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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胰岛素信号传导机制的影响。方法将30只4周龄SPF级雄性SD大鼠随机分为正常饮食组(n=10)和高脂饮食组(n=20)。喂养16周,当两组大鼠体质量出现显著差异后(P<0.05),将高脂饮食组按随机区组原则分为高脂饮食组(n=10)和EGCG干预组(高脂饮食含0.32%EGCG,n=10)。干预16周后检测每组大鼠空腹血糖及胰岛素水平,并计算HOMA-IR指数;应用Western blot方法检测附睾周脂肪组织中胰岛素信号通路中关键分子p-IRS-1、PI3K、GLUT4蛋白的水平。结果 (1)与高脂饮食组相比,EGCG干预组空腹胰岛素水平显著下降[EGCG干预组(13.83±0.79)mIU/L,高脂饮食组(31.71±3.61)mIU/L,P=0.004];EGCG干预组HOMA-IR指数明显改善(EGCG干预组3.36±0.31,高脂饮食组7.59±0.99,P=0.007);正常饮食组、高脂饮食组和EGCG干预组大鼠空腹血糖水平无统计学差异。(2)Western blot结果显示,与高脂饮食组相比,EGCG干预组大鼠附睾脂肪组织中p-IRS-1Ser307蛋白水平明显下降,约为高脂饮食组的62.19%(P=0.005);PI3K及GLUT4水平明显升高,分别为高脂饮食组的2.35倍(P=0.000)和2.03倍(P=0.007)。结论 EGCG可能通过调控高脂饮食大鼠脂肪组织胰岛素信号传导通路中关键蛋白表达,改善胰岛素敏感性。
Objective To investigate the effect of epigallocatechin gallate (EGCG) on insulin signaling in adipose tissue of high fat diet rats. Methods Thirty male SPF rats of 4 weeks old were randomly divided into normal diet group (n = 10) and high fat diet group (n = 20). The rats in high fat diet group were divided into high fat diet group (n = 10) and EGCG intervention group (high fat diet group) according to the principle of random block when the body weight of two groups were significantly different (P <0.05) 0.32% EGCG, n = 10). After 16 weeks of intervention, the fasting blood glucose and insulin levels were measured in each group, and HOMA-IR index was calculated. Western blot was used to detect the levels of p-IRS-1, PI3K and GLUT4 in the insulin signal transduction pathway in epididymis . Results (1) The fasting insulin levels of EGCG intervention group were significantly lower than those of high fat diet group [(13.83 ± 0.79) mIU / L in EGCG intervention group and (31.71 ± 3.61) mIU / L in high fat diet group, P = 0.004] ; The HOMA-IR index in EGCG intervention group was significantly improved (3.36 ± 0.31 in EGCG intervention group and 7.59 ± 0.99 in high fat diet group, P = 0.007); there was no statistical significance in fasting blood glucose level in normal diet group, high fat diet group and EGCG intervention group Differences (2) Western blot results showed that the protein level of p-IRS-1Ser307 in epididymal adipose tissue of EGCG intervention group was significantly lower than that in high-fat diet group (62.19%, P = 0.005). The levels of PI3K and GLUT4 were significantly increased by 2.35-fold (P = 0.000) and 2.03-fold (P = 0.007), respectively, in the high-fat diet group. Conclusion EGCG may improve the insulin sensitivity by regulating the expression of key proteins in the insulin signal transduction pathway of adipose tissue in high fat diet rats.