Expression Of NNOS, ENOS And INOS In Sheep Oocytes And Embryo In Vitro

Nitric oxide (NO),as a multifunctional active molecule with free radical nature.plays an important signalling role in many physiological systems.Nitric oxide synthase (NOS) catalyses the production of NO,now various isoforms of NOS have been identified, including neuronalnitrie oxide synthase(nNOS),inflammatory nitric oxide synthase(iNOS) and endothelial nitric oxide synthase(eNOS).Since the half life period of NO was very shortand instable,NOS was a rate-limiting enzyme of NO production, so the expression of NOS could linearly reflect the production of NO.With the extensive researches on NO,we found that there were several indispensable links with itsreproduction, and the oocytes maturation and preimplantation embryos development of animal ontogeny is the most importantperiod.In order to understand that the expression of nitric oxide synthase(NOS)of three isoforms in oocytes and early embryos invarious developmental stages in vitro.Here,immature oocytes, mature oocytes and early embryos in various developmental stages(2-cell、4-cell、8-cell、morula、blastula) though culture in vitro were used, in addtion, the relative expression level of nNOS,eNOS,iNOS mRNA were detected with real-time quantitative PCR.The results indicated that:1. nNOS,eNOS,iNOS mRNA were sustaining expressed in sheep oocytes and early embryos in various developmental stages.2. The expression of nNOS were higher(p<0.05),compared with eNOS and iNOS in oocytes maturation,and the expression were remarkable higher in mature oocytes than in immature oocytes(p<0.05).3.During the early embryo development,the expression of nNOS,iNOS were hi gh and similar(p<0.05).Compared with2-cell stage,the expression in4-cell stage w ere decreased;and the expression siginificantly increased in8-cell stage(p<0.05);mo reover,the expression in the morula reach the highest level;and the expression in b lasula significantly decreased(p<0.05).The results suggested that NO plays essential roles in sheep oocytes maturationand preimplantation embryo development,especially have the parenchymatous significance in the differential stage of8-cell to morula; meanwhile the production of NO was may be mediated by nNOS,and may be mainly induced by nNOS,iNOS in preimplantation embryos.