| Objective:To explore the therapeutic effect and mechanism of Momordica grosvenori saponins（MGS）on type 2 diabetes（T2DM）rats replicated by high-sugar and high-fat diet combined with streptozotocin（STZ）.Methods:The model of type 2 diabetic rats were established by feeding high-fat and high-sugar diet for 6 weeks combining with low-dose streptozotocin（STZ）.The successful model rats were randomly divided into 5 groups according to their body mass,including,the model group,the metformin group(268 mg·kg-1)and the MGS(100,200,400mg·kg-1).Rats in normal group and model group were given purified water(10m L·kg-1)by gavage,metformin group and MGS dose group were given corresponding concentrations of metformin or MGS solution(10 m L·kg-1),once a day,the administration was last for 30 consecutive days,and fasting blood glucose（FBG）was measured once a week.On day29 of administration,oral glucose tolerance test（OGTT）was performed,and a Roche blood glucose meter was used to detect changes in blood glucose levels.The rats were anesthetized with chloral hydrate on day30 after administration.After blood samples were taken from the abdominal aorta,the rats were sacrificed and the pancreas,liver and kidneys were collected.The biochemical detection technology was used to detect alanine aminotransferase（ALT）,aspartate aminotransferase（AST）,urea nitrogen（BUN）,creatinine（CREA）,triglycerides（TG）,cholesterol（TC）,low-density lipoprotein（LDLC）,high-density lipid Protein（HDLC）levels.Fasting serum insulin（FINS）,leptin（LEP）,adiponectin（ADPN）levels were detected by ELISA kit,and insulin sensitivity index（ISI）was calculated.The levels of superoxide dismutase（SOD）and malondialdehyde（MDA）in liver were detected by enzyme labeling method,and the levels of catalase（CAT）were detected by ultraviolet spectrophotometry.Pancreas,liver,and kidney tissues were analyzed for pathological analysis of HE stained sections;network pharmacology technology was used to construct a"drug-disease-target"network relationship diagram to obtain the relevant targets and pathways of MGS acting on T2DM;Animal experiments were used to verify the mechanism of network pharmacology screening:RT-PCR was used to detect the m RNA expression of insulin receptor substrate-2（IRS-2）,phosphatidylinositol-3-kinase（PI3K）,protein kinase B（Akt）and glucose transporter 4（GLUT-4）,and Western Blot（WB）was used to detect the expression of IRS-2,PI3K,Akt,GLUT-4 protein in liver tissue.Results:Compared with the model group,the general state index,the body mass of each dose group of MGS was significantly increased,the symptoms of polydipsia,polyphagia and polyuria were alleviated,and the differences were statistically significant（P<0.05 or P<0.01）;Glucose metabolism index,the FBG,FINS,ISI and OGTT values of each dose group of MGS were significantly decreased（P<0.05 or P<0.01）; biochemical function index,the levels of serum ALT,AST,BUN,and CREA in each dose group of MGS were significantly decreased（P<0.05or P<0.01）;lipid metabolism indexes,the serum TC,TG,LDL-C and LEP levels of MGS groups were significantly decreased（P<0.05 or P<0.01）,HDL-C and ADPN levels were significantly increased（P<0.05or P<0.01）;HE stained pathological sections,the pathological changes of pancreas,liver and kidney in MGS groups significantly alleviated; oxidative stress indicators,the content of MDA in MGS groups was significantly decreased（P<0.05 or P<0.01）,and the activities of SOD and CAT were significantly increased（P<0.05 or P<0.01）;133 potential targets for MGS and 5025 targets for T2DM were screened through the database.Through network visualization and PPI node analysis of MGS and T2DM,VEGFA and STAT3 were verified to be the core nodes connecting other nodes.Through GO and KEGG pathway enrichment analysis,PI3K Akt,c AMP signaling pathway,insulin resistance and other signaling pathways with higher scores were obtained;the m RNA of IRS-2,PI3K,Akt,GLUT-4 and protein expression of IRS-2,PI3K,Akt,GLUT-4 in liver tissue of MGS groups were significantly up-regulated（P<0.05 or P<0.01）.Conclusion:（1）MGS can decrease blood glucose,improve glucose metabolism,increase insulin sensitivity,and improve insulin resistance in type 2 diabetic rats.（2）MGS can adjust the blood lipid level and improve lipid metabolism in type 2 diabetic rats.（3）MGS can reduce the damage of pancreatic isletβcells,alleviate the pathological changes of liver,pancreas and kidney tissues in type 2diabetic rats,and has a certain protective effect on the tissue and function of pancreas,liver and kidney.（4）MGS can improve the ability of anti-oxidative stress and improve the state of oxidative stress in type 2 diabetic rats.（5）The results of the network pharmacology study showed that the MGS improve type 2 diabetes through multiple targets and multiple pathways,and the PI3K/AKT signaling pathway was selected to verify.It was found that the MGS up-regulate the m RNA and protein expression of key molecules（IRS-2,PI3K,Akt and GLUT-4）in the PI3K/Akt signaling pathway of liver tissue of type 2 diabetic rats by activating the liver PI3K/AKT signaling pathway,which it may be the intrinsic molecular mechanism of anti-type 2 diabetes. |
