Fig. 3.

Upregulation of microglial markers’ mRNA expression in microdissected contralateral VPL 14 days after spinal nerve ligation. Tables summarize the expression of up to nine genes on microdissected contralateral (A1) and ipsilateral (B) VPL as well as contralateral VPM (C) of naïve (n = 8), sham (n = 7), and SNL animals (n = 8) collected 14 days after the beginning of the experiments, with high expression level appearing in yellow and low expression level in dark blue. Red arrows indicate genes for which mRNA expression is significantly altered by the experimental conditions. For these genes, the mean fold change is presented on bar histograms. In the contralateral VPL, mRNA expression of the CTSS gene (A2: one-way ANOVA F(2, 13) = 8.103, p = 0.0052) and of the CX3CR1 gene (A3: one-way ANOVA F(2, 13) = 4.043, p = 0.0431) is significantly increased in SNL animals compared to naïve rats. The expression of these two genes is correlated to the ambulatory pain. The less weight the animal bears on its ipsilateral hind paw, the higher the mRNA expression of the CTSS (A4) and the CX3CR1 (A5) genes is. No significant difference was observed in the mRNA expression of the tested genes in the ipsilateral VPL (B) and contralateral VPM (C). It must be noted that, due to technical problems, only five genes were tested on the contralateral VPM. Post hoc test (Tukey’s multiple comparison test): *p < 0.05; **p < 0.01