AIM: To study the effect and mechanism of humanin ( HN) on inhibition of excitatory neurotoxicity induced by N - methyl - D - asparate ( NMDA). METHODS: Cortical neurons from newborn SD rat were primarily cul -tured. The purity of the cells was assessed by immunofluorescence technique . The neurons were randomly divided into nor -mal group, NMDA group, N - nitro - L - arginine methyl ester (L - NAME) group and HN group. The activity of the neurons was detected by MTT assay. Nitric oxide (NO) concentration was detected by NO detection kit , and the neuronal apoptosis was examined by Hoechst staining . The expression of p - p38 MAPK in the neurons was determined by Western blotting. RESULTS: Immunofluorescence test showed that 90% cells were neuron - specific enolase ( NSE) - positive staining cells. The activity of the neurons in L - NAME group and HN group was lower than that in normal group , but higher than that in NMDA group. NO concentration , the numbers of apoptotic cells , and the expression of p - p38 MAPK in L -NAME group and HN group were higher than those in normal group , but lower than those in NMDA group. Compared with HN group, the activity of the neurons decreased , the numbers of apoptotic cells and the expression of p - p38 MAPK increased in L - NAME group. CONCLUSION: HN inhibits the apoptosis of neurons partly by inhibiting the NO toxicity , thus protecting the neurons.%目的:探讨humanin (HN)拮抗N-甲基-D-天冬氨酸(NMDA)诱导的兴奋性神经毒的作用及其可能的作用机制.方法:原代培养SD新生大鼠皮层神经元,免疫荧光检测神经元特异性烯醇化酶(NSE),细胞随机分为正常组、NMDA组、内皮型一氧化氮合酶抑制剂(L-NAME)组及HN组,分别采用MTT法、一氧化氮(NO)浓度测定、Hoechst染色及Western blotting检测各组细胞中细胞活性、NO浓度、细胞凋亡状况及磷酸化p38 丝裂原活化蛋白激酶( p-p38 MAPK)的表达.结果:免疫荧光显示90%细胞为NSE阳性细胞,L-NAME组与HN组细胞活性均低于正常组而高于NMDA组,NO浓度、细胞凋亡数目及p-p38 MAPK的表达均高于正常组而低于NMDA组;L-NAME组与HN组相比,细胞活性降低,细胞凋亡数目及p-p38 MAPK的表达升高.结论:HN可部分通过抑制NO产生和p38 MAPK的激活而减少神经元的凋亡,从而发挥神经保护作用.
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