Expression Of MiRNA-29b And Its Related Apoptotic Proteins In Cerebral Ischemia-reperfusion Injury And The Intervention Effect Of Adenosine Preconditioning

BackgroundCerebral infarction is difficult to predict and the incidence tends to be younger and younger,which often brings a heavy burden to the affected families.Neuronal apoptosis caused by ischemia-reperfusion injury mainly occurs in the ischemic penumbra,so preventing neuronal apoptosis in this area may reduce the degree of brain injury during cerebral ischemia.Mi RNA can participate in gene expression,inhibit the translation of m RNA or promote the degradation of m RNA,activate or inhibit a variety of downstream target proteins,and regulate the process of cell death.Adenosine is an active substance related to energy metabolism in vivo.Many studies have confirmed that adenosine preconditioning has a protective effect on the brain.However,the exact mechanism has not been clearly studied.ObjectiveThe purpose of this study is to investigate the changes of miRNA-29 b expression and its related apoptotic proteins in ischemia-reperfusion,and to explore the effect of adenosine pretreatment in cerebral ischemia-reperfusion.Methods135 healthy male SD rats are randomly divided into sham operation group(Sham group),ischemia reperfusion group(I/ R group)and adenosine preconditioning group(AP group).The model of middle cerebral artery occlusion(MCAO)is established.The neurobehavioral score is used to investigate the effect of cerebral ischemia reperfusion injury on the neurological function of rats.The brain tissue sections are stained with triphenyltetrazolium chloride(TTC),and the cerebral infarction volume is calculated.HE staining is used to observe the survival of neurons in the cerebral cortex of rats.Real-time fluorescence quantitative polymerase chain reaction(RT-q PCR)is used to detect the expression of miRNA-29 b at 2h,6h,24 h and 48 h after operation.Western Blot is used to detect the expression of apoptotic protein related to miRNA-29 b in brain tissue of rats in each group at the corresponding time after operation.Results(1)After adenosine preconditioning,the neurobehavioral score of rats is significantly improved,and the degree of cerebral infarction are significantly decreased by TTC staining and HE staining compared with I/R group.(2)Compared with Sham group,the expression of miRNA-29 b in AP group are lower than that in Sham group.Compared with Sham group,the expression of miRNA-29 b in AP group increased significantly within 6 hours of reperfusion and begin to decrease gradually after 6 hours of reperfusion.The expression of miRNA-29 b in brain tissue of rats in AP group at 2h,6h,24 h and 48 h after ischemia and reperfusion are higher than that in I/R group(P < 0.05).(3)The expression of p-Akt in brain tissue of rats in AP group are significantly lower than that in I/R group at all stages of reperfusion,but the expression of Bcl-2 and Mcl-1 in AP group are significantly higher than that in I-hand R group(P < 0.05).The expression of Akt in),AP group are not significantly different from that in I/R group.Conclusion(1)Adenosine preconditioning can improve the neurobehavioral score of rats,improve the morphological changes of nerve cells after ischemia-reperfusion,and reduce the volume of cerebral infarction.(2)The expression of miRNA-29 b may be related to the severity of cerebral ischemia and the time of reperfusion.Adenosine preconditioning can significantly up-regulate the expression of miRNA-29 b in the early stage of cerebral ischemia-reperfusion and reduce cerebral ischemia-reperfusion injury.(3)Mi RNA-29 b can reduce cerebral cell apoptosis induced by ischemia-reperfusion injury by down-regulating the phosphorylation level of target protein Akt and promoting the expression of anti-apoptotic proteins Bcl-2 and Mcl-1.