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Doyle MA, Salimando GJ, Altemus ME, Badt JK, Bedenbaugh MN, Vardy AS, Adank DN, Park AS, Winder DG. BNST GluN2D-containing NMDARs contribute to ethanol intake but not negative affective behaviors in female mice. ALCOHOL, CLINICAL & EXPERIMENTAL RESEARCH 2024. [PMID: 39179522 DOI: 10.1111/acer.15432] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2024] [Revised: 07/17/2024] [Accepted: 08/09/2024] [Indexed: 08/26/2024]
Abstract
BACKGROUND Alcohol use disorder (AUD) is a chronic, relapsing disease, highly comorbid with anxiety and depression. The bed nucleus of the stria terminalis (BNST) and Crh+ neurons in this region play a key role in chronic ethanol-induced increases in volitional intake, hypothesized to be driven by emergent negative affective behaviors. Excitatory N-methyl-d-aspartate receptors (NMDARs) are a major target of ethanol, and chronic ethanol exposure has been shown to regulate NMDAR function and expression. Specifically, GluN2D subunit-containing NMDARs have emerged as a target of interest due to their limited distribution and potential roles in affective behavior. METHODS Male and female mice underwent a home cage chronic drinking forced abstinence model (CDFA) to assess the impact of 1 day or 2 weeks of ethanol abstinence on BNST synaptic transmission and BNST Grin gene expression. Constitutive and conditional BNST GluN2D knockout mice were used to assess the impact of GluN2D deletion on continuous access ethanol intake as well as negative affect behaviors, using the open field, elevated zero maze, and forced swim tasks. RESULTS We report here that excitatory transmission undergoes time-dependent upregulation in BNST Crh+ cells. Further, knockdown of dorsal BNST (dBNST) GluN2D expression significantly decreases ethanol intake in female, but not male, mice. While BNST Grin2b expression was significantly increased in protracted abstinence following CDFA, no differences in Grin2d expression were observed in the dBNST or dBNST Crh+ neurons. Finally, we find that deletion of GluN2D fails to alter negative affect in ethanol-naïve female mice. CONCLUSIONS These data suggest a role for BNST GluN2D-containing NMDARs in ethanol drinking but not ethanol abstinence, highlighting sex differences and behavioral specificity. Overall, these data further suggest roles for BNST synaptic signaling in volitional ethanol intake that are partially independent of actions on affective behavior.
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Affiliation(s)
- Marie A Doyle
- Department of Neurobiology, UMass Chan Medical School, Worcester, Massachusetts, USA
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee, USA
- Vanderbilt Center for Addiction Research, Vanderbilt University, Nashville, Tennessee, USA
| | - Gregory J Salimando
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee, USA
- Vanderbilt Center for Addiction Research, Vanderbilt University, Nashville, Tennessee, USA
| | - Megan E Altemus
- Vanderbilt Center for Addiction Research, Vanderbilt University, Nashville, Tennessee, USA
| | - Justin K Badt
- Vanderbilt Center for Addiction Research, Vanderbilt University, Nashville, Tennessee, USA
| | - Michelle N Bedenbaugh
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee, USA
- Vanderbilt Center for Addiction Research, Vanderbilt University, Nashville, Tennessee, USA
| | - Alexander S Vardy
- Vanderbilt Center for Addiction Research, Vanderbilt University, Nashville, Tennessee, USA
| | - Danielle N Adank
- Vanderbilt Center for Addiction Research, Vanderbilt University, Nashville, Tennessee, USA
| | - Anika S Park
- Vanderbilt Center for Addiction Research, Vanderbilt University, Nashville, Tennessee, USA
| | - Danny G Winder
- Department of Neurobiology, UMass Chan Medical School, Worcester, Massachusetts, USA
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee, USA
- Vanderbilt Center for Addiction Research, Vanderbilt University, Nashville, Tennessee, USA
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Doyle MA, Salimando GJ, Altemus ME, Badt JK, Bedenbaugh MN, Vardy AS, Adank DN, Park AS, Winder DG. BNST GluN2D-containing NMDARs contribute to ethanol intake but not negative affective behaviors in female mice. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.19.590258. [PMID: 38659775 PMCID: PMC11042366 DOI: 10.1101/2024.04.19.590258] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/26/2024]
Abstract
