Project description:Neither the molecular basis of the pathologic tendency of neuronal circuits to generate spontaneous seizures (epileptogenicity) nor anti-epileptogenic mechanisms that maintain a seizure-free state are well understood. Here, we performed transcriptomic analysis in the intrahippocampal kainate model of temporal lobe epilepsy in rats using both Agilent and Codelink microarray platforms to characterize the epileptic processes. The experimental design allowed subtraction of the confounding effects of the lesion, identification of expression changes associated with epileptogenicity, and genes upregulated by seizures with potential homeostatic anti-epileptogenic effects. Using differential expression analysis, we identified several hundred expression changes in chronic epilepsy, including candidate genes associated with epileptogenicity such as Bdnf and Kcnj13. To analyze these data from a systems perspective, we applied weighted gene co-expression network analysis (WGCNA) to identify groups of co-expressed genes (modules) and their central (hub) genes. One such module contained genes upregulated in the epileptogenic region, including multiple epileptogenicity candidate genes, and was found to be involved the protection of glial cells against oxidative stress, implicating glial oxidative stress in epileptogenicity. Another distinct module corresponded to the effects of chronic seizures and represented changes in neuronal synaptic vesicle trafficking. We found that the network structure and connectivity of one hub gene, Sv2a, showed significant changes between normal and epileptogenic tissue, becoming more highly connected in epileptic brain. Since Sv2a is a target of the antiepileptic levetiracetam, this module may be important in controlling seizure activity. Bioinformatic analysis of this module also revealed a potential mechanism for the observed transcriptional changes via generation of longer alternatively polyadenlyated transcripts through the upregulation of the RNA binding protein HuD. In summary, combining conventional statistical methods and network analysis allowed us to interpret the differentially regulated genes from a systems perspective, yielding new insight into several biological pathways underlying homeostatic anti-epileptogenic effects and epileptogenicity. Four condition experiment with five samples per condition. The samples include right dentate gyrus from animals with seizures, left dentate gyrus from animals with seizures, right dentate gyrus from animals without seizures, and left dentate gyrus from animals without seizures.

Project description:Neither the molecular basis of the pathologic tendency of neuronal circuits to generate spontaneous seizures (epileptogenicity) nor anti-epileptogenic mechanisms that maintain a seizure-free state are well understood. Here, we performed transcriptomic analysis in the intrahippocampal kainate model of temporal lobe epilepsy in rats using both Agilent and Codelink microarray platforms to characterize the epileptic processes. The experimental design allowed subtraction of the confounding effects of the lesion, identification of expression changes associated with epileptogenicity, and genes upregulated by seizures with potential homeostatic anti-epileptogenic effects. Using differential expression analysis, we identified several hundred expression changes in chronic epilepsy, including candidate genes associated with epileptogenicity such as Bdnf and Kcnj13. To analyze these data from a systems perspective, we applied weighted gene co-expression network analysis (WGCNA) to identify groups of co-expressed genes (modules) and their central (hub) genes. One such module contained genes upregulated in the epileptogenic region, including multiple epileptogenicity candidate genes, and was found to be involved the protection of glial cells against oxidative stress, implicating glial oxidative stress in epileptogenicity. Another distinct module corresponded to the effects of chronic seizures and represented changes in neuronal synaptic vesicle trafficking. We found that the network structure and connectivity of one hub gene, Sv2a, showed significant changes between normal and epileptogenic tissue, becoming more highly connected in epileptic brain. Since Sv2a is a target of the antiepileptic levetiracetam, this module may be important in controlling seizure activity. Bioinformatic analysis of this module also revealed a potential mechanism for the observed transcriptional changes via generation of longer alternatively polyadenlyated transcripts through the upregulation of the RNA binding protein HuD. In summary, combining conventional statistical methods and network analysis allowed us to interpret the differentially regulated genes from a systems perspective, yielding new insight into several biological pathways underlying homeostatic anti-epileptogenic effects and epileptogenicity.

Project description:Here we tested a hypothesis that epileptogenesis influences expression pattern of genes in the basolateral amygdala that are critical for fear conditioning. Whole genome molecular profiling of basolateral rat amygdala was performed to compare the transcriptome changes underlying fear learning in epileptogenic and control animals. Our analysis revealed that after acquisition of fear conditioning 26 genes were regulated differently in the basolateral amygdala of both groups. Thus, our study provides the first evidence that not only the damage to the neuronal pathways but also altered composition or activity level of molecular machinery responsible for formation of emotional memories within surviving pathways can contribute to impairment in emotional learning in epileptogenic animals. Understanding the function of those genes in emotional learning provides an attractive avenue for identification of novel drug targets for treatment of emotional disorders after epileptogenesis-inducing insult. Experiment Overall Design: Experiment description: Experiment Overall Design: Array: Rat Genome 230-2.0 (Affymetrix). Experiment Overall Design: Samples: 2 biological replicates from 4 experimental groups (control unpaired = CU, CU1, control paired = CP, CP1, epileptogenic unpaired = EU, EU1, epileptogenic paired = EP, EP1). Experiment Overall Design: Animals&model: Amygdala stimulation model (Nissinen et al., 2000): Experiment Overall Design: control (C) animals = operated, not stimulated; Experiment Overall Design: epileptogenic (E) animals = stimulated, responded with "good" status epilepticus (at least 40HAFDs within first 3h of SE), not expressing spontaneous seizures through the whole study. Experiment Overall Design: All animals received 5 habituation session to the fear conditioning apparatus lasting 10 min, starting on day 5 (2 sessions on day 5 and 6 and 1 session on day 7) after stimulation (induction of SE). Experiment Overall Design: On 8th day after stimulation: Experiment Overall Design: unpaired (U) = twice received: 2min in apparatus â footshock (1.5mA, 1s)â tone (75dB for 20 sec) Experiment Overall Design: paired (P) = twice received: 2min in apparatus â tone (75dB for 20 sec) co-terminated by footshock (1.5mA, 1s). Experiment Overall Design: RNA isolation: decapitation â ipsilateral temporal lobe isolated, embed in OCT and frozen in -70C. Cut into 10Âµm sections, thionin stained (Ambion protocol), basal and lateral nuclei of the amygdala laser-microdissected; total cellular RNA isolated with PicoPure RNA isolation kit (Arcturus). Experiment Overall Design: RNA amplification: 30ng of of total cellular RNA from each rat underwent of 2 rounds of amplification using MessageAmp II aRNA kit (Ambion), according to manufacturer protocol (in vitro transcription time 14h in both rounds). Experiment Overall Design: Sample pooling: aRNA from 2 animals was pooled (10Âµg in total = 2x5Âµg) and 8 samples were labeled and hybridized: CP, CP1, CU, CU1, EP, EP1, EU, EU1; (altogether aRNA from 16 rats was used).

Dataset Information

Rat model of MTLE: Animals with epilepsy vs animals without epilepsy (Agilent)

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