Prostaglandin E 2 : analysis of effects on pregnancy and corpus luteum in hamsters and rats.

Abstract

ABSTRACT Effects of prostaglandin (PG) E2 on some reproductive processes of hamsters and rats were studied. The PG exerted antifertility effects in either species although it was 4–10 times less potent than PGF2α. Antifertility doses of PGE2 caused morphological degeneration of corpora lutea, induced fresh ovulations during the course of the treatment, significantly decreased peripheral progesterone levels and inhibited development of deciduomata in response to trauma. Both pregnancy and decidual growth could be maintained by simultaneous administration of exogenous progesterone. PGE2 also decreased plasma progesterone concentration in pseudopregnant-hysterectomized hamsters although the decrease was not significant when compared with intact pregnant or pseudopregnant hamsters. PGE2 produced no demonstrable effects on egg transport in hamsters but may have induced delayed implantation in rats by causing tubal retention of zygotes. The antifertility doses of PGE2 but not of PGF2α inhibited implantation of a proportion of blastocysts as studied by the Pontamine blue reaction and adversely affected the spacing mechanism of blastocysts in the uterus significantly reducing the distance between the adjacent implantation sites. When PGs E2 and F2α were given together to pregnant rats in doses which were virtually ineffective individually, the combined treatment caused loss of pregnancy. Administration of PGE2 to near term hamsters produced premature littering but oxytocin in doses tried proved inactive. Antifertility doses of PGE2 produced diarrhoea in rats but not in hamsters. The results demonstrate that PGE2 shares the luteolytic property of PGF2α but in addition possesses several other properties not known to be shared by PGF2α.