Widespread Distribution of Brain Dopamine Receptors Evidenced with 125 IIodosulpride, a Highly Selective Ligand

The new benzamide derivative 125Iiodosulpride is a highly sensitive and selective ligand for D-2 dopamine receptors and displays a very low nonspecific binding to membrane or autoradiographic sections. On autoradiographic images, D-2 receptors are present not only in well-established dopaminergic areas but also, in a discrete manner, in a number of catecholaminergic regions in which the dopaminergic innervation is still unknown, imprecise, or controversial, as in the sensorimotor cerebral cortex or cerebellum. This widespread distribution suggests larger physiological and pathophysiological roles for cerebral dopamine receptors than was previously thought.