Effect of neuronal excitotoxicity on Munc18-1 distribution in nuclei of rat hippocampal neuron and primary cultured neuron  

神经元兴奋性毒性对Munc18-1蛋白在大鼠海马神经元和原代培养神经元胞核内分布的影响(英文)

作　　者：张彦平[1] 万萍[1] 王洪权[1] 赵红[1] 许玉霞[1] 杨茹[1] 朱粹青[1,2] 

机构地区：[1]复旦大学上海医学院医学神经生物学国家重点实验室,上海200032 [2]复旦大学脑科学院,上海200032

出　　处：《Neuroscience Bulletin》2011年第3期163-172,共10页神经科学通报（英文版）

基　　金：supported by grants from the National Natural Science Foundation of China (No. 81071017, 30470536, 90919004)

摘　　要：Objective Muncl8-1 has an important role in neurotransmitter release, and controls every step in the exocy- totic pathway in the central nervous system. In the present study, whether epileptic seizure causes a change of Muncl8 localization in neuronal nuclei was analyzed. Methods Epilepsy models were established by injection of kainic acid （KA） solution into hippocampus of Sprague-Dawley （SD） rats or intraperitoneal injection of KA in Kunming mice. The hippocampal neurons were prepared from embryonic day 18 SD rats, and cultured in neurobasal medium, followed by treatment with glutamate for 3 h. Neuronal and glial nuclei of hippocampus were separated by sucrose density gradient centrifugation. The nucleus-enriched fractions were stained with 0.1% Cresyl Violet for morphological assay. Immuno- chemistry and immunoelectron microscopy with anti-Muncl 8-1 antibody were used to determine the nuclear locatization of Munc 18-1. Immunoblotting was used to detect the protein level of Munc 18-1. Results The localization of Munc 18-1 in nucleus of rat hippocampal neuron was confirmed by immunochemistry, immunoelectron microscopy, and immunob- lotting detection of neuronal nucleus fraction. In animals receiving intrahippocampal or intraperitoneal injection of KA, immunostaining revealed that the expression of Muncl 8-1 decreased in pyramidal cell layer of CA regions, as well as in hilus and granular cell layer of dentate gyrus in hippocampus. Moreover, immunoblotting analysis showed that the expres- sion level of Muncl 8-1 in nucleus fraction of hippocampus significantly decreased in KA-treated animals. The relation- ship between the change of Muncl8-1 expression in neuronal nuclei and neuronal over-activation was also tested in pri- mary cultured neurons. After treatment with 50 ~tmol/L glutamate acid for 3 h, Muncl8-1 level was decreased in nucleus fraction and increased in cytoplasmic fraction of primary cultured neurons. Conclusion These results suggest that excit- atory stimulation can induce the distribution ch目的 Munc18-1在中枢神经系统递质释放过程中具有重要作用,控制着突触囊泡释放步骤的每一个环节。Munc18-1功能异常与癫痫发病相关。本文主要探讨癫痫是否会引起神经元胞核内Munc18-1定位的改变。方法通过海马内注射海人藻酸建立Sprague-Dawley(SD)大鼠癫痫模型,腹腔注射海人藻酸建立昆明小鼠癫痫模型。分离胎龄18天SD大鼠海马神经元,用Neurobasal培养基培养7天后,用谷氨酸处理3h。用蔗糖密度梯度离心法分离神经元和神经胶质细胞的细胞核组份,通过甲酚紫染色对上述富含细胞核的组份进行形态学鉴别。用免疫组化和免疫电镜分析法确定Munc18-1的细胞核定位。免疫印迹法检测不同细胞组分的Munc18-1蛋白的表达水平。结果免疫组化、免疫电镜以及对神经元细胞核组份的免疫印迹证实了Munc18-1在海马神经元细胞核的分布定位。在海人藻酸诱导癫痫的动物海马内,免疫组化染色显示Munc18-1在海马CA区锥体细胞层、齿状回颗粒细胞层和门区的多型细胞表达减少。同时,免疫印迹分析表明,Munc18-1在海马神经元胞核中的表达水平明显下降。免疫印迹检测显示,原代培养神经元经50μmol/L谷氨酸处理3h后,Munc18-1在神经元胞核中的分布减少,而胞浆组份中含量增加。免疫荧光的形态学检测也显示部分神经元明显失去了Munc18-1在细胞核聚集分布的特征。结论兴奋性刺激能够使Munc18-1在神经元的表达分布发生改变,这种变化可能参与调节脑神经元的功能。

关 键 词：Munc 18-1 NUCLEUS kainic acid GLUTAMATE HIPPOCAMPUS primary cultured neurons 

分 类 号：R742.1[医药卫生—神经病学与精神病学]