Autoradiographic localisation of D 1 and D 2 dopamine receptors in primordial striatal tissue grafts in rats

Abstract

Using in vitro autoradiography the study examined the binding of the dopamine (DA) D 1 receptor and D 2 receptor radiolabelled ligands, [ 125I]SCH 23982 and [ 125I]sulpiride, respectively, to striatal sections of control rats, those with unilateral ibotenic acid (IA) lesions of the striatum and those with grafts of primordial striatal tissue implanted into the IA-lesioned striatum. In animals with IA-lesions, there was almost total degeneration of striatal neurones and a complete disappearance of both D 1 and D 2 receptors in the lesioned striatum. Within the striatal grafts, dense ‘patches’ of both D 1 and D 2 receptors were observed with densities comparable to those in the intact neostriatum. These data indicate that both D 1 and D 2 receptors are localized on the soma of intrinsic striatal neurones. Moreover, the specific localisation of D 1 and D 2 receptors in the grafts provides the neurochemical basis for the mechanisms by which the host nigrostriatal DA system can regulate the functional capacity of striatal grafts.