[Erythrocyte membrane transport and plasma levels of tyrosine and tryptophan in depression].

L-Tyrosine and L-Tryptophan were studied in 80 depressed patients, hospitalised in Genova and Marseille. After a washout period of ten days, the erythrocyte membrane transports (MT) of L-Tyrosine and L-Tryptophan were measured, as well as their plasma levels; plasma phenylalanine was moreover measured. 33 normal subjects served as control group. In the whole population of patients, the mean of MT's was different compared to controls (MT tyrosine low and MT tryptophan high) and the plasma tyrosine was low. The perturbations of these variables were different according to diagnostic groups (DSM III): MT tyrosine, plasma tyrosine and tryptophan low in bipolar disorders depressed; MT tyrosine low, MT tryptophan high, plasma tryptophan low in major depressions; MT tryptophan high in dysthymic disorders. Phenylalanine was in the normal range compared to controls. The perturbations of MT's involved the part incubated at 37 degrees C for tyrosine, e.g. the facilitated diffusion, and the part incubated at 0 degrees C for tryptophan, e.g. probably the passive and facilitated diffusion. These results were in agreement with the monoaminergic hypothesis of affective disorders and might provide a useful peripheral model.