艾塞那肽对高脂饮食诱导的肥胖小鼠骨骼肌脂质沉积的作用及机制探讨  

Effect of exendin-4 on lipid deposition in skeletal muscle of diet-induced obese mice and its underlying mechanism

作　　者：曹欢易 徐芬[1] 陈宗兰[1] 林倍思[1] 郑晓彬[1] 袁淑华[1] 梁华[1] 翁建平[1] 

机构地区：[1]中山大学附属第三医院内分泌与代谢病学科广东省糖尿病防治重点实验室,广州510630

出　　处：《中华医学杂志》2017年第2期131-136,共6页National Medical Journal of China

基　　金：国家自然科学基金中加合作项目（81261120565）;国家自然科学基金（81670782,81300705）;广州市科技计划项目珠江新星专项（201610010175）;中央高校基本科研业务费专项资金（16ykzd12）

摘　　要：目的探讨艾塞那肽改善高脂饮食诱导的肥胖小鼠骨骼肌脂质沉积和胰岛素抵抗的作用及机制。方法雄性8周龄C57BL/6J小鼠12只予高脂饮食饲养12周以构建肥胖小鼠模型，再用随机数字表法分组后予艾塞那肽（24 nmol·kg－1·d－1，艾塞那肽组，6只）或生理盐水腹腔注射（高脂饮食组，6只）4周，另设正常对照组（生理盐水腹腔注射，6只），监测干预前后体重及血糖。用油红O染色显示骨骼肌脂质沉积情况；酶联免疫吸附（ELISA）法测定血清三酰甘油（TG）、总胆固醇（TC）、胰岛素以及骨骼肌三酰甘油水平；Western印迹检测腺苷酸活化蛋白激酶（AMPK）介导的脂质代谢通路以及胰岛素信号通路相关蛋白的表达。结果与高脂饮食组相比，艾塞那肽干预能够显著降低高脂饮食诱导的肥胖小鼠的血糖[（5.40±0.33）比（7.65±1.92）mmol/L，P〈0.025]及体重[（37.68±1.80）比（46.03±5.00）g，P〈0.025]，降低血清TG[（37.78±7.14）比（80.76±34.22） mg/dl，P〈0.025]、TC[（180.13±18.75）比（217.57±22.52） mg/dl，P〈0.025]、胰岛素[（0.58±0.01）比（1.67±1.23）ng/ml，P〈0.025]以及骨骼肌TG水平[（9.84±1.08）比（19.35±7.44） mg/g，P〈0.025]。油红O染色显示，艾塞那肽可减轻高脂饮食诱导的肥胖小鼠骨骼肌细胞内的脂质沉积。Western印迹结果显示，艾塞那肽可上调高脂饮食诱导的肥胖小鼠骨骼肌AMPK介导的脂质分解氧化相关蛋白的表达，下调AMPK介导的脂质合成关键转录因子的表达，同时上调胰岛素信号通路关键蛋白的表达（均P〈0.025）。结论艾塞那肽可能通过激活AMPK增加脂质分解氧化，减少脂质合成，并上调胰岛素信号通路关键蛋白活性，从而改善骨骼肌的脂质沉积与胰岛素抵抗。Objective To investigate the effect of exendin-4, a glucagon-like peptide-1 （GLP-1） receptor agonist, on reducing lipid deposition and improving insulin resistance in skeletal muscle and the underlying mechanisms in high-fat diet （HFD）-indueed obese mice. Methods Twelve male C57BL/6J mice were challenged with HFD for 12 weeks to induce obesity and then randomly divided into two groups： exendin-4 group （intraperitoneal injection of 24 nmol ·kg-1· d-1 exendin-4 for 4 weeks） and HFD group （ intraperitoneal injection of normal saline for 4 weeks）, with 6 mice in each group. Additional 6 mice were also selected as control group. Body weight, fasting blood glucose were recorded. Serum triglyceride （TG）, total cholesterol （TC）, insulin and skeletal muscle triglyceride levels were measured by enzyme-linked immunosobent assay （ELISA）. Oil red O staining was used for morphologie changes of frozen sections from skeletal muscle. The protein levels of lipid metabolic pathway mediated by AMP-activated protein kinase （AMPK） and insulin signailing pathway were determined by Western blot. Results Compared with mice in HFD group, exendin-4 significantly decreased body weight [ （ 37.68 ± 1.80 ） vs （46. 03 ± 5.00 ） g, P 〈0. 025], fasting blood glucose[ （5.40±0. 33） vs （7.65 ± 1.92） mmo]/L, P 〈0. 025], serum TG[ （37.78 ± 7. 14） vs （80.76＋34.22） mg/dl, P〈0.025], TC[ （180. 13 ±18.75） vs （217.57 ±22.52） mg/dl, P〈 0. 025 ], insulin [ （ 0. 58 ± 0. 01 ） vs （ 1.67 ± 1.23 ） ng/ml, P 〈 0. 025 ] and skeletal muscle TG levels [ （9. 84 ± 1.08） vs （ 19.35 ± 7.44） mg/g, P 〈 0. 025 ] of obese mice. Oil red O staining revealed that exendin-4 alleviated the accumulation of larger lipid droplets in skeletal muscle. The protein expressions of lipolysis and lipid oxidation mediated by AMPK and insulin signailing pathway were up-regulated, and the protein expressions of Iipogenesis mediated by AMPK were down-regulated after intervention of exendin

关 键 词：小鼠 肥胖 脂质沉积 肌 骨骼 AMP-活化蛋白激酶 艾塞那肽 

分 类 号：R589.2[医药卫生—内分泌]