Repeated D1 receptor agonist treatment blocks cocaine-induced locomotor activity and c-fos expression.

Pretreatment of rats for 4 days with the selective dopamine D1 receptor agonist A-77636 attenuated the ability of cocaine to induce locomotor hyperactivity and to stimulate the expression of the proto-oncogene c-fos in the striatum and nucleus accumbens. Our results suggest that repeated D1 agonist treatment leads to subsensitivity of D1 receptors involved in mediating some of the effects of cocaine on behavior and gene expression.