Authors : Tracy E. Livingston , Dawn M. Eberhardt , Lannett Edwards and James D. Godkin
Abstract: The purpose of the present study was to evaluate energy metabolism during in vitro maturation (IVM) of individual ovine oocytes and determine effects of in vivo retinol administration on this process. Ewes were superovulated with FSH and treated with retinol or vehicle. Oocytes were recovered approximately 12 hours after the last FSH injection, and subjected to metabolic measurements during early (0-3 hours), mid (9-12 hours), or late (21-24 hours) stages of IVM using hanging-drop procedures. Combinations of the following radiolabeled substrates 5-3H glucose, 1-14C and 6-14C glucose, 2-14C pyruvate, and 3,4 3H glutamine were used to evaluate metabolism. Results showed that glucose metabolism through the glycolytic pathway assessed by tracing the fate of the 3H2O from 5-3H glucose, changed from early to mid time periods (0.24 to 21.65 pmoles/oocyte/3hours; p < .02), and early to late time periods (0.24 to 14.24; p < .01). Metabolism of glucose carbon through the Krebs cycle (6-14C glucose) did not significantly change over the twenty-four hour maturation time period (0.29 to – 0.61 pmoles/oocyte/3hours), and likewise, oxidation of 1-14C glucose did not change during IVM. Oxidative metabolism of glutamine appeared to be high early and declined during the later time period, but overall showed no significant differences. Pyruvate oxidation was highest early in maturation and then decreased (3.14 to 1.44; p < .001). These results suggest that ovine oocytes use both glycolytic and oxidative pathways throughout IVM. No significant differences existed between oocytes from retinol-treated ewes and control oocytes.
Tracy E. Livingston , Dawn M. Eberhardt , Lannett Edwards and James D. Godkin , 2004. Metabolism of Sheep Oocytes During In vitro Maturation . Journal of Animal and Veterinary Advances, 3: 788-796.