Effects Of Time Intervals After Ischemic Preconditioning On Ischemia-reperfusion Rats Autophagy

Objectives To research the expression of Autophagy-related proteins Beclin-1, LC3-IIin ischemic preconditioning in rat hippocampal cerebral ischemia-reperfusion,to observethe possible mechanism of autophagy during the nerve cell protection on rat.Methods1.50healthy male SD rats were randomly divided into three groups: sham-operatedgroup, ischemia-reperfusion group, ischemic preconditioning group.And then theischemic preconditioning group were subdivided into24h subgroup,72h subgroup and5dsubgroup.2.Making arterial ischemic preconditioning and ischemia-reperfusion model inrat brain refer to Zea-Longa suture method.3.To observe the volume of infarct,thepathological changes of hippocampal neurons,the expression of hippocampal neuronsautophagy-related proteins Beclin-1and LC3-II,using TTC staining,photoshop imageanalysis,HE staining,immunohistochemistry.4.To observe the change of autophagyultrastructure in nerve cells by transmission electron microscope.5.To compare theneurological deficits in each group,the volume of infarct,the pathological changes ofhippocampal neurons,the expression of hippocampal neurons autophagy-related proteinsBeclin-1and LC3-II,the number of autophagosome and all levels of autophagy-lysosome.6.To analyze the data using SPSS19.0statistical software after finishing withExcel database. The resulting data are expressed by±s,P<0.05was consideredstatistically significance. To draw using Microsoft Excel software.Results1.The neurological deficit symptoms of ischemic preconditioning group wasimproved comparing with ischemia-reperfusion group,and the difference is statisticallysignificant (P<0.05).2.Compared with the ischemia-reperfusion group,the volume ofinfarct of ischemic preconditioning group was decreased,and the difference isstatistically significant (P<0.05).3.The nerve cells in the sham-operated group withoutdamage can be seen by HE staining. Compared with, the harm of the hippocampalneurons in each ischemic preconditioning subgroup were lighten.4.Compared with sham-operated group,the expression of Beclin-1in ischemia-reperfusion group and ischemicpreconditioning group was significantly enhanced,and the difference is statistically significant (P<0.05);The number of Beclin-1positive cells were reduced in ischemicpreconditioning group comparing with ischemia-reperfusion group,and the difference isstatistically significant (P<0.05).5.Very few LC3-II positive cells express in sham-operated group,but a lot of LC3-II positive cells can be seen in ischemia-reperfusiongroup and ischemic preconditioning group,and the difference is statistically significant(P<0.05). The expression of LC3-II positive cells in each ischemic preconditioningsubgroup was significantly lower comparing with ischemia-reperfusion group,and thedifference is statistically significant (P<0.05).6.Autophagosome and autophagy-lysosomein different period can be seen in ischemic preconditioning group and ischemia-reperfusion group.And the number was significantly reduced in ischemic preconditioninggroup.7.The volume of infarct decreased of72h subgroup was improved comparing with24h subgroup and5d subgroup(P<0.05), the damage of hippocampal neurons lighten,thenumber of Beclin-1and LC3-II positive cells reduced by different levels(P<0.05),meanwhile the formation of autophagosome and the activation of lysosome were less.Conclusions1.The arterial ischemic preconditioning and ischemia-reperfusion model in rat brainreferred to the modified Zea-Longa suture method are feasible.And the data isreliable.2.The ischemic preconditioning can reduce the neurological deficit score of ratsafter ischemia reperfusion for24hours,the volume of infarct,the damage of hippocampalneurons,and has a positive effect to the damage of nerve cell after ischemia-reperfusion.3.Ischemic-preconditioning protects brain tissues from injury by lowing theexpression of autophagy-related proteins Beclin-1and LC3-II after ischemia-reperfusionfor24hours, reducing the volume of infarct, reducing the autophagic death of ischemia-reperfusion injury of nerve cells, alleviating the symptoms of neurological deficit.4.Thevolume of infarct in72h subgroup is lower than24h subgroup and5d subgroup, thenumber of Beclin-1and LC3-II positive cells is lowe, the number of autophagosome andall levels of autophagy-lysosome is less occasionally.It is suggested that the bestpretreatment induction time intervals is72h.