表没食子儿茶素没食子酸酯对高脂饮食大鼠脂肪组织TNF-α表达的影响及意义

目的 探讨表没食子儿茶素没食子酸酯（EGCG）对高脂饮食大鼠脂肪组织中肿瘤坏死因子-α（TNF-α）表达的影响及其与胰岛素敏感性的相关性.方法 将30只SPF级雄性SD大鼠随机分为正常饮食组（ND组,n=10）和高脂饮食组（HFD组,n=20）.喂养16w,当两组大鼠体质量出现显著差异后（P〈0.05）,将HFD组按随机区组原则分为单纯高脂组（HFD组,n=10）和EGCG干预组（HFD＋0.32%EGCG,EGCG组,n=10）.干预16w.留取血清及附睾周脂肪组织.检测每组大鼠空腹血糖（FBG）、胰岛素水平（FINS）及游离脂肪酸（FFAs）,并计算胰岛素抵抗指数（HOMA-IR）;应用Real-time PCR及Western blot方法检测附睾周脂肪组织中TNF-α表达水平.结果 （1）与HFD组相比,EGCG组FINS水平显著下降分别为（13.83±0.79）mIU/l vs.（31.71±3.61）mIU/l,P〈0.05];HOMA-IR值下降分别为（3.36±0.31） vs.（7.59±0.99）,P〈0.05];FFAs值亦明显下降分别为（0.38±0.08）mmol/l vs.（0.81±0.11）mmol/l,P〈0.05];三组大鼠FBG水平无明显统计学差异（P〉0.05）.（2）与ND组相比,HFD组脂肪组织中TNF-αmRNA水平显著升高分别为（0.0033±0.00070）vs.（0.0010±0.00008）,P〈0.01];而EGCG组较HFD组则明显下降分别为（0.0018±0.00037）vs.（0.0033±0.00070）,P〈0.05];同时,EGCG组TNF-α蛋白表达量低于HFD组分别为（0.42±0.09）vs.（0.67±0.09）,P〈0.05];（3）EGCG组与ND组无明显差异（P〉0.05）.结论 EGCG改善高脂饮食大鼠胰岛素敏感性可能与减轻脂肪组织TNF-α介导的炎症状态相关.

Effects of Epigallocatechin-3-Gallatein on the Expression of TNF-α in Adipose Tissue of Obesity Rats

Objective To investigate the effects of epigallocatechin-3-gallatein on the expression of tumor necrosis factor-α （TNF-α） in adipose tissue of rats with high-fat diet and its relationship with insulin resistance. Methods 30 male SD rats were divided into two groups： normal diet （ND, n=10） and high-fat diet （HFD, n=20）. When there was a significant difference in body weight between the two groups （P〈 0.05）, the HFD group was divided into two subunits, the HFD group （HFD, n= 10, 16wks） and the EGCG group （HFD＋EGCG, 3.2g/kg diet, n=10, 16wks）. The levels of plasma glucose, fasting plasma insulin （FINS）and free fatty acids （FFAs） were assessed. Insulin resistance was calculated by the homeostasis model assessment-insulin resistance index （HOMA-IR index）. The level of TNF-α was examined in epididymal white fat by Western-blotting and RT-PCR. Results （1）Compared with the HFD group, the EGCG group showed significant decreases in FINS （13.83±0.79） mIU/1 vs. （31.71±3.61） mlU/l, P 〈0.05], HOMA-IR（3.36±0.31） vs. （7.59±0.99）, P〈0.05], andFFAs （0.38±0.08） mmol/lvs. （0.81±0.11） mmol/1, P〈0.05]. （2） The protein level of inflammation-related molecules TNF-α in the EGCG group was significantly lower than that of the HFD group （0.42±0.09）vs. （0. 67±0.09）, P〈0. 05]; so was the level of mRNA expression of TNF-α（0. 0018±0. 00037）vs. （0.0033±0.00070）, P〈0. 05]. （3） There were no significant diffferences between the ND group and the EGCG group （P〉0.05）. Conclusion EGCG enhances insulin signaling, Which may be correlated with its downregulation of TNF-α expression in adipose tissue.