Effects of Prostaglandin E2 on Ripening of the Cervix and Secretion of Relaxin, Luteinizing Hormone (LH), Estradiol-17.BETA. and Progesterone at Term Pregnancy in the Japanese Monkey (Macaca fuscata fuscata).

Abstract

Abstract. Effects of intracervical prostaglandin E2 (PGE2)-gel treatment on ripening of the cervix at term pregnancy were investigated. Concentrations of relaxin, LH estradiol-17 β and progesterone were measured by radioimmunoassays in the maternal peripheral plasma during 48 hours after treatment with PGE2-gel. Treatment with PGE2-gel induced cervical ripening without induction of labor at term. Plasma levels of estradiol-17 β increased after administration of PGE2-gel, whereas plasma levels of relaxin, LH and progesterone were unchanged during the period studied. These results suggest that increased levels of estradiol-17β may be involved in ripening of the cervix without increasing circulating relaxin during the period of PGE2-gel treatment in the Japanese monkey. Key words: Relaxin, Japanese monkey, Prostaglandin E2, Pregnancy, Cervix (J. Reprod. Dev. 48: [607][608][609][610][611] 2002) lthough softening and dilatation of the cervix t o ge t h er w i t h ut er i n e c o n t r a c t i o n s a r e necessary for parturition, the exact mechanism of the onset of labor remains to be determined in the Japanese monkey. A dramatic change in the structure and function of the myometrium and cervix are regulated by the co mbination of estrogen, progesterone, prostaglandins, oxytocin and relaxin during pregnancy and labor. Some of them have been used to promote cervical ripening before the induction of labor to increase the success rate of induction and shortening the delivery time.In our previous study, intracervical administration of prostaglandin E2-gel (PGE2-gel) induced cervical ripening and stimulated uterine contraction without induction of labor at term pregnancy in the Japanese monkey [1]. Moreover, previous studies have demonstrated that exogenous prostaglandins precipitated premature delivery or abortion when administrated to pregnant rhesus monkeys and women [2].Relaxin is a polypeptide hormone found in the blood of pregnant mammals [3] and is known for its actions on the smooth muscle of the uterus and connective tissue of the pubis symphysis and cervix d u r i n g p r e g n an c y [ 4 ]. W e h a v e r e c e n t l y