Evolution of Red Blood Cell Membrane Transport and Plasma Level of L-Tyrosine and L-Tryptophan in Depressed Treated Patients According to Clinical Improvement

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Abstract
The erythrocyte membrane transport (MT) of L-tyrosine (TYR) and L-tryptophan (TRP) and their plasma concentration showed abnormal mean values in 37 depressed patients compared to control subjects before treatment. The pattern of these abnormal values differed according to the clinical subgroup (DSM III criteria). In bipolar disorders the TYR values were all low and the TRP values showed little change, except a low level of plasma TRP. In major depressions, MT were abnormal (MT TYR low, MT TRP high) with a very low plasma TRP. In dysthymic disorders the TYR and TRP values were normal. The normalization of the above biochemical variables was significantly correlated with the clinical improvement; however, the plasma concentration of TRP remained abnormal in some patients who had recovered. In contrast, only plasma TYR and TRP were significantly increased in patients without recovery.