Differential affinity of dopaminergic agonists and antagonists for D 1 and D 2 dopamine receptors in rat striatum

Abstract

Dopamine (DA) receptors have been classified into two types, D1 and D2, on the basis of their pharmacological specifities and localization. We now report that lesions of striatal dopaminergic neurons by kainic acid (KA) injection or cerebral neocortex (CN) ablation, differentially affect the potency of DA agonists and antagonists in displacing 3H-spiroperidol specific binding. In particular, agonists show a preferential affinity in displacing 3H-spiroperidol from those receptors situated on intrastriatal neurons, following CN lesion. On the other hand, antagonists show a higher displacing activity for those receptors mainly located on cortical terminals following KA lesion. These data support the hypothesis of the existence of different types of DA receptors with a differential anatomical location.