Nicotinamide mononucleotide supplement combined with prolonging maturation time improves the quality of oocytes cultured in vitro.

Due to the limited in vitro culture duration, oocyte maturation efficiency in vitro is lower than in vivo. Nicotinamide mononucleotide (NMN), a precursor of NAD+ and a cofactor of Sirtuin deacetylases, exhibits significant antioxidant activity. This study aims to evaluate whether NMN supplementation combined with prolonging maturation time enhances cytoplasmic maturation and improves porcine oocyte quality. The blastocyst rate increased significantly after parthenogenetic activation when maturation time was extended from 44 h to 47 h or 50 h, peaking at 47 h. Prolonged maturation improved mitochondrial function and cortical granule distribution but induced ROS accumulation and apoptosis. Notably, supplementation with 100 μM NMN reversed these negative effects, significantly increasing the total number of blastocyst cells, reducing ROS levels, and upregulating cytoplasmic quality-related gene expression. In conclusion, extending maturation to 47 h with 100 μM NMN supplementation enhances oocyte maturation and embryonic developmental potential in vitro. These findings suggest that NMN, a naturally occurring nucleotide in food, may improve oocyte quality and offer insights for optimizing in vitro culture techniques as well as treating oocyte quality-related infertility.