Temporal and spatial patterns of expression of c-fos, zif/268, c-jun and jun-B mRNAs in rat brain following seizures evoked focally from the deep prepiriform cortex.

Using in situ hybridization, we previously investigated (17) the regional pattern of c-fos mRNA increases in the brain following convulsive seizures elicited from a highly circumscribed epileptogenic site located in the deep prepiriform cortex. In this paper, we focus on the hippocampus and examine mRNAs encoding other immediate early genes (IEGs), namely c-jun, jun-B, and zif/268, for changes following the focally evoked seizures. Although the anatomic distribution of increases in each IEG mRNA was qualitatively comparable, the temporal analysis indicated that increases in zif/268 mRNA appeared prior to the other genes studied. Each of the mRNAs reached a maximum increase by 30 min and declined to basal levels within 3 h following seizure initiation. The data indicate that these four IEGs respond in a coordinated fashion to propagated seizure activity with increases in mRNA and, furthermore, that increased expression of all four genes appears to occur in the same cell types in the hippocampus.