Ohta Hitomi, Okamoto Iwao, Hanaya Toshiharu, Arai Shigeyuki, Ohta Tsunetaka, Fukuda Shigeharu
Fujisaki Institute, Hayashibara Biochemical Laboratories, Inc. 675-1 Fujisaki, Okayama 702-8006, Japan.
Comp Biochem Physiol C Toxicol Pharmacol. 2006 Aug;143(4):484-91. doi: 10.1016/j.cbpc.2006.05.002. Epub 2006 May 10.
Mammalian hibernators are considered a natural model for resistance to ischemia-reperfusion injuries, and protective mechanisms against oxidative stress evoked by repeated hibernation-arousal cycles in these animals are increasingly the focus of experimental investigation. Here we show that extracellular catalase activity provides protection against oxidative stress during arousal from hibernation in Syrian hamster. To examine the serum antioxidant defense system, we first assessed the hibernation-arousal state-dependent change in serum attenuation of cytotoxicity induced by hydrogen peroxide. Serum obtained from hamsters during arousal from hibernation at a rectal temperature of 32 degrees C, concomitant with the period of increased oxidative stress, attenuated the cytotoxicity four-fold more effectively than serum from cenothermic control hamsters. Serum catalase activity significantly increased during arousal, whereas glutathione peroxidase activity decreased by 50%, compared with cenothermic controls. The cytoprotective effect of purified catalase at the concentration found in serum was also confirmed in a hydrogen peroxide-induced cytotoxicity model. Moreover, inhibition of catalase by aminotriazole led to an 80% loss of serum hydrogen peroxide scavenging activity. These results suggest that extracellular catalase is effective for protecting hibernators from oxidative stress evoked by arousal from hibernation.
哺乳动物冬眠动物被认为是抗缺血再灌注损伤的天然模型，并且这些动物中反复的冬眠-觉醒周期所引发的针对氧化应激的保护机制日益成为实验研究的焦点。在此我们表明，细胞外过氧化氢酶活性在叙利亚仓鼠从冬眠中觉醒期间为抵抗氧化应激提供保护。为了检测血清抗氧化防御系统，我们首先评估了过氧化氢诱导的细胞毒性的血清减弱作用中与冬眠-觉醒状态相关的变化。从直肠温度为32摄氏度的冬眠觉醒期仓鼠获取的血清，与氧化应激增加期同时，比来自常温对照仓鼠的血清更有效地减弱细胞毒性四倍。与常温对照相比，血清过氧化氢酶活性在觉醒期间显著增加，而谷胱甘肽过氧化物酶活性降低了50%。在过氧化氢诱导的细胞毒性模型中也证实了血清中发现的浓度的纯化过氧化氢酶的细胞保护作用。此外，氨基三唑对过氧化氢酶的抑制导致血清过氧化氢清除活性丧失80%。这些结果表明，细胞外过氧化氢酶对于保护冬眠动物免受冬眠觉醒引发的氧化应激有效。
