依折麦布长期干预对LDLR^(+/-)仓鼠高脂血症的影响及其对肝脏脂代谢基因的调控

Effects of long-term ezetimibe on hyperlipidemia and genes involved in lipid metabolism in the liver of the LDLR^(+/-)hamster

目的探讨依折麦布长期干预调控脂代谢的效果和对肝脏脂代谢基因的调控。方法雄性低密度脂蛋白受体杂合子(LDLR^(+/-))仓鼠随机分为两组:空白对照组和依折麦布组[25 mg/(kg·d)]。动物高脂饮食同时给药20周后,收集血浆、肝脏等组织样本。分析血浆中总胆固醇(TC)、甘油三酯(TG)、总胆汁酸(TBA)、非酯化脂肪酸(NEFA)和谷草转氨酶(AST)水平;检测肝脏中TC和TG水平;借助KTA快速蛋白液相色谱系统分离脂蛋白组分并检测各组分的TC和TG水平;采用实时荧光定量PCR和Western blot分别检测脂代谢相关基因和蛋白的表达。结果依折麦布长期干预显著下调LDLR^(+/-)仓鼠血浆中的TC、TG、TBA、NEFA和AST水平以及载脂蛋白B(ApoB)蛋白表达水平,但对脂蛋白脂肪酶(LPL)的蛋白表达和活性以及前蛋白转化酶枯草溶菌素9(PCSK9)的蛋白水平无影响;在肝脏中,依折麦布显著降低了TC水平,但对TG无显著影响;在基因水平上,依折麦布显著上调肝脏中甾醇调节元件结合蛋白2(SREBP-2)和PCSK9的表达,同时下调了胆固醇7α羟化酶A1(CYP7A1)、三磷酸腺苷结合盒转运体G5(ABCG5)、ABCG8和肝X受体α(LXRα)的表达。结论在LDLR^(+/-)仓鼠中,依折麦布长期干预可显著降低高脂血症,并展现出对多种肝脏脂代谢相关基因表达调控的复杂性。

Aim To investigate the effects of long-term ezetimibe on hyperlipidemia and genes involved in lipid metabolism in the liver of the LDLR^(+/-)hamster.Methods Male LDLR^(+/-)hamsters were randomly divided into two groups:the vehicle group and the ezetimibe group(25 mg/(kg·d)).Animals were free to access water and high-fat diet.After 20-week administration,hamsters were sampled after overnight fasting.The plasma levels of total cholesterol(TC),triglyceride(TG),total bile acid(TBA),non-esterified fatty acid(NEFA)and aspartate aminotransferase(AST)were detected by assay kits.Mixed plasma in each group was further separated via an KTA fast protein liquid chromatography(FPLC)system and the TC and TG levels in each fraction were also detected.The expression of multiple genes in the liver and proteins in the plasma was determined by qRT-PCR and Western blot,respectively.Results Long-term ezetimibe intervention significantly decreased plasma TC,TG,TBA,NEFA and AST levels,and apolipoprotein B protein expression in the LDLR^(+/-)hamsters,and had no effect on the protein levels of lipoprotein lipase(LPL)and proprotein convertase subtilisin/kexin-type 9(PCSK9)and the activity of LPL.Further KTA-FPLC analysis demonstrated that ezetimibe reduced the TC and TG levels in all the lipoprotein fractions.In the liver,ezetimibe significantly reduced TC,but not TG concentration.Furthermore,ezetimibe significantly increased the mRNA expression of sterol regulatory element binding protein 2 and PCSK9 and dramatically decreased the expression of liver X receptor α,cholesterol 7α-hydroxylase A1,ATP-binding cassette transporter G5(ABCG5)and ABCG8 in the liver.Conclusion Long-term ezetimibe intervention reduces hyperlipidemia and displays complex modulatory effects on the genes involved in lipid homeostasis in LDLR^(+/-)hamsters.