The role of 5-HT in the mechanism of amphetamine action.

AM stereotypy-inducing action was potentiated in rats in proportion to the previously administered doses of pCPA (3 X 100, 3 X 150 or 3 X 200 mg/kg); however, the dose of 3 X 300 mg/kg pCPA brought about the decrease in stereotypy. Reserpinized rats exhibited also increased AM stereotypy but of shorter duration. AM hyperactivity in mice was potentiated also by the pretreatment with pCPA but this action occurred within a further phase of observation (30 min after the injection). It seems then that 5-HT may be a factor suppressing the stimulating action of AM.