Seizure-induced gene expression in area CA1 of the mouse hippocampus

Synaptic plasticity in the hippocampus requires activity-dependent gene expression. We have therefore profiled gene expression in area CA1 following the induction of an electroshock-evoked maximal seizure. Using cDNA microarrays, the differential expression of approximate to 9000 cDNAs was examined. In situ hybridization on 14 transcripts that showed strongest modulation in the microarray screen (1.8-2-fold) confirmed the differential expression of a single gene that encodes for the nuclear hormone receptor NGFI-B (Nur77, N10). Although this gene is only modestly up-regulated (approximate to 2-fold) in area CA1, in situ hybridization revealed that maximal seizures induce a marked (approximate to 12-fold) up-regulation of NGFI-B in the dentate gyrus. These data support the notion [French et al. (2001) Eur. J. Neurosci., 13, 968-976] that CA1 pyramidal neurons are more refractory than granule cells of the dentate gyrus with respect to activity-dependent gene transcription. Furthermore, our results argue against a large cohort of activity-dependent genes in area CA1.