RELEASE OF LUTEINIZING HORMONE IN ANDROGENIZED EWES AFTER PROSTAGLANDIN-INDUCED LUTEOLYSIS OR LUTEINIZING HORMONE RELEASING HORMONE

Publisher Website
Google Scholar
Abstract
Exposure to testosterone during development masculinizes the genitalia and behavior of ewes and causes ovulatory failure. Androgenized ewes do not release luteinizing hormone (LH) after estrogen treatment during anestrus. Experiments were performed to determine the site of action (hypothalamus or anterior pituitary gland) of prenatally administered androgens in blocking the preovulatory release of LH. Ewes exposed to testosterone before day 70 of prenatal life tended to be anovulatory; in ewes which did ovulate, the LH release was probably delayed and reduced in quantity. The time of onset of estrus in androgenized and control ewes was similar, suggesting that estrogen secretion was similar in both groups. The delayed-release of LH was therefore probably due to latency in the response of the hypothalamo-pituitary system to estrogen. The consistent responses to LH-RH, compared with the variable responses to endogenous estrogen, reinforce the belief that androgenization of ewes before day 80 of prenatal life modifies brain function. The pituitary gland functions normally when appropriately stimulated and ovulatory failure appears to derive from the inability of estrogen to stimulate the hypothalamic mechanisms responsible for the preovulatory release of LH.