EFFECT OF 8-HYDROXY-2-(DI-NORMAL-PROPYLAMINO)-TETRALIN ON THE TRYPTOPHAN-INDUCED INCREASE IN 5-HYDROXYTRYPTOPHAN ACCUMULATION IN RAT-BRAIN

The injection of 8-hydroxy-2-(di-n-propylamino)-tetralin [8-OH-DPAT] reduced 5-hydroxytryptophan accumulation in vivo in rat cerebral cortex, hypothalamus and brainstem. Brain trytophan levels were unaffected. Dose-related increases in 5-hydroxytryptophan accumulation produced by single injections of L-tryptophan (0, 25, 75 mg/kg ip) were substantially diminished by pretreatment with 8-OH-DPAT. The drug did not affect the tryptophan-induced increments in brain tryptophan level. Since 8-OH-DPAT is known to reduce the activity of serotonin neurons in vivo, these results suggest that when serotonin neutrons are relatively inactive, the ability of an injection of tryptophan to stimulate serotonin synthesis is greatly attenuated. © 1990.