Abstracts

Rationale: Nuclear factor-kappa B (NF-κB) plays an important role in many physiologic and pathologic processes in the central nervous system. Studies have shown NF-κB activation in experimental seizure and SE models, suggesting that NF-κB-mediated transcriptional activation may have an important role in this disease. To understand the NF-κB transcriptional regulation in seizures and epileptogenesis, it is necessary to characterize the gene candidates under the control of NF-κB. We recently observed that NF-κB regulates BDNF and IκBα gene expression in hippocampus following SE. We now examine additional NF-κB-regulated genes during SE using genomics.Methods: The NF-κB inhibitor, pyrolidine dithiocarbamate (PDTC; 150mg/kg), or vehicle (PBS), was given IP to rats prior to seizure induction with kainate (15mg/kg IP). Latency to onset of forelimb clonus and SE was assessed. After 1hr of SE, animals were sacrificed and the hippocampal subfields were microdissected. mRNA extracted from each subfield was analyzed by Rat Genome 230.20 microarray chips, which contained the entire transcribed rat genome. mRNA expression in kainate+PBS and kainate+PDTC animals were compared.Results: NF-κB inhibition led to a significant decrease in latency to first seizure and SE (p<0.05 and <0.001, respectively). On microarray analysis NF-κB inhibition was associated with down-regulation of transcripts in the CA1 and CA3 regions. Two NF-κB regulated genes, bdnf and nuclear receptor subfamily 4, group A, member 3 (nr4a3), were decreased in the PDTC-treated animals, suggesting that the observed changes were specific to NF-κB inhibition. NF-κB regulated genes differed between CA1 and CA3 regions. Of the candidate transcripts from the CA1 hippocampus, there was enrichment of genes involved in transcription. There was no discernible pattern in CA3. Additional genes identified as NF-κB-regulated transcripts included cAMP responsive element modulator (crem) and LIM domain only protein 7 (lom7) for both regions. Neuron-derived orphan receptor (nor), F-box only protein 33 and TCDD-inducible poly(ADP-ribose) polymerase were specific to CA1. Analysis of the dentate gyrus microarray data is currently in progress.Conclusions: Our data suggest that NF-κB-mediated transcriptional regulation is involved in the alterations in gene expression profiles associated with SE and may serve a protective role during SE. The candidate genes are involved in various cellular processes, highlighting the complexity of NF-κB gene regulation. Future studies will be performed to verify these gene candidates and characterize their functional significance. Support: NIH: NINDS/NICHD, NIH microarray consortium.