缺血后处理减轻缺血再灌注大鼠耳蜗血管损伤的研究

Protection of ischemic postconditioning on cochlear ischemia and reperfusion injury in rats

目的探讨缺血后处理(ischemic postconditioning)对大鼠耳蜗缺血再灌注的保护作用。方法成年雄性SD大鼠42只,随机分为3组(n=14),分别为假手术对照组、缺血再灌注组和缺血后处理组。各组动物于再灌注24h取左侧耳蜗,每组随机4个耳蜗做透射电镜观察血管纹血管的超微结构变化,各组余下耳蜗组织进行匀浆,测定匀浆中过氧化氢酶(catalas,CAT)活性、丙二醛(molondialdehyde,MDA)含量。结果与假手术对照组大鼠相比,缺血再灌注组和缺血后处理组大鼠CAT活性显著降低(P<0.05),MDA含量显著升高(P<0.05);与缺血再灌注组大鼠相比,缺血后处理组大鼠CAT活性升高(P<0.05),MDA含量下降(P<0.05)。形态学缺血再灌注组耳蜗血管内皮细胞超微结构破坏明显,而缺血后处理组超微结构有明显改善。结论耳蜗缺血后处理可能抑制耳蜗缺血再灌注后的氧化损伤,对血管有一定保护作用。

OBJECTIVE To investigate the effect of ischemic postcondioning on cochlea following cochlear ischemia-reperfusion injury in rats. METHODSForty two healthy male SD rats were randomly divided into 3 groups, namely, the sham operation control group, the ischemia reperfusion group and ischemic postcondinging group. There were 14 rats in each group. The content of molondialdehyde（MDA） as well as the activity of catalase（CAT）in cochlea was measured by histochemistry. The ultrastructural changes of stria vascularis capillaries of the cochlea in experimental rats were examined by transmission electron microscopy（TEM）. RESULTS In the ischemia reperfusion group, the CAT activities were decreased and MDA concentrations were increased significantly compared with those in the control group. However, in the ischemic postcondinging group, the activities of CAT were increased and MDA concentrations were decreased compared with those in the ischemia reperfusion group. Moreover, lesions were detected in the stria vascularis capillaries in all the three groups. The capillaries of stria vascularis were injured severely in ischemia reperfusion group. In the ischemic postcondinging group, the damage of capillary of stria vascularis were reduced significantly compared with that in ischemia reperfusion group, the structures were near normal, and no obvious destruction was observed. COCLUSION Ischemic postconditioning may markedly reduce the excessive generation of oxygen free radical during the process of ischemia-reperfusion injury and might be a potential strategy for its therapy.