Immunocytochemistry. Photomicrographs and density quantification of MHC II-IR microglial in hippocampus. In the dentate gyrus (A), the density of MHC II-IR was significantly increased by LPS, P < 0.001, and significantly decreased in LPS + insulin rats, P < 0.05. In the CA3 region (C), LPS increased the density of MHC II-IR microglial cells; however, co-infusion of insulin did not decrease the density of MHC II-IR microglia. There were no observed differences in the CA1 region (D) between groups. There were no age-dependent changes in the density of MHC II-IR cells. (B) Scale bar: 400 μm for top row figures; 70 μm for bottom row. *P < 0.05 versus aCSF; +
P < 0.05 versus LPS.