Mapping Patterns of c- fos Expression in the Central Nervous System After Seizure

Abstract

A dramatic and specific induction of c- fos was observed in identifiable neuronal populations in vivo after administration of the convulsant Metrazole. This effect was time- and dose-dependent and was abolished by prior treatment with the anticonvulsant drugs diazepam or pentobarbital. About 60 minutes after administration of Metrazole, c- fos messenger RNA reached a maximum and declined to basal levels after 180 minutes. A further decrease below that in normal brain was observed before a return to basal levels after 16 hours. While Metrazole still elicited seizures during this period, reinduction of c- fos was largely refractory. At 90 minutes, c- fos protein was observed in the nuclei of neurons in the dentate gyrus, and in the pyriform and cingulate cortices. Subsequently, c- fos protein appeared throughout the cortex, hippocampus, and limbic system. Thus, seizure activity results in increased c- fos gene expression in particular subsets of neurons.