EFFECT OF PROSTAGLANDIN-F(2-ALPHA) ON UTERINE OR OVARIAN SECRETION OFPROSTAGLANDIN-E AND PROSTAGLANDIN-F(2-ALPHA) IN-VIVO IN 90-100 DAY HYSTERECTOMIZED, INTACT OR OVARIECTOMIZED PREGNANT EWES

Vehicle or 8 or 16 mg of PGF2alpha per 58 kg body weight was given int ramuscularly to intact, hysterectomized or ovariectomized 90-100 day p regnant ewes in three separate experiments. Both doses of PGF2alpha in creased PGF2alpha in ovarian venous plasma compared with controls at 7 2 hr post treatment in intact (P less-than-or-equal-to 0.05) but did n ot in hysterectomized (P greater-than-or-equal-to 0.05) 90-100 day pre gnant ewes. Concentrations of PGE in ovarian venous blood of intact ew es did not differ (P greater-than-or-equal-to 0.05) between treatment groups and were equivalent to concentrations of PGE determined in uter ine venous plasma. PGE was decreased in ovarian venous plasma by PGF2a lpha in hysterectomized ewes (P less-than-or-equal-to 0.07). PGE in ut erine venous plasma averaged 6 ng/ml over the 72-hr treatment period i n intact and ovariectomized 90-100 day pregnant ewes and was 12 fold g reater (P less-than-or-equal-to 0.05) than PGF2alpha which averaged 50 0 pg/ml in uterine venous plasma. Both PGF2alpha and PGE increased (P less-than-or-equal-to 0.05) by 64 hr in uterine venous plasma of the 8 mg PGF2alpha-treated intact pregnant ewes. A significant quadratic in crease (P less-than-or-equal-to 0.05) was observed for PGF2alpha and P GE in the vehicle and both PGF2alpha treatment groups of intact ewes a t the end of the 72-hr sampling period. It is concluded that the uteru s and ovaries secrete significant quantities of PGE but little PGF2alp ha during midgestation. In addition, PGF2alpha increased uterine secre tion of PGE in vivo. PGE may be a placental stimulator of ovine placen tal secretion of progesterone or PGE may protect placental steroidogen esis from actions of PGF2alpha.