Protective Effect And Mechanism Of Cordycepin On High-glucose And Palmitate-induced Impairment INS-1 Cells

Diabetes mellitus（DM）is a metabolic disease with clinical manifestations of hyperglycemia,characterized pathologically by damage to pancreatic islet cells and insufficient insulin secretion.The pathogenesis of diabetes mellitus is complex,but it is certain that it is inseparable from the damage of pancreatic islet beta cells.Due to modern people’s preference for high-sugar and high-fat diets,the internal blood glucose and lipid levels often exceed normal levels,and the long-term high concentrations of blood glucose and lipid directly produce toxic damage to pancreaticβ-cells in the body,which in turn leads to a decrease in insulin secretion,resulting in glucolipotoxicity.Glucolipotoxicity affects the vitality ofβ-cells,causing a decrease inβ-cell quality and even apoptosis,which leads to higher than normal blood glucose levels in the body,leading to the development of type 2 diabetes when the body is exposed to high blood glucose for a long time.Cordycepin（3’-Deoxyadenosine,3′-Deoxyadenosine）,is a nucleotide composed of adenosine and deoxypentose with carbon branches,it is also a nucleoside antibiotic and belongs to alkaloids.The main pharmacological effects of cordycepin are anti-inflammatory,antibacterial,antioxidant,anticancer,immune modulation,hypoglycemia,etc.However,the molecular mechanism of the pharmacological effects of cordycepin in the treatment of diabetes has not been fully explained,and further research is needed.In this study,we used MTT,ELISA,fluorescence probe,cell flow assay,real-time quantitative PCR（RT-q PCR）and western blot to investigate the effect of cordycepin on diabetes mellitus at the cellular molecular level.The effects of cordycepin on mitochondrial energy metabolism,apoptosis and insulin secretion and synthesis in INS-1 cells under high glucose and palmitate environment and the related mechanisms were investigated at the cellular molecular level.1.Effects of cordycepin on mitochondrial energy metabolism of INS-1 cells cultured under high sugar and palmitate environment:INS-1 cells were cultured with high sugar and palmitate to establish a diabetic injury model.The experimental results showed that:（1）Cordycepin could significantly improve the viability and cell survival of INS-1 cells induced by high sugar and palmitate.（2）Cordycepin could reduce the production of reactive oxygen species（ROS）and enhance the mitochondrial membrane potential（MMP）in cells damaged by high glucose and palmitate.（3）Cordycepin can increase the content of ATP and down-regulate the expression of UCP-2 m RNA in high glucose and palmitate injury cells.2.The effect of cordycepin on apoptosis of INS-1 cells induced by high glucose and high fat:The results showed that（1）Annexin V-FITC/PI double-staining showed that apoptosis increased in the high glucose and palmitate group compared with the normal control group,and the cordycepin intervention group inhibited apoptosis.（2）JNK,Cyt-c and Caspase3 m RNA expression as well as P-JNK,Cyt-c and Cleaved Caspase3 protein levels were upregulated in the high glucose and palmitate group,and JNK,Cyt-c and Caspase3 m RNA expression as well as P-JNK,Cyt-c and Cleaved Caspase3 protein levels were downregulated in the cordycepin intervention group.3.Effects of cordycepin on insulin secretion and synthesis functions in high-glucose and high-fat induced INS-1 cells:The results showed that（1）cordycepin could improve membrane depolarization and balance intracellular Ca²⁺homeostasis in high-glucose and palmitate environment INS-1 cells.（2）Cordycepin can improve insulin synthesis and secretion function of INS-1 cells damaged by high glucose and palmitate.（3）Cordycepin upregulated the expression of Insulin and PDX-1 m RNA and PDX-1 protein in high-glucose and palmitate injured INS-1 cells.These results indicated that cordycepin could improve energy metabolism in high glucose and high fat environment by reducing intracellular ROS content and UCP-2 expression level;cordycepin could inhibit apoptosis induced by high glucose and palmitate by regulating apoptosis pathway related genes and proteins;cordycepin could increase PDX-1 gene and protein expression to promote insulin synthesis and secretion in INS-1 cells.