CONICET | Buscador de Institutos y Recursos Humanos

Benzophenone-3 (BP3), an ultraviolet radiation filter commonly used in sunscreens and other personal care products, has shown endocrine disrupting properties. Our aim was to evaluate whether in utero exposure to BP3 alters mammary gland (MG) development during puberty. Pregnant C57BL/6 mice were dermally exposed to vehicle (sesame oil; Control), 0.15 (0.15B) or 50mg BP3/kg/day (50B) from gestation day 8.5 to 18. Gestational parameters suchas the length of gestation, the weight gain of dams and the number of pups per litter were recorded. Also, the offspring body weight (BW) gain during lactation was evaluated. After weaning, the onsetof puberty in females was recorded as the day of vaginal opening.MG samples were obtained in diestrus on postnatal day 45. Total and epithelial area, perimeter, longitudinal growth, branching and number of terminal end buds (TEBs) were measured in MG wholemounts (WMs), whereas MG morphology was analyzed in histological sections. The expression of Ki-67, estrogen receptor and progesterone receptor (PR) was evaluated by immunohistochemistry. The gestational parameters in the dams, as well as the BW gain and the onset of puberty in the female offspring were similar between groups. Histo-morphological analysis showed similar MG growth between groups, with ducts extending beyond the lymphnode, ductal-side branching and TEBs. The proliferation index (Ki67) and the expression of steroid hormone receptors were similar in all groups. However, in animals exposed to BP3, PR-positive cellswere observed in clusters in MG ducts, suggesting future branching points. Although in utero exposure to BP3 induces limited changes in the female mammary gland at puberty, these changes could be associated with mammary ductal branching and an acceleration of its development.