Quantitative analyses of α-Synuclein levels in cerebral cortex of 3–12 months old mice. Immunofluorescence intensity of pan α-Syn labeling (A, B) and transgenic hα-Syn labeling (C, D) in the cortex (left panels) and hippocampus (right panels). The expression levels of pan α-Syn are constant throughout life and do not differ between genotypes, whereas hα-Syn expression in D-Line mice doubles between 3 and 12 months of age. D-Line: 3 months (n = 8), 6 months (n = 9), 9 months (n = 6), 12 months (n = 8); ntg mice: 3 months (n = 4), 6 months (n = 4), 9 months (n = 5), 12 months (n = 3). Graphs show mean ± SEM; one-way ANOVA followed by Bonferroni’s post hoc test.