Induction of Ovulation in Rats by Highly Purified Pig LH-Releasing Factor (LRF)

Abstract

Adult female rats in proestrus were given pentobarbital (Nembutal) in order to block spontaneous ovulation. Highly purified LH[luteinizing hormone] releasing factor (LRF) was injected into their carotid arteries at different rates. Ten [mu]g of this LRF, when injected over 30 min, induced full ovulation in all rats tested. One or 2 [mu]g occasionally caused ovulation. One mg of an extract of pig cerebral cortex or 50 [mu]g of FSH-releasing factor (FSH-RF) never did. Similar ovulatory responses were obtained when the LRF was injected quickly or over a 90-min period. On the other hand, LH induced ovulation more effectively when given by quick injection than when given slowly. LH induced ovulation in hypophysectomized animals, whereas our LRF did not These results offer validation of a physiological effect induced by purified LRF preparation.