Fig. 2
The innate immune responses in the brain of mice systemically challenged with different low doses of LPS. A The experimental schedule diagram showing establishment of innate immune memory models in mice. LPS-1: Lipopolysaccharides from Salmonella enterica serotype typhimurium; LPS-2: Lipopolysaccharides from Escherichia coli O111:B4; LPS-3: Lipopolysaccharides from Escherichia coli O26:B6. B The changes in body weight during different paradigms of LPS stimulation. n = 3–10 /group. Differences were analyzed by two-way ANOVA followed by LSD multiple comparison tests. *p < 0.05, **p < 0.01, ***p < 0.001. C Transcription of pro-inflammatory cytokines (Il-1β, Il-6 and Tnf-α) and anti-inflammatory cytokines (Il-4 and Il-10) in mouse striatum detected by RT-qPCR. n = 3–5/group. Differences were analyzed by one-way ANOVA followed by LSD multiple comparison tests. *p < 0.05, **p < 0.01. D Concentration of IL-1β and IL-4 proteins in the striatum of LPS-1 treated mice measured by ELISA. n = 3–5/group. Differences were analyzed by one-way ANOVA followed by LSD multiple comparison tests. *p < 0.05, vs control groups. #p < 0.05. E Representative images of IBA1 immunostaining in the striatum of mice injected with LPS-1. Scale bar, 25 µm. Microglial morphology was shown by zoomed representative images. Scale bar, 5 µm. F Quantification and morphology analysis of IBA1+ microglia in mouse striatum. n = 5–6 mice for each experimental group; N = 20–30 microglia for different groups. Differences were analyzed by one-way ANOVA followed by LSD multiple comparison tests(quantification) or Kruskal–Wallis test (morphology analysis). **p < 0.01, ***p < 0.001, vs control groups. ###p < 0.001. G Protein levels of TH, GFAP and IBA1 in mouse striatum detected by Western Blot. Quantification of relative TH, GFAP and IBA1 protein expression is shown in the right panel. n = 6–7/group. Differences were analyzed by one-way ANOVA followed by LSD multiple comparison tests. *p < 0.05, ***p < 0.001 vs control groups. #p < 0.05, ###p < 0.001