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.