Taurine promotes porcine oocyte maturation and embryonic development by reducing oxidative stress and enhancing energy metabolism.

Taurine (Tau), as a feed additive, is widely used to improve the reproductive performance of pigs. However, the effects and the underlying molecular mechanisms of Tau on in vitro maturation (IVM) of porcine oocytes and embryonic development remain insufficiently elucidated. In the current study, different doses of Tau were supplemented to the porcine oocyte IVM medium. The results showed that 50 μg/mL Tau significantly promoted cumulus cell expansion and increased the rate of oocyte maturation. Tau also significantly increased the rates of cleavage and blastocyst formation after parthenogenetic activation. DCFH-DA staining results showed that Tau significantly decreased reactive oxygen species (ROS) level. qPCR results showed that Tau significantly increased the mRNA levels of antioxidant genes (CAT, SOD1, SOD2, PRDX2, and GPX1). Furthermore, JC-1 staining revealed that Tau significantly improved mitochondrial distribution and enhanced mitochondrial membrane potential (ΔΨm). Fluo-4 AM staining showed an increase in intracellular Ca2+ concentration. Consistent with the energy metabolism findings, qPCR results showed that Tau significantly increased the mRNA levels of energy metabolism genes (NOX4 and COX2). In addition, qPCR results showed that Tau significantly increased the mRNA levels of genes (TAUT, IP3R1, and NRF2) in the TAUT/Ca2+/NRF2 pathway. In conclusion, Tau could reduce oxidative stress and improve energy metabolism to promote porcine oocyte maturation, at least partly, via the TAUT/Ca2+/NRF2 signaling pathway.