Nicotinamide riboside supplementation ameliorated post-ovulatory oocyte quality decline

In brief: Oocyte quality and its NAD+ level decrease with time during in vitro culture. This study shows that nicotinamide riboside (NR) supplementation improves early embryonic development potential in post-ovulatory oocytes by decreasing the reactive oxygen species (ROS) levels and reducing DNA damage and apoptosis which could potentially increase the success rate of assisted reproductive technology (ART). Abstract: The quality of post-ovulatory oocytes deteriorates over time, impacting the outcome of early embryonic development during human ART. We and other groups have found that NAD+, a prominent redox cofactor and enzyme substrate, decreases in both aging ovaries and oocytes. In this study, we found that the NAD+ levels decreased in the post-ovulatory mouse oocytes during in vitro culture and this decrease was partly prevented by NR supplementation. NR treatmenty restored MII oocyte quality and enhanced the early embryonic development potential of post-ovulatory oocytes via alleviating mitochondrial dysfunction and maintaining normal spindle/chromosome structure. Also, treatment with NR decreased ROS levels and reduced DNA damage and apoptosis in post-ovulatory oocytes. Taken together, our findings indicated that NR supplementation increases the oocyte quality and early embryonic development potential in post-ovulatory oocytes which could potentially increase the success rate of ART.