Nitric oxide inhibition of the proliferation of ovarian endometriotic stromal cells in vitro.

OBJECTIVE: To investigate the effects of nitric oxide on endometrial cell proliferation and the effects of peritoneal fluid from women with and without endometriosis on the production of nitric oxide and upon the nature of nitric oxide-induced changes. STUDY DESIGN: Ovarian endometriotic and endometrial stromal cells and peritoneal fluid were obtained from endometriosis patients and controls. Cell proliferation was determined by [3H]thymidine incorporation, and nitrite was measured using Griess reagent. RESULTS: Sodium nitroprusside (SNP), a nitric oxide donor, reduced the proliferation of endometriotic and endometrial cells in primary culture in a dose-dependent manner. SNP-induced production of nitric oxide and the inhibitory effect of nitric oxide on stromal cell proliferation were reduced by peritoneal fluid from women with endometriosis, although stromal cell proliferation was still inhibited by SNP in the presence of peritoneal fluid. However, this SNP-induced inhibition of cell proliferation was unaffected by interleukin-8, 17-beta, estradiol or transforming growth factor beta1. CONCLUSION: Nitric oxide inhibits the proliferation of endometrial stromal cells in vitro, and this inhibitory effect is abrogated by peritoneal fluid from women with endometriosis.