Differential activity of enantiomers of amphetamine in rats

Administration of single doses of d-amphetamine (0.5-4.0 mg/kg i.p.) to adult, male rats produced the expected dose-related increases in spontaneous motor activity. This effect was reduced by pretreatment with alpha-methylparatyrosine (alpha MT) and virtually unaffected by pretreatment with pargyline or parachlorophenylalanine (PCPA). Single doses of l-amphetamine (0.25-8.0 mg/kg) evoked an initial decrease in activity followed by increased activity of smaller magnitude than that caused by the d-isomer. The depressant effects of the l-isomer were prolonged by pretreatment with alpha MT, and abolished by pretreatment with pargyline or PCPA.