Uridine restores oocyte quality and mitigates female reproductive aging by inhibition of ferroptosis in mice

Advanced maternal age is a key factor in female infertility, primarily due to declines in ovarian reserve and oocyte quality. However, the metabolic mechanisms underlying reproductive aging remain unclear. Here, we show that uridine levels in the plasma and ovaries of aged mice are significantly reduced compared with young controls. Building on this, we find that uridine supplementation significantly improves meiotic maturation, fertilization, and early embryonic development of aged oocytes, both in vivo and in vitro. Further microtranscriptomic analyses reveal that uridine enhances oocyte quality by inhibiting ferroptosis and enhancing mitochondrial function. Moreover, integrating Limited Proteolysis-Small Molecule Mapping, western blot and siRNA-based functional assays, we identify that uridine binds Poly(rC)-binding protein 1, thereby suppressing ferroptosis and preserving mitochondrial function. Collectively, these findings demonstrate that uridine supplementation improves fertility in aged female mice and provide mechanistic insight into ferroptosis in oocyte aging.