Partial reversal of the myometrial progesterone 'block' in the non-pregnant ewe in vivo by oestradiol-17 beta.
In ovariectomized non-pregnant ewes myometrial activity, which was suppressed by continued injection of progesterone, showed a significant recovery of both spontaneous activity and oxytocin responsiveness by 12 and by 24 h after intrauterine administration of oestradiol-17 beta. No such recovery occurred in ewes given vehicle only into the uterus. The oestrogen-induced recovery was lost by 60 h after treatment. Infusion of PGF-2 alpha into the uterine lumen instead of oestrogen provided no support for the possibility that the oestrogen-induced recovery was mediated through PGF-2 alpha secretion. It is suggested that oestradiol may participate in the mechanism of parturition in sheep by accelerating myometrial recovery from the effects of progesterone.
D000818:Animals; D002369:Castration; D015237:Dinoprost; D004958:Estradiol / Q000494:pharmacology*; D005260:Female; D009215:Myometrium / Q000187:drug effects* / Q000502:physiology; D011312:Pressure; D011374:Progesterone / Q000494:pharmacology*; D011460:Prostaglandins F / Q000494:pharmacology; D012756:Sheep; D014599:Uterus / Q000187:drug effects*
D011460:Prostaglandins F; D011374:Progesterone; D004958:Estradiol; D015237:Dinoprost