Tryprophan metbolism in alcoholism. Tryptophan but not excitatory amino acid availablity to the brain is increased before the appearance of the alcohol-withdrawal syndrome in men

Tryptophan (Trp) metabolism and disposition and excitatory and other amino acid

concentrations were determined in alcohol-dependent subjects in relation to the alcohol-withdrawal

syndrome (AWS). Parameters were examined in 12 alcohol-dependent male subjects, undergoing

elective upper digestive tract tumour resection, and 12 age-, gender-, and medication-matched controls

on three occasions: pre-operatively, post-operatively, and immediately before (i.e. within 24 h of) the

appearance of the AWS. No significant differences were observed between controls and alcoholic

subjects on the first or second ot these occasions. On the third occasion, within 24 h of the appearance of

the AWS, alcoholics showed a dramatic elevation (117%) in free serum Trp concentration and a

consequent increase (111%) in the ratio of [free Trp]/[competing ammo acids], which is an accurate

predictor of Trp entry into the brain. Increases were also observed on this third occasion in

concentrations of total Trp (49%), cortisol (123%), and norharman (137%). Concentrations of glutamate,

glycine, aspartate, serine, and taurine did not differ significantly within or between the control and

alcohol-dependent groups of subjects on any of the three occasions. The possible significance of the Trp

and related metabolic changes in relation to the behavioural features of the AWS is discussed.