Effect of MAPK inhibitor, PD98059, on LPS-induced c-fos expression in the PVN. Veh (15% DMSO)-treated animals (A), LPS-treated animals (B), and PD98059-treated animals before LPS administration (C). Note profound reduction in LPS-induced c-fos immunoreactivity in the PVN in C. D, Semiquantitative image analysis of the number of c-fos immunoreactive cells in the PVN. *, P < 0.001 compared with Veh/Saline and PD98059/LPS groups. Scale bar, 200 μm. III, Third ventricle.