Myo-inositol improves the in vitro maturation of porcine oocytes and subsequent embryonic development

This study investigated the influence of Myo-inositol (Myo-Ins) treatment during in vitro maturation (IVM) on porcine oocytes and their developmental competence following parthenogenetic activation (PA). To assess oocyte quality and function, several parameters were measured: cumulus cell (CC) expansion, nuclear maturation, intracellular glutathione (GSH) and reactive oxygen species (ROS) levels, mitochondrial membrane potential (MMP), mitochondrial ROS (mtROS) levels, and mitochondrial content. In addition, lipid droplet (LD) accumulation, fatty acid (FA) levels, mRNA expression of key regulatory genes, and overall developmental competence were evaluated. For IVM, oocytes were cultured for 42 h in media supplemented with Myo-Ins at varying concentrations: 0, 5, 10, and 20 mM. Myo-Ins treatment significantly promoted CC expansion, though it did not affect nuclear maturation rates. A significant elevation in intracellular GSH was observed in the 5 and 20 mM groups, whereas ROS levels were reduced by 6 % at 5 mM and by 5 % at 10-20 mM compared with control. Among the treatment groups, 5 mM Myo-Ins notably improved blastocyst formation rates. Mitochondrial function was also enhanced, as indicated by increased MMP in the 10 and 20 mM groups, higher mitochondrial content, and reduced mitochondrial ROS (mtROS) in all treated groups. Furthermore, Myo-Ins significantly increased LD and FA accumulation. Gene expression analysis via qPCR revealed the upregulation of NRF2 in CCs. In oocytes, antioxidant-related genes (NRF2, SOD1, SOD2, GCLC, GPX1), maternal competence markers (NPM2, ZAR1), the anti-apoptotic gene BCL2, and mitochondrial function genes (NRF1, ATP5F1A) were significantly upregulated. Overall, Myo-Ins supplementation during IVM was shown to improve mitochondrial efficiency and alleviate oxidative stress, thereby promoting the developmental potential of porcine embryos derived from PA.