Chrysoeriol Improves In Vitro Porcine Embryo Development by Reducing Oxidative Stress and Autophagy

SIMPLE SUMMARY: In this experiment, porcine embryos were used as a model, and the flavonoid chrysoeriol (CHE) was added to the in vitro culture of the porcine embryo. Then, the effect of CHE on embryo development was studied by microscopic observation, immunofluorescence staining, and quantitative Real-time PCR (qRT-PCR). The results showed that CHE could reduce the accumulation of reactive oxygen species (ROS) and the level of oxidative stress during the development of porcine embryos, thus improving the antioxidant activity of the embryos. We also found that CHE can increase the mitochondrial membrane potential in the embryos and protect mitochondrial function. Further experiments preliminarily showed that CHE can reduce apoptosis and autophagy during embryonic development. We have proved that CHE has good antioxidant activity, and this is the first time that CHE has been used in mammalian embryo culture in vitro. The results show that CHE can improve the development of pig embryos in vitro by reducing oxidative stress and autophagy. ABSTRACT: Chrysoeriol (CHE) is a flavonoid substance that exists in many plants. It has various physiological and pharmacological effects, including anti-inflammatory, antioxidant, anti-tumor, and protective activity, especially for the cardiovascular system and liver. Among common livestock embryos, porcine embryos are often considered high-quality objects for studying the antioxidant mechanisms of oocytes. Because porcine embryos contain high levels of lipids, they are more vulnerable to external stimuli, which affect development. Our study explored the influence of CHE supplementation on oxidative stress in porcine oocytes and its possible mechanisms. Different concentrations of CHE (0, 0.1, 1, and 3 µM) were supplemented in the in vitro culture medium of the porcine oocytes. The results showed that supplementation with 1 µM CHE significantly increased the blastocyst rate and total cell number of embryos in vitro. After finding the beneficial effects of CHE, we measured reactive oxygen species (ROS), glutathione (GSH), and mitochondrial membrane potential (MMP) when the oocytes reached the 4-cell stage of development and determined the levels of apoptosis, cell proliferation, and autophagy at the blastocyst stage of development. The expression levels of some related genes were preliminarily detected by qRT-PCR. The results showed that the apoptosis of blastocysts in the CHE-treated culture also decreased compared with the untreated culture. Furthermore, CHE downregulated intracellular ROS and increased GSH in the embryos. CHE was also shown to improve the activity of mitochondria and inhibit the occurrence of autophagy. In addition, antioxidant-related genes (SOD1, SOD2, and CAT) and cell pluripotency-related genes (SOX2, OCT4, and NANOG) were upregulated. At the same time, apoptosis-related (Caspase 3) and autophagy-related (LC3B) genes showed a downward trend after supplementation with CHE. These results indicate that CHE improved the development of porcine embryos in vitro by reducing oxidative stress and autophagy levels.