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Abstract: Objective: To clarify dopamine''s role in alcohol self-administration in a heterogeneous sample of drinkers using acute phenylalanine/tyrosine depletion (APTD). Methods: Sixteen men with variable drinking histories were characterized on their ethanol-induced cardiac response, a marker previously proposed to index dopamine system reactivity and vulnerability to alcohol abuse. During separate sessions participants were administered (i) a nutritionally balanced (BAL) amino acid (AA) mixture, (ii) a mixture lacking the dopamine precursors, phenylalanine and tyrosine, and (iii) APTD followed by the dopamine precursor, l-DOPA. Five hours after AA administration, participants could earn units of alcohol using a progressive ratio breakpoint task. Results: Alcohol self-administration was reduced in the APTD and APTD+ l-DOPA conditions relative to the BAL condition. In both cases the changes were predicted by ethanol-induced cardiac change. Conclusions: The motivation to drink is likely regulated by more than one neurobiological mechanism. Individual differences in cardiac responsivity to ethanol might provide a peripheral marker of responsiveness to pharmacological manipulations of dopamine. [Copyright &y& Elsevier]

Background: An exaggerated heart rate (HR) increase following alcohol intoxication has been suggested to reflect sensitivity to alcohol-induced reward. The goal of this study is to verify whether pairing alcohol ingestion with conditioned reward and nonreward cues can influence HR responses to alcohol in previously identified individuals with a low and a high HR response. Methods: Fifty-six male social drinkers participated in a 2-day study. On day 1, participants consumed 0.75 g/kg of body weight of pure ethanol. A median split of the alcohol-induced HR responses identified groups of low and high HR responders. On day 2, both groups participated while sober in a computer task where distinct auditory and visual cues were paired either with monetary reward or no monetary reward. Subsequently, participants were randomly assigned to an alcohol challenge, which occurred while they were exposed to either the conditioned cues of reward or to the nonreward cues. Results: The physiological response to alcohol intoxication on day 2 was compared with alcohol-induced HR responses on day 1 (neutral alcohol challenge) for both low and high HR responders. Paired t-tests showed that high HR responders had significantly decreased alcohol-induced HR responses on day 2 in the nonreward condition when compared with day 1. No other relationships between cardiac responses to alcohol and cue conditions were obtained. Conclusions: The rewarding nature of alcohol can be altered by the context in which it is consumed in a subset of individuals who are sensitive to alcohol's stimulating properties. [ABSTRACT FROM AUTHOR]