Astragaloside IV improves the quality of in vitro postovulatory aged oocytes by decreasing oxidative stress in mice

Ovulated oocytes deteriorate rapidly if not fertilized within the optimal timeframe, known as postovulatory aging. Astragaloside IV (AS-IV), an active ingredient of Astragalus membranaceus, has been demonstrated to have anti-aging and antioxidant effects. However, it has not been elucidated whether AS-IV mitigates in vitro postovulatory oocyte aging. Here, AS-IV was administered into the in vitro culture buffer, and we found that its addition could improve the quality of in vitro postovulatory aged oocytes in mice. Specifically, AS-IV treatment enhanced morphological integrity, preserved spindle/chromosome structure, stabilized actin cytoskeleton, maintained centromere cohesion, and improved ovastacin dynamics in aging oocytes. These improvements collectively enhanced sperm binding capacity and subsequent developmental competence following parthenogenetic activation. Mechanistically, AS-IV appears to inhibit mRNA degradation of antioxidant enzymes and sustain mitochondrial function, thereby preventing reactive oxygen species (ROS) accumulation during in vitro oocyte aging. Meanwhile, reduced oxidative stress in AS-IV-treated oocytes may counteract apoptosis-related mRNA accumulation, delaying apoptotic initiation. Taken together, our findings demonstrate that AS-IV supplementation effectively improves the quality of in vitro-aged postovulatory oocytes. This provides a valuable reference and evidence base for its potential application in human-assisted reproductive technology and livestock embryo production.