Bisphenol-A exposure during the period of blastocyst implantation alters uterine morphology and perturbs measures of estrogen and progesterone receptor expression in mice

Bisphenol-A (BPA) has estrogenic properties both in vitro and in vivo. We investigated its impacts upon uterine morphology and estrogen and progesterone receptors after injection on gestational days 1–4 in doses known to disrupt pregnancy. Blastocyst implantation was significantly reduced by doses of 6.75 and 10.125 mg/animal. Uterine luminal area expanded substantially in response to increasing doses of BPA. Luminal epithelial cell height increased following exposure to 10.125 mg/animal, whereas there were no differences in the number of corpora lutea among conditions. The proportion of cells staining positively for estrogen receptors was affected non-monotonically, showing highest levels at 3.375 mg/animal and lowest levels at 10.125 mg/animal. Similarly progesterone receptor expression measured through western blots related non-monotonically to dose, being highest at 3.375 mg/animal and diminishing with increasing dose. These results suggest that BPA exposure during early gestation acts at the uterus to disrupt intrauterine implantation, consistent with an estrogenic effect.