灰树花多糖对四氯化碳肝L-02细胞损伤的保护作用

目的 探讨灰树花多糖（PGF）对四氯化碳诱导的肝L-02细胞损伤的保护作用。 方法 培养人肝L-02细胞，建立CCl4肝细胞损伤模型，分组实验：正常对照组、CCl4损伤组和不同浓度的PGF（50 、100、200和400μg/mL）保护组。采用形态学观察，MTT检测，生化分析培养液中ALT、AST活性及细胞内SOD活性、MDA含量，流式细胞仪检测线粒体膜电位、荧光探针观测胞内Ca2+浓度；Western blot检测细胞bcl-2、bax蛋白表达。结果与CCl4损伤组相比，各PGF保护组细胞活力明显增强，上清液中ALT、AST活性明显降低; 细胞内SOD明显升高、Ca2+浓度MDA含量降低，细胞bcl-2的表达上调、 bax的表达下调。以100μg/mL浓度保护效果最佳。结论 PGF对CCl4诱导的肝L-02细胞损伤有明显的保护作用，其机制可能与清除自由基、抑制肝细胞内Ca2+浓度的升高、改变凋亡相关蛋白bcl-2、bax的表达水平，有效地防止线粒体膜电位的下降、减少细胞凋亡有关。

Inhibitory effect of the polysaccharide of Grifola frondosa on carbon tetrachloride-induced injury to liver cell line L-02

Objective    To investigate the inhibitory effect of the polysaccharide of grifola frondosa (PGF) on carbon tetrachloride (CCl4)-induced injury to liver cell line L-02.  Methods    Human liver cell line L-02 was cultured and the CCl4 -induced liver cell injury model was set up . The cells were divided into the normal control group, the CCl4-damaged group and the PGF inhibitory groups (50, 100, 200 and 400μg/mL). MTT assay was used and morphology was observed to measure cell activity. The contents of alanine aminotransferase (ALT) , aspartate aminotranferase (AST) , superoxide dismutase（SOD） and malondialdehyde (MDA) were detected. The changes of mitochondrial membrane potential of L-02 were analyzed by flow cytometry. The concentration of the intracellular calcium ion was determined by Fluo3-AM. Expressions of  bcl-2 and bax proteins were measured by Western blot analysis.  Results     Compared with the CCl4-damaged group, PGF improved the relative survival of L-02, lowered activities of the AST and ALT in medium, prevented the elevation of MDA, kept the high degree of SOD, prevented the decrease of the mitochondrial membrane potential and increase of the concentration of Ca2+,  up-regulated expression of bcl-2, and down-regulated expression of bax. PGF at a concentration of 100μg/mL had the best inhibitory effect. Conclusion    PGF can significantly prevent L-02 cells from damage induced by CCl4, and the mechanism may be related to scavenging free radicals, inhibiting  intracellular calcium overload, stabilizing mitochondrial membrane potential, and regulating expressions of bcl-2 and bax proteins.