艾塞那肽对肥胖大鼠白色脂肪自噬及棕色化的影响

Effects of exenatide on autophagy and occurrence of brown adipocytes for white adipose tissue in obese rats

目的研究艾塞那肽对肥胖大鼠白色脂肪自噬以及棕色化的影响。方法4N龄雄性SD大鼠20只按随机数字表法分为普通饮食组（对照组，n=10）和高脂饮食组（n=10）。高脂饮食组予连续高脂喂养12周后，再随机分为肥胖组（n=5）、艾塞那肽组（干预组，n=5）。对照组和肥胖组予皮下注射生理盐水，干预组予皮下注射艾塞那肽10μg·kg^-1·d^-1。10周后通过Western blotting、实时荧光定量聚合酶链反应（RT-PCR）和免疫组化法检测脂肪组织中白色脂肪自噬标志蛋白f微管相关蛋白1轻链3B（LC3B）II与LC3BI比值1以及棕色化相关指标解偶联蛋白1（UCP-1）水平等。采用单因素方差分析、独立样本t检验等统计学方法比较各组差异。结果（1）高脂饲养4周后，高脂组体重较对照组明显上升[（472±38）比（420±28）g，t=3．302，P=0．0111，经艾塞那肽干预4周后，干预组体重明显低于肥胖组[（598±24）比（696±35）g，t=4．554，P=0．002]。（2）经艾塞那肽治疗后，干预组大鼠白色脂肪自噬相关蛋白LC3BII／LC3BI水平明显上升，与肥胖组相比差异有统计学意义（2．17±0．12比1，16±0．08，t=3．584，P〈0．05）；棕色化相关蛋白UCP-1表达水平较肥胖组明显增加（1．63±0．09比0．82±0．06，t=8．397，P=0．0014）。结论艾塞那肽可能一方面通过增加白色脂肪自噬，另一方面促进白色脂肪棕色化，进而减轻肥胖大鼠体重。

Objective To explore the effects of exenatide on autophagy and occurrence of brown adipocytes for white adipose tissue in obese rats. Methods Twenty 4-week-old male SD rats were randomly divided into 2 groups according to random number table： control group with normal fat diet （n=10）and high fat diet group（HFD group, n=10 ）. The rats in HFD group was fed with high-fat diet for 12 weeks, then they were randomly divided into intervention group（Exe group） and obesity group. The rats in the Exe group were subcutaneously injected with exenatide 10 μg·kg^-1·d^-1through abdominal wall for 10 weeks, while the rats in control and obesity group were subcutaneously injected with saline solution. Western blotting and real time polymerase chain reaction （RT-PCR） were used for protein and gene expression assays. One-way analysis of variance and independent-samples t test were used for statistical analysis. Results （1） After 4 weeks of high-fat diet feeding, the body weight in the HFD group was increased than that in Me control group （ （472± 38） vs （420 ±28） g , t=3.302, P=-0.011）. After 4 weeks of exenatide treatment, the body weight was significantly decreased in the Exe group than the obesity group （（598 ± 24） vs （696 ± 35） g , t=4.554, P= 0.002）. （2） Compared with the obesity group, the level of autophagy-related protein light chain 3B（LC3B） II/ LC3BI was increased in the Exe group（2.17±0.12 vs 1.16±0.08, t=3.584 , P〈0.05）. The level of uncoupling proteins I（UCP- 1, which represents the occurrence of brown adipocytes for white adipose tissue） was increased than that in the obesity group（1.63 ± 0.09 vs 0.82 ± 0.06, t=8.397, P=0.001g）. Conclusion Exenatide may reduce the body weight in obesity rats induced by high-fat-diet. The mechanism maybe promotion of the autophagy and converting into brown fat in white adipose tissue.