Alcohol use disorder (AUD) is a chronic, relapsing disease, highly comorbid with anxiety and depression. The bed nucleus of the stria terminalis (BNST), and Crh + neurons in this region are thought to play a key role in chronic ethanol-induced increases in volitional ethanol intake. This role has been hypothesized to be driven by emergent BNST-dependent negative affective behaviors. Indeed, we report here that in female mice undergoing a home cage chronic drinking forced abstinence model (CDFA), excitatory transmission undergoes time-dependent upregulation in BNST Crh + cells. Excitatory NMDA receptors (NMDARs) are a major target of ethanol, and chronic ethanol exposure has been shown to regulate NMDAR function and expression. GluN2D subunit-containing NMDARs have emerged as a target of interest due to their limited distribution and potential roles in affective behavior. We find that knockdown of dorsal BNST (dBNST) GluN2D expression significantly decreases ethanol intake in female, but not male, mice. While BNST Grin2b expression was significantly increased in protracted abstinence following CDFA, no differences in Grin2d expression were observed in dBNST or specifically in dBNST Crh + neurons. Finally, to determine the impact of GluN2D expression on negative affective behaviors, open field, elevated zero maze, and forced swim tasks were used to measure anxiety- and depressive-like behaviors in constitutive and conditional BNST GluN2D knockout mice. Surprisingly, we find that deletion of GluN2D fails to alter negative affect in ethanol-naïve female mice. Together, these data suggest a role for BNST GluN2D-containing NMDARs in ethanol drinking behaviors but not abstinence from ethanol, highlighting potential sex differences and behavioral specificity in the context of AUD behaviors. Overall, these data further suggest roles for BNST synaptic signaling in volitional ethanol intake that are partially independent of actions on affective behavior.
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Cannady R, Fisher KR, Graham C, Crayle J, Besheer J, Hodge CW. Potentiation of amygdala AMPA receptor activity selectively promotes escalated alcohol self-administration in a CaMKII-dependent manner. Addict Biol 2017; 22:652-664. [PMID: 26742808 DOI: 10.1111/adb.12357] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2015] [Revised: 10/30/2015] [Accepted: 11/30/2015] [Indexed: 12/21/2022]
Abstract
Growing evidence indicates that drugs of abuse gain control over the individual by usurping glutamate-linked mechanisms of neuroplasticity in reward-related brain regions. Accordingly, we have shown that glutamate α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) activity in the amygdala is required for the positive reinforcing effects of alcohol, which underlie the initial stages of addiction. It is unknown, however, if enhanced AMPAR activity in the amygdala facilitates alcohol self-administration, which is a kernel premise of glutamate hypotheses of addiction. Here, we show that low-dose alcohol (0.6 g/kg/30 minutes) self-administration increases phosphorylation (activation) of AMPAR subtype GluA1 S831 (pGluA1 S831) in the central amygdala (CeA), basolateral amygdala and nucleus accumbens core (AcbC) of selectively bred alcohol-preferring P-rats as compared with behavior-matched (non-drug) sucrose controls. The functional role of enhanced AMPAR activity was assessed via site-specific infusion of the AMPAR positive modulator, aniracetam, in the CeA and AcbC prior to alcohol self-administration. Intra-CeA aniracetam increased alcohol-reinforced but not sucrose-reinforced responding and was ineffective following intra-AcbC infusion. Because GluA1 S831 is a Ca2+/calmodulin-dependent protein kinase II (CaMKII) substrate, we sought to determine if AMPAR regulation of enhanced alcohol self-administration is dependent on CaMKII activity. Intra-CeA infusion of the cell-permeable CaMKII peptide inhibitor myristolated autocamtide-2-related inhibitory peptide (m-AIP) dose-dependently reduced alcohol self-administration. A subthreshold dose of m-AIP also blocked the aniracetam-induced escalation of alcohol self-administration, demonstrating that AMPAR-mediated potentiation of alcohol reinforcement requires CaMKII activity in the amygdala. Enhanced activity of plasticity-linked AMPAR-CaMKII signaling in the amygdala may promote escalated alcohol use via increased positive reinforcement during the initial stages of addiction.
