The D 1 dopamine receptor antagonist SCH 23390 increases cocaine self-administration in the rat

Abstract

Rats trained to intravenously self-administer cocaine hydrochloride on a fixed ratio-5 schedule were subjected to a series of systemic injections of the D 1 dopamine receptor selective antagonist SCH 23390 and the D 2 dopamine receptor selective antagonist spiperone. SCH 23390 produced a dose-dependent increase in cocaine intake at doses of 5, 10 and 20 μg/kg, but the D 2 antagonist failed to reliably increase responding except at a dose of 10 μg/kg. These results suggest that the D 1 antagonist may be more effective at blocking mesolimbic dopamine activity, and that selective D 1 receptor activation may be an important component of psychostimulant reward.