The Effect of Estradiol in the Striatum Is Blocked by ICI 182,780 but Not Tamoxifen: Pharmacological and Behavioral Evidence

Abstract

Estradiol in the striatum enhances amphetamine (AMPH)- or KCl-stimulated dopamine (DA) release and the pacing of sexual behavior in the female rat. These effects of estradiol in the striatum are rapid, steroid specific and thought to be mediated by a G protein-coupled membrane receptor for estradiol. In the current experiments, we examined whether two antiestrogens, ICI 182,780 (ICI) and tamoxifen (TAM), affect the enhancement by estradiol of (1) AMPH-induced DA release from striatal tissue in vitro, and (2) paced mating behavior in the female rat. The steroidal antiestrogen ICI significantly blocked the effect of estradiol on AMPH-induced striatal DA release. In contrast, the nonsteroidal, triphenylethylene antiestrogen TAM did not block the effect of estradiol, even when a concentration 10 times the concentration of estradiol was delivered to the tissue. Neither of the compounds showed estrogenic action when tested in the absence of estradiol. When implanted into the dorsolateral striatum, ICI inhibited the effect of estradiol on pacing of sexual behavior, while TAM did not. The specific effects of ICI, but not TAM, on striatal DA release and pacing behavior provide further information about the binding site for estradiol in the striatum.