Distribution of Tryptophan in the Brain

Abstract

IT is well established that the central nervous system of vertebrates contains a substance which is biologically and chromatographically indistinguishable from 5-hydroxytryptamine. The tissues richest in 5-hydroxytryptamine are the diencephalon and mesencephalon, with little or none in the cerebellum or white matter. In the course of paper chromatographic studies on the distribution of 5-hydroxytryptamine in the brain of vertebrates, a second indole substance was noted and afterwards identified as the amino-acid, tryptophan. The distribution of tryptophan did not always follow closely that of 5-hydroxytryptamine, and this result may be of importance since it is believed that 5-hydroxytryptamine is formed by the decarboxylation of 5-hydroxytryptophan, an amino-acid formed from tryptophan.