| Background: Previous studies demonstrated that remote organ or tissue ischemic preconditioning has clear protective effects on the ischemia/reperfusion in the target organs.Our research also showed that limb ischemic preconditioning in rats can reduce the delayed death of pyramidal neurons in hippocampal CA1 area caused by the instantaneous global brain ischemia,which confirmed the neuroprotective role of LIP.Autophagy,a kind of highly conservative metabolic process generally existing in eukaryotic cells,can achieve the homeostasis of the cell via degrading the damaged,senescent organelles and unfolded proteins and other biological macromolecules in the internal environment by lysosomes.In the studies of organ ischemic diseases,ischemic preconditioning of target organs or distant organs as well as tissues has been proposed to activate the autophagy,which can effectively resist against the damage caused by the subsequent ischemia/reperfusion insult.The aim of the project is to explore whether LIP can protect the global brain ischemia/reperfusion injury in rats by activating autophagy.Objective:This subject is to observe the changes of LC3 and Beclin 1,the marked surface protein of autophagy,in brain ischemia/reperfusion injury in different times and the brain ischemic tolerance induced by limb ischemic preconditioning(LIP)using four vascular occlusion global brain ischemia of rats.Methods:1.The expression of autophagic protein LC3 and Beclin 1 in brain ischemia/reperfusion injury in rats.Animal grouping and methods: 91 male Wistar rats were randomly divided into sham BI and BI groups after two days of permanent occlusion ofbilateral vertebral arteries,and the BI group was further divided into BI 0 h,1h,6 h,12 h,24 h and 48 h subgroups according to the design.We use immunohistochemistry and Western blot to detect the expression of LC3 and Beclin 1 in CA1 region of hippocampus of rats.2.The expression of LC3 and Beclin 1 in rat global brain ischemic tolerance induced by LIP.Animal grouping and methods: 52 male Wistar rats were randomly divided into sham BI,BI,sham LIP+BI and LIP+BI groups after two days of permanent occlusion of bilateral vertebral arteries.The method is the same as before.Results:1.The up-regulation of LC3 and Beclin 1 in brain ischemia/reperfusion in rats1)Immunohistochemistry results shown that the positive expression of LC3 and Beclin 1 were increased gradually in BI group,peaked at 6 h,then decreased.2)Western blot results shown that a weak Beclin 1 band was detected in the sham group of brain ischemia.Compared with the sham group of brain ischemia,Beclin 1 expression in the hippocampal CA1 area was evidently increased at 6 h,and then gradually ameliorated.These results suggested that brain ischemia/reperfusion can activate autophagy.2.The evident up-regulation of LC3 and Beclin 1 in brain ischemic tolerance in rats induced by LIP1)Immunohistochemistry results shown that there was a low level of the expression of LC3 and Beclin 1 in hippocampal CA1 area in the sham BI,BI and sham LIP+BI groups.However,the positive expressions of LC3 and Beclin 1 in the LIP+BI group were evidently increased.There was a significant difference between the LIP+BI and the BI groups.2)Western blot results showed that a weak Beclin 1 was detected in the CA1 area in the sham group of BI.Compared with the sham group of BI,the expression of Beclin 1was significantly enhanced.The expression of Beclin 1 in LIP+BI group was obviously higher than that in BI group,while the expression of Beclin 1 insham LIP+BI group was also increased slightly.The above results showed that LIP played an important role in brain protection by activating the autophagy.Conclusion:1.Brain ischemia/reperfusion injury impaired neurons in hippocampal CA1 area of rats,and the autophagy pathway was activated in this process.2.LIP can up-regulate the expression of LC3 and Beclin 1 in the hippocampal CA1 region of rats,meanwhile reduce the neuronal damage induced by brain ischemia/reperfusion and play neuroprotection. |
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