5-Hydroxytryptamine metabolism in affective illness: the effect of tryptophan administration

Abstract

SYNOPSIS L-tryptophan 50 mg/kg was administered orally to patients suffering from either unipolar or bipolar affective illness, and the concentration of 5-hydroxyindol-acetic acid estimated in their cerebrospinal fluid eight hours later. There was no significant difference between the patient groups or between these and patients with neurological disease. These findings suggest a reduced neuronal activity in the 5-hydroxytryptaminergic system in some depressed patients rather than an absolute deficiency of tryptophan-5-hydroxylase. The synthesis of 5-HIAA in response to tryptophan varied with age.