Quantitative analyses of α-Synuclein levels in nigrostriatal areas of 3–12 months old mice. Immunofluorescence intensity of pan α-Syn labeling (A, B) and transgenic hα-Syn labeling (C, D) in the dorsal striatum (left panels) and substantia nigra pars compacta (right panels). The expression levels of pan α-Syn are relatively constant throughout life and do not differ between genotypes, whereas hα-Syn expression in D-Line mice increases 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.