Implications of Glycolytic and Pentose Phosphate Pathways on the oxidative status and active mitochondria of the porcine oocyte during in vitro maturation

Glycolysis and the pentose phosphate pathway (PPP) were modulated in porcine cumulus-oocyte complexes (COCs) during in vitro maturation (IVM) by the addition of inhibitors and stimulators of key enzymes of the pathways to analyze their influence on the oxidative status, active mitochondria and maturation of the oocyte. The influence of pharmacological and physiological inhibitors of glycolysis (NaF and ATP) and PPP (6-AN and NADPH) were validated by assessing glucose and lactate turnover and brilliant cresyl blue staining in oocytes. Inhibitors of glycolysis and PPP activity significantly perturbed nuclear maturation, oxidative metabolism (Redox Sensor Red CC-1) and active mitochondria (Mitotracker Green FM) within oocytes (P < 0.05). In comparison, physiological stimulators of glycolysis (AMP) and PPP (NADP) did not affect any of evaluated parameter. In the absence of modulators, fluctuations in the oocyte oxidative activity and active mitochondria were observed during porcine IVM. The inhibition of glycolysis and PPP modified the pattern of oxidation and mitochondrial fluctuation, resulting in impaired meiotic progression. We demonstrated the relationship between carbohydrate metabolism in COC and oocyte redox status necessary for porcine oocyte IVM.Gabriel Martín Alvarez, Sebastián Casiró, Cynthia Gutnisky, Gabriel Carlos Dalvit, Melanie L. Sutton-McDowall, Jeremy G. Thompson, Pablo Daniel Cetic