Effects of Lycopene on Sheep Oocyte Maturation and Subsequent Parthenogenetic Embryo Development

Natural pigment lycopene (LYC), a carotenoid, possesses antioxidant, anti-apoptotic, anticancer, and immunoenhancing properties. During in vitro culture, this substance protects oocytes and early embryos from damage caused by reactive oxygen species (ROS), thereby enhancing the in vitro maturation (IVM) rate of oocytes and the developmental competence of early embryos. This study aimed to investigate the effects of supplementing different concentrations of LYC (0, 5, 10, and 15 μM) during in vitro culture of sheep oocytes and early embryos on their developmental competence. In contrast to the control group, the 5 μM LYC treatment group displayed a marked increase in the first polar body extrusion rate and the extent of cumulus cell expansion, as well as a significantly higher proportion of normal spindle assembly in sheep oocytes, but 15 μM LYC appeared to negatively affect oocyte maturation. Relative to all other experimental groups, the 5 μM LYC treatment group displayed significantly elevated rates of cleavage and blastocyst rate during early in vitro embryonic development. The levels of ROS in mature oocytes and early embryos were significantly decreased, whereas the GSH level was significantly elevated. Furthermore, LYC treatment significantly enhanced mitochondrial activity and markedly elevated the mitochondrial membrane potential (MMP) in mature oocytes and early embryos. Moreover, the total cell number of blastocysts was significantly increased. Moreover, in early embryos, the transcript levels of genes associated with both oxidative stress and apoptosis were favorably regulated. In conclusion, LYC supplementation boosted the rates of oocyte maturation and blastocyst formation in sheep, while elevating the developmental capacity of early embryos.