Enhancement of nestin protein-immunoreactivity induced by ionizing radiation in the forebrain ependymal regions of rats

Expression of nestin was immunohistochemically examined in the forebrains of rats receiving ionizing radiation. Nestin-immunoreactive cells were predominately distributed in ependymal regions. Nestin-immunoreactivity in ependymal regions of irradiated rats increased significantly from 1 to 4 weeks after ionizing radiation compared with that of controls. Double immunofluorescence confirmed that about 94% of nestin-positive cells exhibited glial fibrillary acidic protein-immunoreactivity and a minor population of them showed Ki-67-immunoreactivity in these regions. The results have provided evidence for up-regulation of nestin expression induced by ionizing radiation in ependymal cells, suggesting that these reactive ependymal cells may be involved in remodeling and repairing processes of brain irradiation injury.