[Study of free and total tryptophan in the plasma. It value in psychiatry]

The dosage of the whole tryptophan and of the free tryptophan was conducted in 16 normal subjects to establish reference values and in 12 schizophrenic subjects among whom 7 were under treatment and 5 were not. The method of dosage is made by spectrofluorimetry by increasing the native fluorescence of tryptophan. The results give mean values for the free tryptophan and for the ratio of the free tryptophan to the whole tryptophan values that are higher in the schizophrenics than in the normal subjects used as reference, while the whole tryptophan seems to be little modified ; this increase is more noticeable in the schizophrenics under treatment. The limited number of the cases studied does not enable us yet to establish correlations between the increase of the free tryptophan found in some cases and the nature of the schizophrenia, its age and its evolutivity or even the clinical response to the treatment. However, some figures for the free tryptophan being very much higher than the mean value in some schizophrenics, suggest ways of research for understanding the pathogenisis of schizophrenia and the mechanisms of the therapeutic action of the psychotropic drugs.