目的 为探讨生长抑素 (SOM)在癫痫发病中的作用。方法 应用原位杂交组织化学方法研究慢性癫痫大鼠海马回、齿状回、大脑皮质 SOM m RNA表达的变化 ,并用放射免疫法检测了海马、大脑皮质内基因表达产物的变化。结果 慢性癫痫大鼠海马回、齿状回、大脑皮质 SOM m RNA胞体数量、胞体截面积均明显高于对照组 ,胞体灰度值均明显低于对照组。与此同时 ,海马及大脑皮质内 SOM含量亦明显增高。结论 慢性癫痫发病过程中编码 SOM的基因被活化 ,同时伴随着其表达产物的增加 ,SOM与癫痫的发病密切相关。
Background It is known that excessive release of glutamate can induce excitotoxicity in neurons and lead to seizure. Dexamethasone has anti-seizure function. The aim of this study was to investigate glutamatedexamethasone interaction in the pathogenesis of epilepsy, identify differentially expressed genes in the hippocampus of glutamate-induced epileptic rats by mRNA differential display, and observe the effects of dexamethasone on these genes expression. Methods Seizure models were established by injecting 5μl （250 μg/μl） monosodium glutamate （MSG） into the lateral cerebral ventricle in rats. Dexamethasone （5 mg/kg） was injected intraperitoneally at 30 minutes after MSG inducing convulsion. The rats＇ behavior and electroencephalogram （EEG） were then recorded for 1 hour. The effects of dexamethasone on gene expression were observed in MSG-induced epileptic rats at 1 hour and 6 hours after the onset of seizure by mRNA differential display. The differentially expressed genes were confirmed by Dot blot. Results EEG and behaviors showed that MSG did induce seizure, and dexamethasone could clearly alleviate the symptom, mRNA differential display showed that MSG increased the expression of some genes in epileptic rats and dexamethasone could downregulate their expression. From more than 10 differentially expressed eDNA fragments, we identified a 226 bp eDNA fragment that was expressed higher in the hippocampus of epileptic rats than that in the control group. Its expression was reduced after the administration of dexamethasone. Sequence analysis and protein alignment showed that the predicted amino acid sequence of this cDNA fragment kept 43% identity to agmatinase, a member of the ureohydrolase superfamily. Conclusions The results of the current study suggest that the product of the 226 bp eDNA has a function similar to agmatinase. Dexamethasone might relax alleviate seizure by inhibiting expression of the gene.
MA Chun-lingZHU Chang-gengFAN MingLIU Shu-hongLIU Qing-yingCONG Bin
