Cobalamin Supplementation during In Vitro Maturation Improves Developmental Competence of Porcine Oocytes

The objective of this experiment was to explore the effects of cobalamin prior to in vitro maturation (IVM) of immature pig oocyte. Specifically, the effects of cobalamin exposure on nuclear and cytoplasmic maturation, diameter, intracellular glutathione (GSH) and reactive oxygen species (ROS), and embryonic development after parthenogenetic activation (PA) and somatic cell nuclear transfer (SCNT), and gene expression levels in SCNT embryos have been measured. Cumulus oocyte complexes (COCs) have been exposed in 200 pM of cobalamin for 22 h, and afterward cultured for 22 h without exposure of cobalamin. The COCs that were matured in the same IVM for 44 h without cobalamin used as control group. Diameter of cobalamin treated oocytes were significantly greater than control group. GSH was higher in cobalamin group than control oocytes group but reduction of ROS in cobalamin than control group of oocytes. In PA, exposure with cobalamin has been significantly greater than control group in rates of maturation, cleavage and blastocyst formation. Similarly, in SCNT embryos rates of maturation, cleavage and formation of blastocyst have been also significantly greater in cobalamin group than control group. SCNT embryos treated with cobalamin 22 h in IVM showed greater expression levels of POU5F1, DPPA2 and NDP52Il mRNA compared with control group. Our results demonstrate that cobalamin treatment prior to IVM improves the development competence of porcine oocyte.