Generalized seizures induce c-fos protein(s) in mammalian neurons.

We have recently detected low basal levels of c-fos protein-like immunoreactivity in adult mammalian neurons. Here we report that generalized tonic-clonic seizures in mice are associated with a massive increase in c-fos protein-like immunoreactivity in the cingulate and piriform cortices and the dentate gyrus 1 h after injection of pentylenetetrazol. Midazolam, which prevented the pentylenetetrazol seizures also prevented the increase in c-fos protein-like immunoreactivity. These results suggest that seizure activity induces the formation of c-fos proteins in selective brain regions, and raise the possibility that c-fos proteins play as yet undetermined physiological and/or pathological roles in the mature brain.