Effects of topiramate on hippocampal neuronal apoptosis in rats after kainic acid-evoked seizures

摘要

BACKGROUND: Apoptosis plays an important role in brain injury after seizures and the formation of chronic epilepsy. It is important to investigate whether topiramate exhibits either antiepileptic and/or anti-apoptotic effects on hippocampal neurons. OBJECTIVE: To observe neuronal apoptosis in hippocampus of rat seizure models,and to investigate the antagonizing effect of topiramate on neuronal apoptosis after seizures. DESIGN: An animal experiment of comparative observation. SETTING: First Affiliated Hospital of Guangxi Medical University. MATERIALS: Sixty healthy male Sprague Dawley (SD) rats,4-6 weeks old and weighing 160-220 g,were provided by the Experimental Animal Center of Guangxi Medical University. Main apparatus and reagents were as follows: Rat brain solid positioner (SR-6N,made in Japan); kainic acid by Sigma (USA); pathological image analyzer (DMR+550) by Leica (Germany); in situ apoptosis detection kit by Wuhan Boster Biological Technology Co.,Ltd; topiramate by Xi'an-Janssen Pharmaceutical,Ltd. The treatment on animals in the experiment was in accordance with the standards of animal ethics. METHODS: The experiments were performed at the Scientific Experimental Center of Guangxi Medical University from June to December 2006. The rats were randomly divided into a topiramate-treated group (n = 30) and a model group (n = 30). ① After anesthesia,all rats were administered a kainic acid injection (0.2 μL,2 g/L) into the right lateral ventricle. Grade Ⅲ and greater Racine standards were considered to be a successful model establishment. Thirty minutes after seizure ,rats in the topiramate-treated group were treated with an intraperitoneal (i.p.) injection of topiramate every day (40 mg/kg/d) for 2 weeks. The rats in the model group were treated with an equal volume of saline for 2 weeks. ③ Six rats in the topiramate-treated group were sacrificed at 1 day,and 1,2,3,and 4 weeks after treatment,respectively. The model group animals were sacrificed at corresponding time points. The brain tissues of hippocampal dentate gyrus,CA1,CA2,and CA3 region were removed and prepared into sections. Neuronal apoptosis was detected with in situ terminal deoxynucleotidyl transferase dUTP nick-end labeling. MAIN OUTCOME MEASURES: Hippocampal neuronal apoptosis in various rat brain areas was detected in the two groups. RESULTS: All 60 rats were included in the final analysis of results. In the topiramate-treated group,the number of apoptotic cells in hippocampal dentate gyrus and CA3 region at 1 day,1,and 4 weeks after seizures were significantly lower than the model group (P < 0.05-0.01). The number of apoptotic cells in hippocampal CA1 and CA2 regions at 1 day and 4 weeks after seizures in the topiramate-treated group were significantly lower than the model group (P < 0.05). CONCLUSION: Hippocampal apoptosis is closely associated with kainic acid-evoked seizures,and topiramate can alleviate early (1 day and 1 week) and delayed (4 weeks) hippocampal neuronal injury induced by kainic acid.