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Donarum-3R01NS040270-03S1

ABSTRACT: Succinate semialdehyde dehydrogenase (SSADH) deficiency is a rare autosomal recessive disorder effecting approximately 350 people around the world. Patients suffering from SSADH deficiency experience language acquisition failure, memory deficiencies, autism, increased aggressive behaviors, and seizures. There is a chemical buildup of both gamma-aminobutyric acid (GABA) and gamma-hydroxybutyric acid (GHB) in the neurological system of these patients. The Aldh5a1-/- knock out mouse model of SSADH deficiency shows the same chemical imbalances as the human disease, with additional fatal tonic-clonic seizures at three weeks of age. The elucidation of seizure causing pathways will facilitate treatment of seizure phenotypes in diseases with related epilepsy. Gene expression patterns within the hippocampus, cerebellum, and cortex of SSADH deficient mice (Aldh5a1-/- mice) will be compared to wild type mice at a time point immediately prior to fatal seizures. We hypothesis that the SSADH deficient mice experience a dysfunction of glutamate/GABA/ glutamine neurotransmitter cycle linked to astroglial metabolism and/or uptake of neuronally-released glutamate. The increased levels of GHB and GABA lead to down regulation of GABA-B-Receptor leading to seizures. The SSADH deficient phenotype may also be caused by ongoing oxidative damage and the pathological role of succinic semialdehyde. SSADH deficient mice (Aldh5a1-/- knock out) exhibit fatal seizures around three weeks of age. Mutant and wild type mice will be sacrificed between 17 and 19 days of life, and brain sections will be extracted and frozen (using a standard protocol). Hippocampus, cerebellum, and cortex from three mutant mice and three wild type mice will individually be expression profiled on the Affymetrix platform, giving a total of eighteen arrays. Comparative analysis will then be carried out, evaluating the transcript differences between mutant and wild type mice in each brain region. Keywords: other

ORGANISM(S): Mus musculus

PROVIDER: GSE2866 | GEO | 2005/07/06

SECONDARY ACCESSION(S): PRJNA92533

REPOSITORIES: GEO

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Project description:Nicotine, acting through the neuronal nicotinic acetylcholine receptors (nAChR), can induce seizures in mice. We aimed to study brain transcriptional response to seizure and to identify genes whose expression is altered after nicotine-induced seizures. Whole brains of untreated mice were compared to brains one hour after seizure activity, using Affymetrix U74Av2 microaarays. Experimental groups included wild-type mice and both nicotine-induced seizures sensitive and resistant nAChR mutant mice. Each genotype group received different nicotine doses to generate seizures. This approach allowed the identification of significantly changed genes whose expression was dependent on seizure activity, nicotine administration or both, but not on the type of nAChR subunit mutation or the amount of nicotine injected. Significant expression changes were detected in 62 genes (p < 0.05, FDR correction). Among them, GO functional annotation analysis determined that the most significantly over-represented categories were of genes encoding MAP kinase phosphatases, regulators of transcription and nucleosome assembly proteins. In-silico bioinformatic analysis of the promoter regions of the 62 changed genes detected the significant enrichments of 16 transcription regulatory elements (TREs), creating a network of transcriptional regulatory responses to seizures. The TREs for ATF and SRF were most significantly enriched, supporting their association with seizure activity. Our data suggest that nicotine-induced seizure in mice is a useful model to study seizure activity and its global brain transcriptional response. The differentially expressed genes detected here can help understand the molecular mechanisms underlying seizures in animal models, and may also serve as candidate genes to study epilepsy in humans. Experiment Overall Design: Whole brain expression profiles were determined in two experimental groups of mice, sixteen mice that were not treated with nicotine and twelve mice one hour after experiencing nicotine-induced seizure. The untreated group included six wild-type mice, five alpha7+/T and five beta4-/- mice. The group of mice that underwent nicotine-induced seizures included three wild-types, five alpha7+/T and four beta4-/- mice. Different doses of nicotine were injected intraperitoneally (i.p.) to each genotype group of mice in order to achieve a similar seizure score in all three genotypes.

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Donarum-3R01NS040270-03S1

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