Plasma tryptophan to large neutral amino acid ratios in depressed and normal subjects

• Published in: Journal of affective disorders Vol. 19; no. 1; pp. 9 - 14
• Main Authors: Russ, Mark J., Ackerman, Sigurd H., Banay-Schwartz, Miriam, Shindledecker, Richard D., Gerard P., Smith
• Format: Journal Article
• Language: English
• Published: Netherlands 01.05.1990
• Subjects: Adolescent; Adult; Amino Acids - blood; Blood-Brain Barrier - drug effects; Depressive Disorder - blood; Depressive Disorder - drug therapy; Depressive Disorder - psychology; Desipramine - administration & dosage; Double-Blind Method; Eating - drug effects; Female; Humans; Imipramine - administration & dosage; Male; Middle Aged; Nortriptyline - administration & dosage; Psychiatric Status Rating Scales; Randomized Controlled Trials as Topic; Tryptophan - administration & dosage; Tryptophan - blood
• ISSN: 0165-0327
• DOI: 10.1016/0165-0327(90)90003-Q

The ratios of total and free plasma tryptophan to the sum of five large neutral amino acids (LNAAs) were found to be significantly lower in a group of 16 depressed inpatients compared to nine normal subjects after oral loading with L-tryptophan. The group differences in these ratios were significant before, and 2 weeks after starting treatment with a tricyclic antidepressant. Plasma tryptophan ratios and severity of depression were not significantly correlated.