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Affiliation(s)
- Reginald Cannady
- Bowles Center for Alcohol Studies; University of North Carolina at Chapel Hill; Chapel Hill NC USA
- Curriculum in Neurobiology; University of North Carolina at Chapel Hill; Chapel Hill NC USA
| | - Kristen R. Fisher
- Bowles Center for Alcohol Studies; University of North Carolina at Chapel Hill; Chapel Hill NC USA
| | - Caitlin Graham
- Bowles Center for Alcohol Studies; University of North Carolina at Chapel Hill; Chapel Hill NC USA
| | - Jesse Crayle
- Bowles Center for Alcohol Studies; University of North Carolina at Chapel Hill; Chapel Hill NC USA
| | - Joyce Besheer
- Bowles Center for Alcohol Studies; University of North Carolina at Chapel Hill; Chapel Hill NC USA
- Curriculum in Neurobiology; University of North Carolina at Chapel Hill; Chapel Hill NC USA
- Department of Psychiatry; University of North Carolina at Chapel Hill; Chapel Hill NC USA
| | - Clyde W. Hodge
- Bowles Center for Alcohol Studies; University of North Carolina at Chapel Hill; Chapel Hill NC USA
- Curriculum in Neurobiology; University of North Carolina at Chapel Hill; Chapel Hill NC USA
- Department of Psychiatry; University of North Carolina at Chapel Hill; Chapel Hill NC USA
- Department of Pharmacology; University of North Carolina at Chapel Hill; Chapel Hill NC USA
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Mishra D, Zhang X, Chergui K. Ethanol disrupts the mechanisms of induction of long-term potentiation in the mouse nucleus accumbens. Alcohol Clin Exp Res 2012; 36:2117-25. [PMID: 22551245 DOI: 10.1111/j.1530-0277.2012.01824.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2011] [Accepted: 03/06/2012] [Indexed: 11/30/2022]
Abstract
BACKGROUND Long-term changes in the efficacy of glutamatergic synaptic transmission in reward-related brain regions such as the nucleus accumbens (NAc) are proposed to contribute to neuroadaptations that lead to drug addiction. Although alcohol is a widely used addictive substance, the cellular mechanisms by which it influences synaptic plasticity in the NAc are not elucidated. We therefore examined whether acute ethanol (EtOH) alters long-term potentiation (LTP) in the core region of the NAc and investigated the possible underlying mechanisms. METHODS We measured field excitatory postsynaptic potential/population spike (fEPSP/PS) amplitude in mouse brain slices containing the NAc. We also used amperometry to detect, with carbon fiber electrode, evoked dopamine release in brain slices. RESULTS In control slices, high-frequency stimulation (HFS) induced a stable LTP. LTP was reduced in slices perfused with EtOH (50 mM). Given that induction of LTP is dependent on glutamate acting on N-methyl-d-aspartate (NMDA) receptors and group I metabotropic glutamate receptors (mGluRs), we studied the ability of EtOH to modulate these 2 classes of receptors. NMDA (20 μM) depressed the amplitude of the fEPSP/PS, but this effect was not altered by EtOH in our experimental conditions. However, EtOH reversed the ability of the group I mGluR agonist (S)-3,5-Dihydroxyphenylglycine (DHPG) (50 μM) to potentiate the depressant action of NMDA on the fEPSP/PS. We also examined whether EtOH could modulate dopamine release given that dopamine plays important roles in mediating the reinforcing actions of abused drugs and in the induction of LTP in the NAc. We found that EtOH reversibly decreased action potential-dependent dopamine release evoked by single stimulation pulses and by HFS trains in NAc slices. CONCLUSIONS These results show that EtOH impairs the induction of LTP possibly through several mechanisms that include inhibition of group I mGluR-mediated potentiation of NMDA receptor function and of evoked dopamine release. This study provides additional support for a key role of glutamatergic and dopaminergic neurotransmission in the NAc in mediating the reinforcing effects of acute alcohol.
