Benzo(a)pyrene disrupts mouse preimplantation embryo development

Objective: To determine the effects of Benzo(a) pyrene (BaP) on the development of early preimplantation embryo by exposure to physiologic concentrations of BaP based on a previous report in human ovarian follicular fluid and serum. Design: Zygotes were cultured in 5 nM or 50 nM BaP and then examined for development efficiency, embryo quality, and DNA damage. In addition, embryonic stem cells (ESCs) were used as a model to test the toxic effects of BaP on inner cell mass (ICM) of blastocysts. Setting: Laboratory. Animal(s): CD1 mice. Intervention(s): Mouse zygotes and ESCs were cultured in medium with 5 nM or 50 nM BaP. Main Outcome Measure(s): The percentage (rate) of blastocyst development, reactive oxygen species level, and quality of embryos assessed by total cell number, cell apoptosis, Oct4- and Nanog-positive cell ratio, and DNA damage on genomic and telomeric DNA were compared between dimethyl sulfoxide control and BaP treatments. Result(s): The BaP-treated zygotes exhibited significantly higher reactive oxygen species activity, which might lead to more cell apoptosis, low ratio of Nanog-or Oct4-positive ICM cells, and increasing DNA damage in both genomic and telomeric DNA in blastocysts. By using mouse ESCs derived from ICM cells as a model, we showed that pluripotent cells might also show serious DNA damage after a brief exposure to BaP. Conclusion(s): Our data show that BaP could seriously disrupt cell growth and genomic DNA stability and increase cell apoptosis in mouse preimplantation embryo development. ((c) 2015 by American Society for Reproductive Medicine.)