桑叶多糖降血糖作用及其机制研究

目的探讨桑叶多糖降血糖的作用机制。方法以四氧嘧啶诱导小鼠糖尿病模型,桑叶多糖以0.25、0.50、1.00 g/kg ig给药,连续6周,每周称体质量;在实验2、4、6周末各测空腹血糖;实验末期进行糖耐量试验,测定糖化血清蛋白、血清胰岛素水平;测定肝组织肝糖元、肝匀浆蛋白水平及己糖激酶(HK)、丙酮酸激酶(PK)、超氧化物歧化酶(SOD)、谷胱甘肽过氧化物酶(GSH-Px)活性和丙二醛(MDA)水平。结果桑叶多糖能明显缓解糖尿病小鼠症状;具有明显控制糖尿病小鼠空腹血糖值升高,降低糖化血清蛋白和血糖曲线下面积的作用;具有促进血清胰岛素、肝HK的分泌和肝糖元的合成,提高肝SOD活性,降低肝MDA水平,促进体质量恢复的作用;桑叶多糖中剂量还具有促进肝PK分泌的作用,而对肝GSH-Px活性影响不明显;糖尿病小鼠肝脏、肾脏和脾脏指数均增高,桑叶多糖具有降低脏器指数的作用。结论桑叶多糖通过提高四氧嘧啶糖尿病小鼠抗氧化能力,使胰岛素分泌增加,同时提高肝HK、PK活性等综合作用,促使血糖进入肝细胞,使肝糖元合成增加,葡萄糖氧化分解加快,从而达到调节糖代谢、降低血糖、改善糖尿病症状的作用。

Hypoglycemic effects and mechanism of mulberry leaves polysaccharide

Objective To investigate the hypoglycemic mechanism of mulberry leaves polysaccharide(MLP) in diabetic mice.Methods Alloxan-induced diabetic model of mice was continuously ig administered with the distilled water,MLP at doses of 0.25,0.50,and 1.00 g/kg,respectively for six weeks.Body weight was recorded weekly.Blood samples were collected for measurement of blood glucose at the 2nd,4th,and 6th weekends after fasting for 5 h.Glucose tolerance test was carried out and femoral artery blood was taken to measure the glycosylated serum proteins(GSP) and the blood serum insulin content at the 6th weekend.The liver glycogen,homogenate protein content,hexokinase(HK),pyruvate kinase(PK),SOD,GSH-Px activity,and MDA level were measured in the end of the experiments.Results Symptoms of diabetic mice fed with MLP were improved.The blood glucose level,the area under curve of the blood glucose,and GSP of diabetic mice fed with MLP decreased obviously.Their blood serum insulin,liver glycogen synthesis,HK secrection,SOD vitality,and body weight increased significantly.However,their MDA content decreased obviously.The PK vitality of diabetic mice fed with MLP at dose of 0.5 g/kg increased significantly,while there was little effect on GSH-Px activity.The ratios of liver,kidney,and spleen to body weight increased obviously in diabetic mice,but decreased obviously in the diabetic mice fed with MLP.Conclusion It is suggested that MLP has the effects of enhancing their anti-oxidation by increasing SOD vitality and decreasing MDA content in diabetic mice.Through promoting insulin secretion and improving liver HK and PK vitality to promote blood glucose to enter the liver cells,glycogen synthesis,glucose oxidation,and decomposition are accelerated,and MLP can regulate the glucose metabolism,reduce blood sugar,and improve the symptoms in alloxan-induced diabetic mice.