Estrogen receptor-mediated effects of a xenoestrogen, bisphenol A, on preimplantation mouse embryos

The effects of bisphenol A, a xenoestrogen widely used in industry and dent istry, were studied in early preimplantation mouse embryos. Two-cell mouse embryos were cultured with 100 pM to 100 mu M bisphenol A with or without 1 00 nM tamoxifen and evaluated at 24-h intervals for their development to ei ght-cell and blastocyst stages. At 72 h, blastocysts were cultured for anot her 48 h without bisphenol A, and surface areas of trophoblast spread were measured, At 24 h, more embryos exposed to 3 nM bisphenol A than to control s bad reached the eight-cell stage. At 48 h, more embryos exposed to 1 nM a nd 3 nM bisphenol A than to controls had become blastocysts. At 100 mu M, b isphenol A decreased frequency of development to blastocysts. Tamoxifen cou nteracted both stimulatory and inhibitory effects of bisphenol A on blastoc yst formation. Although bisphenol A did not alter blastocyst morphology or cell number, early exposure to 100 mu M bisphenol A increased subsequent tr ophoblast areas. These findings suggest that bisphenol A may not only effec t early embryonic development via estrogen receptors even at low, environme ntally relevant doses, but also exert some late effects on subsequent devel opment of these embryos. (C) 2000 Academic Press.