Tryptophan-Nicotinic Acid Metabolism in Schizophrenia

Abstract

Urinary excretion of 5-hydroxyindolylacetic acid and 3-indo-leacetic acid was estimated in 10 patients suffering from schizophrenia both before and for 3 days after feeding of tryptophan. Similar studies were made on 10 normal subjects. Urinary excretion of 3-indoleacetic acid increased both in normal and schizophrenic subjects after administration of tryptophan. Tryptophan also gave rise to increase in urinary excretion of 5-hydroxyindolylacetic acid in schizophrenia, but no significant rise was detected in normal subjects. Urinary excretions of nicotinic acid, quinolinic acid, nicotinamide mononucleotide (NMN) 6-pyridone, tryptophan, kynurenine, anthranilic acid and 3-hydroxyanthranilic acid were estimated in 10 schizophrenic subjects before and for 3 days after feeding of tryptophan. Nicotinic acid, quinolinic acid, NMN and 6-pyridone were present in urine initially and they were excreted in greater quantities after tryptophan feeding. Tryptophan which was initially absent also appeared in urine after its administration. Kynurenine, anthranilic acid and 3-hydroxyanthranilic acid could not be detected in urine both before and after administration of tryptophan.