【摘要】 目的探讨表没食子儿茶素没食子酸酯(epigallocatechin gallate, EGCG)对高脂饮食大鼠胰腺组织炎症状态的作用及其与胰岛素抵抗的关系。方法将30只SPF级雄性SD大鼠随机分为正常饮食组(the normal diet group as the control,NC组,n=10)和高脂饮食组(high-fat diet group,HFD组,n=20)。喂养16周,当两组大鼠体重出现显著差异后,将HFD组按随机区组原则分为单纯高脂组(high-fat diet group,HFD组,n=10)和EGCG干预组(HFD+0.32%EGCG,EGCG组,n=10);干预16周。留取血清及胰腺组织,检测每组大鼠空腹血糖(fasting blood glucose,FBG)、胰岛素(fasting insulin,FINS)及游离脂肪酸(free fatty acids,FFAs),并计算胰岛素抵抗指数(homeostasis model assessment-insulin resistance index,HOMA-IR);应用免疫组织化学方法检测胰岛中CD68+巨噬细胞数目及TNF-α表达;应用Real-time RT-PCR及Western blot方法检测胰腺组织中CD68及Toll样受体4(Toll-like receptor 4,TLR4)、肿瘤坏死因子受体相关因子6(TNF receptor-associated factor 6,TRAF6)、肿瘤坏死因子α(tumor necrosis factor-α,TNF-α)及白介素6(interleukin-6,IL-6)等炎症相关因子表达水平。结果 HFD组大鼠体重、FFAs和FINS水平与HOMA-IR指数均明显升高,胰岛中巨噬细胞浸润明显增多,胰腺CD68水平及TLR4、TRAF6、TNF-α和IL-6等炎性因子表达明显上升;EGCG干预的HFD大鼠体重、FFAs和FINS水平、HOMA-IR指数、胰岛巨噬细胞浸润、胰腺CD68水平、胰腺TNF-α和IL-6表达的升高不如HFD大鼠明显,与NC大鼠接近;三组大鼠FBG水平无明显统计学差异;EGCG干预的HFD大鼠TLR4表达水平较HFD组未见明显下降。结论 EGCG可减少高脂饮食大鼠胰岛中巨噬细胞浸润,抑制炎症因子TNF-a及IL-6表达的上调,改善胰岛素敏感性;该作用并非通过TLR4信号通路实现。更多还原

【Abstract】 Objective To investigate the effects of epigallocatechin gallate(EGCG) on inflammation state of pancreas in rats fed a high-fat diet(HFD) and the relationship with insulin resistance. Methods 30 specific pathogen-free(SPF) male Sprague-Dawley rats were randomly divided into 2 groups: the normal diet group as the control(NC group) and HFD group. When there was a significant difference in body weight between the 2 groups after 16 weeks of feeding, the HFD group was further divided into 2 subgroups: the high-fat diet group(HFD, n=10, 16 weeks) and the EGCG group(HFD + 3.2 g/kg EGCG, n=10, 16 weeks) according to the randomized block principle. After 16 weeks of intervention, the serum and pancreatic tissues were collected. Fasting blood glucose(FBG),fasting insulin(FINS), free fatty acids(FFAs) in each group were measured and homeostasis model assessment-insulin resistance index(HOMA-IR) were calculated. The number of macrophage with biomarkers CD68 protein positive and the expression of tumor necrosis factor-α(TNF-α) in pancreatic tissues were evaluated by immunohistochemistry(IHC) and Western blot analysis. Meanwhile,the mRNA and proteins levels of CD68, Toll-like receptor 4(TLR4), tumor necrosis factor receptor-related factor 6(TRAF6), TNF-αand interleukin 6(IL-6) in pancreatic tissue were also detected by real-time RT-PCR and Western blot. Results There was a significant increase in the body weight, HOMA-IR, the level of serum FFAs and FINS, the number of CD68+ macrophages in pancreas islets, and the expression of CD68, TLR4, TRAF6, TNF-α and IL-6 in pancreas, in the HFD group than those in the NC group. EGCG treatment significantly inhibited the HFD-induced increase in the number of CD68+ macrophages in pancreas islets, body weight, HOMA-IR,the levels of serum FFAs and FINS, the expression of CD68, TNF-α and IL-6 in pancreas, bringing them closer to the NC group, in addition to the expression level of TLR4. And there was no significant difference in the FBG level among the three groups. Conclusion In pancreas islet of rats with high-fat diet, EGCG can reduce macrophage infiltration, inhibit the up-regulation of inflammatory factors such as TNF-a and IL-6, and improve insulin sensitivity, by TLR4-independent signaling pathways.更多还原