神经途径在肢体缺血预处理抗脑缺血/再灌注损伤中的作用

目的：探讨神经途径在肢体缺血预处理（limbi schemic preconditioning,LIP）抗脑缺血／再灌注损伤中的作用。方法：脑缺血采用四血管闭塞模型,重复短暂夹闭放松大鼠双侧股动脉3次作为LIP。将凝闭椎动脉的大鼠随机分为sham组、脑缺血组、股神经切断＋脑缺血组、LIP＋脑缺血组、股神经切断＋LIP＋脑缺血组。于Sham手术和脑缺血后7d处死大鼠,硫堇染色观察海马CA1区锥体神经元迟发性死亡的变化。于Sham手术和脑缺血后6h心脏灌注固定大鼠,免疫组化法测定海马CAI区c-Fos表达的变化。结果：硫堇染色结果显示,与sham组比较。脑缺血组和股神经切断＋脑缺血组大鼠海马CAI区均有明显组织损伤。LIP＋脑缺血组CAI区无明显细胞缺失,神经元密度明显高于脑缺血组（P〈0．01）。而股神经切断＋LIP＋脑缺血组大鼠海马CA1区明显损伤,锥体细胞缺失较多,与LIP＋脑缺血组组比较,神经元密度显著降低（P〈O．01）,提示LIP前切断双侧股神经取消了LIP抗脑缺血／再灌注损伤作用。c—Fos免疫组化染色结果显示,Sham组海马CAI区未见明显的c-Fos蛋白表达。脑缺血组海马CAI区偶见c—Fm的阳性表达。LIP＋脑缺血组c—Fos表达增强,数量增加,与Sham组和脑缺血组比较。c-Fos阳性细胞数和光密度均明显升高（P〈0．01）。而股神经切断＋LIP＋脑缺血组c-Fos表达明显减少,仅见少量弱阳性e-Fos表达。结论：LIP可通过神经途径发挥抗脑缺血／再灌注损伤作用,而LIP诱导c—Fos表达增加可能是LIP诱导脑缺血耐受神经途径的一个环节。

Neural pathway participates in protection of limb ischemic preconditioning against brain injuries induced by ischemia/reperfusion in rats

Aim: To explore the role of femoral nerves section(FNS) on the protection of limb ischemic preconditioning(LIP) against cerebral ischemia/reperfusion injuries.Methods: Model of brain ischemia induced by Four-vessel occlusion was used.LIP was performed by clamping the bilateral femoral arteries for 10 min 3 times in a interval of 10 min.Rats with vertebral arteries permanently occlu-ded were divided into sham group,cerebral ischemic group,FNS+cerebral ischemic group,LIP+cerebral ischemic group,FNS+LIP+cerebaral ischemic group.The changes of neural density(ND) in the CA1 hippocampus were observed 7d after the sham operation or brain ischemia under thionin staining.The expression of c-Fos in the CA1 hippocampus was measured 6 h after the sham ope-ration or brain ischemia under immunohistochemistry method.Results: Thionin staining revealed that serious neuronal damage was visua-lized in the CA1 hippocampus in both cerebral ischemic group and FNS+ cerebaral ischemic group as compared with sham group.LIP attenuated the neuronal damage of the CA1 subfield induced normally by cerebral ischemia/reperfusion,and ND in LIP+ cerebral ischemic group was significantly higher than that in cerebral ischemic group(P<0.01).But obvious neuronal damage of the CA1 subfield was found in FNS+LIP+cerebral ischemic group,and ND was significantly decreased as compared with LIP+ cerebral ischemic group(P<0.01).These results suggested that the protection of LIP against cerebral ischemia/reperfusion injuries might be cancelled by preceding section of femoral nerve.It was found that there was almost no c-Fos expression in the CA1 hippocampus in sham group.Changes of c-Fos expression in the CA1 subfield in cerebral ischemic group were similar to that in sham group.But in LIP+cerebral ischemic group,c-Fos expression in the CA1 subfield was markedly increased and the number of positive cells and optical density of c-Fos expression were significantly higher than those in sham and cerebral ischemic group.c-Fos expression in the CA1 subfield was again decreased in FNS+LIP+ cerebral ischemic group,and the number of positive cells and optical density of c-Fos expression were significantly lower than those in LIP+cerebral ischemic group.Conclusion: Neural pathway participated in the protective effect of LIP on brain,and increased c-Fos espression in the CA1 hippocampus by LIP after cerebral ischemia/reperfusion,might be a part of neural pathway by which LIP induced brain ischemic tolerance.