Transcriptome Analysis of the Hippocampal CA1 Pyramidal Cell Region after Kainic Acid-Induced Status Epilepticus in Juvenile Rats

Abstract

Molecular mechanisms involved in epileptogenesis in the developing brain remain poorly understood. The gene array approach could reveal some of the factors involved by allowing the identification of a broad scale of genes altered by seizures. In this study we used microarray analysis to reveal the gene expression profile of the laser microdissected hippocampal CA1 subregion one week after kainic acid (KA)-induced status epilepticus (SE) in 21-day-old rats, which are developmentally roughly comparable to juvenile children. The gene expression analysis with the Chipster software generated a total of 1592 differently expressed genes in the CA1 subregion of KA-treated rats compared to control rats. The KEGG database revealed that the identified genes were involved in pathways such as oxidative phosporylation (26 genes changed), and long-term potentiation (LTP; 18 genes changed). Also genes involved in Ca2+ homeostasis, gliosis, inflammation, and GABAergic transmission were altered. To validate the microarray results we further examined the protein expression for a subset of selected genes, glial fibrillary protein (GFAP), apolipoprotein E (apo E), cannabinoid type 1 receptor (CB1), Purkinje cell protein 4 (PEP-19), and interleukin 8 receptor (CXCR1), with immunohistochemistry, which confirmed the transcriptome results. Our results showed that SE resulted in no obvious CA1 neuronal loss, and alterations in the expression pattern of several genes during the early epileptogenic phase were comparable to previous gene expression studies of the adult hippocampus of both experimental epileptic animals and patients with temporal lobe epilepsy (TLE). However, some changes seem to occur after SE specifically in the juvenile rat hippocampus. Insight of the SE-induced alterations in gene expression and their related pathways could give us hints for the development of new target-specific antiepileptic drugs that interfere with the progression of the disease in the juvenile age group.

Differential DNA Methylation Patterns Define Status Epilepticus and Epileptic Tolerance

“…Most of the genes present in the unique differential methylation profiles of injury or tolerance have not been captured previously by microarray-based screening for seizure-regulated or epileptogenesis genes (Becker et al, 2003;Lukasiuk and Pitkänen, 2004;Gorter et al, 2006;Laurén et al, 2010;Wang et al, 2010). The present study therefore identifies potentially new genes regulated by seizures and the mechanism by which they may be regulated, in addition to identifying novel players in epileptic tolerance that may be interesting targets for neuroprotection and anti-epileptogenesis (Jimenez-Mateos and Henshall, 2009).…”

Role of Signal Transducer and Activator of Transcription-3 in Up-Regulation of GFAP After Epilepsy

“…It is now recognized that gliosis occurs in both epilepsy animal models and patients and plays a constant role in recurrent seizures. GFAP, an astrocyte-specific cytoskeletal protein, is used as a marker of reactive astrogliosis during epilepsy [18,22], and is dramatically up-regulated after kainic acid-induced status epilepticus in juvenile rats [23]. STAT members are transcription factors that exist in the cytoplasm in an unphosphorylated form.…”

High-Throughput LC–MS/MS Proteomic Analysis of a Mouse Model of Mesiotemporal Lobe Epilepsy Predicts Microglial Activation Underlying Disease Development

“…This period appears as a time of intense functional and morphological reorganization including neurodegeneration, gliosis, axonal damage or sprouting, dendritic plasticity, blood-brain barrier damage, recruitment of inflammatory cells into the brain tissue, reorganisation of the extracellular matrix and of the molecular architecture of individual neuronal cells 5 . To better understand the molecular mechanisms underlying epileptogenesis, microarrays have been used in animal models [6][7][8][9][10][11] and human samples 12 . Yet, no comprehensive studies at the proteomic level have been performed.…”