administration did not induce robust changes in anandamide or 2-AG levels in mPFC microdialysates. These findings implicate an involvement of CB1 receptors in the NAC and posterior VTA, but not anterior VTA and mPFC in the regulation of ethanol self-administration behavior by outbred Wistar rats.
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Affiliation(s)
- Lily Alvarez-Jaimes
- Committee on the Neurobiology of Addictive Disorders, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Ilham Polis
- Committee on the Neurobiology of Addictive Disorders, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Loren H. Parsons
- Committee on the Neurobiology of Addictive Disorders, The Scripps Research Institute, La Jolla, CA 92037, USA
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Holstein SE, Dobbs L, Phillips TJ. Attenuation of the stimulant response to ethanol is associated with enhanced ataxia for a GABA, but not a GABA, receptor agonist. Alcohol Clin Exp Res 2008; 33:108-20. [PMID: 18945218 DOI: 10.1111/j.1530-0277.2008.00817.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
BACKGROUND The gamma-aminobutyric acid (GABA) system is implicated in the neurobiological actions of ethanol, and pharmacological agents that increase the activity of this system have been proposed as potential treatments for alcohol use disorders. As ethanol has its own GABA mimetic properties, it is critical to determine the mechanism by which GABAergic drugs may reduce the response to ethanol (i.e., via an inhibition or an accentuation of the neurobiological effects of ethanol). METHODS In this study, we examined the ability of 3 different types of GABAergic compounds, the GABA reuptake inhibitor NO-711, the GABA(A) receptor agonist muscimol, and the GABA(B) receptor agonist baclofen, to attenuate the locomotor stimulant response to ethanol in FAST mice, which were selectively bred for extreme sensitivity to ethanol-induced locomotor stimulation. To determine whether these compounds produced a specific reduction in stimulation, their effects on ethanol-induced motor incoordination were also examined. RESULTS NO-711, muscimol, and baclofen were all found to potently attenuate the locomotor stimulant response to ethanol in FAST mice. However, both NO-711 and muscimol markedly increased ethanol-induced ataxia, whereas baclofen did not accentuate this response. CONCLUSIONS These results suggest that pharmacological agents that increase extracellular concentrations of GABA and GABA(A) receptor activity may attenuate the stimulant effects of ethanol by accentuating its intoxicating and sedative properties. However, selective activation of the GABA(B) receptor appears to produce a specific attenuation of ethanol-induced stimulation, suggesting that GABA(B) receptor agonists may hold greater promise as potential pharmacotherapies for alcohol use disorders.
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Affiliation(s)
- Sarah E Holstein
- Portland Alcohol Research Center and the Department of Behavioral Neuroscience, Oregon Health & Science University, Portland, Oregon, USA
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25
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Boyce-Rustay JM, Palachick B, Hefner K, Chen YC, Karlsson RM, Millstein RA, Harvey-White J, Holmes A. Desipramine potentiation of the acute depressant effects of ethanol: modulation by alpha2-adrenoreceptors and stress. Neuropharmacology 2008; 55:803-11. [PMID: 18625256 PMCID: PMC2632577 DOI: 10.1016/j.neuropharm.2008.06.032] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2007] [Revised: 05/15/2008] [Accepted: 06/18/2008] [Indexed: 12/15/2022]
Abstract
Ethanol exerts effects on the brain noradrenergic system, and these are thought to contribute to the sedative/hypnotic (depressant) effects of ethanol. Recent studies suggest that the norepinephrine transporter (NET) plays an important role in modulating ethanol's depressant effects. The aim of the present study was to further characterize this role. Transporter blockers with varying affinity for NET versus the serotonin transporter (desipramine>fluoxetine>citalopram) were tested for their ability to alter ethanol's depressant effects, and for comparison, hypothermic effects. Effects of desipramine on another depressant, pentobarbital, were examined. Desipramine potentiation of ethanol's depressant effects was assessed following depletion of brain norepinephrine via N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine hydrochloride (DSP-4) treatment, or depletion of brain 5-HT via para-chlorophenylalanine methyl ester hydrochloride (PCPA) treatment. The effects of co-administration of either the selective alpha2-adrenoreceptor agonist (dexmedetomidine) or the selective alpha2-adrenoreceptor antagonist (atipamezole) on desipramine's effect on ethanol's depressant effects were examined. Given the close link between stress, ethanol and norepinephrine, desipramine potentiation of ethanol's depressant effects was tested following repeated forced swim stress. Results showed that desipramine, but not SERT-selective doses of citalopram or fluoxetine, strongly potentiated the depressant (not hypothermic) effects of ethanol. These effects were mimicked by dexmedetomidine and blocked by atipamezole, but not by depletion of either norepinephrine or 5-HT. Desipramine potentiation of ethanol's depressant effects was abolished following repeated stress. Present findings further support a major role for NET and the alpha2-adrenoreceptor in modulating the depressant effects of ethanol, with possible implications for understanding the role of noradrenergic dysfunction in stress-related alcoholism.
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Affiliation(s)
- Janel M Boyce-Rustay
- Laboratory for Integrative Neuroscience, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Rockville, MD, USA.
