Effect Of Metformin On Mandibular Osteoblasts In Hyperglycemia

Pathologic changes induced by hyperglycemia in diabetic patients have been considered to contribute to implant failures.Therefore,it plays a key role to reduce the retarding effects of diabetes on bone healing through diabetic control for the placement of implants for those diabetic patients.Systemic insulin and other anti-diabetic drugs treatment may work,but their effects are limited to some extent.As of today,there is no ideal therapeutics in clinic practice.To validate the feasibility of medicine administration of dental implant system raised by Liu Hongchen and enhance implant survival rate,it is very necessary to investigate the effects of widely used anti-diabetic drugs on the partial bone cells to the implants.Metformin is one of the insulin-sensitizing agents most commonly used for the management of type 2 diabetes,which has been widely used for more than four decades.Its efficacy in reducing hyperglycemia and insulin resistance has been proved.However,the direct effect of metformin has rarely been studied.In the present study,we used a model system of primary rat mandibular osteoblasts in culture and focused on the metabolism and glucose uptake of metformin on osteoblasts incubated with high glucose.The possible mechanisms were investigated.It was expected to provide experimental gist for anti-diabetic drug administration of dental implant.Partâ… Effects of metformin on proliferation,differentiation and mineralization of rat mandibular osteoblasts in hyperglycemiaObjective:To explore the effect of hyperglycemia and metformin on proliferation,differentiation and mineralization of rat mandibular osteoblasts to verify the hypothesis of dental implant administration.Methods:Primary osteoblasts were isolated and cultured.Metformin were administrated to cells in medium containing 5.5mmol/L and 16.5mmol/L glucose respectively.Cell proliferation was valuated through MTT assay,and collagenâ… mRNA levels were analyzed by RT-PCR.Alkaline phosphatase(ALP)activity, calcium uptake were determined by biochemistry method,and bone gla protein were detected by radio-immunity assay.Mineralized nodules were quantitated by Alizarin Red S calcium stain.Results:Metformin significantly increased cell proliferation,collagenâ… mRNA expression,calcium uptake,mineralized nodules and calcium deposition incubated with 5.5mM glucose.With 16.5mM glucose,metformin significantly increased ALP activity,collagenâ… mRNA levels.However,bone gla protein, calcium uptake,mineralized nodules formation and calcium deposition were greatly reduced.Conclusions:Metformin of some consistence promotes rat mandibular osteoblasts proliferation,differentiation and mineralization.However,the results that Metformin promotes osteoblasts differentiation but inhibits mineralization with 16.5mM glucose suggest that the effect of metformin may be altered by hyperglycemia.Partâ…¡Effect of metformin on glucose uptake of rat mandibular osteoblasts in hyperglycemiaExperimentâ… Effect of hyperglycemia on glucose uptake of rat mandibular osteoblastsObjective:To explore the effect of hyperglycemia on glucose uptake,glucose transporterl(GLUT1)and GLUT3 expression induced by insulin of rat mandibular osteoblasts.Methods:Primary osteoblasts were isolated and cultured.Cells were incubated for 24h with medium containing 5.5mmol/L and 16.5mmol/L glucose respectively,then treated with or without Ins for 24h.Glucose uptake was detected by using ¹⁸F-FDG in the cells and GLUT1,GLUT3 expression levels were evaluated by Western blot analysis.Results:Insulin significantly promoted ¹⁸F-FDG uptake,and increased GLUT1 expression simultaneously of osteoblasts with 5.5mM glucose.With 16.5mM glucose,glucose uptake has not been materially changed,but GLUT1 expression was increased obviously,Insulin had no significant effect on glucose uptake,butit decreased GLUT1 expression.GLUT3 expression has not been detected with 5.5mM glucose.Hyperglycemia could stimulate GLUT3 expression,Insulin treatment could further up-regulate GLUT3 expression.Conclusions:High glucose can induce insulin resistance of osteoblasts,in which alteration in transport activity and function of GLUT1 and GLUT3 might be involved.Experimentâ…¡Effect of metformin on glucose uptake of rat mandibular osteoblasts in hyperglycemiaObjective:To explore the effect of metformin on glucose uptake,GLUT1 and GLUT3 expression of rat mandibular osteoblasts in hyperglycemia.Methods:Primary osteoblasts were isolated and cultured.Cells were incubated for 24h with medium containing 5.5mmol/L and 16.5mmol/L glucose respectively,then treated with or without metformin and Ins for 24h.Glucose uptake were detected by using ¹⁸F-FDG in the cells and GLUT1,GLUT3 expression levels were evaluated by Western blot analysis.Results:¹⁸F-FDG uptake of osteoblasts that treated with metformin in the absence/presence of insulin was increased significantly in media containing a 5.5mM or 16.5mM glucose.The more stimulation of glucose uptake was reached at group treated with metformin in the presence of insulin.With 5.5mM glucose, GLUT1 expression was increased obviously in osteoblasts treated with insulin or metformin in the absence/presence of insulin.GLUT1 expression was increased with 16.5mM glucose.However,Ins or metformin in the absence/presence of insulin could down-regulate GLUT1 expression.There were no differences between MF treatment with 5.5mM group.However,insulin treatment inhibited GLUT1 expression significantly compared with 5.5mM group.Hyperglycemia could stimulate GLUT3 expression.Insulin or metformin treatment could further up-regulate GLUT3 expression.The most stimulation was reached at group treated with metformin in the presence of insulin.Conclusion:MF could alleviate impaired glucose uptake in insulin resistant osteoblasts,in which regulation in expression and activity of GLUT1 and GLUT3 might be involved.