Prenatal and lactational bisphenol A exposure does not alter serotonergic neurons morphologically in the murine dorsal raphe nucleus

Abstract Objective There is concern that bisphenol A (BPA), an endocrine-disrupting chemical, affects brain development when exposed to a fetus and/or infant. We previously reported that increased serotonin (5-HT) and its metabolite (5-HIAA) in the dorsal raphe nucleus (DRN) in murine adult brains when they were prenatally exposed to low doses of BPA. This study investigates the morphological alteration of the dorsal raphe nucleus (DRN) in order to explain the disrupted serotonergic system after prenatal and lactational exposure to bisphenol A (BPA). Methods The murine dams were orally administrated with 500 μg/kg/day of BPA from embryonic day 0 to postnatal 3 weeks. The DRN, the main region of serotonin production, was morphometrically analyzed at 14 weeks, using immunohistochemistry and image analysis combined with 3-dimensional reconstruction. Results No significant differences were revealed in the number of tryptophan hydroxylase 2-immunoreactive neurons in any of the DRN sub-regions or the morphometric parameters, including the whole volume, ventrodorsal, longitudinal, and wing lengths of the DRN among the BPA treatment and sex groups. Conclusions The murine DRN was not morphologically affected by prenatal and lactational exposure to low doses of BPA. Further studies are necessary regarding the function of serotonergic neurons and the activity of different kinds of related receptors in the brain.