Acute tyrosine depletion and alcohol ingestion in healthy women

Background: Recently we reported that, in vevret monkeys, ingestion of an a mino acid mixture deficient in the catecholamine precursors, phenylalanine and tyrosine, produced a decrease in alcohol selfadministration. We now rep ort the results of a similar study in humans. Methods: Three groups of healthy female social drinkers were administered a nutritionally balanced amino acid mixture (B, n = 13), a mixture deficient in the serotonin precursor, tryptophan (Trp-free, n = 14), or a phenylalan ine/tyrosine deficient mixture (Phe/Tyr-free, n = 12). Six hours after admi nistration of the amino acid mixture, alcohol ingestion was measured during a free-choice "Taste Test." Results: Compared to the B mixture, Phe/Tyr-free, but not Trp-free, signifi cantly decreased the ingestion of alcohol [p < 0.02]. Neither Phe/Tyr-free nor Trp-free significantly decreased orange juice ingestion or the self-rep orted "Liking" of either substance. Some subjects experienced transient nau sea and/or regurgitated the amino acid mixtures, but excluding these subjec ts did not change the results. Conclusions: The results suggest that (a) Phe/Tyr-free may be a suitable me thod for investigating the role of catecholamines in the self-administratio n and subjective effects of alcohol, (b) acutely decreased catecholamine ne urotransmission might disrupt mechanisms mediating alcohol self-administrat ion, and (c) acutely decreased serotonin neurotransmission seems not to alt er alcohol self-administration.