PT - JOURNAL ARTICLE AU - JÉQUIER, ERIC AU - LOVENBERG, WALTER AU - SJOERDSMA, ALBERT TI - Tryptophan Hydroxylase Inhibition: the Mechanism by Which <em>p</em>-Chlorophenylalanine Depletes Rat Brain Serotonin DP - 1967 May 01 TA - Molecular Pharmacology PG - 274--278 VI - 3 IP - 3 4099 - http://molpharm.aspetjournals.org/content/3/3/274.short 4100 - http://molpharm.aspetjournals.org/content/3/3/274.full SO - Mol Pharmacol1967 May 01; 3 AB - Administration of the specific serotonin depletor p-chlorophenylalanine to rats results in marked inhibition of tryptophan hydroxylase of the brain. The enzyme inhibition can be correlated with and is assumed to be responsible for brain serotonin depletion. Although p-chlorophenylalanine is a competitive inhibitor of tryptophan hydroxylase in vitro, it causes an irreversible inactivation of the enzyme in vivo. The findings also support the conclusion that tryptophan hydroxylation is the rate-limiting enzymic step in serotonin biosynthesis. ACKNOWLEDGMENT The authors would like to thank Dr. Sidney Udenfriend for helpful discussions during the course of this work.