Effect And Regulation Of Polysaccharides From Natural Portulaca Oleracea L. On Lipid Metabolism In Type Ⅱ Diabetes

Portulaca oleracea L. is a medicinal and edible plant, and polysaccharide is one of the major functional components. Antimicrobial, antiviral, antioxidant, anti-cancer effects, lowering blood sugar and improving insulin resistance of POP have been reported in many studies. However, reports of POP on lipid regulation and hypoglycemic effect are few, especially mechanism aspects of POP regulating lipid metabolism and reducing blood sugar in the cellular and molecular level research. Therefore, this paper is intended to regard3T3-L1preadipocytes and SD rats as the research objects. From the level of the whole animal、cellular and molecular biology, the mechanisms of lipid regulation、lowering blood glucose and improving insulin resistance of POP were studied. Several experimental studies were carried out from the following aspects:I. Effects of POP on3T3-L1preadipocytes proliferation. Replace with fresh DMEM containing various concentrations of POP medium (0.01～0.5mg/mL) and culture to a predetermined time (1,3,5d). MTT、neutral red dye uptake and LDH assay were used to test cell proliferation levels. MTT assay results showed that POP inhibited3T3-L1preadipocytes cell proliferation in a time and concentration-dependent trends; Similar results were obtained by NRU and LDH release method test. However, compared with MTT test results, they showed differences in sensitivity. The results show that with the increase of POP concentration and prolonged treatment time, the results showed that POP can significantly inhibit the cell proliferation.II. Effects of POP on3T3-L1preadipocytes differentiation. Insulin, IBMX, Dexamethasone were used to induce3T3-L1preadipocyte to mature adipocyte cells; Use oil red O staining to observe the levels of fat deposition in cells and use RT-PCR technique to detect PPAR-y, PKB/Akt, GLUT4expression in the insulin signaling pathway. The results show that high concentrations of POP can regulate adipocyte differentiation by promoting the expression of target genes related to insulin signaling. III. Research of improving insulin resistance in3T3-L1adipocytes by POP. Insulin, IBMX, Dexamethasone were used to induce3T3-L1preadipocyte to insulin resistance model and the levels of medium glucose were measured by glucose oxidase method. Use RT-PCR technique to detect IR、IRS-1、PKB/Akt expression in the insulin signaling pathway. POP can significantly promote glucose uptake and improve insulin resistance by improving the expression of IR、IRS-1、PKB/Akt.IV. Research of regulating lipid metabolism of type II diabetes by POP. A combination of high-fat diet and STZ (30mg/kg) intraperitoneal injection was used to build type II diabetes model which was treated by different concentrations of polysaccharide (25,50,100mg/mL)1week. Blood and relative organization sample were collected to conduct a physiological and biochemical detection, and to test the expression of realated genes. POP can significantly lower blood sugar in diabetic rats, improve glucose tolerance and raise HDL levels and enhance activity of antioxidant enzymes. The results showed that POP can significantly enhance the expression of PPAR-y and IR. The results were similar to those of rosiglitazone. The lipid regulation and hypoglycemic effect of POP were regulated by the expression of PPAR-y and IR.From the results of this paper, POP has good lipid regulation and hypoglycemic effect, and the mechanism is to regulate the expression of insulin signaling pathway in the molecular target. The results of this study can lay the theoretical foundation for the development of functional foods or drugs with hypoglycemic effect and weight loss.