Nitroxides as Protectors Against Oxidative Stress

氮氧化物作为抗氧化应激的保护剂摘要氮氧化物被证明在许多疾病过程和/或表现过度氧化应激的条件下具有广泛的用途。氮氧化物在如此广泛的条件下发挥活性的事实说明了组织中自由基反应的重要性。同样，自由基在正常分子信号通路和相关基因表达中的重要作用也越来越明显。在合作研究中，对两种表现出神经变性和/或神经损伤的小鼠模型进行了长期给药（通过食物补充）的效果评估。铁调节蛋白2敲除小鼠（IRP2-/-）表现出与年龄相关的神经变性（类似于帕金森病患者）。Tempol治疗减轻了IRP2-/-小鼠神经退行性变的进展。Tempol在实验性自身免疫性脑脊髓炎（EAE）小鼠模型中也显示出高度保护作用。EAE小鼠模型是一种急性或慢性脱髓鞘性自身免疫性疾病，其临床表现为瘫痪和四肢瘫痪，与多发性硬化症患者非常相似。这些初步数据令人兴奋，可能代表了治疗这些疾病的新方法。最后，我们继续寻找长期服用Tempol（在食物或饮用水中）如何导致小鼠体重显著减轻和自发性肿瘤发生率降低的机制。首先，我们已经开始使用体外脂肪生成系统（3T3L1细胞）进行研究，并发现Tempol在该模型中抑制脂肪生成。此外，我们发现在这个系统中，诱导脂肪生成导致HIF-1 α的减少；而Tempol则可以防止脂肪球的减少和形成。将进行进一步的机理研究。其次，我们进行了广泛的基因表达阵列研究，评估了年龄匹配的对照小鼠和补充Tempol食物1个月或1年的小鼠的组织。在补充Tempol的小鼠中，已经鉴定出许多基因在肝脏和脑组织中有差异的上调或下调，包括与谷胱甘肽代谢相关的基因（上调）。与脂肪合成和储存相关的基因被发现被坦波尔调节。基因阵列研究表明，天波尔还能调控缺氧相关基因。最后，Tempol也显著延缓了Atm和p53缺陷小鼠以及最近的Fanconis贫血基因敲除小鼠的肿瘤发生。我们最近发现，在Tempol治疗的动物中，IGF-1的全身水平下降，与在热量限制动物中观察到的情况相似。此外，在初步研究中，我们已经表明，（在食物中）给药Tempol可以减少小鼠中前列腺素诱导的浆细胞瘤，进一步表明Tempol可能干扰/延迟癌症诱导的发生。这些研究有望使我们更好地了解氮氧化物的复杂细胞/分子机制，这些机制触发了氮氧化物抗氧化性能的重要反应，以及与体重和化学预防相关的反应。

Nitroxides as Protectors against Oxidative Stress Summary Nitroxides are proving to have broad utility in a number of disease processes and/or conditions that represent excessive oxidative stress. The fact that nitroxides exert activity over such a range of conditions speaks to the importance of free radical reactions in tissue. Likewise, it is becoming apparent that free radicals are important in normal molecular signaling pathways and related gene expression. In collaborative studies, the effects of chronic administration of Tempol (supplemented in food) of two mouse models that exhibit neurodegeneration and/or neurological damage have been evaluated. Iron regulatory protein 2 knockout mice (IRP2-/-) exhibit age-related neurodegeneration (similar to Parkinsons disease patients). Tempol treatment attenuated the progression of neurodegeneration in IRP2-/- mice. Tempol was also shown to be highly protective in an experimental autoimmune encephalomyelitis (EAE) mouse model. The EAE mouse model is an acute or chronic demyelinating autoimmune disease whose clinical manifestations of paralysis and quadriparesis that closely resemble those observed in Multiple Sclerosis patients. These preliminary data are exciting and may represent a new approach toward treating these diseases. Lastly, we continue to search for the mechanism(s) of how long-term administration of Tempol (in the food or drinking water) results in dramatic weight reduction and a decrease in spontaneous tumor incidence in mice. First, we have initiated studies using an in vitro lipogenesis system (3T3L1 cells) and have found that Tempol inhibits lipogenesis in this model. Further, we have found that in this system that induction of lipogenesis results in a reduction in HIF-1 alpha; whereas, Tempol prevents the reduction and hence the formation of fat globules. Further mechanistic studies will be conducted. Second, we have conducted an extensive gene expression array study evaluating tissue taken from age-matched control mice and mice on Tempol food supplementation for 1 month or 1 year. A number of genes have been identified in Tempol supplemented mice that are differentially up- or down-regulated in liver and brain tissue, including genes associated with glutathione metabolism (up-regulated). Genes associated with fat synthesis and storage were found to be modulated by Tempol. The gene array study suggested that hypoxic related genes were also modulated by Tempol. Finally, Tempol administration also significantly delayed the onset of tumors in Atm and p53 deficient mice and more recently in Fanconis Anemia knockout mice. We have recently found that systemic levels of IGF-1 are decreased in Tempol treated animals, similar to that observed in caloric restricted animals. Additionally in preliminary studies, we have shown that Tempol administration (in the food) decreases pristane-induced plasmocytomas in mice, further suggesting that Tempol may interfere/delay the onset of cancer induction. These studies will hopefully enable us to better understand the complex cellular/molecular mechanisms of nitroxides that trigger responses important in the antioxidant properties of nitroxides as well as those related to weight and the chemopreventive findings.