D-1 RECEPTOR-BINDING IN RAT STRIATUM - MODIFICATION BY VARIOUS D-1 AND D-2 ANTAGONISTS, BUT NOT BY SIBUTRAMINE HYDROCHLORIDE, ANTIDEPRESSANTS OR TREATMENTS WHICH ENHANCE CENTRAL DOPAMINERGIC FUNCTION

[H-3]SCH 23390 is a selective high affinity ligand for D-1 receptors in vitro. Using this ligand persistent blockade of D-1 receptors by SCH 23390 and cis-flupenthixol was shown to significantly increase the number of D-1 receptor binding sites in rat striatum. In contrast, repeated administration of the D-2-selective antagonist, clebopride, resulted in a small, but significant, reduction in number. No differences in binding affinity were observed and a single dose of these compounds was without effect. The D-2-selective antagonist, haloperidol, the non-selective D-1/D-2 receptor antagonist, chlorpromazine, the dopamine reuptake inhibitors, bupropion, GBR 12909 and nomifensine, and the dopamine releasing agent, d-amphetamine, had no effect on D-1 receptors. The antidepressant treatments, desipramine, zimeldine, amitriptyline, tranylcypromine, mianserin and ECS and the monoamine reuptake inhibitor, sibutramine, similarly did not alter striatal D-1 sites. Thus, of the treatments investigated only chronic receptor blockade by high affinity antagonists altered D-1 receptor binding in rat striatum.