Downregulative effects of nitric oxide on oocyte fertilization and embryo development: possible roles of nitric oxide in the pathogenesis of endometriosis-associated infertility

AIMS: To investigate the effects of elevated nitric oxide (NO) levels in peritoneal fluids (PF) on oocyte fertilization and pre-implantation embryo development, and the relation of those effects to endometriosis-associated infertility. METHODS: PF from women undergoing laparoscopy for infertility of minor endometriosis, tubal blockage and operation for tubal ligation was aspired at the pouch of the cul-de-sac during surgery. Oocytes and embryos of adult ICR mice were cultured in vitro with or without endometriotic PF. The fertilization rate of oocyte and the cleavage rate of 2-cell embryos were examined. Also, the clinical indexes of IVF-ET of women with minor endometriosis and tubal infertility were analyzed. RESULTS: Oocyte fertilization rate of endometriotic women with IVF-ET treatment was significantly lower than that of tubal block women. The dose-related adverse effects of endometriotic PF and SNP (NO donor) in culture medium on oocyte fertilization and embryos development were confirmed. CONCLUSION: Increased NO levels in PF play an important role in mediating the effects of endometriotic PF on oocyte fertilization and embryo development. IVF might serve as an alternative treatment for endometriosis-associated infertility.