Fig. 3

Effect of BDNF on microglial activation in the substantia nigra of mice. a Areas of Iba1⁺ cells in the SN of 18-month-old mice that were injected (osmotic pump) with different doses of BDNF (s.c.) for 1 month. Kruskal-Wallis test: p = 0.079 versus Saline (0 μg) treated mice (0 μg: n = 4; 0.1 μg and 1 μg: n = 5). b Iba1⁺ cells in the SN of 3-month-old mice 6 h after an intraperitoneal LPS (0.15 mg/kg of body weight) injection. Thirty minutes before the LPS injection, the right SNs were injected with BDNF (1 μl), and the left SNs with an equal amount of saline. The middle panels are enlargements of the boxes in the top panels. Quantitative data for a fixed region (0.049 mm²) immediately next to the injection site are shown in the bottom panels. ***p < 0.001 versus the saline injection side of the LPS treatment group (n = 4). Sal (i.p.): a group of 3-month-old mice given an intraperitoneal injection of saline, but no BDNF injection. The Sal (i.p.) group was a reference group and was not included in the statistical analysis. c Representative immunohistochemical micrographs show Iba1⁺ cells in the SN one week after a single injection of shTrkB to their right SNs and shLacZ viruses to the left SNs of 3-month-old mice. Scale bar, 20 μm. *p < 0.05 versus shLacZ injection side (n = 3). Data are presented as mean ± S.D