EFFECTS OF SODIUM FLUORIDE ON THE APOPTOSIS AND THE DEVELOPMENT OF PREIMPLANTATION BOVINE EMBRYOS

Oocyte quality, which can determine embryonic viability, is easily perturbed. Thus, the factors affecting normal oocyte maturation require further study. The fluoride ion (F) is an endocrine system-disrupting chemical that elicits a variety of deleterious reproductive effects. F has previously been found to disrupt meiosis during gestation. However, its embryonic effects in mammals are not well documented. Here, bovine oocytes were matured in vitro either with or without sodium fluoride (NaF) treatment. Our study found that increased NaF concentration also increased the generation of reactive oxygen species (ROS) and disturbed the oxidant-antioxidant balance. The resulting embryos exhibited decreased embryonic development rates. Moreover, the NaF-induced apoptosis increased the levels of caspase-3 and caspase-9 mRNA in addition to the levels of the apoptotic protein Bax. Treatment with NaF also decreased the gene expression associated with embryo development (Oct4, Nanog, Sox2, and Cdx2) in blastocysts. NaF exposure during oocyte maturation in vitro can, therefore, decrease oocyte quality, embryo quality, and the developmental potential in a dose-dependent fashion. In summary, our findings suggest that NaF exposure causes oxidative damage during bovine embryonic development and leads to apoptosis.