Intracellular calcium chelation by BAPTA-AM prevents AβO-induced neuronal CCR. (A) Primary cortical neurons were treated for 18 hours with AβOs with or without 10 μM BAPTA-AM to chelate intracellular calcium. CCR neurons were identified by their immunoreactivity with antibodies to both cyclin D1, which marks nuclei during G1 of the cell cycle, and NeuN, which marks nuclei in all neurons. Neuronal somatodendritic compartments were labeled with an antibody to MAP2. (B) Quantification of the immunofluorescence results and statistical analysis by one-way ANOVA. Error bars indicate S.E.M. Abbreviations: AβO, amyloid-β oligomer; ANOVA, analysis of variance; CCR, cell cycle reentry.