白藜芦醇改善高脂血症小鼠脂肪组织胰岛素抵抗的机制探讨

Research of mechanisms of resveratrol improving insulin resistance in white adipose tissues of hyperlipidemic mice

目的探讨白藜芦醇对高脂血症小鼠2种白色脂肪组织胰岛素抵抗相关基因瘦素(Leptin)、肿瘤坏死因子α(TNF-α)和葡萄糖调节蛋白78(GRP78)表达的影响。方法24只雄性C57BL/6小鼠随机分为标准饮食组(SCD)、高热量高胆固醇饮食组(HCD)及高热量高胆固醇饮食+白藜芦醇组[HCD+RES,白藜芦醇400 mg/(kg·d),12周]。葡萄糖耐量实验和胰岛素耐量实验分析胰岛素抵抗的改善作用,检测血脂指标,称取皮下脂肪(SAT)和肾周脂肪组织(VAT)重量,HE染色检测脂肪组织的病理学变化,免疫组化和实时荧光定量PCR分析Leptin、TNF-α、GRP78的胞内分布和基因表达的改变。结果 HCD组小鼠出现明显的胰岛素抵抗,血清总胆固醇(TC)、三酰甘油(TG)、低密度脂蛋白C(LDL-C)显著增高,高密度脂蛋白C(HDL-C)明显降低,体重、SAT、VAT的重量均明显增加,脂肪细胞体积明显增大,Leptin、TNF-α、GRP78的mRNA和蛋白表达显著增加,且均位于胞质中;白藜芦醇能显著改善胰岛素抵抗,明显降低体重和逆转血脂水平变化,明显下调SAT和VAT中Leptin、TNF-α、GRP78的蛋白表达和分布,显著降低SAT中Leptin、TNF-α、GRP78和VAT中Leptin、TNF-αmRNA的表达。结论白藜芦醇具有明显的改善胰岛素抵抗和降脂作用,其机制可能是通过抗炎、减少Leptin表达和内质网(ER)应激有关,但对不同部位白色脂肪组织基因表达的影响差异不大。

Objective To study the influences of resveratrol on insulin-resistance related gene expression of Leptin,TNF-α,glucose regulated protein 78 （GRP78） in two different adipose tissues of hyperlipidemic mice.Methods Twenty-four C57BL/6 mice were randomly divided into standard control diet （SCD）,high-calorie and highcholestrol diet （HCD） and high-calorie and high-cholestrol diet group treated with resveratrol [HCD ＋ RES,400 mg/（kg · d）,12 weeks].Glucose tolerance test （GTT） and insulin tolerance test （ITT） were used to analyze the improvement on insulin resistance.The serum lipid indices were detected,the body weight,subcutaneous adipose tissues （SAT） and visceral adipose tissues （VAT） were weighed respectively.The pathological changes of two adipose tissues were detected with HE staining,the protein distribution and mRNA levels of Leptin,TNF-α and GRP78 were measured with immunohistochemistry and real-time fluorescence quantification RT-PCR respectively.Results Compared with SCD group mice,mice fed with HCD showed obvious insulin resistance,higher serum levels of total cholesterol（TC）,triglyceride（TG） and low density lipoprotein-cholesterol（LDL-C） and lower serum level of high density lipoprotein-cholesterol（HDL-C）,the body weight,weight of SAT and VAT,cell volume of adipocytes were also obviously increased.The mRNA and protein levels of Leptin,TNF-α and GRP78 were remarkably augmented,mainly distributed in cytosol.Resveratrol could obviously improve insulin resistance,reverse the serum lipid levels and body weight,decrease the protein expression and distribution of Leptin,TNF-α and GRP78in SAT and VAT,reduce the mRNA expression of Letpin,TNF-α,GRP78 in SAT,and Leptin,TNF-α in VAT respectively.Conclusion Resveratrol has obvious effects of improving insulin resistance and lipid-lowering.The mechanisms are possibly related with anti-inflammatory and reduce Leptin resistance and endoplasmic reticulum stress.Its influence on the gene expressions of white adipose tissues in different sites has no obvious differences.