Cui J, Holmes E H, Liu P K
Department of Neurosurgery, Baylor College of Medicine, Houston, Texas 77030, USA.
J Neurochem. 1999 Sep;73(3):1164-74. doi: 10.1046/j.1471-4159.1999.0731164.x.
We investigated oxidative damage to the c-fos gene and to its transcription in the brain of Long-Evans rats using a transient focal cerebral ischemia and reperfusion (FCIR) model. We observed a significant (p < 0.001) increase in the immunoreactivity to 8-hydroxy-2'-guanine (oh8G) and its deoxy form (oh8dG) in the ischemic cortex at 0-30 min of reperfusion in all 27 animals treated with 15-90 min of ischemia. Treatment with a neuronal nitric oxide synthase (nNOS) inhibitor, 3-bromo-7-nitroindazole (60 mg/kg, i.p.), abolished the majority but not all of the oh8G/oh8dG immunoreactivity. Treatment with RNase A reduced the oh8G immunoreactivity, suggesting that RNA may be targeted. This observation was further supported by decreased levels of mRNA transcripts of the c-fos and actin genes in the ischemic core within 30 min of reperfusion using in situ hybridization. The reduction in mRNA transcription occurred at a time when nuclear gene damage, detected as sensitive sites to Escherichia coli Fpg protein in the transcribed strand of the c-fos gene, was increased 13-fold (p < 0.01). Our results suggest that inhibiting nNOS partially attenuates FCIR-induced oxidative damage and that nNOS or other mechanisms induce nuclear gene damage that interferes with gene transcription in the brain.
我们使用短暂性局灶性脑缺血再灌注（FCIR）模型，研究了Long-Evans大鼠大脑中c-fos基因及其转录的氧化损伤。在所有27只经历15 - 90分钟缺血的动物中，我们观察到再灌注0 - 30分钟时，缺血皮层中8-羟基-2'-鸟嘌呤（oh8G）及其脱氧形式（oh8dG）的免疫反应性显著增加（p < 0.001）。用神经元型一氧化氮合酶（nNOS）抑制剂3-溴-7-硝基吲唑（60 mg/kg，腹腔注射）处理，消除了大部分但不是所有的oh8G/oh8dG免疫反应性。用核糖核酸酶A处理降低了oh8G免疫反应性，表明RNA可能是靶点。使用原位杂交技术在再灌注30分钟内，缺血核心区c-fos和肌动蛋白基因的mRNA转录水平降低，进一步支持了这一观察结果。在以c-fos基因转录链中对大肠杆菌Fpg蛋白敏感位点检测到核基因损伤增加13倍（p < 0.01）的时候，mRNA转录减少。我们的结果表明，抑制nNOS可部分减轻FCIR诱导的氧化损伤，并且nNOS或其他机制会诱导核基因损伤，从而干扰大脑中的基因转录。
