Sakai Kazuo
Low Dose Radiation Research Center, Nuclear Technology Research Laboratory, Central Research Institute of Electric Power Industry, Tokyo, Japan.
Yakugaku Zasshi. 2006 Oct;126(10):827-31. doi: 10.1248/yakushi.126.827.
"Hormesis" is defined, originally in the field of toxicology, as a phenomenon in which a harmful substance gives stimulating effects to living organisms when the quantity is small. The concept was extended and applied to ionizing radiation, high doses of which are harmful. Although radiation has been thought to be, based on findings in high dose ranges, harmful no matter low the dose is, recent investigation revealed that living organisms possess the ability to respond to low-dose radiation in very sophisticated ways. A good example of such responses is the so-called radiation adaptive response, a process in which acquired radioresistance is induced by low-dose radiation given in advance. The stimulation of certain bioprotective functions, including antioxidative capacity, DNA repair functions, apoptosis, and immune functions are thought to underly the adaptive response. The adaptive response is effective for chromosome induction, acute death, and tumorigenesis induced by high doses of radiation. Radiation hormesis and adaptive response provide a new scope in the risk assessment and medical application of ionizing radiation.
“兴奋效应”最初在毒理学领域被定义为一种现象，即当有害物质的量很小时，它会对生物体产生刺激作用。这一概念后来被扩展并应用于电离辐射，高剂量的电离辐射是有害的。尽管根据高剂量范围的研究结果，人们一直认为辐射无论剂量多低都是有害的，但最近的研究表明，生物体具有以非常复杂的方式对低剂量辐射作出反应的能力。这种反应的一个很好的例子就是所谓的辐射适应性反应，即预先给予低剂量辐射可诱导获得性抗辐射能力的过程。某些生物保护功能的激活，包括抗氧化能力、DNA修复功能、细胞凋亡和免疫功能，被认为是适应性反应的基础。适应性反应对高剂量辐射诱导的染色体畸变、急性死亡和肿瘤发生具有防护作用。辐射兴奋效应和适应性反应为电离辐射的风险评估和医学应用提供了新的视角。
