Decreased plasma tryptophan concentration in major depression: relationship to melancholia and weight loss.
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.
Anderson
I M
IM
MRC Unit of Clinical Pharmacology, Littlemore Hospital, Oxford, U.K.
Parry-Billings
M
M
Newsholme
E A
EA
Poortmans
J R
JR
Cowen
P J
PJ
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*
D000597:Amino Acids, Branched-Chain; D014364:Tryptophan