白藜芦醇降低高脂小鼠体内胆固醇水平的作用及胆汁酸转化分子机制的初步研究

目的:研究白藜芦醇对高脂小鼠体内胆固醇水平的降低作用及其调节胆汁酸转化的分子机制。方法:选取40只Apo E-/-小鼠给予高脂饮食制备高胆固醇小鼠模型,随机分为4组:模型组、白藜芦醇低剂量组、白藜芦醇中剂量组及白藜芦醇高剂量组,分别每天灌胃0.2 mL生理盐水、10 g·L-1白藜芦醇,20 g·L-1白藜芦醇和40 g·L-1白藜芦醇。分别在第0,5,10,20周比较4组小鼠血浆总胆固醇(total cholesterol,TC)、三酰甘油(triglyceride,TG)的水平。在第20周实验结束时,比较4组小鼠血浆低密度脂蛋白胆固醇(low density lipoprotein cholesterol,LDL-C)、高密度脂蛋白胆固醇(high density lipoprotein cholesterol,HDL-C)含量、动脉粥样硬化指数(arteriosclerosis index,AI)水平以及肝脏中TC、TG的含量。在人肝癌细胞株HepG2细胞系中加入0,6.25,12.5,25μmol·L-1白藜芦醇,检测加入白藜芦醇后各组细胞内胆固醇含量、细胞外胆汁酸含量差异。最后用25μmol·L-1白藜芦醇处理细胞,采用RT-PCR及Western blot分别检测细胞中胆固醇代谢相关基因胆固醇7-羟化酶(cholesterol 7α-hydroxylase,CYP7A1)、腺苷三磷酸结合盒转运体超家族成员(ABCG5)的mRNA及蛋白的表达水平。结果:白藜芦醇各剂量组小鼠的TC、TG、LDL-C、AI水平均显著低于模型组,而HDL-C显著高于模型组。白藜芦醇可降低HepG2细胞中总胆固醇含量,并促进细胞分泌胆汁酸含量。RT-PCR及Western blot结果显示,25μmol·L-1白藜芦醇处理HepG2细胞后,CYP7A1、ABCG5的mRNA及蛋白的表达水平明显增加。结论:白藜芦醇可以降低高脂小鼠体内胆固醇水平,这种作用可能是通过调节胆汁酸转化过程中相关基因CYP7A1、ABCG5的表达来实现的。

Preliminary research of resveratrol reduced plasma cholesterol level in high-fat mice and its mechanism

OBJECTIVE To explore the effect of resveratrol on the levels of cholesterol in plasma and liver and its mechanism.METHODS A total of 40 Apo E-/- mice were selected to prepare a high-cholesterol mouse model with high-fat diet, and then randomly divided into four groups. The four groups were simple high cholesterol model group, low dose of resveratrol, medium dose of resveratrol and high dose of resveratrol, which was treated with 0.2 mL normal saline, 10 g·L^-1 resveratrol, 20 g·L^-1 per day, respectively. The levels of total cholesterol (TC) and triglyceride (TG) in the plasma of the four groups were detected and compared at 0, 5, 10, and 20 weeks, respectively. At the end of the 20th week, the plasma low density lipoprotein cholesterol (LDL-C), high density lipoprotein cholesterol (HDL-C) content and Atherosclerosis index (AI) level and the content of TC and TG in the liver of the four groups were compared. The HepG2 cell line was treat with 0, 6.25, 12.5,25 μmol·L^-1 resveratrol respectively, and the differences in cholesterol content and extracellular bile acid content in each group were detected and compared. Finally, the cells were treated with 25 μmol·L^-1 resveratrol, the expression level of cholesterol metabolism related gene cholesterol 7-hydroxylase (CYP7A1) and ABCG5 on mRNA and protein level were detected and compared through RT-PCR and Western blot.RESULTS The total cholesterol (TC), triglyceride (TG), low density lipoprotein cholesterol (LDL-C), and arteriosclerosis index (AI) levels in the resveratrol group were significantly lower than those in the model group, while high density lipoprotein cholesterol (HDL-C) was significantly higher than the model group. When treated with resveratrol, the total cholesterol content of the HepG2 cells was significantly decreased, and the extracellular bile acid content was increased. The mRNA and protein expression levels of CYP7A1 and ABCG5 were significantly increased.CONCLUSION Resveratrol reduces the levels of cholesterol in plasma and liver by up-regulating the expression of important genes CYP7A1 and ABCG 5 in cholesterol metabolism.