Effect Of Procyanidin B2 On The Oocytes Of Sheep Of Different Ages In Vitro Maturation And Embryonic Development

Object: The quality of oocytes not only plays a decisive role in vitro Fertilization and embryonic development,but also has a long-term impact on later fetal growth and development.Currently,oxidative stress and asynchronous Cytoplasmic maturation are two important factors contributing to the reduced quality of oocytes cultured in vitro.Procyanidin are flavonoids with strong antioxidant properties.This study aimed to investigate the effects of the antioxidant procyanidin on oocyte maturation in vitro by assessing oocyte developmental capacity,oxidative stress levels,mitochondrial function and early apoptosis levels using oocytes from different sources as a model.Methods: 1.Oocytes from 2-4 mm follicles of adult sheep were collected and the effect of PCB2 on the first polar body expulsion rate of oocytes was explored by adding different concentrations(0,2.5,5,7.5 μg/m L)of PCB2 during IVM to screen the optimal PCB2 concentration,and subsequently the optimal concentration of PCB2 was added during IVM to investigate the effect of PCB2 on oxidative stress of oocytes;in the IVC solution.2.The oocytes were collected from 2-4 mm follicles of adult sheep with the aim of investigating the effect of the optimal PCB2 concentration on oocyte cytoplasmic maturation.3.Lambs 4-8 weeks of age were screened for supernumerary ovulation protocols,oocytes from the best protocols were collected,and the optimal concentration of PCB2 was added during IVM to investigate its effect on oocyte oxidative stress.Results: 1.The addition of 5 μg/m L PCB2 during IVM was significantly higher than that of the 0,2.5,7.5μg/m L(P < 0.05)PCB2 groups;The addition of 7.5 μg/m L PCB2 oocyte blastocyst rate was significantly higher than that of the control group(P < 0.05);further studies showed that the addition of 5 μg/m L PCB2 during IVM significantly reduced oocyte ROS levels and increased GSH levels(P < 0.05),but not significantly on oocyte apoptosis(P > 0.05).2.Addition of 5 μg/m L PCB2 significantly increased oocyte mitochondrial activity,endoplasmic reticulum activity,and endoplasmic reticulum activity.0.41,P < 0.05),mitochondrial membrane potential and cortical granule dynamics(P < 0.05).3.6 injections of FSH over 3days were more effective than 4 injections of FSH over 2 days,and a total of 348 follicles developed in the4 sheep after supernumerary ovulation.A total of 348 developing follicles were obtained and 220 oocytes were recovered from the four sheep after supernumerary ovulation.Oocytes subsequently cultured in IVM solution supplemented with 5 μg/m L PCB2 had a significantly higher rate of first polar body expulsion(P <0.05)but no significant difference in oocyte cleavage and blastocyst rate(P > 0.05)compared to the control group.difference.In addition,the addition of 5 μg/m L PCB2 to the IVM solution significantly reduced oocyte ROS levels and increased GSH levels,mitochondrial activity and mitochondrial membrane potential(P <0.05).Conclusion: In summary,the addition of 5 μg/m L PCB2 during IVM reduced oxidative stress in oocytes,improved mitochondrial function and cytoplasmic maturation,thereby improving the quality of oocytes from2-4 mm follicles and superovulated lamb follicles and increasing the efficiency of in vitro embryo production.