Effect of progesterone on the spontaneous motility and prostaglandin synthesis in uterine horns isolated from ovariectomized rats

The motility of isolated uterine horns as well as the generation of PGE and PGF-like material by uterus from spayed rats, treated or untreated with progesterone or progesterone plus estradiol-17-beta, were studied. The changes of Functional Activity (FA) with time (constancy) of control uterine horns and that preparations treated wtih 2 mg of progesterone (P) were not significantly different. However, the PGF-like material released into the bathing solution was significantly higher when the animals were treated with P. PGE-like material in the medium was similar in both groups. With higher doses to P (4 mg/day/2 days) the constancy of FA was similar to that observed in untreated animals, and the PGF-like material released into the medium was significantly higher than in the control group FA and PGs releases into the bathing medium by uterine horns from supra-renalectomized-ovariectomized animals (treated or not with P) were similar to those obtained in spayed rats with the intact suprarenal gland, but the absolute values of PGF-like material were always lower than in this group. Estradiol-17-beta injected prior or after P diminished the stimulation induced by P on the release of PGF-like material into the medium. The constancy of the contractile activity as well as the uterine release of PGE-like material was also diminished in rats treated with P plus estradiol-17-beta. The novel finding that progesterone stimulates the synthesis of PGF in uterine horns from ovariectomized rats without changing that of PGE is discussed.