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.