Study On Production Of Nitric Oxide Free Radical During Mouse Early Embryo Development

Nitric oxide (NO) is a free radical molecule which has biological activity. As a signaling molecule, it plays an important role in many physiological processes, such as host defence mechanisms, neuronal signal transmission and vasodilation. In recent years, many studies demonstrate that NO also exerts in early embryo development both in vivo and in vitro.In this study, NO concentrations during early mouse embryos were determined indirectly using the method of Griess reagent, the results were as follows: (1) NO was present in the conditioned medium from unfertilized oocytes and early embryos, its concentration increased from day 2 embryos to day 3 embryos and decreased on day 4 embryos, but there were no difference between unfertilized oocytes and day 1 embryos (P>0. 05). (2) After treatment with vitamin E, NO production by embryos exhibited a declined trend comparing with control group (P<0. 05) except unfertilized oocytes. (3) NO production was significantly higher under low oxygen concentration than that of high oxygen concentration. There was strong negative correlation between NO free radical production and oxygen concentration (P<0.01). (4) No statistical difference was found in NO production by early embryos between treatments of L-A and L-NA after culturing for 4 hours. (5) However, medium with L-NA can inhibit day 2 embryos developed to the 4-cell stage or beyond, while L-A can increase the percentage of embryos development to the next stage after 24 hours culture.Also NO free radical from early mouse embryos was trapped for the first time with the method of ESR. All data indicate that NO participates the regulation of early embryo development.