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Affiliation(s)
- Devesh Mishra
- Section of Molecular Neurophysiology , Department of Physiology and Pharmacology, The Karolinska Institute, Stockholm, Sweden
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Keng NT, Lin HH, Lin HR, Hsieh WK, Lai CC. Dual regulation by ethanol of the inhibitory effects of ketamine on spinal NMDA-induced pressor responses in rats. J Biomed Sci 2012; 19:11. [PMID: 22300389 PMCID: PMC3296648 DOI: 10.1186/1423-0127-19-11] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2011] [Accepted: 02/02/2012] [Indexed: 12/12/2022] Open
Abstract
Background Acute exposure of ethanol (alcohol) inhibits NMDA receptor function. Our previous study showed that acute ethanol inhibited the pressor responses induced by NMDA applied intrathecally; however, prolonged ethanol exposure may increase the levels of phosphorylated NMDA receptor subunits leading to changes in ethanol inhibitory potency on NMDA-induced responses. The present study was carried out to examine whether acute ethanol exposure influences the effects of ketamine, a noncompetitive NMDA receptor antagonist, on spinal NMDA-induced pressor responses. Methods The blood pressure responses induced by intrathecal injection of NMDA were recorded in urethane-anesthetized rats weighing 250-275 g. The levels of several phosphorylated residues on NMDA receptor GluN1 subunits were determined by western blot analysis. Results Intravenous injection of ethanol or ketamine inhibited spinal NMDA-induced pressor responses in a dose-dependent and reversible manner. Ketamine inhibition of NMDA-induced responses was synergistically potentiated by ethanol when ethanol was applied just before ketamine. However, ketamine inhibition was significantly reduced when applied at 10 min after ethanol administration. Western blot analysis showed that intravenous ethanol increased the levels of phosphoserine 897 on GluN1 subunits (pGluN1-serine 897), selectively phosphorylated by protein kinase A (PKA), in the lateral horn regions of spinal cord at 10 min after administration. Intrathecal administration of cAMPS-Sp, a PKA activator, at doses elevating the levels of pGluN1-serine 897, significantly blocked ketamine inhibition of spinal NMDA-induced responses. Conclusions The results suggest that ethanol may differentially regulate ketamine inhibition of spinal NMDA receptor function depending on ethanol exposure time and the resulting changes in the levels of pGluN1-serine 897.
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Affiliation(s)
- Nien-Tzu Keng
- Institute of Medical Sciences, Tzu Chi University, Hualien, Taiwan
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Martin GE. BK channel and alcohol, a complicated affair. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2010; 91:321-38. [PMID: 20813247 DOI: 10.1016/s0074-7742(10)91010-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Alcohol is a fast acting molecule that alters behavior within a few minutes of absorption. Its rapid behavioral impact suggests early action on ion channels. Of all voltage-gated potassium ion channels, BK channels, a subcategory of potassium channels characterized by their large unitary conductance, and by their capacity of being activated synergistically by membrane potential and intracellular free calcium, are unique due to their high sensitivity to alcohol. In this review, we discuss BK channels structure and function, and how they help us understand the various ways BK channel mediates alcohol's effects on neuronal function and on behavior in the striatum.
