Increased expression of mRNA encoding ferritin heavy chain in brain structures of a rat model of absence epilepsy

Differential mRNA display was carried out to find genes that are differenti ally regulated in the brain of;a rat strain with absence epilepsy, the gene tic absence epilepsy rats from Strasbourg (GAERS). Among the 32 differentia lly displayed cDNA fragments actually cloned and sequenced, one shows 100% identity with the rat heavy chain ferritin (IP-ferritin) mRNA. Northern ern blot analysis confirmed the up-regulation of the W-ferritin mRNA. Using do t blotting, a 40% increase in expression was reported in the subcortical fo rebrain of the adult GAERS, while cortex, brain stem, and cerebellum appear ed unmodified. This change was not observed in the brain of 25-day-old rats , an age at which the epileptic phenotype is not present. By in situ hybrid ization, the enhanced expression was localized in the hippocampus. The incr ease in mRNA encoding H-ferritin was mot immunodetected at the protein leve l by Western blotting These results are not apparently relates to the neura l substrate of SWD or to the distribution of local increase in glucose meta bolism previously described in the GAERS. It is hypothesized that the up-re gulation of the H-ferritin mRNA is part of a mechanism protecting the hippo campus, a seizure-prone area, against a possible overactivation during abse nce seizures. (C) 2000 Academic Press.