Oleanolic acid improves the in vitro developmental competence of early porcine embryos by reducing oxidative stress and ameliorating mitochondrial function.

Objective: Oleanolic acid (OA) is a pentacyclic triterpenoid with antioxidant activity that can be an effective scavenger of free radicals in cells. This study was designed to investigate the effects of OA on porcine early embryo developmental competence in vitro and its possible mechanisms of action.

Methods: In the present study, parthenogenetically activated porcine embryos were used as models to assess the effects of OA on the in vitro developmental capacity of early porcine embryos in vitro. Zygotic genome activation, mitochondrial function, oxidative stress, cell proliferation and apoptosis in early porcine embryos were examined after supplementing the culture medium with 5 μM OA.

Results: The results showed that 5 μM OA supplementation not only significantly increased the blastocyst diameter in early embryos on day 6 but also increased the total cell number of blastocysts. Furthermore, OA supplementation increased the blastocyst proliferation rate and decreased blastocyst apoptosis. Moreover, OA supplementation significantly increased the proportion of embryos that developed to the 4-cell stage after 48 h of in vitro culture and upregulated the expression of genes associated with zygotic genome activation (DPPA2 and ZSCAN4). Notably, OA alleviated oxidative stress by reducing the intracellular levels of reactive oxygen species and increasing the intracellular levels of reduced glutathione at the 4-cell stage and increased the activities of superoxide dismutase and catalase. Concurrently, OA significantly increased the mitochondrial membrane potential and intracellular adenosine 5'-triphosphate content.

Conclusion: These results suggest that OA promotes the in vitro developmental competence of parthenogenetically activated porcine embryos by reducing oxidative stress and improving mitochondrial function during in vitro culture and that OA may contribute to the efficiency of in vitro embryo production.