Impact of acute bisphenol-A exposure upon intrauterine implantation of fertilized ova and urinary levels of progesterone and 17β-estradiol

Bisphenol-A (BPA), a monomer used in production of polycarbonate plastics and epoxy resins, has established estrogenic properties. We assessed the impact of acute and repeated subcutaneous BPA administration upon intrauterine implantation of fertilized ova and urinary levels of 17beta-estradiol and progesterone in inseminated female mice. In Experiment 1, females received varied doses of BPA on days 1-4 of gestation. Daily doses of 6.75 and 10.125mg/animal significantly reduced the number of implantation sites. Urinary progesterone was significantly reduced by the higher dose, but no other dose had an effect on progesterone levels and no dose altered estradiol levels. In Experiment 2, inseminated females received a single dose of BPA on days 0, 1, or 2 of gestation. A single dose of 10.125mg reduced the number of implantation sites when given on day 0 or day 1, and 6.75mg on day 1 also produced fewer implantation sites, but there was no such effect of any dose when administered on day 2. These data show a lower threshold for BPA-induced pregnancy disruption than previously reported, also indicating effects of just one exposure. They confirm that this disruption is due to the actions of BPA upon implantation sites, and show that higher doses can influence systemic progesterone levels.