Increased phosphorylation of caveolin-1 in the spinal cord of irradiated rats

Phosphorylation of caveolin-1 occurs during cell activation by various stimuli. In this study, the involvement of caveolin-1 in an irradiation injured spinal cord was examined by analyzing the phosphorylation of caveolin-1 in the spinal cord of rats after irradiation with a single dose of 15 Gray from a (60)Co γ-ray source at 24 h post-irradiation (PI). A Western blot analysis showed that the phosphorylated form of caveolin-1 (p-caveolin-1) was expressed constitutively in the normal spinal cords and was significantly higher in the spinal cord of irradiated rats at 24 h PI. The increased expression of ED1, which is a marker of activated microglia/macrophages, was matched with that of p-caveolin-1. In the irradiated spinal cords, there was a higher level of p-caveolin-1 immunoreactivity in the isolectin B4-positive microglial, ependymal, and vascular endothelial cells, in which p-caveolin-1 was weakly and constitutively expressed in the normal control spinal cords. These results suggest that total body irradiation induces activation of microglial cells in the spinal cord through the phosphorylation of caveolin-1.