小叶苦丁提取物通过上调Nrf2/INS蛋白质水平表达降低小鼠高血糖

Small-leaf Kuding Extract Decreases Hyperglycemia in Mice by Upregulating Nrf2/INS Expression at the Protein Level

近年来,高血糖的患病率不断增加,患者身体损伤严重。与常规西药相比,天然产物不良反应少,可延缓高血糖并发症。小叶苦丁是一种珍贵的天然产品资源,含有多种对人体有益的成分。本研究旨在研究不同剂量的小叶苦丁提取物对高血糖小鼠血糖代谢的调节作用。本研究采用脂多糖加链脲佐菌素诱导小鼠高血糖模型,小叶苦丁提取物以低、中、高(5g·kg^(-1)·d-1,10g·kg^(-1)·d-1,15g·kg^(-1)·d-1)3个剂量灌胃给药,连续7周。每周于固定时间采集小鼠尾静脉血测定小鼠空腹血糖值。给药7周后,按规定取每只小鼠的血清和脏器,测定血清中甘油三酯(TG)、胆固醇(CHO)、高密度脂蛋白-胆固醇(HDL-C)、低密度脂蛋白-胆固醇(LDL-C)、糖化血清蛋白(GSP)、胰高血糖素样肽-1(GLP-1)、空腹胰岛素(FINS)和胰高血糖素(GC)含量水平。结果显示,模型组小鼠血糖值、各项血清生化指标与正常组小鼠均具有显著性差异(P<0.01或P<0.05),高血糖症状明显。小叶苦丁提取物低、中、高剂量组HDL-C、FINS含量显著高于模型组(P<0.01),TG、CHO、LDL-C含量减少,血糖值显著降低,与模型组相比具有极显著性差异(P<0.01)。中、高剂量组GSP含量较模型组显著降低(P<0.01或P<0.05)。小鼠胰腺组织的H&E染色结果显示,高血糖小鼠在灌胃小叶苦丁提取物后,胰岛细胞形态有所改善;免疫组织化学法观察胰腺组织胰岛素、核因子E2相关因子2蛋白质水平的表达,并采用免疫印迹实验(WB)和实时荧光定量(RT-qPCR)验证。结果表明,胰岛素(INS)、核因子E2相关因子2(Nrf2)蛋白质表达水平上调,其中高剂量组效果最佳(P<0.01)。以上结果提示,小叶苦丁提取物能够降低高血糖小鼠的血糖值,对其胰岛细胞损伤具有改善作用,能够改善高血糖小鼠症状,为临床治疗高血糖提供了新参考。

In recent years,the prevalence of hyperglycemia has been increasing,and patients’bodies have been seriously damaged.Compared with conventional Western drugs,natural products have fewer adverse reactions and delay the complications of hyperglycemia.As a valuable natural product resource,Small-leaf Kuding(SLK)contains various beneficial components for the human body.The aim of this study was to study the regulation effect of SLK extract at different doses on blood glucose metabolism in hyperglycemic mice.Lipopolysaccharide and streptozotocin were used to induce hyperglycemia in mice.Extract of SLK were administered intragastrically at low,medium,and high doses(5 g·kg^(-1)·d-1,10 g·kg^(-1)·d-1,15 g·kg^(-1)·d-1).After 7 weeks of administration,serum and organs from each mouse were taken and the contents of triglyceride(TG),cholesterol(CHO),high density lipoprotein-cholester-ol(HDL-C),low density lipoprotein-cholesterol(LDL-C),glycosylated serum protein(GSP),gluca-gon-like peptide-1(GLP-1),fasting insulin(FINS)and glucagon(GC)in serum were determined.The results showed that the blood glucose and serum biochemical indexes of mice in the model group were significantly different from those in the normal group(P<0.01 or P<0.05),and the symptoms of hyper-glycemia were obvious.The contents of HDL-C and FINS in low-dose,medium-dose and high-dose groups were significantly higher than those in model group(P<0.01),but the contents of TG,CHO,LDL-C and the blood glucose was significantly decreased,which had a very significant difference com-pared with the model group(P<0.01).Furthermore,the content of GSP in medium and high dose groups was significantly decreased compared with model group(P<0.01 or P<0.05).H&E staining of the pancreatic tissue showed that the morphology of islet cells of hyperglycemic mice was improved after intragastric administration of SLK extract.The expression levels of insulin(INS)and nuclear factor E2-related factor 2(Nrf2)protein in pancreatic tissue were observed by immunohistochemistry,and verified by Western blot(WB)and real-time fluorescence quantification(RT-qPCR).The results showed that the protein expression levels of INS and Nrf2 were up-regulated,and the high dose group had the best effect(P<0.01).These results indicate that SLK extract can reduce the blood glucose value of hypergly-cemic mice by up-regulating the expression levels of INS and Nrf2 proteins,and improve the damage of islet cells.These findings provide a new reference for clinical treatment of hyperglycemia.