Abstract: The purpose of this study was to explore the protective effect of mitochondria-targeted antioxidant Mitoquinone (MitoQ) on frozen sperm of Hu sheep. The semen of healthy adult rams was equally divided into 6 groups. M0, M1, M2, M3, M4 and M5 were the groups containing 0, 50, 100, 150, 200 and 400 nmol·L^-1 MitoQ in semen,respectively. After freezing and thawing, the sperm quality indexes, such as motility, viability, plasma integrity, acrosome integrity and mitochondrial activity, and antioxidative parameters, such as SOD, GSH-Px, ROS and MDA were detected. The results showed that the thawed 150 nmol·L^-1 MitoQ addition group (M3 group) got the highest motility, viability, plasma integrity, acrosome integrity and mitochondrial activity of thawed sperm, which were 55.00%, 52.34%, 48.32%, 54.51% and 51.28%, respectively. And the mitochondrial activity in M3 group was significantly higher than those in the other groups(P<0.05). The SOD and GSH-Px values of thawed sperm in M3 group were 203.90 U·mL^-1 and 123.62 U·L^-1, which were higher than those in M0, M1,M4 and M5 groups(P<0.05). The ROS and MDA values of thawed sperm in M3 group were 298.34 U·mL^-1 and 4.99 nmol·L^-1, which were significantly lower than those in the other groups(P<0.05). When the MitoQ concentration was 200 (M4 group) and 400 nmol·L^-1 (M5 group), the quality of frozen sperm began to decline and showed oxidative damage to sperm. In conclusion, during the freezing of Hu sheep sperm, 150 nmol·L^-1 MitoQ addition in the diluent could reduce sperm oxidative damage and improve frozen sperm quality. Further increasing the MitoQ concentration to more than 200 nmol·L^-1 had no protective effect on frozen semen of Hu sheep.

Key words: frozen semen, Hu sheep, MitoQ, antioxidant