Selective effects of the D1 dopamine receptor agonist, SKF 38393, on behavior maintained by cocaine injection in squirrel monkeys

Rats trained to intravenously self-administer cocaine hydrochloride on a fixed ratio-5 schedule were subjected to a series of systemic injections of the D1 dopamine receptor selective antagonist SCH 23390 and the D2 dopamine receptor selective antagonist spiperone. SCH 23390 produced a dose-dependent increase in cocaine intake at doses of 5, 10 and 20 micrograms/kg, but the D2 antagonist failed to reliably increase responding except at a dose of 10 micrograms/kg. These results suggest that the D1 antagonist may be more effective at blocking mesolimbic dopamine activity, and that selective D1 receptor activation may be an important component of psychostimulant reward. Show more