肢体缺血预处理对大鼠脊髓缺血再灌注损伤的作用及机制

目的探讨肢体缺血预处理对大鼠脊髓缺血再灌注损伤的作用及机制。方法将72只SD大鼠按随机数字表法分为3组：假手术组（Sham组）、缺血再灌注损伤组（I/R组）和缺血预处理组（LIPC组）,每组24只。Sham组仅暴露腹主动脉,不结扎;I/R组采用Zivin法建立脊髓缺血再灌注损伤模型,麻醉后夹闭左肾下腹主动脉30 min;LIPC组大鼠在麻醉后使用止血带阻断右下肢血运10 min,恢复血运10 min,反复2次后同I/R组办法建模。3组分别于手术缝合后6 h（T1）、1 d（T2）、3 d（T3）和7 d（T4）时随机抽取6只大鼠,采用改良Tarlov评分法进行下肢神经功能评分。各组在T1—T4时的评分结束后,取L2-4脊髓组织,行HE染色,双目光学显微镜下观察脊髓组织的病理变化,并采用免疫组织化学法检测脊髓组织中胶质纤维酸性蛋白（GFAP）的表达水平。结果与Sham组比较：I/R组、LIPC组大鼠T1—T3时改良Tarlov得分均明显降低（均P〈0.05）,T1—T4时大鼠GFAP表达水平均明显升高（P〈0.05）;与I/R组比较：LIPC组大鼠T1—T3时改良Tarlov得分,T2、T3时大鼠脊髓组织中GFAP表达水平均明显升高（均P〈0.05）。结论肢体缺血预处理有减轻大鼠脊髓缺血再灌注损伤的作用,其机制可能与GFAP表达上调有关。

Effect of Limb Ischemic Preconditioning on Spinal Cord Ischemia / Reperfusion Injury in Rats and Its Mechanism of Action

Objective To investigate the effect of limb ischemic preconditioning on spinal cord ischemia / reperfusion injury in rats and its mechanism of action. Methods Seventy-two SD rats were randomly divided into three groups： sham operation group（ sham group）,ischemia-reperfusion injury group（ I/R group） and limb ischemic preconditioning group（ LIPC group）,with 24 rats in each group. In sham group,the abdominal aorta was exposed but was not ligated. In I / R group,the left renal abdominal aorta was occluded for 30 minutes to induce the spinal cord ischemia / reperfusion injury. In LIPC group,the ischemic preconditioning was performed by blocking the right lower limb blood supply for 10 minutes with a tourniquet and restoring the blood supply for 10 minutes,and the spinal cord ischemia / reperfusion injury was induced after 2 cycles of ischemic preconditioning. Six rats in each group were randomly selected 6 hours（ T1）,1 day（ T2）,3 day（ 3） and 7 days（ T4） after surgical suture,respectively,and the lower extremity nerve function was evaluated by a modified Tarlov score. Furthermore,spinal cord tissue（ L2-4）was collected for histopathological examination. Spinal cord tissue sections were stained with hematoxylin and eosin and were observed under an optical microscope. Moreover,the expression of glial fibrillary acidic protein（ GFAP） in spinal cord tissue was measured by immunohistochemistry. Results Compared with sham group,Tarlov scores decreased at T1-T3 and GFAP expression increased at T1-T4 in both I / R group and LIPC group（ P〈0. 05）. Compared with I / R group,Tarlov scores at T1-T3 and GFAP expression at T2-T3 increased in LIPC group（ P〈0. 05）. Conclusion Limb ischemic preconditionin can alleviate spinal cord ischemia-reperfusion injury through up-regulating the expression of GFAP in rats.