The effect of low doses of d-amphetamine on drug-induced hyperactivity in the mouse.

The effect of low doses (7.5-250 micrograms/kg) of d-amphetamine was studied on benztropine- or gamma-butyrolactone-induced hyperactivity in the mouse. Amphetamine 30-125 micrograms/kg significantly attenuated the drug-induced hyperactivity. This effect was antagonised by both cinanserin and p-chlorophenylalanine. The results suggest that low doses of d-amphetamine release 5-hydroxytryptamine, which in turn has an inhibitory effect on locomotor activity. This effect was masked at higher doses of d-amphetamine due to a release of dopamine.