Stage and region dependent expression of a radial glial marker in commissural fibers in kindled mice.

Amygdala kindling is regarded as a model of temporal lobe epilepsy in humans because of many points of similarity. In amygdala kindling, bilateralization of epileptic seizures follows from the accumulation of stimulation and commissural fibers may play a role in this process. However, new progenies of cells following amygdala kindling have not been reported and the precise nature of how bilateralization occurs is not clear. In the present study, we aim to clarify the emergence of radial glia during the progress of amygdala kindling in mouse brain. For this purpose, immunohistochemical staining for 3CB2, which is a specific marker of radial glia, was employed. Immunoreactivity for 3CB2 was observed in the forceps minor, radiation of trunk and forceps major regions at Clonus 3 and more strongly at Clonus 5. In the forceps major, the cingulate gyrus showed immunopositive staining at Clonus 3, but the corpus callosum and alveus hippocampi showed staining only at Clonus 5. In the fimbria hippocampus, the anterior commissure posterior showed staining at Clonus 5. However, the anterior commissure anterior was not stained at the stage progressed to Clonus 5. These findings indicate stage and region dependent expression of progenitor cells in commissural fibers and suggest that these changes may accompany the formation of new circuits in seizure progression during amygdala kindling.