mGluR5 is expressed in chronically activated microglia at one month post TBI. (A and B) mGluR5 expression was evaluated in the cortex (A) and hippocampus (B) of sham or TBI brains at one month post-injury. Iba-1 (green) and ED1 (magenta) labeled activated microglia. mGluR5 expression (red) was undetectable in resting microglia that displayed a ramified cellular morphology, but was strongly up-regulated in highly reactive microglia that displayed a hypertrophic or bushy cellular morphology and co-expressed ED1 (merged). (C) The membrane bound component of the NADPH oxidase enzyme, gp91phox (red), co-localized (merged) with ED1-positive reactive microglial (green) at one month post-TBI. Bar = 25 μm.