EFFECTS OF PROSTAGLANDIN-F2-ALPHA (PGF(2-ALPHA)) ON SECRETION OF ESTRADIOL-17-BETA AND CORTISOL IN 90 TO 100 DAY HYSTERECTOMIZED, INTACT AND OVARIECTOMIZED PREGNANT EWES

Vehicle or 8 or 16 mg PGF(2 alpha)/58 kg/body weight (BW) was given in tramuscularly to intact, hysterectomized and ovariectomized 90 to 100 day pregnant ewes in three separate experiments. Hysterectomy alone de creased (P less than or equal to 0.05) estradiol-17 beta in jugular ve nous blood by 80 percent within 16 hours and profiles of estradiol-17 beta did not differ (P greater than or equal to 0.05) among vehicle or 8 or 16 mg PGF(2 alpha)/58 kg/BW-treated ewes. Profiles of estradiol- 17 beta differed (P less than or equal to 0.05) in intact pregnant ewe s treated with 8 or 16 mg PGF(2 alpha)/58 kg/BW when compared to contr ols and in ovariectomized (P less than or equal to 0.10) 90 to 100 day pregnant ewes treated with 16 mg PGF(2 alpha)/58 kg/BM. Estradiol-17 beta decreased (p less than or equal to 0.05) over time in vehicle and 8 mg PGF(2 alpha)/58 kg/BW-treated intact and in vehicle-treated ovar iectomized 80 to 100 day pregnant ewes. Cortisol decreased (P less tha n or equal to 0.05) over time in hysterectomized, intact, and ovariect omized 90 to 100 day pregnant ewes, but did not differ (P greater than or equal to 0.05) among vehicle or 8 or 16 mg PGE(2 alpha)/58 kg/BW-t reated ewes. It is suggested that estradiol-17 beta has a role in regu lating ovine placental steroidogenesis.