Study The Hypoglycemic Effect And The Pancreas Proteomics Of Stigma Maydis On Spontaneous Type 2 Diabetic Gk Rats

ObjectiveTo study the hypoglycemic effect of Stigma Maydis aqueous extract on diabetic GK rats and to explore the pancreas proteomics in rats,and to lay a foundation for further research on the pharmacological effects of corn water extract on diabetes and its complications.Methods1.Evaluating hypoglycemic effect of Stigma Maydis on Diabetic GK Rats.15 GK rats(4-week-old,male)were randomly divided into three groups according to body weight and blood glucose levels after 1 week of adaptive feeding: model control group,positive drug control group(Metformin),and Stigma Maydis group,5 rats in each group.At the same time,five male Wistar rats of the same age were as the normal control group.The Stigma Maydis group was treated with Stigma Maydis aqueous extract,the positive drug group was treated with metformin,the model and normal control group were given the same amount of normal saline,and the drug was intervened for 6 weeks.During the experimental period,the general signs of the rats were observed daily,the body weight of the rats was weighed and the fasting blood glucose(FBG)was measured every week;the glycated hemoglobin(GHb)and 24 h Metabolic rate were measured at the 3rd and 6th weekend,the urine were collected at the 6th week.At the end of the 6th week,the urine glucose(U-GLU)was detected by biochemical method;After the intervention,rats in each group were fasted for 12 hours,and 3% of pentobarbital 1.5 m L/kg was injected intraperitoneally.Rats were bled from the heart and biochemical assays were used to detect Creatinine(CREA),uric acid(UA),alanine aminotransferase(ALT),aspartate aminotransferase(AST)and free fatty acid(NEFA),total cholesterol(TC),triglyceride(TG),low-density lipoprotein(LDL-C)and high-density lipoprotein(HDL-C)levels;pancreatic tissue was taken,and the pancreatic tissue surface blood was blotted with filter paper and were stored in a-80℃ refrigerator for follow-up studies.2.Quantitative proteomics was used to investigate the expression of pancreatic protein in diabetic GK rats.Direct extraction method was used to extract pancreatic tissue protein both model control group and Stigma Maydis group.Protein content was measured by Bradford.Protein samples were analyzed by SDS-PAGE and protein samples were separated by capillary HPLC.mass spectrometry analysis of protein samples using Orbitrap Fusion.In the database uniprot-rat＿170221.fasta with the software Mascot and Proteome Discoverer qualitatively and quantitatively analysis the isolated protein,to obtain the total number of peptides and total protein in the sample,then by differential threshold conditions,differential protein screening.GO function analysis was performed on differential proteins to participate in the major biological process.Results1.The results showed that the FBG,GHb,U-GLU,U-TP,U-ALB,U-ALB/U-CREA,24 h metabolism rate,serum CREA,UA,ALT,AST,NEFA,TC,TG,LDL-C and HDL-C levels were significantly higher(P<0.05)in the model group,compared with the normal control group.Compared with the model group,the Stigma Maydis group: FBG,GHb,U-GLU,U-TP,U-ALB,U-ALB/U-CREA,24 h metabolism rate,serum CREA,UA,ALT,AST,NEFA and TC were significantly lower(P<0.05).2.The results showed that(1)There were 2366 proteins and 13306 peptides in the two sample groups by mass spectrometry analysis identified;(2)Differential protein screening results under 1.5 fold difference threshold: Compared with the model group,there were 112 protein up-regulated and 35 protein down-regulated in Stigma Maydis group.Among the proteins related to this study,selenoprotein F(FC=4.19,P=0.019)and HDL-C protein(FC=1.52,P=0.026)were up-regulated in Stigma Maydis group;protein DEK(FC=0.63,P=0.017),Transgelin(FC=0.59,P=0.045),C-reactive protein(FC=0.58,P=0.006)were down-regulated in Stigma Maydis group.(3)GO function analysis of the differential proteins identified revealed the differential protein-associated biological functions identified.The selenoprotein F is located in the lumen of the endoplasmic reticulum and can bind to proteins and undergo protein folding;the HDL-C protein is located in thenucleusand binds to RNA;the protein DEK is located in the nucleus and binds to DNA;the Transgelin is located in the cytoplasm and binds to actin;and the C-reactive protein is located in the cell membrane.Conclusion1.Stigma Maydis can improve blood glucose and blood lipid levels in diabetic GK rats,and it can also improve liver and kidney function indicators.2.The GO function analysis was performed on the identified differential proteins.From the first part,the blood glucose and blood lipid levelsin the Stigma Maydis were decreased in diabetic GK rats,and improves liver and kidney function indicators,possibly related to up-regulate the selenoprotein F and HDL-C protein expression,down-regulate the DEK protein,Transgelin protein and C-reactive protein expression.