OXYTOCIN-STIMULATED PRODUCTION OF PROSTAGLANDIN F-2-ALPHA BY ISOLATED ENDOMETRIUM OF RABBIT - MODULATION BY OVARIAN STEROIDS

To test the hypothesis that ovarian steroid hormones modulate oxytocin-induced release of prostaglandin F2α (PGF2α) from uterine endometrium, 2 ovariectomized rabbits were pretreated with progesterone (5 mg/day for 10 days), 2 with estradiol-17β (25 μg/day for 10 days), 2 with both steroids, and one with sesame oil only. On the last day of treatment, endometrial fragments were excised and incubated in vitro with or without oxytocin (100 μU/ml). Although endometrium from rabbits pretreated with combined steroids released more PGF2α immediately after excision than did tissue from animals pretreated with either steroid by itself, endometrium from animals pretreated with estrabdiol-17β alone released the most PGF2α during sustained incubation in vitro. Moreover, only this tissue exhibited significant oxytocin-dependent release of PGF2α. At the dosages used, progesterone completely antagonized both of these effects of estradiol-17β. The results support the hypothesis that ovarian steroid hormones regulate oxytocindependent release of PGF2α from endometrial cells. A possible mechanism of action is suggested. © 1978 Geron-X, Inc.