Effect of dehydroepiandrosterone sulphate, oestrogens and prostaglandins on collagen metabolism in human cervical tissue in relation to cervical ripening.

To clarify the mechanism of cervical ripening at term, collagenase activity in human cervical tissue was studied. The effects of steroids and prostaglandins on collagenase activity were also examined. Collagenase activities in cervical tissues obtained from non-pregnant (n = 5) and pregnant women (early-pregnant, n = 3; late-pregnant, n = 14) were measured, with or without the addition of steroids and prostaglandins into the incubation medium prior to the measurement of enzyme activity. The enzyme activity was significantly (P < 0.01-0.05) higher in the cervical tissue obtained from late-pregnant women than that from non-pregnant and early-pregnant women. Collagenase activity was significantly (P < 0.05) elevated when steroid sulphates such as dehydroepiandrosterone sulphate and oestrone sulphate were added to the incubation medium, while the addition of free steroids, prostaglandin E2 and prostaglandin F2 alpha did not alter the activity. These data suggest that conjugated steroid produced in the foetoplacental unit during pregnancy may be involved in cervical ripening through the enhancement of collagenase activity.