What is Tryptophan Hydroxylase?

I have recently read articles that describe MDMA as a Tryptophan Hydroxylase inhibitor.

I understand MDMA's effect on Serotonin levels in the brain, but what is Tryptophan Hydroxylase?

Reply from Nick Cozzi

Tryptophan hydroxylase is the rate-limiting enzyme in serotonin

biosynthesis. It is present in serotonergic neurons and it catalyzes the

addition of the 5-hydroxy group to tryptophan to give 5-hydroxytryptophan.

This substance is then decarboxylated to give 5-hydroxytryptamine

(serotonin).

Nicholas V. Cozzi, Ph.D.

Department of Pharmacology

University of Wisconsin Medical School