姜黄素对ERS诱导NASH大鼠肝细胞保护作用的研究

Protective effect of curcumin on ERS-induced NASH rat hepatocytes

目的:探讨姜黄素是否通过抑制内质网应激(ERS)来减轻非酒精性脂肪性肝炎(NASH)大鼠肝细胞凋亡,从而发挥对肝脏的保护作用。方法:30只雄性SD大鼠随机分为正常对照组(n=10)、模型组(n=10)及姜黄素组(n=10)。模型组和姜黄素组采用高脂饮食喂养4周以建立NASH模型。继续喂养4周,姜黄素组每日给予姜黄素(200 mg/kg)灌胃,模型组与正常对照组给予等量生理盐水。4周后处死大鼠,留取血液及肝脏组织,检测血清丙氨酸转氨酶(ALT)和天冬氨酸转氨酶(AST)水平;HE染色观察肝组织病理学变化;Western blot法检测葡萄糖调节蛋白78(GRP78)和C/EBP同源蛋白(CHOP)蛋白的表达;TUNEL法检测细胞凋亡情况。结果:与正常对照组相比,模型组大鼠血清ALT和AST水平均显著升高,姜黄素组大鼠血清ALT和AST较模型组显著降低(P<0.05);同时,姜黄素组大鼠的肝细胞脂肪变性及炎性程度均较模型组减轻,未见明显坏死灶。模型组GRP78和CHOP蛋白的表达水平均较正常对照组显著增加,姜黄素组GRP78和CHOP的表达水平较模型组显著降低(P<0.01)。TUNEL结果表明,模型组大鼠肝组织内凋亡细胞较正常对照组增多,姜黄素组大鼠的凋亡肝细胞较模型组减少。结论:高脂饮食能诱发肝脏细胞发生过度ERS,从而启动细胞凋亡,导致NASH的发生。姜黄素减轻肝细胞凋亡的作用机制可能与其抑制ERS有关。

AIM: To investigate whether curcumin reduces hepatocyte apoptosis in the rats with non-alcoholic steatohepatitis(NASH) by inhibiting endoplasmic reticulum stress(ERS) and thus exerting a protective effect on the liver. METHODS: Male SD rats(n=30) were randomly divided into normal control group(n=10), model group(n=10) and curcumin group(n=10). NASH model was established by feeding the rats with high-fat diet for 4 weeks. The rats in curcumin group was given curcumin(200 mg/kg) daily by gavage, while the rats in model group and normal control group were given the same volume of saline. Four weeks later, the rats were killed, and their blood and liver tissues were collected. The serum levels of alanine aminotransferase(ALT) and aspartate aminotransferase(AST) were detected, liver histopathological changes were observed by HE staining, the expression of glucose-regulated protein 78(GRP78) and C/EBP homologous protein(CHOP) was determined by Western blot, and apoptosis was detected by TUNEL method. RESULTS: Compared with normal control group, the levels of serum ALT and AST in model group were significantly increased, and the levels of serum ALT and AST in curcumin group were significantly lower than those in model group(P<0.05). At the same time, the steatosis and inflammation of hepatocytes in curcumin group were less than those in model group, and no obvious necrosis was observed. Compared with normal control group, the protein expression levels of GRP78 and CHOP in model group were increased, while the protein expression levels of GRP78 and CHOP in curcumin group were decreased compared with model group(P<0.01). TUNEL results showed that apoptotic hepatocytes in model group were significantly more than those in normal control group, while those in curcumin group were significantly fewer than those in model group. CONCLUSION: Hyperlipidemia induces excessive ERS in the hepatocytes, thus triggering apoptosis and leading to NASH. The mechanism of curcumin reducing hepatocyte apoptosis may be related to its inhibition of ERS.