DNA methylation in early mice embryogenesis under the influence of bisphenol A

Abstract

Background. Nonsteroid estrogen – bisphenol A (BPA) can have a detrimental effect on human health, and therefore poses a potential threat to humans. The critical window for the effect of BPA is the time of early development of the embryo, especially during the activation of the embryonic genome during development to the stage of blastocyst. Therefore, it is especially important to understand how DNA methylation is modified in embryos of the earliest developmental period under the influence of BPA. Materials and methods. Mice hybrids F1 (CBAXC57BL) were once administered 0, 8 mg of BPA per mouse and the level of DNA methylation was estimated by detection the fluorescence of antibodies against 5-MeC in nuclei of GD3 and GD9 embryos. In other series, the level of DNA methylation and the rate of blastocyst development were estimated following cultivation of one- and two cells embryos in the presence of BPA (50 or 100 µM) during 72-96 hours in vitro. Results. BPA exposure induced the decrease of the level of DNA methylation in GD3embryos received toxicant in utero, the amount of blastomeres in these embryos was decreased too. The level of DNA methylation in GD9 embryos was slightly higher than in control group. Upon cultivation of one-two cells embryos, BPA decreased the level of DNA methylation and the rate of embryos development to blastocyst stage. Conclusion. We have determined that early embryogenesis is highly sensitive period to the BPA effects. Such effect is most likely due to active reprogramming processes in this period, primarily related to DNA demethylation/methylation de novo of both the whole genome and individual genes.