title: Repeated exposure to low doses of kainic acid activates nuclear factor kappa B (NF-κB) prior to seizure in transgenic NF-κB/EGFP reporter mice.
abstract: Predicting seizurogenic properties of pharmacologically active compounds is difficult due to the complex nature of the mechanisms involved and because of the low sensitivity and high variability associated with current behavioral-based methods. To identify early neuronal signaling events predictive of seizure, we exposed transgenic NF-κB/EGFP reporter mice to multiple low doses of kainic acid (KA), postulating that activation of the stress-responsive NF-κB pathway could be a sensitive indicator of seizurogenic potential. The sub-threshold dose level proximal to the induction of seizure was determined as 2.5mg/kg KA, using video EEG monitoring. Subsequent analysis of reporter expression demonstrated significant increases in NF-κB activation in the CA3 and CA1 regions of the hippocampus 24h after a single dose of 2.5mg/kg KA. This response was primarily observed in pyramidal neurons with little non-neuronal expression. Neuronal NF-κB/EGFP expression was observed in the absence of glial activation, indicating a lack of neurodegeneration-induced neuroinflammation. Protein expression of the immediate-early gene, Nurr1, increased in neurons in parallel to NF-κB activation, supporting that the sub-threshold doses of KA employed directly caused neuronal stress. Lastly, KA also stimulated NF-κB activation in organotypic hippocampal slice cultures established from NF-κB/EGFP reporter mice. Collectively, these data demonstrate the potential advantages of using genetically encoded stress pathway reporter models in the screening of seizurogenic properties of new pharamacologically active compounds.
authors.affiliation: Center for Environmental Medicine, Colorado State University, USA.
authors.forename: James A
authors.initials: JA
authors.lastname: Miller
authors.affiliation: Center for Environmental Medicine, Colorado State University, USA.
authors.forename: Kelly A
authors.initials: KA
authors.lastname: Kirkley
authors.affiliation: Center for Environmental Medicine, Colorado State University, USA.
authors.forename: Rachel
authors.initials: R
authors.lastname: Padmanabhan
authors.affiliation: Department of Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, Aurora, CO, USA.
authors.forename: Li-Ping
authors.initials: LP
authors.lastname: Liang
authors.affiliation: Department of Pediatrics, Division of Neurology, Translational Epilepsy Research Program, University of Colorado Anschutz Medical Campus, Aurora, CO, USA.
authors.forename: Yogendra H
authors.initials: YH
authors.lastname: Raol
authors.affiliation: Department of Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, Aurora, CO, USA.
authors.forename: Manisha
authors.initials: M
authors.lastname: Patel
authors.affiliation: AstraZeneca, Department of Drug Safety and Metabolism, USA.
authors.forename: Russell A
authors.initials: RA
authors.lastname: Bialecki
authors.affiliation: Center for Environmental Medicine, Colorado State University, USA. Electronic address: Ron.Tjalkens@colostate.edu.
authors.forename: Ronald B
authors.initials: RB
authors.lastname: Tjalkens
mesh_terms: D000818:Animals; D001921:Brain / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D005260:Female; D017930:Genes, Reporter; D005911:Gliosis; D049452:Green Fluorescent Proteins; D006624:Hippocampus / Q000378:metabolism; D007608:Kainic Acid / Q000008:administration & dosage / Q000633:toxicity*; D008297:Male; D051379:Mice; D008822:Mice, Transgenic; D016328:NF-kappa B / Q000235:genetics / Q000378:metabolism*; D017966:Pyramidal Cells; D012640:Seizures / Q000139:chemically induced / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects*
chemical_list: D016328:NF-kappa B; C485184:enhanced green fluorescent protein; D049452:Green Fluorescent Proteins; D007608:Kainic Acid
keywords: Kainic acid; NF-κB; Neurotoxicity; Safety assessment; Seizure