Modulation of apomorphine-induced climbing behavior by estradiol.

The acute and chronic effects of estradiol benzoate were studied on apomorphine-induced climbing behavior in intact female mice. Climbing behavior was measured by determining the maximum climbing time and climbing index. Mice pretreated with estradiol benzoate (0.1 or 0.3 mg/kg, SC) for 3.5 or 24 hours prior to apomorphine administration showed no significant difference in climbing behavior when compared to corn oil-treated controls. However, mice pretreated with estradiol benzoate (0.1 mg/kg, SC) for 3 consecutive days showed an attenuation in apomorphine-induced climbing at 24 or 72 hours after the last steroid injection. This study shows that the mouse climbing behavioral model provides a simple and quantitative procedure for studying the antidopaminergic effects of estrogen.