Influences Of Oxytocin On Ischemia/reperfusion Injury Of Rat Heart And The MicroRNA Expression Profiling

Objectives:To study the role of oxytocin(OT)in attenuating ischemia/reperfusion injury(IRI),to detect microRNA expression profiling and to predict target genes,target gene functions,and potential signaling pathways.To provide novel insights into investigating underlying mechanism involved in cardioprotection of oxytocin and to further find new targets on IRI.Methods:Thirty two rats were randomly divided into 4 groups:control group(C),ischemia/reperfusion group(IR),ischemia preconditioning group(IP+IR)and oxytocin preconditioning group(OT+IR).Hearts of C group were perfused constantly with K-H buffer for 130 min.Hearts of IR group were subjected to 30min ischemia,followed by 60min reperfusion.5min-ischemia/5min-reperfusion for 3 cycles was applied in IP+IR group.K-H buffer containing 0.01μM OT was perfused for 40 min before ischemia in OT+IR group.LVSP,LVEDP,HR,and±dp/dt max were recorded at different time points.Then LVDP,RPP were calculated.LVDP,RPP,hs-cTnT and infarction size were measured to evaluate cardiac injury.microRNA array was used to detect microRNA expression profiling of heart samples in IR and OT+IR group(n=4).qRT-PCR was conducted to validate the differentially expressed microRNAs.Targetscan7.1 and mirdbV5 were used to predict target genes of the differentially expressed microRNAs.Prediction of target gene functions and signaling pathways was performed by GO and KEGG analysis,respectively.Results:Changes in LVDP,RPP,HR,±dp/dt max and hs-cTnT level in C group showed no significance in the whole process,nor did the infarction size(p>0.05).Compared with C group,ischemia/reperfusion led to significant decrease of LVDP,RPP,HR and±dp/dt max,and increase of hs-cTnT and infarction size in IR,IP+IR or OT+IR group(p<0.05).However,differences between IP+IR and OT+IR did not reach significance(.p>0.05).We selected 21 differential microRNAs through analysis of microRNA array.After validation of qRT-PCR,we determined four up-regulated microRNAs(miR-X1,miR-X3,miR-X4 and miR-X9)and four down-regulated ones(miR-X11,miR-X12,miR-X16 and miR-X17)induced by oxytocin preconditioning.Functions of target genes were associated with numerous molecular functions,biological processes and cellular components.KEGG analysis suggested some significant pathways including PI3K-Akt,Wnt,MAPK,Ras pathways and some pathways relating to cancer.Conclusions:(1)Oxytocin exerts attenuation of cardiac IRI with equivalent efficiency to IPC.(2)Oxytocin preconditioning changes microRNA expression profiling in ischemia/reperfusion rat heart.(3)Differentially expressed microRNAs are involved in signaling pathways that refer to cardioprotection.These findings may provide novel insights into cardioprotective effects of oxytocin and targets of myocardial IRI.