EFFECTS OF MIFEPRISTONE AND PROGESTERONE ON COLLAGEN-SYNTHESIS IN THEHUMAN UTERINE CERVIX

Antiprogestins are used to induce first trimester abortion and to dila te the cervix before vacuum aspiration. Cervical dilatation is associa ted with profound changes in the connective tissue. in what respect an tiprogestins interfere with this process has hitherto been sparsely in vestigated. The aim of present study was to examine the influence of t he antiprogestin mifepristone on cervical collagen synthesis in nonpre gnant, early and late pregnant women. The effects were compared with t hose of progesterone. The content of collagen in cervical tissue was d etermined by measuring hydroxyproline. Collagen synthesis was studied in vitro either by incubation of cervical tissue specimens from women, pretreated with mifepristone in vivo, in the presence of C-14-proline or by incubation of cervical tissue of not pretreated women in the pr esence of the isotope and mifepristone or progesterone. Pretreatment w ith mifepristone, but not progesterone, induced a significant increase in cervical dilatation. The cervical concentration of collagen was no t altered after mifepristone administration. Pretreatment with mifepri stone did not quantitatively influence the time course of radiolabelin g in vitro or the pattern of radiolabeling in different protein compon ents as revealed by electrophoresis. In vitro mifepristone, like proge sterone, reduced the incorporation of C-14-proline. From the present d ata we conclude that mifepristone pretreatment in connection with firs t trimester abortion is not associated with any major changes, qualita tively or quantitatively, of collagen synthesis. However, we cannot ex clude that mifepristone still may affect the de novo formation of coll agen since mifepristone, administered in vitro, did reduce collagen sy nthesis.