Melatonin Improves the Development Ability of Sheep Embryos by Reducing ROS During IVEP

Sheep in vitro embryo production (IVEP) is of great economic and scientific value, while reactive oxygen species (ROS) can negatively impact the quality and developmental potential of sheep embryos. Therefore, reducing ROS may enhance the efficacy of sheep IVEP. In this study, different concentrations of melatonin (10^-9, 10^-7, 10^-5, 10^-3 M) were supplemented during oocyte in vitro maturation (IVM) and embryo in vitro culture (IVC). The developmental ability of sheep oocytes and embryos, the survival rate of vitrified blastocysts, ROS level, ATP content, ATP synthase activity and related gene expression levels of sheep blastocysts were detected. The results showed that 10^-7 M melatonin significantly improved the developmental ability of sheep oocytes and embryos, elevated the survival rate of blastocysts after vitrification, reduced the ROS level, increased the ATP content and ATP synthase activity and improved the expression levels of quality-related genes in sheep blastocysts. We speculated that melatonin may enhance the developmental competence of sheep oocytes and embryos by reducing the ROS level and promoting ATP synthesis. In addition, high concentrations of melatonin may have an adverse impact on the development of sheep embryos.