Key Laboratory of Resource Biology and Biotechnology in Western China, College of Life Sciences, Northwest University, Ministry of Education, Xi'an 710069, People's Republic of China.
School of Basic Medical Sciences, Ningxia Medical University, Yinchuan 750004, People's Republic of China.
Open Biol. 2018 Oct 10;8(10):180068. doi: 10.1098/rsob.180068.
Mammalian hibernators experience repeated hypoxic ischaemia and reperfusion during the torpor-arousal cycle. We investigated levels of oxidative stress, antioxidant capacity, and the underlying mechanism in heart, liver, brain and kidney tissue as well as plasma during different periods of hibernation in Daurian ground squirrels (). Our data showed that the levels of hydrogen peroxide significantly increased in the heart and brain during late torpor (LT) compared with levels during the summer active (SA) state. The content of malondialdehyde (MDA) was significantly lower during interbout arousal (IBA) and early torpor (ET) than that during SA or pre-hibernation (PRE), and MDA levels in the LT brain were significantly higher than the levels in other states. Superoxide dismutase 2 protein levels increased markedly in the heart throughout the entire torpor-arousal cycle. Catalase expression remained at an elevated level in the liver during the hibernation cycle. Superoxide dismutase 1 and glutathione peroxidase 1 (GPx1) expression increased considerably in all tissues during the IBA and ET states. In addition, the activities of the various antioxidant enzymes were higher in all tissues during IBA and ET than during LT; however, GPx activity in plasma decreased significantly during the hibernation season. The expression of p-Nrf2 decreased in all tissue types during IBA, but significantly increased during LT, especially in liver tissue. Interestingly, most changed indicators recovered to SA or PRE levels in post-hibernation (POST). These results suggest that increased reactive oxygen species during LT may activate the Nrf2/Keap1 antioxidant pathway and may contribute to the decreased MDA levels found during the IBA and ET states, thereby protecting organisms from oxidative damage over the torpor-arousal cycle of hibernation. This is the first report on the remarkable controllability of oxidative stress and tissue specificity in major oxidative tissues of a hibernator.
哺乳动物在冬眠-觉醒周期中经历反复的缺氧缺血和再灌注。我们研究了达乌尔黄鼠在冬眠不同时期（）心脏、肝脏、大脑和肾脏组织以及血浆中的氧化应激水平、抗氧化能力和潜在机制。我们的数据显示，与夏季活跃（SA）状态相比，晚期冬眠（LT）期间心脏和大脑中的过氧化氢水平显著升高。在间睡眠觉醒（IBA）和早期冬眠（ET）期间，丙二醛（MDA）的含量明显低于 SA 或预冬眠（PRE）状态，而 LT 大脑中的 MDA 水平明显高于其他状态。超氧化物歧化酶 2 蛋白水平在整个冬眠-觉醒周期中在心脏中显著增加。整个冬眠-觉醒周期中，过氧化氢酶在肝脏中的表达保持在较高水平。在 IBA 和 ET 状态下，所有组织中的超氧化物歧化酶 1 和谷胱甘肽过氧化物酶 1（GPx1）表达显著增加。此外，在 IBA 和 ET 期间，所有组织中的各种抗氧化酶活性均高于 LT；然而，在冬眠季节，血浆中的 GPx 活性显著降低。在 IBA 期间，所有组织类型中的 p-Nrf2 表达均下降，但在 LT 期间显著增加，尤其是在肝脏组织中。有趣的是，大多数变化的指标在冬眠后（POST）恢复到 SA 或 PRE 水平。这些结果表明，LT 期间活性氧的增加可能会激活 Nrf2/Keap1 抗氧化途径，并有助于 IBA 和 ET 状态下 MDA 水平的降低，从而保护生物体免受冬眠期间的氧化损伤。这是首例报道冬眠动物主要氧化组织中氧化应激的显著可控性和组织特异性。
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