Both ischemic preconditioning and ghrelin administration protect hippocampus from ischemia/reperfusion and upregulate uncoupling protein-2.
Both ischemic preconditioning and ghrelin administration protect hippocampus from ischemia/reperfusion and upregulate uncoupling protein-2.
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DOI：
10.1186/1472-6793-9-17
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发表时间：
2009-09-22
期刊：
影响因子：
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通讯作者：
Sercombe R
中科院分区：
文献类型：
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作者：
Liu Y;Chen L;Xu X;Vicaut E;Sercombe R
缺血预处理（IPC）是许多器官抗缺血/再灌注（I/R）损伤的主要内源性保护机制。通过适度解偶联线粒体呼吸链和减少活性氧（ROS）的产生，IPC通过减少线粒体释放细胞色素c来减少I/R诱导的细胞凋亡。据信有助于减少ROS产生的一个因素是解偶联蛋白UCP 2（和心脏中的UCP 3）。尽管其在脑中IPC中的意义已在体外显示，但没有蛋白质的体内研究显示其上调。我们的第一个目标是确定在大鼠海马中UCP 2蛋白上调是否与IPC诱导的保护和增加ROS产生相关。第二个目标是确定具有抗氧化和保护特性的肽ghrelin是否以与IPC相同的方式在保护期间改变UCP 2 mRNA水平。全前脑缺血（15 min）再灌注72 h（I/R组）后，海马CA 1区神经元损伤明显，预处理3 min（IPC+I/R组）可减轻损伤，而单纯预处理组（IPC组）无明显损伤。与对照组相比，I/R组和IPC+I/R组UCP 2蛋白表达中度增加（+39%，NS），IPC组显著增加（+339%，P < 0.05）。在预处理缺血时给予超氧化物歧化酶（10000 U/kg ip）在72 h时大大减弱了UCP 2染色的增加（-73%，P < 0.001），这意味着氧自由基在UCP 2诱导中的作用。与对照组相比，I/R组和IPC+I/R组海马UCP 2 mRNA中度升高（+33%，P <0.05），IPC组升高幅度较大（+333%，P < 0.001）。在ghrelin实验中，I/R+ghrelin组（3次/d）显示出与I/R动物相比相当大的CA 1神经元保护，并且增加海马UCP 2 mRNA（+151%，P < 0.001）。我们证实，IPC导致UCP 2蛋白在体内的表达增加，在适当的时刻对I/R在海马保护。两种不同的保护策略，IPC和ghrelin给药，都与UCP 2的上调有关，这表明UCP 2可能通常代表了I/R保护的最终共同途径。
A major endogenous protective mechanism in many organs against ischemia/reperfusion (I/R) injury is ischemic preconditioning (IPC). By moderately uncoupling the mitochondrial respiratory chain and decreasing production of reactive oxygen species (ROS), IPC reduces apoptosis induced by I/R by reducing cytochrome c release from the mitochondria. One element believed to contribute to reduce ROS production is the uncoupling protein UCP2 (and UCP3 in the heart). Although its implication in IPC in the brain has been shown in vitro, no in vivo study of protein has shown its upregulation. Our first goal was to determine in rat hippocampus whether UCP2 protein upregulation was associated with IPC-induced protection and increased ROS production. The second goal was to determine whether the peptide ghrelin, which possesses anti-oxidant and protective properties, alters UCP2 mRNA levels in the same way as IPC during protection. After global forebrain ischemia (15 min) with 72 h reperfusion (I/R group), we found important neuronal lesion in the rat hippocampal CA1 region, which was reduced by a preceding 3-min preconditioning ischemia (IPC+I/R group), whereas the preconditioning stimulus alone (IPC group) had no effect. Compared to control, UCP2 protein labelling increased moderately in the I/R (+39%, NS) and IPC+I/R (+28%, NS) groups, and substantially in the IPC group (+339%, P < 0.05). Treatment with superoxide dismutase (10000 U/kg ip) at the time of a preconditioning ischemia greatly attenuated (-73%, P < 0.001) the increase in UCP2 staining at 72 h, implying a role of oxygen radicals in UCP2 induction. Hippocampal UCP2 mRNA showed a moderate increase in I/R (+33%, P < 0.05) and IPC+I/R (+40%, P < 0.05) groups versus control, and a large increase in the IPC group (+333%, P < 0.001). In ghrelin experiments, the I/R+ghrelin group (3 daily administrations) showed considerable protection of CA1 neurons versus I/R animals, and increased hippocampal UCP2 mRNA (+151%, P < 0.001). We confirm that IPC causes increased expression of UCP2 protein in vivo, at a moment appropriate for protection against I/R in the hippocampus. The two dissimilar protective strategies, IPC and ghrelin administration, were both associated with upregulated UCP2, suggesting that UCP2 may often represent a final common pathway in protection from I/R.