Bisphenol A (BPA), a widely used raw component of polycarbonate plastics and epoxy resins, has been reported to induce developmental neurotoxicity in offspring born to dams exposed to low doses of BPA; however, the toxicity mechanism remains elusive. To study the effects of in utero BPA exposure on neuronal morphology, we studied spine density and dendritic growth in the hippocampal CA1 of aged mice and developing mice prenatally exposed to low doses of BPA. Pregnant mice were orally administered BPA at a low dose of 0, 40, or 400 μg/kg body weight/day on gestational days 8.5–17.5/18.5. Mouse progenies were euthanized at 3 weeks or 14 months, and their brains were analyzed for dendritic arborization of GFP-expressing neurons or spine densities of Golgi-stained neurons in the hippocampal CA1. Regardless of the dose, in utero BPA exposure reduced spine densities in the hippocampal CA1 of the 14-month-old mice. In the developing brain from the 3-week-old mice born to dams exposed to BPA at a dose of 400 μg/kg body weight/day, overall length and branching number of basal dendrites but not apical dendrites were decreased. In utero low doses of BPA exposure disrupts hippocampal CA1 neuronal morphology during development, and this disruption is believed to persist in adulthood.
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