title: A functional polymorphism of the mu-opioid receptor gene (OPRM1) influences cue-induced craving for alcohol in male heavy drinkers.
abstract: BACKGROUND
  The mu-opioid receptor gene (OPRM1) codes for the mu-opioid receptor, which binds beta-endorphin. The A118G polymorphism in this gene affects beta-endorphin binding such that the Asp40 variant (G allele) binds beta-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.
  
  
  METHODS
  Participants were either homozygous for the A allele (n=84) or carrying at least 1 copy of the G allele (n=24). All participants took part in a cue-reactivity paradigm where they were exposed to water and beer in 3-minute trials. The dependent variables of main interest were subjective craving for alcohol, subjective arousal, and saliva production.
  
  
  RESULTS
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Faculty of Psychology, Maastricht University, 6200 MD Maastricht, The Netherlands. E.vandenWildenberg@Psychology.unimaas.nl
authors.forename: Esther
authors.initials: E
authors.lastname: van den Wildenberg
authors.forename: Reinout W
authors.initials: RW
authors.lastname: Wiers
authors.forename: Joelle
authors.initials: J
authors.lastname: Dessers
authors.forename: Rob G J H
authors.initials: RG
authors.lastname: Janssen
authors.forename: Ellen H
authors.initials: EH
authors.lastname: Lambrichs
authors.forename: Hubert J M
authors.initials: HJ
authors.lastname: Smeets
authors.forename: Gerard J P
authors.initials: GJ
authors.lastname: van Breukelen
mesh_terms: D000293:Adolescent; D000328:Adult; D000339:Affect / Q000187:drug effects; D000428:Alcohol Drinking / Q000235:genetics* / Q000523:psychology*; D000437:Alcoholism / Q000235:genetics* / Q000523:psychology*; D000483:Alleles; D001143:Arousal / Q000502:physiology; D001515:Beer; D003463:Cues; D004247:DNA / Q000235:genetics; D005838:Genotype; D006801:Humans; D008297:Male; D011110:Polymorphism, Genetic; D017450:Receptors, Opioid, mu / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012472:Salivation / Q000187:drug effects; D019966:Substance-Related Disorders / Q000235:genetics / Q000523:psychology; D011795:Surveys and Questionnaires
chemical_list: C485764:OPRM1 protein, human; D017450:Receptors, Opioid, mu; D004247:DNA