COX2 expression in frontal cortex and hippocampus. (A and D) COX2 mRNA abundance was measured by RT-PCR and normalized for 18s rRNA levels. Means ± SEMs are shown. COX2 mRNA was significantly elevated in the high exposure group in both frontal cortex (A, * p = 0.009) and hippocampus (D, * p = 0.04) from the high exposure group. (B and E) COX2 protein expression in sections of paraffin-embedded tissues was localized by COX2 immunohistochemistry (IHC) and the percent of tissue area that was immunoreactive (COX2 IR) was measured by quantitative image analysis. Means ± SEMs are shown. COX2 IR was significantly elevated in frontal cortex (B, * p = 0.01), but not in hippocampus (E) from the high exposure group. (C) Representative COX IHC in frontal cortex from a subject in the high exposure group showing strong staining of endothelial cells in the capillaries (*), and pyramidal neurons (arrow), while other neurons were negative (arrowheads). Scale = 20 μm. (F) Representative COX IHC in dentate gyrus from a subject in the high exposure group showing COX2 positive neurons (arrowheads) and capillaries (short arrow). Scale = 15 μm.