Abstracts

Nuclear-factor kappa B (NF-[kappa]B) has been well characterized in the immune system as a transcriptional regulator of inflammatory responsive genes. More recently, NF-[kappa]B activation has been implicated in neuronal plasticity and in disorders of the CNS. Gene expression profiles are altered in epilepsy but the transcription factors regulating these changes are not defined. NF-[kappa]B has been identified as a potential key regulator of gene responses in epilepsy. In these studies we characterized activation of NF-[kappa]B in the kainate (KA)-seizure model [italic]in vivo[/italic]. We also investigated whether KA-induced NF-[kappa]B activation couples to specific gene expression changes in hippocampus. For these studies, we evaluated NF-[kappa]B activation in hippocampus following KA (15 mg/kg IP) administration in male rats. KA-mediated NF-[kappa]B activation was determined by western blotting using phospho-selective antibodies and through assessment of DNA binding activity by electrophoretic mobility shift assay analysis. Using RT-PCR, we determined whether NF-[kappa]B activation coupled to hippocampal gene changes following KA-induced status epilepticus using an inhibitor of NF-[kappa]B, diethyldithiocarbamate (DDTC). Immunoblot analysis of hippocampal whole cell extracts from animals with KA-induced status epilepticus (SE) showed increased levels of phospho-NF-[kappa]B in area CA3 (p[lt]0.05). We observed no significant change in phospho-NF-[kappa]B levels in whole cell extracts from area CA1 and dentate gyrus. In parallel, NF-[kappa]B DNA binding activity increased in area CA3 (p[lt]0.05) following SE. NF-[kappa]B-mediated gene expression changes in area CA3 of hippocampus included increases in I[kappa]B[alpha] (NF-[kappa]B autoregulatory loop), BDNF, and [italic]bcl-2 [/italic]following SE compared to controls. Preliminary inhibitor studies using DDTC suggest that NF-[kappa]B activation may be necessary for the KA-induced activation of BDNF gene expression in area CA3. Similar DDTC inhibitor studies are currently underway for assessment of I[kappa]B[alpha] and [italic]bcl-2[/italic] genes. In summary, we have shown modulated NF-[kappa]B activation in hippocampal area CA3 following KA-induced SE. Furthermore, we have pilot data suggesting that at this early time point following KA-induced seizures there is evidence of altered NF-[kappa]B gene regulation. These findings suggest that NF-[kappa]B is a candidate transcriptional regulator of gene expression changes in the KA model of epilepsy. (Supported by NIH/NINDS, Epilepsy Foundation Awards, and SFN Travel Fellowships.)