Mechanisms Of High Sugar Affect Visfatin Expression In Rat Myocardial Cells

Objective: As an adipokine,visfatin is identified in2004, and visfatin ishighly preserved across animal evolution.It has confirmed that visfatin is theinsulin analogues. It can reduce glucose concentration in the plasma, increasethe production of cytokines and induce the generation of vascular. Its role maybe related to the proinflammatory of adipokine.Diabetes (diabetes mellitus, DM) as endocrine and metabolicdiseases.Diabetic cardiomyopathy is one of the cardiovascular complicationsof diabetes,which is closely related to the high incidence of heart failure andhigh mortality of diabetic patients.The promoting proliferation and Yandengrole of visfatin may play a role in the pathological process of diabeticcardiomyopathy.There has been a lot of study on the role of visfatin in thecardiovascular system, but so far there has been no study about the visfatinexpression of heart cells in high glucose conditions. The early part of thisexperiment has been explored that the secretion of visfatin has concentration-time dependence with high sugar,but pathway by which high glucose mediatedthe expression of visfatin has been unknown.Numerous studies show that MAPK pathway can be activated in theeffect of high sugar in the process of diabetic nephropathy.Then MAPKpathway can activate a variety of nuclear transcription factor and leading toincreased expression of target genes.There is no in-depth study of MAPKpathway in diabetic cardiomyopathy. This study was to investigate themechanism of the MAPK pathways in the visfatin secretion stimulated by highglucose, This study will provide an important theoretical basis and guidancefor the clinical treatment of diabetes and reduction the damage of diabetes onmyocardial.The pre-test study has proven that SD rat cardiac myocyte could express visfatin. Simulating a high glucose environment,we observed within a certaintime frame,and found that the secretion of visfatin has concentration-timedependence with high sugar.The early study results show that cardiomyocytespretreated with increasing concentrations of glucose (5.5mmol/L,10mmol/L,30mmol/L,50mmol/L) for48hours.The expression of visfatin is increased ina dose-dependent manner peaking at a glucose concentration of50mmo1/L.Visfatin expression in myocardial cells exposed to50mmol/L is higher thanthe cells exposed to30mmol/L, but never reached statistical significanc.Cardiomyocytes exposed to the glucose concentration of30mmo1/L.Wedetected at6h,12h,24h and48h.The result showed that the expression ofmyocardial visfatin reach to the peak at24h.Methods: Primary cultures the cardiomyocytes from the hearts of2-3days’ neonatal Sprague-Dawley (SD) rats aseptically. cardiomyocytes culturedwith serum48hours and without serum24hours, then cells in good conditionsare selected and put into5groups randomly:(1)low glucose (5.5mmol/L),(2)high glucose(30mmol/l),(3)high glucose and SP600125(10mmol/l),(4) highglucose and PD098059(10mmol/l),(5) high glucose and SB203580(10mmol/l).Using the following inhibitors respectively:SP600125[c-Jun NH2-terminalkinase (JNK);10μmol/L)],PD098059[extra cellular signal-regulated kinase(ERK1/2);10μmol/L)] and SB203580[p38mitogen-activated protein kinase(MAPK),p38MAPK;10μmol/L)].Cells were exposed to inhibitors for30minutes prior to the addition of30mmol/L glucose and incubated for24hours.RT-PCR is used to detect the expression level of myocardial visfatinmRNA and Elisa is used to detect visfatin protein content in culture fluid at24hour respectively.Results: We pretreated myocardial cells with high glucose conditionsand results are as follows.The expression of visfatin mRNA and visfatinprotein in the high glucose+SB203580group are significantly decreased butstill higher than that in the low glucose group; The expression of visfatinmRNA and protein in the high glucose+PD098059group and high glucose+SP600125are higher than that in low glucose group and have no significantly difference with the high glucose group.Conclusion: p38MAPK is an important pathway in highglucose-induced visfatin expression in cardiac myocytes,which may be one ofthe mechanisms of myocardial cell damage caused by diabetes.