DECREASE IN CIRCULATING TRYPTOPHAN AVAILABILITY TO THE BRAIN AFTER ACUTE ETHANOL-CONSUMPTION BY NORMAL VOLUNTEERS - IMPLICATIONS FOR ALCOHOL-INDUCED AGGRESSIVE-BEHAVIOR AND DEPRESSION

Acute ethanol consumption by fasting male volunteers decreases circula ting tryptophan (Trp) concentration and availability to the brain as d etermined by the ratio of (Trp) to the sum of its five competitors ([T rp]/[CAA] ratio). These effects of alcohol are specific to Trp, becaus e levels of the 5 competitors are not increased. The decrease in circu lating (Trp) is not associated with altered binding to albumin and may therefore be due to enhancement of hepatic Trp pyrrolase activity, It is suggested that, under these conditions brain serotonin synthesis i s likely to be impaired and that, as a consequence, a possible strong depletion of brain serotonin in susceptible individuals may induce agg ressive behaviour after alcohol consumption, The possible implications of these findings in the relationship between alcohol and depression are also briefly discussed.