The effect of ovarian steroids on prostaglandin F2 catabolism in ovariectomized rat uterus.

The effects of ovarian steroids, estradiol and progesterone, on the prostaglandin F2 (PGF2) catabolism in vitro in rat uterus were examined by using labeled PGF2. The formation of 13,14-dihydro-15-keto-PGF2 (13,14H2-15K-PGF2) from PGF2 was stimulated by a single injection of estradiol (10 micrograms) or progesterone (1 mg). A remarkable increase in the 13,14H2-15K-PGF2 formation was recognized at 12 hours after estradiol treatment and the formation reached the maximal level at 24 hours. Progesterone also raised the gradual increase of PGF2 catabolism at 24 and 48 hours. In the case of the simultaneous administration of estradiol and progesterone, the additive effect in the PGF2 catabolism was not observed at 24 hours after a single injection of steroids. However, the additive effect was observed by the repeated treatment (once a day for 3 days) of both estradiol (1 microgram) and progesterone (1 mg). These results indicate that PGF2 catabolism in rat uterus is accelerated by ovarian steroids, and also suggest that ovarian hormones closely take part in the regulation of the levels of PGF2 in rat uterus.