Equol Alleviates the In Vitro Aging-Induced Disruption of Porcine Oocytes

Oocyte quality is crucial for determining the subsequent embryo developmental capacity and reproductive outcomes. However, aging is detrimental to oocyte quality. Previous studies have demonstrated that soy isoflavones have positive effects on the reproductive performance of female pigs. Equol, the primary metabolite of soy isoflavones, is renowned for its antioxidant properties and its ability to scavenge reactive oxygen species (ROS). However, the potential role of equol in reversing aging-mediated oocyte decline has not yet been elucidated. In this study, we treated the porcine oocytes with different concentrations of equol (2.5, 5 and 10 μM) during prolonged in vitro culture. Our findings showed that aging led to decreased embryonic developmental capacity, indicating the decline of oocyte quality. We further found that aging disrupted spindle assembly and chromosome arrangement, impaired actin polymerisation and reduced mitochondrial activity and function. Moreover, aging increased ROS levels; thereafter, DNA damage and apoptosis was induced in the porcine oocytes. Interestingly, treatment with 2.5 μM equol during the aging process significantly mitigated the above-mentioned defective parameters in porcine oocytes and finally improved embryo development rates. Collectively, these results imply that equol has potential benefits in attenuating the aging-mediated defects on porcine oocytes.