TNF-α, and TNF receptor expression
In non-SE induced animals of the saline-infused groups, TNF-α immunoreactivity was weakly detected in PC neurons (data not shown). In 12 hr-post SE animals of the saline-infused group, most of the activated microglia showed strong TNF-α immunoreactivity (Figure 1A). This expression pattern was maintained up to 1 week after SE. In non-SE-induced animals of the saline-infused groups, TNFp55R and TNFp75R immunoreactivities were also weakly observed in astrocytes (data not shown). In 12 hr-post SE animals of the saline-infused group, TNFp55R immunoreactivity was observed in astrocytes (Figure 1B). Unlike TNFp55R, TNFp75R immunoreactivity was detected in endothelial cells as well as astrocytes (Figures 1C-E). One day to 1 week after SE, both TNFp55R and TNFp75R immunoreactivities were significantly reduced in astrocytes, not in endothelial cells, due to massive astroglial loss (data not shown) [5,7,8,20].
Figure 1  Expression of TNF-α and TNF receptor in the PC 12 hr-post SE. (A) TNF-α immunoreactivity in Ox-42-positive microglia (arrows). (B) TNFp55R expression in astrocytes (arrows). (C-D) TNFp75R expression in astrocytes as well as endothelial cells (arrows). Bar = 25 (A-D) μm.