Effects of ovariectomy and estrogen replacement on intrastriatal dopamine-elicited postural deviation.

The effects of ovariectomy, sham ovariectomy, and estradiol benzoate replacement on unilateral intrastriatal dopamine-induced postural deviation were studied in rats. Animals were tested prior to surgery, and at both two and seven days after surgery. Relative to the pre-surgery test, ovariectomized rats greatly increased this behavioral response two days after surgery while sham ovariectomy resulted in no significant change. Estradiol benzoate treatment in ovariectomized animals not only prevented this increase but significantly suppressed it at both two and seven days after surgery relative to pre-surgery levels. Thus, removal of endogenous estrogen in female rats resulted in an acute increase in a striatal DA-mediated behavior which could be prevented by hormone replacement. These results are consistent with the hypothesis that estrogen suppresses some striatal DA-mediated behaviors.