Withdrawal of Ovarian Steroids Stimulates Prostaglandin F2 alpha Production Through Nuclear Factor-kappa B Activation via Oxygen Radicals in Human Endometrial Stromal Cells: Potential Relevance to Menstruation

摘要

The present study was undertaken to investigate whether withdrawal of estrogen and progesterone (EP-withdrawal) stimulates prostaglandin F2 alpha (PGF2a) production through oxygen radical (ROS)-induced NF-KB activation in human endometrial stromal cells (ESC). To study the EP-withdrawal, ESC that had been treated with estradiol (E, 10~(-8) M) and medroxyprogesterone acetate (MPA, 10~(-6) M) for 12 days were then incubated with or without E+MPA for a further 11 days, PGF2 alpha concentrations in the medium and cydooxygenase-2 (COX-2) mRNA levels were significantly increased after EP-withdrawal, while they were unchanged by the continuous treatment with E+MPA, When ESC were incubated with N-acetyl-L-cysteine (Nac, 50 mM), an antioxidant, during EP-withdrawal, Nac blocked the increases in PGF2 alpha production and COX-2 mRNA expression caused by EP-withdrawal. Next, we examined whether ROS generated in response to EP-withdrawal acted through NF-KB activation. Electrophoretic mobility shift assay revealed that EP-withdrawal caused marked increases in NF-KB DNA binding activity, which was completely suppressed by Nac. Furthermore, when ESC were incubated with MG132 (3 mu M), which inhibits NF-KB activation, during EP-withdrawal, MG132 blocked the increases in PGF2 alpha production and COX-2 mRNA expression caused by EP-withdrawal. In conclusion, EP-withdrawal stimulates COX-2 expression and PGF2 alpha production through ROS-induced NF-KB activation, suggesting a possible mechanism for menstruation.