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Int Clin Psychopharmacol. 1993 Summer;8(2):87-93.

Evidence for a defective platelet L-tryptophan transport in depressed patients.

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Unité de Psychiatrie Biologique, C.N.R.S., Faculté de Médecine, Marseille, France.


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.

[Indexed for MEDLINE]

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