The D1 dopamine receptor antagonist, SCH 23390 reduces locomotor activity and rearing in rats.

Dopamine receptors have been found to be of at least two types, and interest has focused on the possible differential role played by each in the control of behavior. The recent finding that SCH 23390 selectively blocks D1 receptors has provided a new tool. To examine the contribution of D1 receptors to locomotor activity and rearing, rats were injected SC with doses of 0.01, 0.1 and 1.0 mg/kg and monitored for 3 hr in photocell cages. SCH 23390 suppressed both behaviors in a dose-dependent fashion. These results suggest that D1 receptors participate in dopamine's control of locomotor activity and rearing.