6-keto-prostaglandin E 1 and the decidual cell reaction in rats

Abstract

Although there is considerable evidence that prostaglandins (PGs) are involved in the decidual cell reaction in rats, which PGs are involved is uncertain. In the present study, we investigated the possibility that 6-keto-PGE 1 is involved. To determine its ability to induce decidualization, 6-keto-PGE 1 was infused unilaterally from Alzet osmotic minipumps into the uterine lumen of ovariectomized rats treated with estrogen and progesterone to sensitize their uteri for the decidual cell reaction. To reduce endogenous PG production, indomethacin was injected 2–3 h prior to pump insertion and was included in the vehicle for PG infusion. As determined by uterine weights 5 days after pump insertion, 6-keto-PGE 1 and PGE 2 produced decidualization which was equivalent. As indicated by a dose-response study, 6-keto-PGE 1 and PGE 2 did not differ in their ability to bring about decidualization. To determine if a deciduogenic stimulus resulted in increased uterine production of 6-keto-PGE 1, as assessed by uterine concentrations, 6-keto-PGE 1 and PGE concentrations in the uterus were determined after the unilateral intrauterine injection of 100 μ1 sesame oil. There were no significant differences between stimulated and non-stimulated horns in 6-keto-PGE 1 concentrations, whereas the concentrations of PGE 2 were elevated in the stimulated horns. These data indicate that while both exogenous 6-keto-PGE 1 and PGE 2 induce decidualization, only uterine PGE concentrations are elevated by deciduogenic stimuli. Thus it is unlikely that 6-keto-PGE 1 plays a role in decidualization.