hrC5a protected against glutamate mediated decrease in GluR2 receptor expression in vitro. In primary murine neuronal cultures, 50 μM glutamate for 24 hr significantly decreased GluR2 expression as assessed by GluR2 immunostaining in primary cultures from both WT and C5aRKO mice (n = 4). However, while WT primary cultures treated with glutamate and hrC5a (100 nM) which is able to neuroprotect significantly against glutamate neurotoxicity in WT cultures did not show significant decrease in GluR2, primary cultures from C5aR KO mice co-treated with glutamate and hrC5a showed significant decrease in the expression of GluR2. Results were expressed as a percent of controls and significance was assessed using one way ANOVA with Bonferroni's multiple testing correction. All results are expressed as mean ± SD. WT Control vs Glutamate: p < 0.01; WT Control vs Glutamate+hrC5a: **p < 0.0001; C5aRKO Control vs Glutamate: *p < 0.006; C5aRKO Control vs Glutamate+hrC5a: *p < 0.006.