Effects of RU486 on the Interstitial Collagenase in the Process of Cervical Ripening in the Pregnant Rat.

Abstract

Abstract. Changes in interstitial collagenase activity in the rat uterine cervix during ripening were clarified in a time-dependent manner. Premature delivery was induced by an antiprogesterone agent, RU486, for rats in late pregnancy. The presence of interstitial collagenase in the extract from the rat cervical tissue was demonstrated, by sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis using the natural and unaffected collagen as a substrate. The collagenase activity was determined as the release of digested peptides from the radio-labeled collagen. Our experiments with RU486 were performed in rats on the 18th day of pregnancy. A single administration of RU486 (15 mg/kg) resulted in the premature delivery of all treated rats within 30 h after the injection (average time was 23.9 h). The marked increase in cervical wet weight was observed up to the time to premature delivery along with a significant acceleration from 18 h after the adminsitration of RU486. In this state, the cervical collagenase activity was enhanced, the highest levels being recorded at 21 h after the administration. The interstitial collagenase in the uterine cervix appears to play a significant role in the regulation mechanisms of cervical ripening in late pregnant rats.

Novel concepts on pregnancy clocks and alarms: redundancy and synergy in human parturition

“…This suggests that appropriate PR signaling is essential for pregnancy maintenance and that disruption of PR signaling alone is sufficient to trigger the full parturition cascade. It is therefore hypothesized that human parturition is triggered by functional rather than systemic progesterone withdrawal that involves a physiological control of PR signaling to desensitize target cells in the uterus to pro-gestational actions of progesterone (Avrech et al, 1991;Henshaw and Templeton, 1991;Ikuta et al, 1991;Carbonne et al, 1995;Cadepond et al, 1997). According to this model, up-stream gestation clocks/monitoring signals could induce labor by modulating PR signaling to cause functional progesterone withdrawal.…”

Endogenous Hyaluronan: A Cytokine-Like Factor Present in Rabbit Uterine Cervix during Pregnancy

“…It is thought that sex hormones such as progesterone and estrogen play important roles as regulatory factors of these changes in the uterine cervix. Administration of anti-progesterone to pregnant women 5) and to pregnant rats 6) promotes uterine cervical ripening and dilatation.…”