Regional effect of estradiol on rat caudate-putamen dopamine receptors: lateral-medial differences

The effect of a chronic 17 beta-estradiol (10 micrograms, b.i.d.) treatment of 2 weeks to ovariectomized rats was investigated on lateral and medial caudate-putamen dopamine receptors. Dopamine D2 receptors were assayed with [3H]spiperone binding to caudate-putamen homogenates or by autoradiography of forebrain sections. Estradiol treatment leads to a significant increase in the density of lateral caudate-putamen dopamine receptors while for the medial dopamine receptors the increase is non-significant. This effect is observed when plasma levels of 17 beta-estradiol and prolactin are increased. These results indicate that the effect of estradiol on striatal dopamine receptors is heterogeneous and that those in the lateral part are more susceptible to this steroid.