Study On The Protective Effect Of BFGF On Mycardiol Ischemia-reperfusion Injury By Inhibiting Endoplasmic Reticulum Stress

BackgroundIschaemic heart disease, which is secondary to acute myocardial infarction, isone of the most prevalent disease in the world and is a common refractory disease ofhigh morbidity and mortality. After ischaemia, myocardial reperfusion isaccompanied by a long period of secondary myocardial injury which may includeoxidative stress, inflammation, apoptosis and necrosis. The loss of myocardial cells isthe major factor that interferes with recovery from the secondary damage. Severalprevious studies have indicated that bFGF delivered during reperfusion protectsagainst ischaemia-reperfusion injury. However, as a multifunctional nutritional factor,the protective effect of basic fibroblast growth factor on oxidative stress-induced celldeath observed in the myocardial I/R model is not yet fully understood. In ourprevious study, we have confirmed that the administration of bFGF immediately afterreperfusion protected the heart from ischaemia/reperfusion induced injuries. However,the molecular mechanism of bFGF in the treatment of myocardial injury in theearly-stage after reperfusion is still unclear. Therefore, in this study, we aimed toelaborate on the molecular mechanism of bFGF treatment in the recovery frommyocardial I/R injuries.MethodsIn vivo, Adult male C57/B6mice (8–12weeks) were supplied by the AnimalCenter of the Chinese Academy of Sciences. Experimental I/R model was induced bytransient myocardial ischaemia for30min, and was followed by reperfusion for4hours. The mice that survived from surgery were randomly assigned to the differenttreatment groups which are sham operation mice, I/R mice and bFGF treated I/R mice.the recovery of function was observed by Echocardiography, the number of cellapoptosis was detected by TUNEL staining, The expression levels of ER stress-relatedprotein were analyzed by Western Blot and Immunofluorescence staining.In vitro, Oxidative damage model of H9C2cells by TBHP were established.Flow cytometry detected the number of apoptosis cell. To further understand the mechanism underlying behind the effect of bFGF on I/R injury, Based on the currentresearch and our data in the experiment, Using LY294002and PD98059to inhibit thePI3K/Akt and ERK1/2pathways respectively, p-Akt, p-ERK and ER stress-relatedprotein expression after myocardial cell oxidative stress were detected by westernblot.Results1. bFGF was delivered into the mouse myocardium at30min after ischaemia.2-D echocardiographic was used to monitor cardiac contractility. After3days withnormal feeding, the LVEDd and LVESd of the I/R group are statistically higher thanthe normal animals. By contrast, bFGF treated animals had lower LVEDd and LVESdvalues compared to the myocardial I/R groups. The left EF and FS decreasedsignificantly from the animal model group.2. In the TUNEL fluorescent staining of myocardial tissue, the positive cells ofapoptosis in ischemia-reperfusion injury group was significantly increased, comparedwith the control group, after the bFGF treatment, the number of apoptotic cellsdecreased significantly. In addition, The protein expression of cleaved caspase-3andcleaved caspase-12in bFGF treatment group is lower than I/R injury group.3. bFGF treatment inhibited the activation of ER stress-related proteins in theischaemic heart, bFGF treatment increased the phosphorylation of Akt and ERK1/2inthe hearts of I/R mice when compared with the control group.4. In vitro, the apoptosis of H9C2cell induced by hydroperoxide (TBHP) wasdecresed under the bFGF treatment. bFGF activated PI3K/AKT and ERK1/2pathwayin H9C2cell, and inhibited ER stress-related protein expression induced by TBHP inH9C2cells.Conclusions1. bFGF improves cardiac function after myocardial I/R.2. bFGF decreases myocardial apoptosis in myocardial I/R mouse.3. The protective effect of bFGF in myocardial I/R injury recovery is alsorelated to inhibiting ER stress-related protein expression via the activation of bothPI3K/Akt and ERK1/2pathways.4. In vitro, bFGF also protects H9C2cell from apoptosis. bFGF inhibits ERstress-related protein expression induced by TBHP, via the activation of bothPI3K/Akt and ERK1/2pathways.