title: Increased expression of GluR2-flip in the hippocampus of the Wistar audiogenic rat strain after acute and kindled seizures.
abstract: The Wistar Audiogenic Rat (WAR) is an epileptic-prone strain developed by genetic selection from a Wistar progenitor based on the pattern of behavioral response to sound stimulation. Chronic acoustic stimulation protocols of WARs (audiogenic kindling) generate limbic epileptogenesis, confirmed by ictal semiology, amygdale, and hippocampal EEG, accompanied by hippocampal and amygdala cell loss, as well as neurogenesis in the dentate gyrus (DG). In an effort to identify genes involved in molecular mechanisms underlying epileptic process, we used suppression-subtractive hybridization to construct normalized cDNA library enriched for transcripts expressed in the hippocampus of WARs. The most represented gene among the 133 clones sequenced was the ionotropic glutamate receptor subunit II (GluR2), a member of the alpha-amino-3-hydroxy-5-methyl-4-isoxazoleopropionic acid (AMPA) receptor. Although semiquantitative RT-PCR analysis shows that the hippocampal levels of the GluR2 subunits do not differ between naïve WARs and their Wistar counterparts, we observed that the expression of the transcript encoding the splice-variant GluR2-flip is increased in the hippocampus of WARs submitted to both acute and kindled audiogenic seizures. Moreover, using in situ hybridization, we verified upregulation of GluR2-flip mainly in the CA1 region, among the hippocampal subfields of audiogenic kindled WARs. Our findings on differential upregulation of GluR2-flip isoform in the hippocampus of WARs displaying audiogenic seizures is original and agree with and extend previous immunohistochemical for GluR2 data obtained in the Chinese P77PMC audiogenic rat strain, reinforcing the association of limbic AMPA alterations with epileptic seizures.
authors.affiliation: Department of Cellular and Molecular Biology, Ribeirão Preto School of Medicine, University of São Paulo, São Paulo, Brazil.
authors.forename: Daniel Leite Góes
authors.initials: DL
authors.lastname: Gitaí
authors.forename: Heloisa Nakashima
authors.initials: HN
authors.lastname: Martinelli
authors.forename: Valeria
authors.initials: V
authors.lastname: Valente
authors.forename: Marilia G Alves Goulart
authors.initials: MG
authors.lastname: Pereira
authors.forename: José Antonio Cortes
authors.initials: JA
authors.lastname: Oliveira
authors.forename: Carol Fuzeti
authors.initials: CF
authors.lastname: Elias
authors.forename: Jackson Cioni
authors.initials: JC
authors.lastname: Bittencourt
authors.forename: João Pereira
authors.initials: JP
authors.lastname: Leite
authors.forename: Claudio Miguel
authors.initials: CM
authors.lastname: Costa-Neto
authors.forename: Norberto
authors.initials: N
authors.lastname: Garcia-Cairasco
authors.forename: Maria Luisa
authors.initials: ML
authors.lastname: Paçó-Larson