title: Decreased plasma tryptophan concentration in major depression: relationship to melancholia and weight loss.
abstract: Plasma total tryptophan (TRP) concentration was significantly lower in 31 patients with major depression compared to a healthy control group. The ratio of plasma TRP concentration to that of other branch chain amino acids (the TRP:BCAA ratio) was also decreased. Further analysis revealed that the decrease in plasma TRP and TRP:BCAA ratio was most apparent in patients with major depression and melancholia. Overall, women but not men had significantly decreased plasma tryptophan concentrations, perhaps because of a contributory effect of weight loss; this latter effect, however, could not be distinguished clearly from a diagnosis of melancholia. Our data suggest that in some depressed patients, reductions in plasma tryptophan availability may contribute to abnormalities in brain 5-hydroxytryptamine function.
authors: MRC Unit of Clinical Pharmacology, Littlemore Hospital, Oxford, U.K.
authors: I M
authors: IM
authors: Anderson
authors: M
authors: M
authors: Parry-Billings
authors: E A
authors: EA
authors: Newsholme
authors: J R
authors: JR
authors: Poortmans
authors: P J
authors: PJ
authors: Cowen
mesh_terms: D000328:Adult; D000597:Amino Acids, Branched-Chain / Q000097:blood; D003866:Depressive Disorder / Q000097:blood* / Q000523:psychology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D014364:Tryptophan / Q000097:blood*; D015431:Weight Loss / Q000502:physiology*
chemical_list: D000597:Amino Acids, Branched-Chain; D014364:Tryptophan