Metformin Inhibits Meta-inflammation In β-cells Through The GPR40-PLC-IP3 Pathway

Background and Aim: Metformin,the most widely used anti-diabetic drug in clinical practice,has recently been reported to have an anti-inflammatory effect;nevertheless,its influence on β-cells meta-inflammation remains unclear.The following study investigated how metformin affects meta-inflammatory in glycolipid toxic β-cells,and whether the underlying mechanism is associated with the G protein-coupled receptor 40-phospholipase C-inositol 1,4,5-trisphosphate(GPR40-PLC-IP3)signaling pathway.Furthermore,the relationship between metformin and AMPK was further investigated.Methods: 1.Cell experiment(1)Effect of metformin on β-cell injury induced by palmitic acid or lipopolysaccharide Palmitic acid(PA)or lipopolysaccharide(LPS)induced glycolipid toxic damage or inflammatory damage in βTc6 cells,and treated with different concentrations of metformin.Then,the secretion of insulin and the expression of related proteins were detected,and the effects of metformin on glucosamine toxic damage or inflammatory damage were observed.(2)Effect of metformin on GPR40-PLC-IP3 signaling pathway GPR40,PLC,IP3 inhibitors or agonists were used to interfere with glycolipid-toxic βTc6 cells or inflammatory βTc6 cells,respectively,and then observe whether GPR40-PLC-IP3 signaling pathway is involved in the protective effect of metformin on β-cells damage.(3)Relationship between the effect of metformin and AMPK The relationship between AMPK activity and the protective effect of metformin was observed by using AMPK inhibitor or agonist in metabolic injury βTc6 cells.2.Animal experiment Male SD rats were randomly divided into two groups: normal control diet,and high-sugar,high-fat diet(HSFD),fed for 16 weeks.Rats in the control group or HSFD were subdivided into two subgroups,half of which were given metformin orally for 16 weeks,while the other group continued to be fed for 16 weeks without any intervention.Serum index and related protein levels were detected,apoptosis of islet cells was detected by TUNEL method.The distribution and quantity of α-cells and β-cells in pancreatic tissue were observed by fluorescence immunoassay.Results: 1.Metformin reduced glycolipid toxicity-induced β-cells meta-inflammatory injury in vitro.We observed that metformin decreased apoptosis of β-cells in a concentration-dependent manner,and increased insulin secretion,expression of GPR40 and decreased TLR4 and NF-κB subunit P65 expression.2.The regulation of GPR40 expression altered the protective effects of metformin;Our results showed that up-regulation of GPR40 improved the effect of metformin.Conversely,down-regulation of GPR40 attenuated the protective effects of metformin on β-cells.3.GPR40 was involved in metformin reversing LPS-induced β-cells inflammatory injury.Up-regulation or activation of GPR40 expression enhances the protective effect of metformin on inflammatory damage,while down-regulation or inhibition of GPR40 attenuates this effect.4.Downstream signaling protein PLC-IP3 of GPR40 were both involved in the protective effect of metformin on meta-inflammation,and the above process of metformin was partially independent of AMPK activity.5.The anti-inflammatory effects of metformin were observed in obese rats and diabetic patients.Metformin reduced body weight and inflammatory factors in obese rats,improved islet function,increased the expression of GPR40,PLC,IP3 and p AMPKα,decreased the expression of TLR4 and NF-κB P65 subunit.At the same time,improved the distribution and quantity of α-cells and β-cells in the pancreas.Conclusion: To sum up,we found that metformin could inhibit the metabolic inflammatory damage of β-cells through the GPR40-PLC-IP3 signaling pathway.This study revealed a new pathway for metformin to protect glycolipid toxic cells and provided experimental evidence for GPR40 as a therapeutic target for the treatment of metabolic inflammation injury in β-cells.