Regional expression of the radial glial marker vimentin at different stages of the kindling process.

The classical view of the function of radial glia in brain development is a supporting function guiding radial neural migration. However, recent evidence indicates that they may play key roles in neurogenesis and gliogenesis, as ubiquitous precursors that generate neurons and glia. Although we previously reported the emergence of radial glia after spinal cord injury in adult rats, their precise function in this process is still unknown. In the present study, we examined emergence of radial glia in rat brain during progression of kindling, by performing immunohistochemical staining for vimentin which is a specific marker of radial glia. Vimentin immunoreactivity was found to be highest at clonus 3 and then decreased at clonus 5 in the hippocampal formation, regions around the third ventricle, caudate putamen and lateral habenular nucleus. Contrast, vimentin immunoreactivity consistently increased with progression of kindling in the cingulum and parietal cortex. These findings indicate dynamic changes in vimentin expression dependent on the kindling stage of seizure-prone state, and suggest that these changes play roles in formation of new circuits following kindling.