Matz P G, Massa S M, Weinstein P R, Turner C, Panter S S, Sharp F R
Department of Neurology, University of California, San Francisco, USA.
J Neurosurg. 1996 Nov;85(5):892-900. doi: 10.3171/jns.1996.85.5.0892.
Induction of the hemeoxygenase-1 (ho-1) stress gene is of importance for rapid heme metabolism and protection against oxidative injury in vitro and in vivo. Although ho-1 expression is observed in glia following exposure to whole blood and oxyhemoglobin, expression is mild, and other stress genes are not induced simultaneously in this setting. Hemeoxygenase-1 can be induced by several other physiological stresses in addition to heme. In the brain, ho-1 induction has been observed in the penumbra following focal cerebral ischemia. Because lysed blood is a spasmogen, the authors studied focal hyperexpression of the ho-1 gene after injection of lysed blood, whole blood, or saline into the cisterna magna of adult rats. Immunocytochemical analysis of HO-1 was performed at 1, 2, 3, and 4 days after the injections. Because the 70-kD inducible heat shock protein (HSP70) is induced by cellular stress, alternate sections were immunostained for HSP70 to assess whether focal hyperexpression was a stress phenomenon. An oligonucleotide probe was also used for in situ hybridization to demonstrate that ho-1 messenger (m)RNA was present. Focal HO-1 immunostained areas were observed after lysed blood injection only and were located mainly in the basal cortex and cerebellar hemisphere, although focal hyperexpression was also found in many other regions. The intensity of staining and the number of regions were maximum at 1 day. Double-labeled immunofluorescence revealed that many HO-1-immunoreactive cells were microglia. The HSP70 immunostaining of adjacent sections from the same animals demonstrated focal regions of immunoreactivity whose topography corresponded exactly with the topography of the HO-1-immunostained areas. Conventional histology in regions of HO-1 hyperexpression was often normal. In situ hybridization using the same oligonucleotide demonstrated that ho-1 mRNA was induced in focal areas of forebrain and in large regions of cerebellum within 6 hours of injection. These results demonstrate that focal hyperexpression of the ho-1 stress gene occurs after lysed blood injection and appears to be an indicator of cellular stress and injury in regions in which infarction does not occur. These results also suggest that cellular injury that occurs after injection of lysed blood may go undetected using conventional histology. Although direct heme metabolism was not investigated, our results indicate that rapid metabolism of heme, both intracellular and extracellular, may prove to be beneficial after subarachnoid hemorrhage.
诱导血红素加氧酶-1（HO-1）应激基因对于体外和体内血红素的快速代谢以及抵御氧化损伤具有重要意义。尽管在暴露于全血和氧合血红蛋白后，胶质细胞中可观察到HO-1表达，但表达程度较轻，且在此情况下其他应激基因并未同时被诱导。除血红素外，血红素加氧酶-1还可被其他几种生理应激所诱导。在大脑中，局灶性脑缺血后，在半暗带中可观察到HO-1的诱导。由于裂解血是一种致痉剂，作者研究了向成年大鼠脑池内注射裂解血、全血或生理盐水后HO-1基因的局灶性过表达情况。在注射后1、2、3和4天对HO-1进行免疫细胞化学分析。由于70-kD诱导型热休克蛋白（HSP70）可被细胞应激所诱导，因此对相邻切片进行HSP70免疫染色，以评估局灶性过表达是否为应激现象。还使用寡核苷酸探针进行原位杂交，以证明HO-1信使（m）RNA的存在。仅在注射裂解血后观察到局灶性HO-1免疫染色区域，主要位于基底皮质和小脑半球，尽管在许多其他区域也发现了局灶性过表达。染色强度和区域数量在1天时达到最大值。双重标记免疫荧光显示，许多HO-1免疫反应性细胞为小胶质细胞。对同一只动物相邻切片的HSP70免疫染色显示出免疫反应性的局灶区域，其形态与HO-1免疫染色区域的形态完全一致。HO-1过表达区域的常规组织学检查通常正常。使用相同的寡核苷酸进行原位杂交显示，注射后6小时内，前脑的局灶区域和小脑的大片区域诱导产生了HO-1 mRNA。这些结果表明，注射裂解血后会出现HO-1应激基因的局灶性过表达，这似乎是未发生梗死区域细胞应激和损伤的一个指标。这些结果还表明，使用常规组织学检查可能无法检测到注射裂解血后发生的细胞损伤。尽管未研究血红素的直接代谢，但我们的结果表明，蛛网膜下腔出血后，细胞内和细胞外血红素的快速代谢可能被证明是有益的。
