Cervical softening in late pregnant sheep by infusion of prostaglandin E-2 into a cervical artery

Abstract

Cervical softening was induced in late pregnant sheep by infusion of PGE-2 into a cervical artery. The effect of this treatment was assessed by measurement of the extensibility in vitro of a strip of cervical tissue. After infusion of a saline/ethanol mixture extensibility was 2.84 X 10(-3) +/- 0.3 X 10(-3) min-1 (mean +/- s.e.m., N = 5); after infusion of PGE-2 it increased significantly (P less than 0.02) to 8.6 X 10(-3) +/- 1.8 X 10(-3) min-1 (N = 6). Infusion of PGE-2 did not increase uterine activity, and there was no significant change in the concentration of progesterone in the maternal jugular venous plasma. These data suggest that PGE-2 might act as a mediator of cervical softening in vivo and show that the cervix can soften in the absence of uterine contractions.

Follicle-Stimulating Hormone Receptor and Its Messenger Ribonucleic Acid Are Present in the Bovine Cervix and Can Regulate Cervical Prostanoid Synthesis1

“…It is thought that stretching of the cervix is a factor in causing the release of these prostaglandins [25,26]. The effect of PGE in causing cervical softening in the ewe is also well documented [27][28][29]. In both nonpregnant and pregnant cows, PGE 2 causes an increase in cervical opening within 3 h of treatment [30].…”

Prenatal maturation, the timing of birth and how it may be regulated in domestic animals

“…In the sheep a sudden drop in progesterone in the absence of any rise in oestrogen will induce cervical ripening within a few hours (Ledger, Webster, Anderson & Turnbull, 1985) while oestrogen alone will also elicit softening (Fitzpatrick & Dobson, 1981). That prostaglandins are the primary factors in cervical ripening is shown by the effectiveness of exogenous PGE and by the inhibitory action of PG synthetase inhibitors (Fitzpatrick & Dobson, 1981;Ledger, Ellwood & Taylor, 1983). It seems likely that a local or paracrine release of PGE occurs in the cervix because no rise in levels of PGE in the maternal circulation occur at parturition.…”

“…If the affected areas are within the uteroplacental tissues then the likelihood of such PG synthesis resulting in premature labour is even greater. PGE production can stimulate fetal adrenal activity (Thorburn et al 1988) and may accelerate cervical ripening and relaxation (Ledger et al 1983), while PGF2. will affect the myometrium and corpus luteum .…”

Cervical dilation and improvement of reproductive performance in fat-tailed ewes via cervical dilator treatments

“…The minimum dosage needed for dilating the cervix is 50 IU [12]. Also, PGE 2 remodels the extracellular matrix of the cervix which ultimately lead to the process of cervical dilation [25,26]. PGE 2 exerts its action mainly through the expansion of smooth muscle and increasing the production of glycosaminogly can by activating EP4 and EP2 receptors in the cervix.…”