Psychotomimetic N-methylated tryptamines: formation in brain in vivo and in vitro.

The use of a sensitive enzymatic assay demonstrates that tryptamine occurs normally in rat brain. Intracisternal administration of [(14)C]tryptamine results in the formation of N-methyl-and dimethyltryptamine(a psychotomimetic compound)in the rat brain. An enzyme that converts tryptamine and N-methyl-tryptamine to N-methyl-and dimethyltryptamine was found to be present in rat and human brain. The N-methylation of tryptamine was inhibited by normally occurring compounds present in rat brain.