Gene Profiling of Epileptogenesis in the Pilocarpine Model of Mesial Temporal Lobe Epilepsy

• Main Authors: Chien-Chen Chou, 周建成
• Other Authors: Yung-Yang Lin
• Format: Others
• Language: en_US
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/29033765654644779473

碩士 === 國立陽明大學 === 腦科學研究所 === 96 === Background: Sustained seizures, called status epilepticus (SE), increase the risk for subsequent spontaneous seizures. In addition, SE can result in mesial temporal lobe epilepsy (MTLE) in animals. This suggests that SE plays a crucial role in the epileptogenesis of MTLE. Hypothesis: We postulated that SE leads to changes of expressions in many genes. Among these genes, some are related to the SE activities and some to epileptogenesis. The expressions of the former would be changed when SE was present, and return back to normal when SE was suppressed. We named them ‘SE activity-related genes’. The genes related to epileptogenesis would change their expressions in rats that would develop MTLE in the future. These genes were called ‘epileptogenesis-related genes’. Aim: We wanted to explore the gene expression profiles after SE, and find the candidates participating in the epileptogenesis of MTLE. Materials and Methods: We used pilocarpine (350 mg/kg, i.p.) to induce seizures in SD rats and classified them into four groups: control group (n = 8, without seizures), non-SE group (n = 7, with non-sustained seizures), SE-persistent group (n = 6, with SE and SE was persistent until decapitation), and SE-suppressed group (n = 6, with SE but SE was suppressed by diazepam (10 mg/kg, i.p.) later). The last two groups were expected to have MTLE but the first two groups weren’t because SE is required to develop MTLE in pilocarpine-injected rats. Next, we microdissected the hippocampal dentate gyrus and isolated the total RNA from these brain tissues. We used cDNA microarrays (Affymetrix Rat 230 2.0 arrays, n = 2 per group) to determine the gene expressions in the different groups. The criteria to select the epileptogenesis-related genes from the array data were: (1) No significant change in the non-SE group compared to the control group. (2) A significant difference between the SE-persistent and the non-SE groups. (3) No significant change in the SE-suppressed group compared to the SE-persistent group. Genes, which fitted criteria simultaneously, were recognized as the epileptogenesis-related genes. The selection criteria of the SE activity-related genes from the array data were: (1) A significant increase in the SE-persistent group compared to the control and SE-suppressed groups. (2) A significant decrease in the SE-persistent group compared to the control and SE-suppressed groups. Genes, which fitted one of the criteria, were recognized as the SE activity-related genes. Furthermore, we selected six genes from the gene profiles to validate the array data using quantitative real time PCR (qRT-PCR). Results: Among 31000 genes, there were 85 epileptogenesis-related genes and 81 SE activity-related genes. The epileptogenesis-related genes were mostly involved in inflammation and regulation of transcription, but the SE activity-related genes were participating in diverse biological processes. The results of qRT-PCR showed that the trends of gene expressions in qRT-PCR were similar to those in the microarrays. Conclusions: This study provided the candidate genes that might participate in epileptogenesis. Some were novel, and some have been described in previous studies. The genes involved in axon guiding, cell death and neurogenesis (including Bdnf, Nr4a3, Ccl2, Hsp 70, Serpinb2, Oldlr1, Crem, Crh, Fosl2, Fosb, Pcna, Ifrd1, Hmox1, Irs2, Plk2) were the potential candidates involved in the epileptogenesis of MTLE. We will further confirm the influence of the genes on hippocampal sclerosis and explore the roles of the genes in epileptogenesis in future studies.