| Objective: To investigate the anti-diabetic activity and mechanism of polysaccharide from Lycopus lucidus turcz(LLP)at animal and molecular cellular levels.Methods:Polysaccharide was extracted from Lycopus lucidus turcz by hot water extraction and ethanol precipitation.Based on single factor experiment,response surface methodology was used to optimize the extraction process of polysaccharide from Lycopus lucidus turcz.and the antioxidant activity of polysaccharide from Lycopus lucidus turcz.was investigated.Streptozotocin(STZ)was used to construct a mouse model of induced diabetes,and the constructed diabetic mice were randomly divided into five groups.Fasting blood glucose(FBG),serum insulin and oral glucose tolerance were measured to detect the hypoglycemic effect of LLP on diabetic mice in each group;the contents of total cholesterol(TC),triglyceride(TG),low-density lipoprotein(LDL)and high-density lipoprotein(HDL)in the serum of mice in each group were measured to detect the hypolipidemic effect of LLP on diabetic mice;superoxide dismutase(SOD)and glutathione peroxidase(GSH-PX)in the serum of mice in each group were measured to detect the antioxidant effect of LLP on diabetic mice;HE staining was used to detect the improvement and repair ability of LLP on the kidney,liver and pancreas tissues of diabetic mice;real time-PCR assay was used to detect the effect of LLP on the gene expression of insulin and its receptor(Ins R),insulin receptor substrate-1(IRS-1)and glucose transporter 4(GLUT4)in the liver,kidney and pancreas tissues of diabetic mice;Western blotting was used to detect the effects of LLP on the protein expression of insulin and its receptor(Ins R),insulin receptor substrate-1(IRS-1),and glucose transporter-4(GLUT-4)in the liver,kidney,and pancreas tissues of diabetic mice;immunofluorescence was used to detect the effects of LLP on the protein expression of insulin and its receptor(Ins R),insulin receptor substrate-1(IRS-1),and glucose transporter 4(GLUT4)in the liver,kidney,and pancreas tissues of diabetic mice.Thus,the effect of LLP on the insulin signaling pathway was understood.Results: The extraction of Lycopus lucidus turcz.polysaccharide was performed according to the steps,and the extraction process of Lycopus lucidus turcz.polysaccharide was preferably selected.The analysis results showed that the best extraction process parameters of Lycopus lucidus turcz.polysaccharide from Yunnan Province were the material-liquid ratio of 1:20 g/m L,the extraction temperature of70 ℃,the extraction time of 3 h,and the number of extraction times of 3 times,and the yield of Lycopus lucidus turcz.polysaccharide reached(31.69±0.78)% under these conditions.Lycopus lucidus turcz.polysaccharides from Yunnan Province showed good scavenging effect on both DPPH free radicals and ABTS free radicals.A preliminary study on the hypoglycemic and hypolipidemic as well as antioxidant ability of Lycopus lucidus turcz.polysaccharides was conducted by establishing a diabetic mouse model through high sugar and high fat diet and STZ induction.The results showed that the blood glucose,serum insulin,TC,TG and LDL-C in the serum of the diabetic model group(DM group)were significantly higher than those in the blank control group(NC group);the levels of HDL-C,SOD and GSH-Px were lower than those in the blank control group,and insulin resistance existed in the diabetic mice,and H Lycopus lucidus E staining of liver and kidney tissues also showed obvious lesions,suggesting that the diabetic modeling Successful.The gavage of medium and high doses of Lycopus lucidus turcz.polysaccharide significantly improved the weight loss and reduced the intake of food and water in type 2 diabetic mice;it effectively reduced the fasting blood glucose and improved the glucose tolerance,i.e.,the glucose regulation ability of diabetic mice,and also improved the insulin resistance in diabetic mice;it increased the serum HDL-C level and reduced the TC,TG and LDL-C levels in diabetic mice,and improved the abnormal blood glucose level in diabetic mice.levels and improved the abnormal ester metabolism in diabetic mice;to some extent,it repaired the liver and kidney of diabetic mice and improved the damage to liver and kidney tissues caused by diabetes and had a protective effect;it was suggested to have an effect on increasing superoxide dismutase(SOD)and glutathione peroxidase(GSH-Px)activity in the serum of diabetic mice and could improve the antioxidant capacity of diabetic mice.Real time-PCR,Western blotting and immunofluorescence assays were performed to investigate the regulatory effects of Lycopus lucidus turcz.polysaccharide on key factors in the insulin signaling pathway.The results showed that Lycopus lucidus turcz.polysaccharide upregulated the expression of key molecules in the insulin signaling pathway,insulin receptor(Ins R),glucose transporter-4(GLUT-4)and insulin receptor substrate-1(IRS-1),at the This suggests that the ability of Lycopus lucidus turcz.polysaccharide to regulate blood glucose in diabetic mice may be achieved by regulating the insulin signaling pathway,thereby altering the abnormalities of glycogen synthesis and glucose metabolism in diabetic mice.Conclusion: The experimental results of this experiment showed that the obtained Lycopus lucidus turcz.polysaccharide extraction process is stable and feasible,and Lycopus lucidus turcz.polysaccharide has good antioxidant activity and has the effect of improving abnormal glucose metabolism and lipid metabolism in diabetic mice,and its specific mechanism of occurrence may be related to the fact that Lycopus lucidus turcz.polysaccharide has the activity of regulating the key factors in insulin signaling pathway. |
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