Folbergrová Jaroslava, Ješina Pavel, Nůsková Hana, Houštěk Josef
Institute of Physiology, Academy of Sciences of the Czech Republic, Prague, Czech Republic.
Int J Dev Neurosci. 2013 Apr;31(2):123-30. doi: 10.1016/j.ijdevneu.2012.11.011. Epub 2012 Dec 10.
We have recently demonstrated the evidence of oxidative stress in brain of immature rats during seizures induced by DL-homocysteic acid (DL-HCA). The aim of the present study was to investigate the antioxidant defense mechanisms under these conditions. Seizures were induced in immature 12-day-old rats by bilateral icv infusion of DL-HCA (600 nmol/side), and the activities of the main antioxidant enzymes were examined in supernatants of the cerebral cortex during the acute phase of seizures and at several periods of survival, up to 5 weeks, following these seizures. In control animals individual antioxidant enzymes revealed different changes during the studied postnatal period (PD 12 till PD 47). Total superoxide dismutase (SOD), CuZn SOD (SOD1), Mn SOD (SOD2) and glutathione peroxidase (GPX) activities were increasing while, catalase activity decreased and the activity of glutathione reductase (GR) remained unchanged. In HCA-treated animals, the activity of total SOD, SOD1 and particularly SOD2 significantly increased at 20 h and 6 days of survival. Importantly, upregulation of SOD2 was also confirmed in mitochondria at the protein level by immunoblotting. The activities of other antioxidant enzymes including catalase and GPX did not significantly differ upon HCA treatment from the appropriate controls at any of the studied time intervals. The pronounced and selective upregulation of SOD2 points to enhanced ROS levels in the mitochondrial matrix. This may be associated with inhibition of respiratory chain complex I that we have demonstrated in our previous studies. The present findings suggest that oxidative stress occurring in the brain of immature rats during and following the seizures induced by DL-HCA is apparently due to both the increased free radical production and the limited antioxidant defense.
我们最近证明了在由DL-高半胱氨酸（DL-HCA）诱导的未成熟大鼠癫痫发作期间，其大脑中存在氧化应激的证据。本研究的目的是调查在这些条件下的抗氧化防御机制。通过双侧脑室内注射DL-HCA（600 nmol/侧）诱导12日龄未成熟大鼠癫痫发作，并在癫痫发作急性期以及发作后的几个存活期（长达5周）检测大脑皮质上清液中主要抗氧化酶的活性。在对照动物中，个体抗氧化酶在研究的出生后时期（出生后第12天至第47天）显示出不同的变化。总超氧化物歧化酶（SOD）、铜锌超氧化物歧化酶（SOD1）、锰超氧化物歧化酶（SOD2）和谷胱甘肽过氧化物酶（GPX）的活性增加，而过氧化氢酶活性降低，谷胱甘肽还原酶（GR）的活性保持不变。在HCA处理的动物中，总SOD、SOD1尤其是SOD2的活性在存活20小时和6天时显著增加。重要的是，通过免疫印迹在蛋白质水平上也证实了线粒体中SOD2的上调。在任何研究的时间间隔内，包括过氧化氢酶和GPX在内的其他抗氧化酶的活性在HCA处理后与相应对照相比均无显著差异。SOD2的显著且选择性上调表明线粒体基质中的活性氧水平升高。这可能与我们先前研究中证明的呼吸链复合体I的抑制有关。目前的研究结果表明，DL-HCA诱导的未成熟大鼠癫痫发作期间及之后大脑中发生的氧化应激显然是由于自由基产生增加和抗氧化防御有限所致。
