苜蓿皂甙对高脂血症大鼠胆固醇代谢及肝脏ACAT-2和HMG-CoAr基因表达的影响

摘要

探讨苜蓿皂甙对高脂血症大鼠胆固醇代谢及肝脏胆固醇酰基转移酶2(ACAT-2),羟甲基戊二酸单酰辅酶A还原酶(HMG-CoAr)基因表达的影响.取雄性健康Sprague Dawley大鼠(SD) 40只,随机分为4组,分别为:正常对照组A、高脂模型组B、苜蓿皂甙预防组C和苜蓿皂甙治疗组D.除正常对照组外,其余各组均饲喂高脂饲料,其中预防组从第1周开始灌胃苜蓿皂甙,治疗组从第5周开始灌胃苜蓿皂甙,试验期8周.观察试验大鼠体重、肝脏系数、血脂水平和肝脏病理变化情况,并用酶联免疫法(ELISA)和Real-time PCR技术分别检测大鼠肝脏HMG-CoAr和ACAT-2的蛋白和mRNA表达结果.结果表明,1)苜蓿皂甙可以显著降低高脂模型大鼠体重、肝脏系数、血清TC和低密度脂蛋白(LDL-C)水平及改善肝脏脂化程度(P＜0.05).2)苜蓿皂甙预防组和治疗组ACAT-2的蛋白和mRNA表达量极显著低于模型组(P＜0.01),而HMG-CoAr的蛋白及mRNA表达水平与模型组比较则差异不显著.苜蓿皂甙通过降低肝脏ACAT-2的表达,抑制机体对外源胆固醇的吸收,发挥对高脂血症的预防和治疗作用.%The effect of alfalfa saponins on cholesterol metabolism and the expressions of ACAT-2 and HMG-CoAr in the liver of hyperlipidemia rats was investigated. Forty healthy male Sprague Dawley (SD) rats were randomly divided into four groups: normal (control, A), hyperlipidemia model (B), alfalfa saponins prevention group (C) , alfalfa saponins treatment group (D). Except for the controls, rats were fed a high-fat diet for eight weeks. Alfalfa saponins were added by gavage to group C from the first week, and to group D from the fifth week. Body weight, liver index and serum lipid level of the rats were measured. Protein and mRNA expressions of ACAT-2 and HMG-CoAr were measured by enzyme linked immunosorbent assay (ELISA) and real-time PCR methods respectively. 1) The body weight, liver index and serum lipid level of hyperlipidemia rats were significantly reduced, and the fatty degeneration and steatosis in the liver were ameliorated by alfalfa saponins. 2) The protein and mRNA expressions of ACAT-2 in groups C and D were significantly lower than those in group B(P<0. 01), but there was no significant difference for HMG-CoAr. In conculsion, alfalfa saponins prevented hyperlipidemia by reducing the expression of hepatic ACAT-2, and by inhibiting the absorption of exogenous cholesterol.