The effect of estradiol on isolated rat uterine motility and on prostaglandin generation.

The motility of isolated uterine horns as well as the generation of PGE and PGF like material by the uterus from estrus and spayed rats, treated or untreated with 17-beta estradiol, were studied. Following 40 minutes of mounting the spontaneous motility of uteri from estrus rats had a lower magnitude than that from spayed ones. The amount of PGF-like material was similar in both groups whereas the first one liberated less PGE-like substance. In spayed animals treated wth 1 microgram of 17-beta estradiol the decay of spontaneous c ontractile force was higher that that observed in untreated rats, and similar to that displayed by uteri from estrus. Less PGE-like material was liberated in comparison with spayed animals and a tendency to produce higher quantity of PGF-like compounds was observed, although the level was not significantly different. With 50 micrograms of 17-beta estradiol the spontaneous reduction of contractile activity was higher than in spayed animals and than in those treated with 1 microgram. The amount of PGF-like material liberated was higher than in spayed rats and less PGE-like substance was generated comparing with spayed and 1 microgram-treated animals. These findings show that estradiol decreases the release of PGE-like compound. It would also appear that this may have some relationship with the levels of spontaneous contractile activity of the isolated rat uterus.