Retinal Tnfα mRNA expression increases after optic nerve crush. (A) Tnfα gene expression was monitored by quantitative PCR at 1, 3, 5, 7 and 14 days after optic nerve crush. Within 1 day of optic nerve crush, the level of TNFα expression began to increase compared to contralateral naïve eyes. At 3, 5, and 7 days after crush, TNFα expression was significantly elevated (P <0.05). By 14 days after injury, a time when about half of retinal ganglion cells have died from crush injury, TNFα levels were no longer statistically significant (P = 0.94). (B) The rise in Tnfα mRNA correlated with the increase in mRNA accumulation of glial activation markers Aif1 (microglia) and Gfap (macroglia). Expression peaked for both markers between 5 and 7 days before declining at 14 days. The increase in expression in the injured retina was significant for all genes at all time points (P <0.01, relative to the contralateral eye). (C) Retinal ganglion cell gene markers, Nrn1 and Sncg, declined within 1 day of optic nerve crush and remained low, consistent with RGC injury following optic nerve damage (P <0.05, relative to the contralateral eye). Data are presented as mean ± SE; n≥3 for all timepoints.