ERK1/2和Akt通路对控制性低压后处理兔缺血/再灌注损伤脊髓线粒体功能的影响

目的研究PI3K/Akt和ERK1/2通路对控制性低压后处理兔缺血/再灌注损伤脊髓线粒体功能的影响。方法30只日本大耳白兔随机分为5组(n=6):假手术组(Sham)、缺血/再灌注组(I/R),控制性低压后处理组(Post),控制性低压后处理+PD98059组(Post+PD)、控制性低压后处理+LY294002组(Post+LY)组。除Sham组外,其余各组分别于肾动脉下水平阻断腹主动脉25 min。Post组:再灌注开始10 min采用控制性低灌注压后处理法球囊部分排空,将腹主动脉远端血压控制在5.99～7.32 kPa,10min后球囊完全开放。Post+PD组、Post+LY组:同Post组,并分别于腹主动脉开放前1 min鞘内注射ERK抑制剂PD98059(3μg,20μl)、PI3K/AKT抑制剂LY294002(10μg,20μl)。再灌注24 h后将实验动物处死,取脊髓组织用Western blot技术测定Caspase-3、胞质Cytochrome C蛋白表达;电镜观察线粒体结构。结果与I/R组比较,Post组Caspase-3和胞质Cytochrome C蛋白表达明显减少,线粒体结构破坏减轻。ERK抑制剂PD98059和PI3K/Akt抑制剂LY294002减弱了Post的作用。结论控制性低压后处理对缺血/再灌注损伤脊髓线粒体功能有保护作用,其机制可能与激活PI3K/Akt和ERK1/2通路有关。

Effect of Akt and ERK1/2 pathway in the mitochondrial function by controlled low perfusion pressure against spinal ischemia/reperfusion in rabbits

Aim To observe the influence of Akt and ERK1/2 pathway on the mitochondrial function by controlled low perfusion pressure against spinal ischemia-reperfusion.Methods Thirty Japanese white rabbits weighing 2.0～2.5 kg were randomly divided into five groups(n=6):sham group,ischemia/reperfusion(I/R) group,controlled low perfusion pressure ischemic postconditioning(Post) group,Post+PD98059(Post+PD) group and Post+LY294002(Post+LY) group.Except sham group,the spinal ischemia was induced by occlusion of the infrarenal aorta for 25 min.Post group:postconditioning was accomplished by the blood flow partially restored and the mean blood pressure of the distal aorta was controlled between 5.99 and 7.32 kPa by adjusting the volume of the balloon during the first 10 min of reperfusion.Post+PD and Post+LY group:PD98059(3 μg,20 μl,a specific ERK1/2 inhibitor)and LY294002(10 μg,20 μl,a specific PI3K/Akt inhibitor) were intravenously administered 1 minute before ischemic postconditioning.All rabbits were sacrificed 1 d after reperfusion,the spinal cord was removed for determination of the expression of Caspase-3 and Cytochrome C by Western blot and the ultrastructural change of mitochondrial was observed by electronmicroscope.Results Compared with I/R group,the expressions of Caspase-3 and Cytochrome C were decreased,and ultrastructure of mitochondrial was less damaged in Post group.However,the protective effect of Post was reduced by PD98059 and LY294002.Conclusion Controlled low perfusion pressure can reduce the spinal cord I/R injury through activiting PI3K/Akt and ERK1/2 pathways and protecting mitochondrial function.