Folate Supplementation during Oocyte Maturation Positively Impacts the Folate-Methionine Metabolism in Pre-Implantation Embryos

Abstract Folic acid is vital for DNA synthesis and methylations through one-carbon (C1) metabolism. Thus, it is essential for cell division during embryonic development. The present study investigated the effect of folic acid supplementation on oocyte maturation, blastocyst development and the expression of folate transporters as well as folate metabolism enzymes in oocytes and pre-implantation embryos of goat. Immature goat oocytes, matured in maturation medium comprising different folic acid concentrations (0, 10, 50, 100 and 150 µM), were in vitro fertilized and cultured. Cumulus expansion markers (Ptx3 and Ptgs2) in cumulus cells were highly upregulated after 50 µM folic acid supplementation indicating higher degree of maturation. Supplementation of 50 µM folic acid during oocyte maturation resulted in significantly higher blastocyst production rate, reduction in intracellular ROS levels as well as upregulation of the transcripts for folate transporters and key folate-methionine cycle enzymes in comparison to control. The present study demonstrates the existence of active folate-methionine cycle in oocytes and pre-implantation goat embryos. Supplementation of 50 µM folic acid in maturation medium increases the blastocyst production rate, improves oocyte maturation, reduces ROS production as well as upregulate the expression of Folr1 and folate metabolism enzyme, Mtr.