Effects of amphetamine on the turnover rate of brain catecholamines and motor activity.

1. Rats receiving (+)-amphetamine (either 0.3 or 0.2 mg/kg, i.v.) are anorexic. Only the former dose increases their motor activity. Both doses fail to change dopamine (DM) and noradrenaline (NA) concentrations in striatum and teldiencephalon. The turnover rate of striatal DM is increased only by 0.3 mg/kg of (+)-amphetamine; neither dose changes NA turnover rate in teldiencephalon.2. (-)-Amphetamine (1 mg/kg, i.v.) causes anorexia and hyperthermia in rats but it changes neither the steady-state concentration nor the turnover rate of striatal DM and tel-diencephalic NA. Motor activity is not increased by this dose of (-)-amphetamine.3. Cocaine (3 mg/kg, i.v.) increases motor activity and accelerates the turnover rate of striatal DM. This drug neither accelerates turnover rate of teldiencephalic NA nor causes anorexia.4. These observations suggest that the acceleration of striatal DM turnover rate elicited by (+)-amphetamine and cocaine may be associated with an effect on motor activity. In contrast, the increase of motor activity seems unrelated to the effects of these drugs on noradrenergic tracts of the teldiencephalon.