Unknown,Transcriptomics,Genomics,Proteomics

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Changes in the gene expression in the inferior colliculus of the sound stimulated rats both Wistar and the strain susceptible to audiogenic seizures WAR

ABSTRACT: Using microarray analyses and subsequent verification by RT-PCR, we studied the changes in gene expression in the inferior colliculus after an ictal event in one models of audiogenic epilepsy, Wistar audigenic rat (WAR). WAR is a genetically selected strain susceptible to audiogenic seizures that was inbred in the School of Medicine of RibeirÃ£o Preto (Brazil) beginning in 1990. This strain is a model of audiogenic idiopathic epilepsy that develops tonic-clonic generalized seizures. Genetic animal models of epilepsy are an important tool for further understanding the basic cellular mechanisms underlying epileptogenesis and for developing novel antiepileptic drugs. We conducted a comparative study of gene expression in the inferior colliculus, a nucleus that triggers audiogenic seizures, using two animal models, the Wistar audiogenic rat (WAR) and the genetic audiogenic seizure hamster (GASH:Sal). For this purpose, both models were subjected to auditory stimulation, and 60 minutes after stimulation, the inferior colliculi were collected. As a control, intact Wistar rats and Syrian hamsters were subjected to identical stimulation and tissue preparation protocols to those performed on the experimental animals. A total of 15 animals were used in this study according to the following distribution: 9 male WAR and 6 male control rats (Rattus norvegicus, Wistar albino, Charles River Laboratories) at 12 weeks of age and a body weight of approximately 230 g. The animals were exposed to auditory stimulation, and 60 min after the seizures, we harvested the IC for all gene expression analyses. As controls, normal Wistar rats were exposed to the same stimulation according to the identical procedure. For gene microarray (Rat Gene 1.0 ST), the rats were randomly divided into two groups, and we used both sides of the IC (ipsilateral and contralateral) from each animal: stimulated Wistar rats and stimulated WAR rats.

ORGANISM(S): Rattus norvegicus

SUBMITTER: Raquel Rodriguez

PROVIDER: E-GEOD-74150 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:Traumatic brain injury occasionally causes posttraumatic epilepsy. To elucidate the molecular events responsible for posttraumatic epilepsy, we established a rodent model that involved the injection of microliter quantities of FeCl3 solution into the amygdalar nuclear complex. We previously compared hippocampal gene expression profiles in the traumatic epilepsy model and normal rats at 5 days after brain injury (acute phase) and observed the role of inflammation. In this study, we focused on later stages of epileptogenesis. We compared gene expression profiles at 5, 15 (sub-chronic phase), and 30 days (chronic phase) after brain injury to identify temporal changes in molecular networks involved in epileptogenesis. A total of 81 genes was significantly (at least 2-fold) up- or downregulated over the course of disease progression. We found that genes related to lipid metabolism, namely, Apoa1, Gh, Mc4r, Oprk1, and Pdk4, were temporarily upregulated in the sub-chronic phase. Changes in lipid metabolism regulation might be related to seizure propagation during epileptogenesis. This temporal description of hippocampal gene expression profiles throughout epileptogenesis provides clues to potential markers of disease phases and new therapeutic targets. We employed amygdalar FeCl3 injection to induce chronic, recurrent limbic-type partial seizures with spontaneous secondarily generalized seizures in rats . Sixteen male Wistar rats were kept in hanging cages with unlimited access to food and water and 12-h light-dark cycles. Surgical procedures were conducted following anesthesia with intraperitoneal (i.p.) sodium pentobarbital injections (37.5 mg/kg) at 5 weeks of age. Stereotaxic coordinates were determined with the rat brain atlas. The incisor bar was set 3.3 mm below the interaural line. While under anesthesia, a polyethylene tube containing a stylet to serve as an external guide cannula (1.09-mm outer diameter (o.d.), 0.55-mm inner diameter (i.d.), 2.5 cm in length) was stereotaxically implanted and anchored to the skull with miniature screws and dental cement. The cannula was fixed 5.6 mm anterior and 4.8 mm to the right of the lambda and 8.5 mm below the surface of the skull, positioning it at the right amygdaloid body. Randomly selected rats for in vivo microdialysis to estimate redox had guide cannula placed but were prepared without dental cement on the skull where the microdialysis guide cannula was to be placed. Five days later, the stylet was replaced with an internal delivery cannula (0.5 mm o.d., 0.25 mm i.d.). FeCl3 was dissolved in saline solution (100 mM, pH 2.2). FeCl3 solution (1.0 M-NM-<l) was injected through the inner cannula by means of a microinfusion pump (EP-60; Eicom, Tokyo, Japan) set at a rate of 1.0 M-NM-<l/min (Fe group; n = 12). The external guide cannula was used for electroencephalogram (EEG) recording with an electroencephalograph (type 1A63; SAN-EI, Tokyo, Japan). Rats in the control group (n = 4) were each injected with 1.0 M-NM-<l saline (pH 2.2). Both EEG and behavior were observed for at least 6 h after the injection. While we did not measure the rate or frequency of seizures, we did confirm that the animals had recurrent seizures. These observations and the acute recording confirmed the accuracy of the amygdalar injection. No seizure activity was observed in control group rats. Animals in the control group were sacrificed by cervical dislocation 15 days after amygdalar injection. Animals in the Fe group were subdivided into 3 groups and were sacrificed at 5 (acute phase), 15 (sub-chronic phase of injury), and 30 days (chronic phase of injury) after amygdalar injection. The stages of disease development were categorized according to the EEGs of the model rats; within 5 days after amygdalar injection, epileptiform discharges were recorded in the contralateral and ipsilateral amygdalae; by 15 days after injection, interictal spike discharges were more consistently observed in the contralateral uninjected amygdala; at 30 days after injection bilateral interictal spike discharges continued to be observed. After sacrifice, the right hippocampi were immediately removed and placed in ice-cold phosphate-buffered saline and homogenized (Polytron PT 3000; Brinkmann Instruments, Inc., Westbury, NY, USA) for RNA extraction.

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Changes in the gene expression in the inferior colliculus of the sound stimulated rats both Wistar and the strain susceptible to audiogenic seizures WAR

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