大鼠肢体缺血-再灌注后脑HO-1表达的变化及意义

Changes of HO-1 gene expression in brain following ischemia and reperfusion of limbs

目的 :观察肢体缺血 -再灌注 (I-R)后脑组织内诱导型血红素氧合酶 (HO - 1)表达的变化及意义。方法 :夹闭大鼠双侧股动脉根部 4h、开放 2 - 2 4h复制肢体I-R模型。反转录多聚酶链反应检测脑内HO - 1mRNA表达的变化 ;免疫组化染色法标记HO - 1蛋白的组织分布 ;用锌原卟啉抑制HO - 1活性后 ,光镜观察脑组织的病理学变化。结果 :肢体I-R后脑组织HO - 1mRNA表达水平明显高于各对照组 ,再灌 12h表达至峰值 ,再灌至 2 4h仍显著高于各对照组 (P <0 .0 1)。肢体I-R组大脑皮质、海马等区出现大量弥散分布的HO - 1免疫阳性胶质细胞 ,皮质及海马部分锥体细胞呈HO - 1免疫阳性 ;抑制HO - 1活性 ,I-R组脑组织损伤加重。结论 :肢体I -R后 ,脑组织内胶质细胞及神经元HO - 1基因表达上调 ,所诱生的HO - 1对神经元具有保护效应。

AIM: To detect the changes of heme oxygenase-1(HO-1) expression in brain following ischemia-reperfusion of hindlimbs in rats and to elucidate their significance. METHODS: Ischemia-reperfusion was established using the occlusion for 4 h and re-opening for 2-24 h of the femoral arteries. The expression of HO-1 mRNA in brain was detected with reverse transcription-polymerase chain reaction (RT-PCR). The expression and location of HO-1 protein were detected with immunohistochemical technique. The observation of pathologic changes of brain was made following the inhibition of HO-1 by zinc protoporphyrin (ZnPP). RESULTS: The relative expression level of HO-1 mRNA significantly increased in I-R group, compared to those in control group. It was maximal in I-R 12 h group, and thereafter expression level of HO-1 mRNA decreased, however significant expression was still detected in I-R 24 h group (P<0.01). A lot of HO-1 positive microglial cells and some positive pyramidal neurons were diffusively localized in cerebral cortex and hippocampus. Inhibition of HO-1 activity induced more severe brain injury in I-R group. CONCLUSION: The expression of HO-1 mRNA and protein in microglial cells and neurons was significantly upregulated, induction of HO-1 was involved in protection for neurons during the ischemia-reperfusion of hindlimbs.