Abstract：The objective of the present study was to investigate the effects of NO donor nitroprusside sodium (SNP) (1mM) on mouse oocytes spontaneous maturation and to explore the mechanisms by which NO influenced oocyte spontaneous maturation. Oocytes maturation was evaluated through in vitro cell culture and intracellular cGMP levels were determined by Radioimmunoassay (RIA). The results showed that NO donor SNP (1mM) could delay the occurrence of GVBD and inhibit the first polar body (PB1) extrusion of cumulus-oocyte complexes (COCs). The data of RIA demonstrated that NO donor SNP significantly increased the cGMP levels in COCs and that the stimulative effect of SNP on cGMP level could be eliminated by soluble guanylate cyclase (sGC) inhibitor ODQ (10μM). ODQ could also reverse the inhibitory effects of SNP on COCs spontaneous maturation. However, the suppressive effects of SNP on COCs spontaneous maturation were not abolished by PKG inhibitor KT5823 (1μM). These results indicated that NO elicited its effects on spontaneous maturation through activating sGC and elevating the intracellular cGMP levels and suggested that PKG signal pathway was not involved in NO-mediated mouse COCs spontaneous maturation.
