Kihara T, Sakata S, Ikeda M
Kanzakigawa Laboratory, Shionogi Research Laboratories, Shionogi & Co. Ltd., Osaka, Japan.
J Neurochem. 1995 Jul;65(1):282-6. doi: 10.1046/j.1471-4159.1995.65010282.x.
To examine the role played by free radicals in brain injury, we performed experiments to detect radicals in the frontal cortex of rats, using electron spin resonance (ESR) and microdialysis. A dialysis probe was inserted into the frontal cortex, and spin adducts in perfusates were immediately detected by ESR. We obtained a relatively stable doublet signal, with parameters of g = 2.0057 and aH = 0.17 mT. This signal corresponded with that of the ascorbyl radical. Ascorbyl radical in the perfusate collected from the frontal cortex was augmented by microinjection of H2O2 and FeCl2 adjacent to the dialysis probe. When the rats were challenged with cold-induced brain injury, ascorbyl radical and lactate dehydrogenase (LDH) level in the perfusate increased significantly. Pretreatment with superoxide dismutase and catalase attenuated the increase in ascorbyl radical and LDH level induced by the cold injury. Infusion of FeCl2 dissolved in perfusate caused a pronounced increase in ascorbyl radical and LDH level after the cold injury. We conclude that the direct detection of free radical formation further supports the hypothesis that free radicals play an important role in traumatic brain injury. Our findings also indicate that combined microdialysis with ESR spectroscopy is a useful in vivo method for monitoring free radical production in the brain.
为了研究自由基在脑损伤中所起的作用，我们进行了实验，利用电子自旋共振（ESR）和微透析技术检测大鼠额叶皮质中的自由基。将透析探针插入额叶皮质，通过ESR立即检测灌流液中的自旋加合物。我们获得了一个相对稳定的双峰信号，其参数为g = 2.0057和aH = 0.17 mT。该信号与抗坏血酸自由基的信号相对应。通过在透析探针附近微量注射H2O2和FeCl2，从额叶皮质收集的灌流液中的抗坏血酸自由基增加。当大鼠遭受冷诱导的脑损伤时，灌流液中的抗坏血酸自由基和乳酸脱氢酶（LDH）水平显著升高。用超氧化物歧化酶和过氧化氢酶预处理可减轻冷损伤诱导的抗坏血酸自由基和LDH水平的升高。在冷损伤后，向灌流液中注入溶解的FeCl2会导致抗坏血酸自由基和LDH水平显著升高。我们得出结论，自由基形成的直接检测进一步支持了自由基在创伤性脑损伤中起重要作用的假说。我们的研究结果还表明，将微透析与ESR光谱相结合是一种监测脑中自由基产生的有用的体内方法。
