Abstract
We have demonstrated that perinatal six weeks exposure to Bisphenol A (BPA) impairs the sexual differentiation of brain and behaviors even if the dosage is below the tolerable daily intake level (TDI, 50μg/kg/day) (Kubo et al. 2003). In addition, we reported recently that a low dose of BPA during the last one week of prenatal period abolished the sex difference of the exploratory behavior and enhanced depressive behavior (Fujimoto et al. 2004). In this study, 0.1ppm of BPA was exposed to mother rats just after delivery until postnatal day 7 (PND7). We examined sexually dimorphic behaviors (exploratory behavior, locomotor activity) and emotional behaviors (anxiety, depression). In the open field test at 6 weeks of age, control females explored more frequently than males, this sex difference was also shown in BPA-treated rats. BPA exposure increased the time spent in open arms in the elevated plus maze test in female rats but sex difference (female>male) was also shown in both control and BPA-treated groups. In the forced swimming test, BPA exposure increased the immobility time in male rats and reduced the latency to induce immobility in both sexes. These findings suggest that a low dose of BPA during a neonatal period was less effective on sexual differentiation of exploratory behavior, but this chemical enhanced depressive behavior in a similar manner as the case of prenatal exposure. [Jpn J Physiol 55 Suppl:S186 (2005)]
