蒲公英水提取物对2型糖尿病大鼠胰岛素抵抗的作用研究

目的观察蒲公英水提取物对2型糖尿病大鼠胰岛素抵抗的影响,并探讨其改善胰岛素抵抗的作用机制。方法用高脂高糖饮食联合小剂量链脲佐菌素(STZ)建立2型糖尿病大鼠胰岛素抵抗模型。将成模大鼠随机分为模型组,蒲公英水提取物高、中、低剂量组及吡格列酮组,并设正常组作对照。蒲公英水提取物高、中、低剂量组分别灌胃500、250、125 mg·kg^-1蒲公英水提取物稀释液,吡格列酮组灌胃3.15 mg·kg^-1吡格列酮溶液,正常组及模型组灌胃等体积生理盐水,每日1次,连续4周。观察大鼠一般状态及测定体质量;测定大鼠空腹血糖(FBG),行口服葡萄糖耐量试验(OGTT)并计算血糖曲线下面积(AUC);测定大鼠血清胰岛素(FINS)并计算胰岛素敏感指数(ISI)及胰岛素抵抗指数(IRI);测定大鼠血清白细胞介素6(IL-6)、肿瘤坏死因子α(TNF-α)及肝脏组织IkB激酶β(IKK-β)、核因子κB(NF-κB)mRNA表达;HE染色观察大鼠胰岛形态;免疫组化染色观察大鼠胰岛β细胞数目及胰岛素表达。结果与正常组比较,模型组大鼠多饮、多食、多尿现象明显,精神不振、活动减少,体质量下降明显(P<0.01);FBG、OGTT各时间点血糖、AUC均明显升高(P<0.01);FINS、IRI明显升高(P<0.01),ISI明显降低(P<0.01);IL-6、TNF-α、IKK-β、NF-κB均明显增加(P<0.01);HE染色胰岛形态不规则,边界模糊,胰岛细胞数目明显减少;免疫组化染色胰岛β细胞数目及胰岛素表达均明显减少。与模型组比较,蒲公英水提取物高、中剂量组大鼠的多饮、多食、多尿现象及精神状态明显改善,体质量增加明显(P<0.01,P<0.05);FBG、OGTT各时间点血糖及AUC均明显降低(P<0.01,P<0.05);FINS、IRI明显降低(P<0.01,P<0.05),ISI明显升高(P<0.01);IL-6、TNF-α、IKK-β、NF-κB均明显减少(P<0.01,P<0.05);HE染色胰岛形态及胰岛细胞数目改善明显,以高剂量组为佳;免疫组化染色胰岛β细胞数目及胰岛素表达明显增加,以高剂量组为佳。结论蒲公英水提取物可以有效改善2型糖尿病大鼠的胰岛素抵抗,以高剂量为佳,其机制可能与下调IKK-β/NF-κB信号通路中IKK-β、NF-κB的表达,减少炎症因子IL-6、TNF-α的生成有关。

Effect of Dandelion Water Extract on Insulin Resistance in Type 2 Diabetic Rats

Objective To observe the effect of dandelion water extract on insulin resistance in type 2 diabetic rats,and to explore its mechanism of improving insulin resistance.MethodsThe insulin resistance model of type 2 diabetic rats was established by high-fat and high-sugar diet combined with low-dose streptozotocin(STZ). The model rats were randomly divided into model group, dandelion water extract high, medium and low dose group,pioglitazone group, and normal group as control. The dandelion water extract high, medium and low dose group were given 500,250,125 mg·kg^-1 water extract dilutions by gavage,pioglitazone group was given 3.15 mg·kg^-1 pioglitazone solution, normal group and model group were given equal volume of normal saline, once a day for4 weeks. The body weight of rats was measured and the general state was observed;The fasting blood glucose(FBG)in rat was measured,oral glucose tolerance test(OGTT)was performed and area under blood glucose curve(AUC)was calculated;ELISA was used to quantify fasting insulin(FINS),and insulin sensitivity index(ISI)and insulin resistance index(IRI)were calculated;Subsequently,serum interleukin-6(IL-6),tumor necrosis factor-α(TNF-α),expression of inhibitor kappa B kinaseβ(IKK-β) and nuclear factor κB(NF-κB) mRNA in liver tissue were measured;HE staining was used to observe the morphology of islets;Immunohistochemical staining was used to investigate the number of islet β cells and insulin expression.ResultsCompared with the normal group,the rats in the model group had polydipsia, polyphagia, polyuria, listlessness, less activity and weight loss(P < 0.01);FBG, blood glucose at each time point of OGTT and AUC increased significantly(P < 0.01);FINS and IRI increased significantly(P < 0.01), ISI decreased significantly(P < 0.01);IL-6, TNF-α, IKK-β and NF-κB increased significantly(P < 0.01);HE staining showed that the shape of islet was irregular, the boundary was fuzzy,and the number of islet cells reduced significantly;Immunohistochemical staining showed that the number of islet β cells and the expression of insulin reduced significantly. Compared with the model group, the polydipsia,polyuria and mental state of rats in the high and medium dose dandelion water extract group were significantly improved,and the body weight was significantly increased(P < 0.01,P < 0.05);FBG,blood glucose at each time point of OGTT and AUC decreased significantly(P < 0.01,P < 0.05);FINS and IRI decreased significantly(P <0.01,P < 0.05),ISI increased significantly(P < 0.01);IL-6,TNF-α,IKK-β and NF-κB decreased significantly(P < 0.01,P < 0.05);HE staining showed that the islet morphology and the number of islet cells were significantly improved,especially in the high dose group;Immunohistochemical staining showed that the number of islet β cells and the expression of insulin increased significantly,especially in the high dose group.ConclusionDandelion water extract can effectively improve insulin resistance in type 2 diabetic rats, especially in high dose. The mechanism may be related to down regulating the expression of IKK-β and NF-κB in IKK-β/NF-κB signal pathway, and reducing the production of inflammatory factors IL-6 and TNF-α.