Expression of nestin in the hippocampal formation of rats submitted to the pilocarpine model of epilepsy

Nestin is an embryonic intermediate filament component protein, transiently expressed by the immediate precursor cells of neurons and glia, during brain development. We studied the nestin distribution in the hippocampal formation of rats submitted to pilocarpine model of epilepsy. Animals were studied during the acute, silent and chronic phases. Rats from control and acute groups presented absence of nestin-immunoreactivity (IR) in the hippocampal cells. In contrast, cells from this region presented strong nestin IR during the silent phase (3 and 7 days after status epilepticus (SE) onset), disappearing 14 days after SE. Nestin IR cells were scattered expressed in all hippocampal formation during the chronic phase. Almost all nestin IR cells exhibited glial fibrillary acidic protein (GFAP), which seems to revert to a more primitive glial form, as part of an adaptive response, transiently re-expressing phenotypic features typical of earlier stages of glial development. The re-expression of this developmental protein in the damaged cerebral tissue suggests that nestin may play an important role in the reconstruction of the glial cytoskeleton and/or remodeling events occurring in the pilocarpine model of epilepsy. Understanding how astrocytes influence network function in the injured hippocampus may, therefore, provide insight into epileptogenic mechanisms.