Fig. 1

Temporal profiles of BDNF, TrkB, and microglial activation in the substantia nigra during aging. a Representative immunohistochemical images show Iba1⁺ cells in the SN of 3-, 6-, and 12-month-old mice. Quantitative results of Iba1⁺ cell areas and numbers (n = 8 in each age group) are shown on the right panels. To control for non-specific binding, Iba1 and MHC class II antibodies were replaced by their respective isotype antibodies. b Intensity of Iba1⁺ signal in isolated microglia. The distribution of the intensity of Iba1⁺ cells of 3-month-old mice is shown in red as a reference peak. The intensity of 12-month-old mice was much stronger than that of 3-month-old mice as indicated by the right-shifted distribution of the intensity (n = 3). c Representative confocal micrographs show the Iba1⁺ cells in the SN of 6- and 12-month-old mice. An enlarged single Iba1⁺ cell is both shown on the right panel. d Representative immunohistochemical images show MHC class II⁺ cells in the SN of 3-, 6-, and 12-month-old mice. Quantitative results of MHC class II⁺ cell areas and numbers (n = 5 in each age group) are shown on the right panels. e–i Levels of p-p65, TNF, IL-6, BDNF, and FL-TrkB (n = 8 in each age group). To control for non-specific binding, Iba1 and MHC class II antibodies were replaced by their respective isotype antibodies. Kruskal-Wallis test: *p < 0.05, **p < 0.01, ***p < 0.001 versus 3-month-old mice. Data are presented as mean ± S.D.