A comparison of the characteristics of parturition induced by prostaglandin F2alpha, infused intra-aortically, with those following ovariectomy in the rat.
Prostaglandin F2alpha (PGF2alpha) was infused intra-aortically at different rates into rats for 11-5 h from day 18 of gestation. At doses in excess of 5 mug/h premature delivery invariably occ'rred 40-41 h later. At lower doses an all-or-none effect was observed, some animals delivering prematurely and others continuing to term. Parturition could not be induced earlier than 40 h after the start of the treatment even by a continuous infusion of PGF2alpha, suggesting that the luteolytic role of PGF2alpha is more important than its oxytocic action in this case. The rate of fall in plasma progesterone was greater in the rats delivering prematurely than those delivering at term, although the final concentrations of between 15 and 30 ng/ml at delivery were the same. Labour appeared more normal in the animals receiving PGF2alpha than in those which had been bilaterally ovariectomized. The possible significance of this in relation to an effect of PGF2alpha on oestrogen secretion is discussed.
D000818:Animals; D001011:Aorta; D002339:Carotid Arteries; D002369:Castration; D005260:Female; D007263:Infusions, Parenteral; D007751:Labor, Induced; D007743:Labor, Obstetric; D011247:Pregnancy; D011374:Progesterone / Q000097:blood; D011453:Prostaglandins / Q000008:administration & dosage / Q000494:pharmacology*; D011863:Radioimmunoassay; D051381:Rats; D013997:Time Factors
D011453:Prostaglandins; D011374:Progesterone