Estrogen and progesterone receptors in human decidua after RU486 treatment.

ABSTRACT

PIP: In China, physicians randomly placed 60 pregnant women of 6-7 weeks gestational age into a group receiving one oral dose of RU-486 12 or 24 hours before undergoing vacuum aspiration or into a group receiving a placebo. Aspirate samples were submitted to a laboratory to determine the effect of Ru-486 on progesterone (P) and estrogen (E) receptors in human decidua. RU-486 multiplied P and E receptor staining in vessel and stoma cells of decidua (decidua parietalis) without fetal trophoblast invasion (89% for 12-hour group and 84% in 24-hour group vs. 26%; p M .005). This did not occur, however, in decidua with fetal trophoblast invasion (decidual capsularis or basalis). These findings confirmed the hypothesis that the P antagonist, RU-486, increases P and E receptor levels in decidual tissue. Further, the findings indicated that the contragestive mechanisms of RU-486 is directed at the maternal endometrium and not at the developing embryo or those interfacing cells which anchor it to the endometrium. In fact, the cytological barrier inhibits antiprogestin effects and may even play a role in protecting against spontaneous abortion.