[The effect of mifepristone on progesterone and estrogen receptors in human decidua and serum hormone levels].

OBJECTIVE: To examine the effects of mifepristone on progesterone and estrogen receptors in human decidua and steroid hormone levels in serum for investigating the mechanisms of antigestational action of mifepristone. METHODS: Decidual progesterone receptor (PR) and estrogen receptor (ER) concentrations or binding sites were measured by both dextran coated charcoal (DCC) and histochemical methods in normal subjects and after 100 mg-mifepristone treatment. Meanwhile, the concentrations of serum beta-human chorionic gonadotropin (beta-hCG), estradiol (E2), progesterone (P) and testosterone (T) were also determined by radioimmunoassay. The reactions of these two groups were compared. RESULTS: Mifepristone therapy significantly reduced decidual cytosol PR content (P < 0.05) and increased decidual cytosol ER content (P < 0.05). Histochemical analyses indicated mifepristone treatment increased ER staining in vessel and glandular cells of decidua. The serum beta-hCG, E2 and T levels elevated significantly after mifepristone administration, while the progesterone levels were unaffected. CONCLUSION: Our data suggested that the anti-gestational effect of mifepristone may act through decreasing the decidual PR and increasing the ER concentrations, which interfered the balance between these two components, and also through increasing serum T levels.