Effects of prostaglandins F-2  and E-2 on cervical extensibility in the late pregnant rat

Abstract

The extensibility of the cervix of rats was measured in vitro on Day 19 of pregnancy and was doubled after 2 s.c. injections of PGF-2 alpha (1 mg/kg) or PGE-2 (5 mg/kg) on Day 18. Progesterone (10 mg/kg) given on Day 18 had no effect alone or on the effect of PGE-2 but abolished the action of PGF-2 alpha. PGE-2, but not PGF-2 alpha, increased extensibility when given on Day 18 to rats which had been bilaterally ovariectomized on Day 16 and given oestradiol benzoate plus progesterone twice daily. High concentrations of PGF-2 alpha or PGE-2 had no effect on the extensibility of Day-18 pregnant rat cervix in vitro. It is suggested that PGF-2 alpha acts via the ovaries to decrease progesterone secretion and perhaps release relaxin, but PGE-2 would appear to have another site of action.

Fluprostenol-induced softening of the cervix of the pregnant rat

“…The present results demonstrate that fluprostenol, a synthetic prostanoid, can produce softening of the cervix of the pregnant rat, as do the endogenous prostanoids PGF2c[ and PGE2 (Hollingsworth et al 1980). We have considered three possible sites and mechanisms of action of fluprostenol, namely, a direct action upon the cervix, or an indirect action either by increasing uterine contractions or by changes in ovarian hormone secretion.…”

“…This steroid regime enabled pregnancy to continue with normal fetal growth and prevented the increased uterine contractions which developed in ovariectomized rats (Hollingsworth & Gallimore, 1981). Prostaglandin E2 is able to produce cervical softening in both intact and ovariectomized steroid-maintained rats (Hollingsworth et al 1980). Large doses of fluprostenol were unable to produce cervical softening in pro-oestrous rats, an oestrogen-dominated state.…”

“…It is well established that prostaglandin E2 (PGE2) and prostaglandin F2x (PGF2a) can produce softening of the cervix of pregnant women (Mackenzie, 1981), ewes (Fitzpatrick, 1977;Stys, Dresser, Otte & Clark, 1981) and rats (Hollingsworth, Gallimore & Isherwood, 1980). It has been suggested that in the rat PGF2ci-induced softening is by an indirect hormonal action while PGE2 possibly acts directly on the cervix (Hollingsworth et al 1980).…”

“…It has been suggested that in the rat PGF2ci-induced softening is by an indirect hormonal action while PGE2 possibly acts directly on the cervix (Hollingsworth et al 1980). Fluprostenol is a potent and selective F-type prostanoid with known luteolytic properties (Dukes, Russell & Walpole, 1974;Warnock & Csapo, 1975;Coleman, Humphrey, Kennedy, Levy & Lumley, 1980).…”

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

“…Prostaglandins (PGs) have been implicated in the mechanism of cervical softening at parturition in various species (Liggins, Fairclough, Grieves, Forster & Knox, 1977;Cooke, Knifton, Fitzpatrick & Ward, 1977;Fitzpatrick, 1977a;Hollingsworth, Gallimore & Isherwood, 1980;Ellwood, Mitchell, Anderson & Turnbull, 1980b). In late pregnant sheep the involvement of PGs has been investigated in a number of ways.…”