Effects Of Regulation Of Cyclic Adenosine Monophosphate On The Meiosis Resumption In Sheep Oocytes

Cyclic adenosine monophosphate(cAMP)is a key factor in the regulation of meiosis resumption in mammalian oocytes.It is particularly important to improve the maturation quality of oocytes by adjusting the concentration of cAMP in oocytes.In order to clarify the appropriate addition factors in the in vitro maturation system of sheep oocytes,regulate the concentration of cAMP in oocytes and improve the quality of in vitro maturation of oocytes,in this study,we firstly added the phosphodiesterase 3 inhibitor Cilostamide or its agonist Linderane into the conventional in vitro maturation system to investigate the time effect of these two agents on the regulation of cAMP concentration in sheep oocytes and cumulus and oocyte nucleus maturation.Then the effects of Cilostamide or estradiol(E2)on cAMP concentration in oocytes and cumulus and oocyte nucleus maturation were investigated in a biphasic in vitro maturation system.The results showed that Cilostamide could increase the cAMP concentration of oocytes and cumulus within 2h after culture in a conventional in vitro maturation system(p<0.05);Culture for 4h can block the resumption of meiosis of oocyte.In culture for 1h,Linderane could specifically reduce the concentration of cAMP in oocytes(p<0.05)and culture for 4h can promote the resumption of oocyte meiosis.In a biphasic in vitro maturation system,COCs pretreated with Cilostamide or/and E2 maintained a high concentration of cAMP in oocytes,and there was no additive effect when Cilostamide was combined with E2.The addition of Cilostamide inhibited oocyte meiosis(p<0.05)and improved nuclear maturation.In conclusion,this study revealed for the first time that Linderane could reduce the concentration of cAMP in sheep oocytes and promote the resumption of oocyte meiosis;adding Cilostamide or E2 to the biphasic in vitro maturation system can increase the concentration of cAMP in oocytes and improve the state of nuclear maturation.It has positive significance for improving the dyssynchrony of in vitro nucleocytoplasmic maturation of sheep oocytes.