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Affiliation(s)
- Gilles Erwan Martin
- Department of Neurosciences, Medical University of South Carolina, Charleston, SC 29425, USA
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Mitchell RM, Neafsey EJ, Collins MA. Essential involvement of the NMDA receptor in ethanol preconditioning-dependent neuroprotection from amyloid-betain vitro. J Neurochem 2009; 111:580-8. [PMID: 19694907 DOI: 10.1111/j.1471-4159.2009.06351.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
In several epidemiological studies, moderate ethanol consumption has been associated with reduced risks of cognitive decline or Alzheimer's dementia. Of potential relevance is that brain cultures preconditioned with moderate ethanol concentrations are resistant to neurotoxic Alzheimer's amyloid-beta (Abeta) peptides. Using rat cerebellar mixed cultures we investigated whether certain membrane receptors were early 'sensors' in moderate ethanol preconditioning (MEP). In a 6-day MEP protocol (30 mM ethanol), neuroprotection from Abeta25-35 was undiminished by antagonism during the first 3 days of either adenosine A(1) or Galpha(i/o) protein-coupled receptors. However, similar cotreatment with memantine or DL-2-amino-5-phosphono-pentanoic acid (AP-5), antagonists of NMDA receptors (NMDAR), abolished neuroprotection, indicating key early involvement of this ionotropic glutamate receptor. Also in these cultures, directly activating NMDAR using subexcitotoxic NMDA preconditioning prevented Abeta neurotoxicity. By day 2 of MEP, we observed increased levels of NMDAR subunits NR1, NR2B, and NR2C that persisted through day 6. Interestingly, memantine co-exposure blocked elevations in the obligatory NR1 subunit. Furthermore, 2 days of MEP significantly increased two indicators of synaptic NMDAR localization, NR2B phospho-Tyr1472, and post-synaptic density 95 scaffolding protein. The results indicate that ethanol preconditioning-dependent neuroprotection is associated with early increases in NR subunits concomitant with enhancement of synaptic localization and activity of NMDAR.
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Affiliation(s)
- Robert M Mitchell
- Department of Pharmacology, Division of Biochemistry, Loyola University Stritch School of Medicine, Maywood, Illinois 60153, USA
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Identification of a BK channel auxiliary protein controlling molecular and behavioral tolerance to alcohol. Proc Natl Acad Sci U S A 2008; 105:17543-8. [PMID: 18981408 DOI: 10.1073/pnas.0801068105] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Tolerance, described as the loss of drug effectiveness over time, is an important component of addiction. The degree of acute behavioral tolerance to alcohol exhibited by a naïve subject can predict the likelihood of alcohol abuse. Thus, the determinants of acute tolerance are important to understand. Calcium- and voltage-gated (BK) potassium channels, consisting of pore forming alpha and modulatory beta subunits, are targets of ethanol (EtOH) action. Here, we examine the role, at the molecular, cellular, and behavioral levels, of the BK beta4 subunit in acute tolerance. Single channel recordings in HEK-293 cells show that, in the absence of beta4, EtOH potentiation of activity exhibits acute tolerance, which is blocked by coexpressing the beta4 subunit. BK channels in acutely isolated medium spiny neurons from WT mice (in which the beta4 subunit is well-represented) exhibit little tolerance. In contrast, neuronal BK channels from beta4 knockout (KO) mice do display acute tolerance. Brain slice recordings showed tolerance to EtOH's effects on spike patterning in KO but not in WT mice. In addition, beta4 KO mice develop rapid tolerance to EtOH's locomotor effects, whereas WT mice do not. Finally, in a restricted access ethanol self-administration assay, beta4 KO mice drink more than their WT counterparts. Taken together, these data indicate that the beta4 subunit controls ethanol tolerance at the molecular, cellular, and behavioral levels, and could determine individual differences in alcohol abuse and alcoholism, as well as represent a therapeutic target for alcoholism.
