Ovarian function and progestin content in response to gonadotrophins.

Abstract

Summary. Luteinizing hormone was administered to rats hypophysectomized on the morning of pro-oestrus or metoestrus after a 7-day rest. The following changes were noted: vaginal smears contained cornified epithelial cells; ovarian weights were unchanged compared to those of controls; uterine weights increased, and the lumina contained fluid. These observations indicate that lh induces oestrogen secretion. Analyses of the sterol and steroid content of the ovaries showed trends without statistical significance. Prolactin was administered immediately after hypophysectomy in similar animals and the following changes were noted: vaginal smears contained leucocytes; vaginal epithelia were bilaminar; ovarian weights decreased in rats operated on during pro-oestrus and remained the same in rats operated on during metoestrus when compared to those of hypophysectomized controls; and uterine weights were not different from those of hypophysectomized controls. The amount of esterified cholesterol increased in animals which were operated on during pro-oestrus but not during metoestrus. In contrast, when prolactin and lh were administered, the vaginal smear still contained leucocytes but the vaginal epithelia were stratified and mucified; ovarian weights increased in animals operated on during metoestrus, but not during pro-oestrus, and uterine weights increased in animals operated on during pro-oestrus. lh reduced the esterified cholesterol in the ovaries of rats operated on during pro-oestrus. The amounts of progesterone and 20α-hydroxy-pregn-4-en-3-one were greater in rats operated on during metoestrus and lh treatment tended to increase the content of these steroids. The data suggest the ovaries of animals operated on during pro-oestrus which contain older corpora lutea are capable of secreting progesterone as well as oestrogen.