Relationship between porcine cumulus-oocyte complex energy charge and glycolysis during in vitro maturation

Abstract

The aim of the present work was to evaluate the relationship between COC energy and glycolysis in the porcine species. COCs were individually matured in IVM media supplemented with Gonadotropins, Gonadotropins + 0,1 mM ATP and Gonadotropins + 1 mM ATP and without supplementation (control) to modulate glycolytic activity. Glucose uptake and lactate production per COC were enhanced by the presence of FSH and LH in maturation medium, even in the presence of 0.1 mM ATP. However, 1 mM ATP was effective to inhibit gonadotropin stimulation on glucose consumption, lactate production and nuclear maturation (p < 0.05). Endogenous ATP concentration was similar in immature COCs and those matured in absence of FSH + LH. However, endogenous ATP concentration, increased after 48 h of culture in the presence of gonadotropins (p < 0.05). According to these results, we determined if glycolytic activity is inhibited by a rise in the COC energy charge. Glucose uptake and lactate production increased from 24 to 48 h of culture (p < 0.05), but no difference in these parameters were observed between 48 and 72 h of in vitro culture. This study confirmed the stimulation of glycolysis by gonadotropins in porcine COCs, and the inhibition of this pathway by the addition of exogenous ATP. We demonstrated the relationship between the gonadotropic stimulation of glycolytic activity and the increase in ATP content in porcine COC during IVM. However, the endogenous ATP content reached in the matured COC seems to not decrease glycolytic activity in the COC.