西罗莫司抑制脂肪酸摄取改善小鼠肝脏脂质积聚

Sirolimus ameliorates liver lipid accumualtion in mice by inhibiting fatty acid uptake

目的:研究西罗莫司对小鼠肝脏脂质积聚的影响及机制初探。方法:6~8周龄雄性C57BL/6J小鼠,随机分为3组:A组为普通饮食组(n=12),B组为高脂饮食组(n=9),C组为高脂饮食加隔天注射西罗莫司组(n=7),喂养14周。全自动生化分析仪检测血清生化指标。酶联免疫吸附法和酶偶联比色法分别检测肝脏游离脂肪酸(free fatty acid,FFA)和甘油三酯(triglyceride,TG)的含量。Western blot检测脂肪酸转运酶(fatty acid translocase,FAT/CD36)蛋白的表达水平。荧光显微镜观察原代肝细胞对荧光标记FFA的动态摄取。结果:与A组相比,B组小鼠体质量(q=6.68,P=0.000),血清TG(q=4.88,P=0.045),高密度脂蛋白(high-density lipoprotein,HDL)(q=6.311,P=0.002),谷草转氨酶(aspirate aminotransferase,AST)(q=8.84,P=0.001)水平明显增高,肝脏组织TG(q=14.4,P=0.000),FFA(q=18.0,P=0.000)也明显增高。C组小鼠较B组体质量(q=7.99,P=0.000),血清TG(q=4.636,P=0.050),AST(q=5.16,P=0.016)及肝脏TG(q=8.91,P=0.000)和FFA(q=14.1,P=0.000)都显著降低。Western blot结果显示C组小鼠肝脏CD36的蛋白表达水平较B组明显降低。FFA动态摄取实验通过定量荧光强度显示西罗莫司能明显抑制肝细胞对FFA的摄取速度(各时间点P均<0.05)。结论:西罗莫司能抑制肝细胞对外源性FFA的摄取,减轻肝脏脂质积聚,其作用机制可能与CD36相关。

Objective：To study the effects of sirolimus on hepatic lipid accumulation in mice and to expose the related mechanisms. Methods：Six-eight week C57BL/6J mice were randomly divided into three groups：mice in group A were fed with normal chaw food, mice in group B were fed with high fat diet,and mice in group C were fed with high fat diet plus sirolimus injected every other day. All mice were fed for 14 weeks. Serum biochemical parameters were analyzed by an automatic biochemical analyzer. The levels of free fatty acid （FFA） and triglyceride（TG） were measured by enzyme-linked immunosorbent assay and enzyme-coupled colorimetric assay respectively. The hepatic fatty acid translocase （FAT/CD36） protein levels were determined by Western blot. Fluorescence mi- croscopy was used to observe the time-dependent FFA uptake by the primary hepatocytes. Results ： Compared with those of group A, the body weight （q=6.68, P=O.O00）, serm TG（q=4.88, P=0.045 ）, high-density lipoprotein （HDL） （q =6.311, P=O.002）, aspirate amino- transferase （AST） （q =6.3 ll,P=O.001 ）, and liver TG （q =14.4,P=0.000）, FFA （q =18.0, P=O.000） levels of group B were highly in- creased. The body weight（q=7.99,P=O.O00）,serum TG（q=4.636,P=O.050）,AST（q=5.16,P=0.016）,liver TG（q=8.91 ,P=0.000） and FFA（q=14.1 ,P=0.000） were significantly lower in group C than in group B. The expression of FAT/CD36 in the liver was significantly lower in group C than in group B. The time-dependent FFA uptake experiment showed that sirolimus decreased the efficiency of flu- orescent FFA uptake into hepatocytes. Conclusion ： Sirolimus can inhibit the uptake of FFA by hepatocytes and reduce the lipid accu-mulation in the liver,which may be related to CD36.