桑叶多糖MLPⅡ对糖尿病模型大鼠肝脏胰岛素抵抗的改善作用

Improvement Effect of Polysaccharide MLPⅡ from Mulberry Leaves on Hepatic Insulin Resistance in Diabetic Model Rat

从桑叶中分离纯化获得一种具有降血糖活性的均一多糖组分MLPⅡ,通过检测分析MLPⅡ治疗组糖尿病模型大鼠的胰岛素敏感指数和肝脏生理指标,探究桑叶多糖MLPⅡ对糖尿病模型大鼠肝脏胰岛素抵抗的改善作用。与糖尿病对照组模型大鼠相比,150 mg/kg MLPⅡ治疗组糖尿病模型大鼠肝脏组织中的总胆固醇(TC)、甘油三酯(TG)和丙二醛(MDA)含量分别降低了40.59%、38.58%和52.81%,而肝脏组织中的超氧化物歧化酶(SOD)活性、肝糖原含量和肝脏葡萄糖激酶活性则分别升高了15.88%、198.48%和169.77%,均达到极显著水平。与糖尿病对照组模型大鼠相比,桑叶多糖MLPⅡ治疗组糖尿病模型大鼠的胰岛素敏感指数均明显提高,肝脏的脂肪变性程度明显减轻,其中150 mg/kg MLPⅡ治疗组均达到极显著水平。研究结果提示,桑叶多糖MLPⅡ可显著改善糖尿病模型大鼠的肝脏糖脂代谢和胰岛素抵抗,其作用可能与调节胰岛素的释放和肝脏的氧化应激水平有关。

MLPⅡ,a uniform polysaccharide ingredient isolated and purified from mulberry（Morus L.） leaves,possesses hypoglycemic activity.In this study,we investigated the improvement effect of mulberry leaf MLPⅡ on hepatic insulin resistance in diabetic model rats through measuring and analyzing the insulin sensitive index and hepatic physiological indicators of diabetic model rats in the MLPⅡ-treated group.Compared with model rats in the diabetic control group,the content of total cholesterol（TC）,triglyceride（TG） and malondialdehyde（MDA） in liver tissue of the diabetic model rats in the 150 mg/kg MLPⅡ-treated group was reduced by 40.59%,38.58% and 52.81% respectively,while superoxide dismutase（SOD） activity,glycogen content and glucokinase activity was increased by 15.88%,198.48% and 169.77% respectively,all of which reached extremely significant level.In addition,compared with model rats in the diabetic control group,the insulin sensitive index of diabetic model rats in all MLPⅡ-treated groups was obviously improved,and the degree of hepatic adipose degeneration was obviously alleviated,both reached extremely signifi-cant level in the 150 mg/kg MLPⅡ-treated group.These results suggest that mulberry leaf polysaccharide MLPⅡ can significantly improve hepatic glucose and lipid metabolism,and hepatic insulin resistance in diabetic model rats,and this effect is probably associated with the regulation of insulin release and the response level to oxidative stress in the liver.