EFFECTS OF RAT HYPOTHALAMIC AND CEREBRAL TISSUE ON PMS-INDUCED OVULATION.

Abstract

Immature female rats were treated with 30 IU PMS for inducing superovulation. Hypothalamic and cerebral tissues were taken from cycling female rats, homogenized in saline, and tested for their effects on induced ovulation. The tissue preparations were given as crude homogenates, after dialysis against saline, or after centrifugation. All preparations were given subcutaneously and administered approximately 49 hr after PMS treatment. Ovulation was depressed to 4% of the control count by as little as 1.25 mg equivalent of dialyzed hypothalamic tissue from diestrous rats. The nondialyzed preparation had no apparent effects on ovulation. Rat cerebral tissue was equally as effective in depressing ovulation. Cerebral tissue also contained ovulation-facilitating activity. Separation of the 2 activities could be effected by centrifugation. Most of the inhibiting activity was removed from solution by centrifuging 20 min at 10,000 Xg. The remaining supernatant was essentially inactive with respect to ovulation. Centrifugation of homogenized cerebral tissue for 20 min at 20,000 Xg removed all inhibiting activity, with facilitating activity remaining in the supernatant phase. These studies show that gonadotropin-induced superovulation may be influenced (depressed or facilitated) by substances present in rat hypothalamic and cerebral tissue homogenates. (Endocrinology76:1177, 1965)