Evidence for a defective platelet L-tryptophan transport in depressed patients.
The kinetic characteristics of platelet L-tryptophan uptake were investigated in 23 untreated depressed patients and 18 healthy volunteers. A significant increase of 50% in the apparent Michaelis constant (Km) was observed in depressed patients compared with controls, without significant change in the maximal velocity (Vmax). After 1 month of successful antidepressant treatment the mean Km value decreased significantly and reached the control value. This result raises the possibility that the decrease in platelet tryptophan uptake affinity is a state-dependent marker for depression. It is likely that the transport alteration results in a decrease in platelet tryptophan accumulation. The effect of this peripheral membrane defect on brain serotonin function is discussed.
Gronier
B
B
Unité de Psychiatrie Biologique, C.N.R.S., Faculté de Médecine, Marseille, France.
Azorin
J M
JM
Dassa
D
D
Jeanningros
R
R
D000284:Administration, Oral; D000328:Adult; D000368:Aged; D000928:Antidepressive Agents / Q000627:therapeutic use; D001792:Blood Platelets / Q000187:drug effects / Q000378:metabolism*; D002478:Cells, Cultured; D003866:Depressive Disorder / Q000097:blood* / Q000188:drug therapy; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D014364:Tryptophan / Q000493:pharmacokinetics*
D000928:Antidepressive Agents; D014364:Tryptophan