Nicotinamide mononucleotide improves the quality of porcine oocytes deteriorated by heat stress

Elevated ambient temperature results in heat stress which is a major concern for productivity and product quality due to its negative impact on animal health, productivity and product quality. As global warming becomes more and more serious, the impact of heat stress (HS) on animal husbandry cannot be ignored. However, the effect of NMN on the quality of porcine oocytes after heat stress and the prevention strategies are not yet fully understood. Here, we report that nicotinamide mononucleotide (NMN) treatment ameliorates the quality of porcine oocytes exposed to heat stress. Specifically, we found that HS caused oocyte meiosis failure by disrupting the dynamics and arrangement of meiotic organelles, showing obvious damage to cytoskeleton assembly. Furthermore, heat stress can cause damage to oocyte mitochondria, which is an indicator of oocyte cytoplasmic maturation. On the contrary, supplementation of NMN can improve this phenomenon, maintain the normal chromosome/spindle structure, and the dynamics of CGs and its core content ovastacin. Transcriptomic analysis of porcine oocytes at the GV phase for 24 hours was carried out using a protocol for RNA-Seq. The constructed library was sequenced with Illumina Novaseq6000 platform.