Measurement of Aβ peptide levels in brains of Tg-SwDI, Tg-5xFAD, and bigenic Tg-SwDI/Tg-5xFAD mice. The levels of soluble and insoluble Aβ40 and Aβ42 peptides were measured in mouse forebrain extracts of 3- (A), 6- (B), and 9-month-old (C) Tg-SwDI mice (black bars), Tg-5xFAD mice (blue bars), and bigenic Tg-SwDI/Tg-5xFAD mice (red bars) by ELISA analysis, as described under “Experimental Procedures.” The levels of soluble Aβ oligomers were measured by ELISA (D) and quantitative dot blot analysis using OC antibody (E and F) in the different mice at 3, 6, and 9 months of age, as described under “Experimental Procedures.” Data are mean ± S.D. of eight to 10 mice of each genotype at each age. a, p < 0.05; b, p < 0.01; c, p < 0.001; d, p < 0.0001; ns, not significant.