Heterogeneous distribution of dopamine D2 receptors within the rat striatum as revealed by autoradiography of [3H]N-n-propylnorapomorphine binding sites.

The precise topographical distribution of dopamine D2 receptors in the rat striatum has been studied autoradiographically through the use of [3H]N-n-propylnorapomorphine (NPA) as a ligand. The highest densities of [3H]NPA binding sites were found in the ventrolateral aspect and medial margin of the striatum, while sparse grain densities were present in the medial and latero-dorsal striatum. Moreover, a clear gradient of [3H]NPA binding was observed along the rostro-caudal axis of the striatum. These heterogeneities in the distribution of dopamine receptors provide further evidence for a functional compartmentalization of the striatum.