Ascorbic Acid Improves the Developmental Competence of Porcine Oocytes After Parthenogenetic Activation and Somatic Cell Nuclear Transplantation

In this study, a dose-response assessment was performed to understand the relationbetween supplementation of media with L-ascorbic acid or vitamin C and porcine oocytematuration and the in vitro development of parthenotes (PA) and handmadecloned (HMC) embryos. Various concentrations (0, 25, 50 and 100 µg/ml) of vitamin Csupplemented in in vitro maturation (IVM) and culture (IVC) media weretested. None of these vitamin C additions affected nuclear maturation of oocytes, yetsupplementation at 50 µg/ml led to significantly increased intracellular glutathione (GSH)levels and reduced reactive oxygen species (ROS). When cultured in IVM- and/orIVC-supplemented media, the group supplemented with 50 µg/ml of vitamin C showed improvedcleavage rates, blastocyst rates and total cell numbers per blastocyst (P<0.05)compared with other groups (control, 25 µg/ml and 100 µg/ml). In contrast, supplementationwith 50 µg/ml vitamin C decreased (P<0.05) the apoptosis index as compared with thegroups supplemented with 100 µg/ml. In addition, even with a lower blastocyst rate tostart with (37.6 vs. 50.3%, P<0.05), supplementation of HMC embryoswith vitamin C ameliorated their blastocyst quality to the extent of PA embryos asindicated by their total cell numbers (61.2 vs. 59.1). Taken together, anoptimized concentration of vitamin C supplementation in the medium not only improvesblastocyst rates and total cell numbers but also reduces apoptotic indices, whereasoverdosages compromise various aspects of the development of parthenotes and clonedporcine embryos.