Opiates and alcohol self-administration in animals.

During the past 25 years, numerous animal studies have demonstrated a relationship between alcohol consumption and opiates. Converging lines of evidence suggest that (1) alcohol consumption enhances opioid receptor activity and (2) conditions associated with relative deficiencies in opioid receptor activity stimulate increases in alcohol preference. This evidence leads to the hypothesis that alcohol drinking is reinforced, in part, by enhanced opioid receptor activity; thus, these effects should be blocked by opiate antagonists. In fact, the animal data are consistent with this prediction. Opiate antagonists reduce excessive alcohol intake without reducing the ingestion of other biologically important reinforcers.