Fig. 4
Neuronal loss in MSA mice during aging. a In the substantia nigra pars compacta (SNc), two-way ANOVA shows a significant effect of aging and genotype on the neuronal number, but no interaction between the factors (effect of genotype F1,39 = 23.58, p < 0.0001, effect of age F3,39 = 11.37, p < 0.0001, interaction F3,39 = 1.089, p = 0.3653). After post hoc Bonferroni correction, MSA mice present with significant loss of TH neurons with respect to the controls at 6, 12 and 18 months of age. Within the control group, a significant cell loss over time is visible only between 2 and 18 months of age, while for the MSA animals this can be noticed between 2 and 6 months and 6 and 18 months of age. Photomicrographs represent TH-immunoreactivity in SNc at 12 months of age in control and MSA tg mice; (b) In the striatum, significant loss of dopaminergic terminals can be seen after post hoc Bonferroni correction at 12 and 18 months of age in MSA mice compared to healthy controls. Progression of dopaminergic terminal loss can be detected between 2 and 12 months and 2 and 18 months of age in MSA mice (two way ANOVA indicates a general effect of genotype but not aging: effect of genotype F1,40 = 14.12, p = 0.0005, effect of age F3,40 = 1.692, p = 0.1841, interaction F3,40 = 4.825, p = 0.0058). Photomicrographs represent TH-immunoreactivity in striatum at 12 months of age in control and MSA tg mice; (c) Again post hoc Bonferroni test indicates that, at 12 and 18 months of age, the striatum of the MSA tg mice presents with reduced DARPP-32+ medium-spiny neurons compared to the controls, and an age-related decrease of these cells is present as well (two way ANOVA indicates a general effect of both genotype and aging: effect of genotype F1,40 = 41.62, p < 0.0001, effect of age F3,40 = 11.99, p < 0.0001, interaction F3,40 = 2.925, p = 0.0454). Photomicrographs represent DARPP-32-immunoreactivity in striatum at 12 months of age in control and MSA tg mice; (d) After post hoc Bonferroni test in the cerebellar cortex, no significant differences in the numbers of Purkinje cells between transgenic and control mice are noticed at any time point, but there is an age-related decrease in these cells’ numbers between 6 and 12 months and 6 and 18 months of age in the transgenic line (two way ANOVA indicates a general effect of aging, but not genotype: effect of genotype F1,24 = 3.443, p = 0.0758, effect of age F3,24 = 4.2, p = 0.016, interaction F3,24 = 0.2905, p = 0.8318). Photomicrographs represent DARPP-32-immunoreactivity of Purkinje cells in the cerebellar cortex at 12 months of age in control and MSA tg mice; (e) The pontine nuclei show some age-related decreases in neuronal numbers in both mouse lines, but no differences between the two genotypes at any age (two way ANOVA indicates a general effect of aging, but not genotype: effect of genotype F1,39 = 0.3153, p = 0.5777, effect of age F3,39 = 9.324, p < 0.0001, interaction F3,39 = 0.4115, p = 0.7456). Photomicrographs represent neurons of the pontine nuclei in cresyl violet staining at 12 months of age in control and MSA tg mice; (f) In the inferior olives, the only time-point with significant lower neuronal numbers in the MSA than in the control mice after post hoc Bonferroni correction is 12 months of age, possibly indicating accelerated aging in the transgenic inferior olives. There is a clear age-related neuronal loss in both genotypes as indicated (two way ANOVA indicates a general effect of aging and genotype without interaction: effect of genotype F1,24 = 6.215, p = 0.02, effect of age F3,24 = 22.63, p < 0.0001, interaction F3,24 = 1.867, p = 0.1621). Photomicrographs represent neurons of the inferior olives in cresyl violet staining at 12 months of age in control and MSA tg mice. * p < 0.05, ** p < 0.01, ***p < 0.001 versus control age-matched mice; # p < 0.05, ## p < 0.01, ###p < 0.001. Scale bars, if not otherwise indicated, 200 μm. For all n = 4–8