Anti-diabetic Activity Of Polysaccharides From Tuberous Root Of Liriope Spicata Var. Prolifera On IR Cell Model And KKAY Type2Diabetic Mice And Its Probable Mechanisms

Objective: This study was to investigate anti-diabetic activity of polysaccharides fromthe tuberous root of Liriope spicata (Thunb.) var. prolifera （TLSP、LSP1and LSP2）on theHepG2, proliferation of3T3-L1adipocytes and NIT-1cells and the diabetic KKAy miceand its mechanisms of anti-insulin-resistance.Method: The activity of HepG2, proliferation of3T3-L1adipocytes and NIT-1cellwas estimated by MTT method and the glucose consumption of cells was mearured withglucose oxidase method (GOD). Insulin secretion of NIT-1cells was estimated byradioimmunoassay.The KKAy diabetic mice received daily administration of TLSP, LSP1and LSP2atdoses of50,100and200（mg/kg/day）and rosiglitazone at a2mg/kg/day for28days. Inaddition, normal control and diabetic control were treated with vehicle. FBG, OGTT andFINS were measured, TC, TG, HDL and LDL were alse estimated to evaluate theanti-diabetic activity of Liriope spicata (Thunb.) var. prolifera. Immunohistochemistry andwestern blotting were estmited the protein expressions of InsR-α, IRS-1, PI3K and PPARγin liver tissue of KKAy diabetic mice. In addition, liver histological analysis was observedby HE stanning. The hepatic glycogen content, GK and G6Pase activities were alsodetected to evaluate the effects of polysaccharides on glucose metabolism.Results: In vitro study， MTT method showed that absorbance at570nm ofpolysaccharides-treated HepG2, proliferation of3T3-L1adipocytes and NIT-1cell wassignificantly decrease. Glucose oxidase method indicated that TLSP、LSP1and LSP2couldenhanced the glucose consumption of cells, compared with the untreated insulin resistancecell model (P<0.05). Compared with untreated group，insulin secretion level on NIT-1cellsis increased significantly in TLSP, LSP1and LSP2-treated group (P<0.05).In vivo experiment, the type2diabetic KKAy mice were received daily oraladministration of the preparations for28days. TLSP, LSP1and LSP2all caused a markeddecrease of fasting blood glucose (FBG) and a remarkable amelioration on insulin resistance(IR) and serum lipid condition in diabetic models. In addition, liver histological analysis shown that TLSP, LSP1and LSP2ameliorated the hepatocyte hypertrophy andsignificantly decreased the lipid accumulation in KKAy diabetic mice. TLSP, LSP1andLSP2, caused a remarkable lower of FBG, also had a significant amelioration on OGTT andinsulin resistance in KKAy diabetic mice. As well as decreasing total cholesterol (TC),triglyceride (TG). TLSP, LSP1and LSP2were also increse the relative of HDL/LDL. Theresult of immunohistochemistry and western blot indicated that greater positive expressionof immunoprotein for InsR-α, IRS-1, PI3K and PPARγ was observed in the tubulointerstitialregions of TLSP, LSP1and LSP2group compared with diabetic group. The proteinexpression of these four signaling pathway of insulin were marked enhanced in liver tissuesof KKAy mice. The glycogen content of TLSP, LSP1and LSP2groups were remarkableenhanced, and GK activity of TLSP, LSP1and LSP2groups was alse markedly increase, aswell as the G6Pase activity was remarkably decrease.Conclusion: TLSP, LSP1and LSP2present the remarkable activities of amelioatingHypoglycemia, hypolipidemia, hypoinsulinemia and the amelioration of insulin resistance.The mechanisms of insulin resistance may be related with the improvement of insulinsignaling transduction and glucose metabolism.