Anticataleptic action of psychostimulating drugs and serotonin in brain

The effects of drugs changing serotonin activity in rats were studied observing changes in the anticataleptic action of amphetamine and ephedrine. It was observed that: 1) parachlorophenylalanine prolonged the anticataleptic action of ephedrine and, in part also, that of amphetamine, 2) methysergide alone exerted an anticataleptic effect and enhanced somewhat the same effect of both psychostimulating drugs used, 3) d, 1-tryptophan increased the intensity of catalepsy and reduced very significantly or abolished completely the anticataleptic action of ephedrine and amphetamine. These results support the view that the serotonin system exerts a suppressing effect on the central effects resulting from stimulation of catecholamine dependent functions.