TNFα is not required for glial activation as a function of Aif1 or Gfap expression. (A,B) Wild-type and Tnfα -/- mice were subjected to crush, and expression levels for activation markers of microglia (Aif1) and microglia (Gfap) were assessed by quantitative PCR. Wild-type and knockout mice followed similar glial activation trends for both markers. Micoglial activation (A) peaked in the injured retina 7 days after crush in both wild-type and Tnfα -/- mice. Macroglial activation (B) was also significantly elevated in the injured retina by 7 days in both genotypes, with peak expression occurring between 7 and 14 days. (C,D) Immunolabeling revealed a similar increase in allograft inflammatory factor (AIF)1 (red) and glial fibrillary acid protein (GFAP; green) protein 7 days after crush injury. AIF1-positive cells were prominent in the ganglion cell layer (GCL) and inner and outer plexiform layers. GFAP processes labeled through the retinal layers, consistent with Müller cell activation. Tnfα deficiency did not affect baseline levels of Aif1 or Gfap. Overall, there was no discernible difference in the expression patterns of AIF1 or GFAP between the wild-type and Tnfα-deficient mice either before or after injury. Sections were counterstained with 4’,6-diamidino-2-phenylindole (blue). Data are presented as mean ± SD; *P <0.001, **P <0.01; n ≥3 for each genotype at each time point. Scale bar (C,D) =50 μm. INL, inner nuclear layer; ONL, outer nuclear layer.