CCI-mediated mRNA expression of the glial markers Iba1 and GFAP in the three rat strains. The relative expression level of (A) the microglial activation marker Iba1 and (B) the activation marker of astrocytes GFAP was measured at the spinal cord level L4/5 of Lewis (LEW), Fischer (FIS) and Wistar (WIS) rats on days 4 and 21 after chronic constriction injury of the right sciatic nerve. Strains only differed in their temporal activation profile of microglia: Lewis rats reacted shortly after CCI with a significant increase of Iba1, whereas Fischer rats displayed a high upregulation of this marker at a later time point. The relative expression level indicates the fold difference of the CCI group to the sham-operated control group (control?=?1). Data are expressed as mean ± s.e.m. *p < 0.05, **p < 0.01, ***p < 0.001.