A Functional Polymorphism of the μ-Opioid Receptor Gene (OPRM1) Influences Cue-Induced Craving for Alcohol in Male Heavy Drinkers
Alcoholism: Clinical and Experimental Research 31 (1), 1–10.


The μ-opioid receptor gene (OPRM1) codes for the μ-opioid receptor, which binds β-endorphin. The A118G polymorphism in this gene affects β-endorphin binding such that the Asp40 variant (G allele) binds β-endorphin 3 times more tightly than the more common Asn40 variant (A allele).

This study investigated the influence of the A118G polymorphism on cue reactivity after exposure to an alcoholic beverage in male heavy drinkers.

G allele carriers reported significantly more craving for alcohol than the A allele participants (as indicated by the within-subject difference in craving after beer vs after water exposure). No differences were found for subjective arousal and saliva. Both groups did not differ in family history of alcoholism. Participants with the G allele reported a significantly higher lifetime prevalence of drug use than participants homozygous for the A allele.

A stronger urge to drink alcohol after exposure to an alcoholic beverage might contribute to a heightened risk for developing alcohol-related problems in individuals with a copy of the G allele. The G allele might also predispose to drug use in general.

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