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Simpson TL, Saxon AJ, Meredith CW, Malte CA, McBride B, Ferguson LC, Gross CA, Hart KL, Raskind M. A pilot trial of the alpha-1 adrenergic antagonist, prazosin, for alcohol dependence. Alcohol Clin Exp Res 2008; 33:255-63. [PMID: 18945226 DOI: 10.1111/j.1530-0277.2008.00807.x] [Citation(s) in RCA: 117] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
BACKGROUND Current medications for alcohol dependence (AD) show only modest efficacy. None target brain noradrenergic pathways. Theory and preclinical evidence suggest that noradrenergic circuits may be involved in alcohol reinforcement and relapse. We therefore tested the alpha-1 adrenergic receptor antagonist, prazosin, as a pharmacotherapy for AD. METHODS We randomized 24 participants with AD but without posttraumatic stress disorder to receive either prazosin or placebo in a 6-week, double-blind pilot study. Medication was titrated to a target dose of 4 mg QAM, 4 mg QPM, and 8 mg QHS by the end of week 2. Participants received 5 medical management treatment sessions. Participants were reminded 3 times each day via a text pager to take medications and to call a telephone monitoring system once daily to provide self-reports of alcohol consumption and craving, the primary outcome measures. Results were analyzed using mixed linear regression adjusted for drinking days per week at baseline and week number. RESULTS Twenty of the 24 (83%) subjects completed. Among the completers, the prazosin group reported fewer drinking days per week than the placebo group during the final 3 weeks of the study. Since only 1 woman was randomized to placebo and only three women completed the trial, the following results focus on the 17 male completers. The prazosin group reported fewer drinking days per week and fewer drinks per week during the final 3 weeks of the study; average total number of drinking days for the placebo group 5.7 (SEM 1.9) versus 0.9 (SEM 0.5) for the prazosin group, and average total number of drinks 20.8 (SEM 6.5) for the placebo group versus 2.6 (SEM 1.3) for the prazosin group. Rates of adverse events were equivalent across conditions. CONCLUSIONS Prazosin holds promise as a pharmacologic treatment for AD and deserves further evaluation in a larger controlled trial.
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Affiliation(s)
- Tracy L Simpson
- Center of Excellence in Substance Abuse Treatment and Education, University of Washington, Seattle, WA 98108, USA.
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Fehr C, Hohmann N, Gründer G, Dielentheis TF, Buchholz HG, Chechko N, Yakushev I, Landvogt C, Bartenstein P, Urban R, Schreckenberger M. Tiagabine does not attenuate alcohol-induced activation of the human reward system. Psychopharmacology (Berl) 2007; 191:975-83. [PMID: 17265078 DOI: 10.1007/s00213-006-0696-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/01/2006] [Accepted: 12/26/2006] [Indexed: 10/23/2022]
Abstract
RATIONALE The rewarding effects of ethanol and other drugs of abuse are mediated by activation of the mesolimbic dopamine system. Recent neuroimaging studies in primates and humans suggest that cocaine-induced dopamine stimulation might be diminished by drugs augmenting gamma-aminobutyric acid A (GABA-A) receptor function such as the GABA transaminase inhibitor vigabatrin. OBJECTIVES The objective of this study was to test the property of the selective GABA transporter 1 (GAT1) inhibitor tiagabine to block ethanol-induced activation of the mesolimbic reward system in an i.v. ethanol challenge. MATERIALS AND METHODS Twenty nonaddicted healthy volunteers underwent an i.v. ethanol challenge after 1 week of tiagabine (15 mg/day) administration. Neuronal activation was measured using [(18)F]-fluoro-deoxyglucose positron emission tomography (PET). RESULTS Tiagabine did not prevent ethanol-induced stimulation of the mesolimbic reward system but augmented ethanol-induced hypometabolism within areas of the visual system and the cerebellum. Tiagabine alone also decreased neuronal metabolism within parts of the right temporal cortex that are highly enriched with GABA-ergic neurons. CONCLUSIONS Our ethanol challenge imaging study does not provide supporting evidence that the GAT1 inhibitor tiagabine diminishes the rewarding effects of ethanol. Further PET imaging studies using established anticraving compounds, such as the mu-opioid receptor antagonist naltrexone and antiepileptic drugs affecting the GABA-ergic system more broadly, will provide additional important insights on the interaction between the GABA-ergic and the brain reward system in vivo and the suitability of GABA-ergic drugs as anticraving compounds.
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Affiliation(s)
- Christoph Fehr
- Department of Psychiatry, University of Mainz, Untere Zahlbacher Strasse 8, 55131, Mainz, Germany.
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Affiliation(s)
- William R Miller
- Center on Alcoholism, Substance Abuse and Addictions and the Department of Psychology, University of New Mexico, Albuquerque 87131-0001, USA.
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