Shin Eun-Joo, Ko Kwang Ho, Kim Won-Ki, Chae Jong Seok, Yen Tran Phi Hoang, Kim Hyun Ji, Wie Myung-Bok, Kim Hyoung-Chun
Neuropsychopharmacology and Toxicology Program, College of Pharmacy, Kangwon National University, Chunchon 200-701, South Korea.
Neurochem Int. 2008 May;52(6):1134-47. doi: 10.1016/j.neuint.2007.12.003. Epub 2007 Dec 8.
Oxidative stress may contribute to epileptogenicity in genetic models of epilepsy. To address this, we examined the enzymatic activity of cytosolic Cu/Zn superoxide dismutase (SOD-1), mitochondrial Mn superoxide dismutase (SOD-2), and glutathione peroxidase (GPx) in the developing hippocampus of genetically epilepsy-prone rats (GEPR-9s). We also measured changes in the GSH/GSSG ratio, lipid peroxidation, and protein oxidation at post-natal days (PD) 7, 30, and 90, respectively. Compared with control Sprague-Dawley (SD) rats, GEPR-9s showed similar SOD-1 and SOD-2 activity but lower GPx activity. Epilepsy-prone rats also showed lower GSH/GSSG ratios than controls, and more lipid peroxidation (as measured by malondialdehyde levels) and protein oxidation (as measured by carbonyl levels). Treatment with kainic acid (KA) resulted in more pronounced seizures, less GPx activity, and lower GSH/GSSG ratios in GEPR-9s than in controls, but KA did not significantly affect SOD-1 or SOD-2 activity, suggesting that GEPR-9s do not compensate for reduced GPx activity by increasing SOD. Moreover, KA treatment resulted in significantly a lower GSH/GSSG ratio and GPx-like immunoreactivity and higher malondialdehyde and carbonyl levels in GEPR-9s than in controls. These findings were more evident in GEPR-9s at PD 90 than at PD 30, indicating that oxidative stress is age-dependent. Double-labeling immunocytochemical analysis demonstrated co-localization of GPx-immunoreactive glia-like cells and reactive astrocytes, as labeled by glial fibrillary acidic protein (GFAP). This suggests that mobilization of astroglial cells for synthesis of GPx protein is a response to KA insult, intended to decrease the neurotoxicity induced by peroxides. These responses were more pronounced in control SD rats than in GEPR-9s. Our results suggest that impairment of the GPx (including glutathione)-mediated antioxidant system contributed to epileptogenesis in GEPR-9s.
氧化应激可能在癫痫的遗传模型中导致癫痫发作。为了探究这一点，我们检测了遗传性癫痫易感大鼠（GEPR - 9s）发育中的海马体中胞质铜锌超氧化物歧化酶（SOD - 1）、线粒体锰超氧化物歧化酶（SOD - 2）和谷胱甘肽过氧化物酶（GPx）的酶活性。我们还分别测量了出生后第7天、30天和90天谷胱甘肽/氧化型谷胱甘肽（GSH/GSSG）比值、脂质过氧化和蛋白质氧化的变化。与对照的斯普拉格 - 道利（SD）大鼠相比，GEPR - 9s表现出相似的SOD - 1和SOD - 2活性，但GPx活性较低。癫痫易感大鼠的GSH/GSSG比值也低于对照组，脂质过氧化（通过丙二醛水平测量）和蛋白质氧化（通过羰基水平测量）更多。用 kainic 酸（KA）处理后，GEPR - 9s比对照组出现更明显的癫痫发作、更低的GPx活性和更低的GSH/GSSG比值，但KA对SOD - 1或SOD - 2活性没有显著影响，这表明GEPR - 9s不会通过增加SOD来补偿降低的GPx活性。此外，KA处理导致GEPR - 9s的GSH/GSSG比值和GPx样免疫反应性显著低于对照组，丙二醛和羰基水平更高。这些发现在出生后第90天的GEPR - 9s中比在第30天更明显，表明氧化应激具有年龄依赖性。双标记免疫细胞化学分析表明，GPx免疫反应性胶质样细胞与由胶质纤维酸性蛋白（GFAP）标记的反应性星形胶质细胞共定位。这表明星形胶质细胞动员以合成GPx蛋白是对KA损伤的一种反应，旨在降低过氧化物诱导产生的神经毒性。这些反应在对照SD大鼠中比在GEPR - 9s中更明显。我们的结果表明，GPx（包括谷胱甘肽）介导的抗氧化系统受损促成了GEPR - 9s的癫痫发生。