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Abstract
Despite the generally held view that alcohol is an unspecific pharmacological agent, recent molecular pharmacology studies demonstrated that alcohol has only a few known primary targets. These are the NMDA, GABA(A), glycine, 5-hydroxytryptamine 3 (serotonin) and nicotinic ACh receptors as well as L-type Ca(2+) channels and G-protein-activated inwardly rectifying K(+) channels. Following this first hit of alcohol on specific targets in the brain, a second wave of indirect effects on a variety of neurotransmitter/neuropeptide systems is initiated that leads subsequently to the typical acute behavioural effects of alcohol, ranging from disinhibition to sedation and even hypnosis, with increasing concentrations of alcohol. Besides these acute pharmacodynamic aspects of alcohol, we discuss the neurochemical substrates that are involved in the initiation and maintenance phase of an alcohol drinking behaviour. Finally, addictive behaviour towards alcohol as measured by alcohol-seeking and relapse behaviour is reviewed in the context of specific neurotransmitter/neuropeptide systems and their signalling pathways. The activity of the mesolimbic dopaminergic system plays a crucial role during the initiation phase of alcohol consumption. Following long-term, chronic alcohol consumption virtually all brain neurotransmission seems to be affected, making it difficult to define which of the systems contributes the most to the transition from controlled to compulsive alcohol use. However, compulsive alcohol drinking is characterized by a decrease in the function of the reward neurocircuitry and a recruitment of antireward/stress mechanisms comes into place, with a hypertrophic corticotropin-releasing factor system and a hyperfunctional glutamatergic system being the most important ones.
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27
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Márton ML, Dresselhaus T. A comparison of early molecular fertilization mechanisms in animals and flowering plants. ACTA ACUST UNITED AC 2008. [DOI: 10.1007/s00497-007-0062-8] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
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Kelm MK, Criswell HE, Breese GR. Calcium Release from Presynaptic Internal Stores Is Required for Ethanol to Increase Spontaneous γ-Aminobutyric Acid Release onto Cerebellum Purkinje Neurons. J Pharmacol Exp Ther 2007; 323:356-64. [PMID: 17652632 DOI: 10.1124/jpet.107.126144] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Recent data have demonstrated that ethanol increases gamma-aminobutyric acid (GABA) release in many brain regions, but little is known about the mechanism responsible for this action. Consistent with previous results, ethanol increased miniature inhibitory postsynaptic current (mIPSC) frequency at the interneuron-Purkinje cell synapse in the slice and in mechanically dissociated neurons. These data suggest that ethanol is increasing spontaneous GABA release at this synapse. It is generally accepted that ethanol increases levels of intracellular calcium and that changes in intracellular calcium can alter neurotransmitter release. Therefore, we examined the contribution of calcium-dependent pathways to the effect of ethanol on spontaneous GABA release at the interneuron-Purkinje cell synapse. Ethanol continued to increase mIPSC frequency in a nominally calcium-free extracellular solution and in the presence of a voltage-dependent calcium channel inhibitor, cadmium chloride. These data suggest that influx of extracellular calcium does not play a critical role in the mechanism of ethanol-enhanced spontaneous GABA release. However, a sarco/endoplasmic-reticulum calcium ATPase pump inhibitor (thapsigargin), an inositol 1,4,5-trisphosphate receptor antagonist (2-aminoethoxydiphenylborate) and a ryanodine receptor antagonist (ryanodine) significantly reduced the ability of ethanol to increase mIPSC frequency. In addition, ethanol was still able to increase mIPSC frequency in the presence of intracellular 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA) and a cannabinoid receptor antagonist N-(piperidin-1-yl)-5-(4-iodophenyl)-1-(2,4-dichlorophenyl)-4-methyl-1H-pyrazole-3-carboxamide (AM-251); thus, retrograde messengers are not involved in ethanol-enhanced spontaneous GABA release. Overall, these data suggest that calcium release from presynaptic internal stores plays a vital role in the mechanism of ethanol-enhanced spontaneous GABA release at the interneuron-Purkinje cell synapse.
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Affiliation(s)
- M Katherine Kelm
- Bowles Center for Alcohol Studies, CB 7178, Thurston-Bowles Building, Chapel Hill, NC 27599-7178, USA.
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Mody I, Glykys J, Wei W. A new meaning for "Gin & Tonic": tonic inhibition as the target for ethanol action in the brain. Alcohol 2007; 41:145-53. [PMID: 17521846 PMCID: PMC2012942 DOI: 10.1016/j.alcohol.2007.03.009] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2007] [Revised: 02/28/2007] [Accepted: 03/01/2007] [Indexed: 12/14/2022]
Abstract
Gamma-aminobutyric acid (GABA) is the main chemical inhibitory neurotransmitter in the brain. In the central nervous system, it acts on two distinct types of receptor: an ion channel, that is, an "ionotropic" receptor permeable to Cl- and HCO3- (GABAA receptors [GABAARs]) and a G-protein coupled "metabotropic" receptor that is linked to various effector mechanisms (GABAB receptors). This review will summarize novel developments in the physiology and pharmacology of GABAARs, specifically those found outside synapses. The focus will be on a particular combination of GABAAR subunits responsible for mediating tonic inhibition and sensitive to concentrations of ethanol legally considered to be sobriety impairing. Since the same receptors are also a preferred target for the metabolites of steroid hormones synthesized in the brain (neurosteroids), the ethanol-sensitive tonic inhibition may be a common pathway for interactions between the effects of alcohol and those of ovarian and stress-related neurosteroids.
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Affiliation(s)
- Istvan Mody
- Department of Neurology, The David Geffen School of Medicine at UCLA, 635 Charles Young Dr S, University of California, Los Angeles, CA 90095, USA.
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