Tryptophan metabolism in alcoholism, tryptophan but not excitatory amino acid availability to the brain is increased before the appearance of the alcohol-withdrawal syndrome in men
Aab. Badawy et al., Tryptophan metabolism in alcoholism, tryptophan but not excitatory amino acid availability to the brain is increased before the appearance of the alcohol-withdrawal syndrome in men, ALC ALCOHOL, 33(6), 1998, pp. 616-625
Tryptophan (Trp) metabolism and disposition and excitatory and other amino
acid concentrations were determined in alcohol-dependent subjects in relati
on 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 seco
nd of;these occasions. On the third occasion, within 24 h of the appearance
of the AWS, alcoholics showed a dramatic elevation (117%) in free serum Tr
p concentration and a consequent increase (111%) in the ratio of [free Trp]
/[competing amino acids], which is an accurate predictor of Trp entry into
the brain. Increases were also observed on this third occasion in concentra
tions of total Trp (49%), cortisol (123%), and norharman (137%). Concentrat
ions of glutamate, glycine, aspartate, serine, and taurine did not differ s
ignificantly within or between the control and alcohol-dependent groups of
subjects on any of the three occasions. The possible significance of the Tr
p and related metabolic changes in relation to the behavioural features of
the AWS is discussed.