Caratero A, Courtade M, Bonnet L, Planel H, Caratero C
Laboratoire d'Histologie-Embryologie-Cytogénétique, Faculté de Médecine Toulouse-Rangueil, Toulouse, France.
Gerontology. 1998;44(5):272-6. doi: 10.1159/000022024.
There is epidemiological evidence that suggests there are beneficial effects of ionizing radiation at low doses. Some experimental studies confirmed this hormetic effect with doses of about 1 cGy/day, but no data concerning very low dose rates are available.
The aim of this study was to determine the life span of mice exposed to very low doses of ionizing radiation.
Six hundred female C57BL/6 mice, 1 month old, were exposed to chronic gamma irradiation at very low dose rates of 7 or 14 cGy/year. These doses are about 25 or 50 times higher than background, but much lower than the doses of about 1 cGy/day used in previous experiments. Three hundred mice living in the same room were used as controls.
The life span, after the beginning of the experiment, determined by the survival time of 50% of each population, is increased in irradiated mice: 549 days in controls, 673 days in both irradiated groups. The differences are significant between the control and the irradiation mice. Differences between mice irradiated with 7 or 14 cGy are not significant.
These results confirm the possibility of a nonharmful effect (hormesis) of ionizing radiation. They demonstrate that the paradigm, which states that low-dose effects can be predicted high-dose effects, cannot be systematically applied in radiation biology in general and gerontology in particular.
有流行病学证据表明低剂量电离辐射具有有益作用。一些实验研究证实了约1厘戈瑞/天剂量下的这种兴奋效应，但尚无关于极低剂量率的数据。
本研究旨在确定暴露于极低剂量电离辐射的小鼠的寿命。
600只1月龄雌性C57BL/6小鼠接受7或14厘戈瑞/年极低剂量率的慢性γ射线照射。这些剂量比本底剂量高约25或50倍，但远低于先前实验中使用的约1厘戈瑞/天的剂量。将饲养在同一房间的300只小鼠作为对照。
实验开始后，由每组50%小鼠的存活时间确定的寿命，在受照射小鼠中增加：对照组为549天，两个受照射组均为673天。对照组和受照射小鼠之间的差异具有显著性。7厘戈瑞和14厘戈瑞照射的小鼠之间的差异不显著。
这些结果证实了电离辐射产生无害效应（兴奋效应）的可能性。它们表明，认为低剂量效应可由高剂量效应预测的范式，在辐射生物学尤其是老年学中不能一概而论。
