PT - JOURNAL ARTICLE AU - ALESSANDRO TAGLIAMONTE AU - PAOLA TAGLIAMONTE AU - JORGE PEREZCRUET AU - STEPHEN STERN AU - GIAN L. GESSA TI - EFFECT OF PSYCHOTROPIC DRUGS ON TRYPTOPHAN CONCENTRATION IN THE RAT BRAIN DP - 1971 Jun 01 TA - Journal of Pharmacology and Experimental Therapeutics PG - 475--480 VI - 177 IP - 3 4099 - http://jpet.aspetjournals.org/content/177/3/475.short 4100 - http://jpet.aspetjournals.org/content/177/3/475.full SO - J Pharmacol Exp Ther1971 Jun 01; 177 AB - The administration of d-amphetamine. reserpine, dibutyryl cyclic adenosine monophosphate and lithium or the exposure to hot environmental temperature, conditions known to increase brain serotonin synthesis, increased tryptophan concentration in brain by more than 100%. Brain tryptophan concentration was also markedly increased by phenmetrazine, phenelzine, dl-fenfluramine, bulbocapnine, γ-hydroxybutyrate and probenecid. On the other hand, p-chlorophenylalanine which inhibits serotonin synthesis decreased brain tryptophan level by about 50%. Morphine, apomorphine, chlorpromazine, α-methyltyrosine, haloperidol or exposure to cold environment did not change brain tryptophan level. Changes in tyrosine levels in brain were similar, but less pronounced than those of brain tryptophan. The increase in brain tryptophan could be dissociated from changes in plasma tryptophan and in body temperature. However, when body temperature rose above 40°C the rise in brain tryptophan was associated with a proportional rise in plasma tryptophan. Since the concentrations of tryptophan normally present in the mammalian brain are below the Km for tryptophan hydroxylase, all drugs capable of increasing tryptophan level in brain should also stimulate serotonin synthesis. Accordingly, treatments found to increase brain tryptophan level also increased that of brain 5-hydroxyindoleacetic acid. Tryptophan measurements in brain might be used in screening for drugs affecting serotonin turnover. © 1971 by The Williams & Wilkins Co.