Table 1 Groups and number of mice used for each experiment

Age effects on microglial activation in region of interest (Fig. S1)

2 (3 and 12 months)

6 (3/group)

Expression of Iba-1, p-p65/p65, BDNF, TrkB, TNF, IL-6, TH, and DAT in the SN of mice (Figs. 1a, c, e–i, 2e–h, and 7a–b)

3 (3, 6, and 12 months)

24 (8/group)

Flow cytometry assay of number of Iba1⁺ cells in the brain of mice (Fig. 1b)

3 (3, 6, and 12 months)

9 (3/group)

Expression of MHC class II in the SN of mice (Fig. 1d)

3 (3, 6, and 12 months)

15 (5/group)

Dual immunofluorescence staining of BDNF/TrkB and Iba1 in the SN of mice (Fig. 2a–d)

2 (6 and 12 months)

6 (3/group)

Effects of subcutaneous BDNF supplementation on expression of Iba1in the SN of age mice (Fig. 3a)

3 (0, 0.1, and 1 μg of BDNF)

14 (4, 5, and 5)

Effects of intra-brain infusion of BDNF on systemic LPS-induced local microglial activation in mice (Fig. 3b and S2a)

3 (SN, striatum, and hippocampus)

Each mouse received saline injection to the left hemisphere and BDNF to the right hemisphere.

12 (4/group)

Effects of knockdown of TrkB on the microglial activation in the SN, striatum, and hippocampus of mice (Figs. 3c and S2b)

3 (SN, striatum, and hippocampus)

Each mouse received shLacZ virus injection to the left hemisphere and shTrkB viruses to the right hemisphere.

9 (3/group)

Primary microglial cultures (Figs. 4e–h and 7d)

not applicable

42 pups