Comparative effects of estradiol stereoisomers on pimozide-induced catalepsy, locomotor activity and body-weight in the rat.

The effects of 17-alpha and 17-beta estradiol were compared at three dose levels on locomotor activity, pimozide-induced catalepsy, and changes in body weight. At 10 micrograms/kg/day they increased locomotor activity to a similar degree but at 5 and 1 microgram/kg/day the beta form was mor effective. However the alpha isomer failed to potentiate catalepsy, or reduce body weight, even at the highest dose whereas 17-beta estradiol did both. From these and other results it is suggested that estradiol might act on intracellular receptors and not by changing catecholamine metabolism.