The Pretective Effect And Mechanism Of Morpholinoethyl Ester Of Mycophenolic Acid On Myocardial Ischemia-reperfusion Injury In Rats

Myocardial ischemia reperfusion (MI/R) injury is a complex pathophysiologic process which has been found to play important role in serious acute and chronic heart diseases such as acute myocardial infarction and angina pectoris. Although the exact mechanism responsible for MI/R injury is poorly understood, it has been generally accepted that inflammatory response and accumulation of neutrophils play a pivotal role in the pathogenesis of Ml/R injury。Toll-like receptor4(TLR4), one of the pattern recognition receptors, has been found to play a crucial role in the induction of inflammatory response and its activation has been linked to the activation of nuclear factor kappa B (NF-κB). Up-regulation of TRL4/NF-κB signaling pathway stimulated the release of cytokines including tumor necrotic factor a (TNF-a) and interleukin1(IL-1), and also induced the infiltration of leukocytes and monocytes. TNF-a in turn can initiate the inflammatory reaction during MI/R. TNF-a has a negative inotropic effect, which can impair the systolic function of the myocardium, lower the blood pressure, and also promote neutrophil adhesion to endothelial cells, thus amplifying inflammation. Biside, TLR4activation and increased realeased of TNF-a could aggregate cell apoptosis, so a therapeutic approach capable of inhibiting both the TLR4pathway and subsequent cell apoptosis might be of potential to become an effective strategy for treatment of MI/R injury.Mycophenolate mofetil is Morpholino ethyl ester of Mycophenolic Acid and has been successfully applied in prevention and treatment of rejection reaction after organ transplantation. In rat model of ischemia reperfusion injury, MMF treatment effectively prevented the deterioration of renal function and interstitial fibrosis, which was associated with downregulated TLR4signaling and reduced inflammatory responses. MMF could be used as a powerful immunosuppressant in cases of heart transplantation because it could postpone the onset of cardiac allograft vasculopathy (CAV) and reduce its progression. Therefore we speculated that MMF has protective effects against MI/R injury. Part I The protective effects of Mycophenolate mofetil pretreatment on myocardial ischemia and reperfusion injury in ratsObjective:The aim of the present study was to investigate the protective effect of Mycophenolate mofetil (MMF) on myocardial ischemia reperfusion injuryMethods:30healthy male SD rats were randomly divided into3groups:①sham operation group (Sham group),②myocardial ischemia-reperfusion (MI/R) group:the left anterior descending coronary artery was ligated for30min and followed by90min of reperfusion③MMF group.20mg/kg MMF was daily administered by gavage5days prior to the induction of ischemia until the animals were killed. Myocardial infarct size was determined by NBT staining technique and a digital imaging system; myocardial pathological changes were observed by HE staining; LDH and CK activity were determined by ELISA.Results:Compared with sham group, Myocardial infarct size (P<0.05) and LDH and CK activity (P<0.05) were significant increased in the MI/R group. The myocardium form the MI/R group showed local swelling, myocardial necrosis, distorted cardiac muscles and breaked fibers by HE staining. Pretreatment of MMF before MI/R could attenuate the morphological change of myocardial tissue, decreased the infracted sized, and the activity of LDH and CK.Conclusion:MMF pretreatment could attenuate MI/R injury. Part Ⅱ The effects of Mycophenolate mofetil on myocardial apoptosis induced by myocardial ischemia reperfusion injuryObjective:The aim of the present study was to investigate the effects of Mycophenolate mofetil (MMF) on myocardial apoptosis induced by myocardial ischemia reperfusion injuryMethods:Ischemia was produced by ligating the left anterior descending coronary artery.30healthy male SD rats were randomly divided into3groups:①sham operation group (Sham group),②myocardial ischemia-reperfusion (MI/R) group:the left anterior descending coronary artery was ligated for30min and followed by90min of reperfusion③MMF group.20mg/kg MMF was daily administered by gavage5days prior to the induction of ischemia until the animals were killed. The mitochondrial membrane potential (MMP) was determined by JC-1assay; The pretein level of Bcl-2、 Bax and caspase-3were determined by western blot.Results:Compared with sham group, MMP and Bcl-2protein expression were decreased, while Bax and caspase-3expression level were increased in the MI/R group. Pretreatment of MMF before MI/R could increased the MMP and Bcl-2expression, decreased Bax and caspase-3expressionConclusion:MMF pretreatment could attenuate myocardial apoptosis induced by MI/R injury. Part Ⅲ The effects of Mycophenolate mofetil on myocardial inflammatory response and inflammatory signaling pathway induced by myocardial ischemia reperfusion injuryObjectiverThe aim of the present study was to investigate the effect of Mycophenolate mofetil (MMF)’on myocardial inflammation and inflammatory signaling pathway induced by myocardial ischemia reperfusion injury.Methods:Ischemia was produced by ligating the left anterior descending coronary artery.30healthy male SD rats were randomly divided into3groups:①sham operation group (Sham group),②myocardial ischemia-reperfusion (MI/R) group:the left anterior descending coronary artery was ligated for30min and followed by90min of reperfusion③MMF group.20mg/kg MMF was daily administered by gavage5days prior to the induction of ischemia until the animals were killed. TLR4expression was determined by immunohistochemistry and western blot; nuclear protein NF-κBp65expression was determined by western blot. TNF-α and MPO were measured by ELISA.Results:compared with sham group, TLR4and NF-κBp65were significantly increased (P<0.05), and the level of TNF-a and MPO were significantly increased (P<0.05) in the MI/R group. Pretreatment of MMF before MI/R could decreased the expression of TLR4and NF-κBp65, and the level of TNF-α and MPO content.Conclusion:MMF pretreatment could attenuate myocardial inflammatory response, and inhibit TLR/NF-κB activation induced by MI/R injury.