Cortical synaptophysin is significantly reduced in aged Tg2576/PS1P264L mice, and the reduction is genotype dependent. A, The topdemonstrates 3 μg of cortical protein per sample stained with an antibody recognizing synaptophysin (Syn). At 12 months, a reduction was seen only in the Tg2576/PS1P264Lcortex compared with wild type. The bottom demonstrates approximately equivalent actin (Act) protein per well on the same blot, as a control. Graphs depict the density ratios of synaptophysin/actin. B, A 50% reduction is found in the Tg2576/PS1P264L cortex compared with the wild-type controls at 12 months. Three subjects per group with seven immunoblot assay replicates. C, Progressive reductions in the synaptophysin/actin ratio exist at 7 and 12 months in the Tg2576/PS1P264L mice compared with wild-type controls. Six samples per group with duplicate assays. *p ≤ 0.05 indicates significant differences.WT 12, Wild-type mice at 12 months of age.