Regulatory of Oleuropein on the In Vitro Maturation of Oocytes and the Development of Parthenogenetic Embryos in Sheep

Oleuropein (OLE), as the main effective active component in olive leaves, is a natural cyclic ether terpene polyphenolic compound found in plants of the genus Olea. It has antioxidant, anti-inflammatory and anti-apoptotic properties, and can reduce damage caused by reactive oxygen species. These characteristics indicate that it can enhance the maturation rate of oocytes and the developmental capacity of embryos-two key indicators in animal breeding. This study evaluated the effects of OLE on the in vitro maturation and early embryonic development of sheep oocytes. 20 μM OLE has the best promoting effect on the maturation rate of oocytes, and 30 μM OLE has the best increasing effect on the blastocyst rate. Compared with the control group, glutathione (GSH) level and mitochondrial membrane potential (MMP) level were significantly increased, ROS level was significantly decreased, the expression of antioxidant genes <i>SOD1</i> and <i>GPX3</i> was significantly elevated, and the expression of anti-apoptotic gene <i>BCL2</i> was significantly elevated in the experimental group. In addition, during the in vitro development stage of early embryos, the expression level of the embryo development-related gene <i>OCT4</i> significantly increased. The study has shown that OLE can effectively alleviate oxidative stress during in vitro culture, increase oocyte maturation rate and promote embryo development.