Perinatal Exposure to Bisphenol A or Diethylstilbestrol Increases the Susceptibility to Develop Mammary Gland Lesions After Estrogen Replacement Therapy in Middle-Aged Rats (original) (raw)

The development of the mammary gland is a hormone-regulated event. Several factors can dysregulate its growth and make the gland more susceptible to cellular transformation. Among these factors, perinatal exposure to xenoestrogens and hormone replacement therapy has been associated with increased risk of developing breast cancer. Here, we assessed the effects induced by estrogen replacement therapy (ERT) in ovariectomized (OVX) middle-aged rats and whether perinatal exposure to diethylstilbestrol (DES) or bisphenol A (BPA) modified these effects in the mammary gland. Pregnant rats were orally exposed to vehicle, 5 μg DES/kg/day, or 0.5 or 50 μg BPA/kg/day from gestational day 9 until weaning. Then, 12-month-old offspring were OVX and treated with 17β-estradiol for 3 months. Morphological changes and the percentage of epithelial cells that proliferated or expressed estrogen receptor alpha (ESR1) and progesterone receptor (PR) were analyzed in mammary gland samples of 15-month-old ani...