Day Tanya K, Zeng Guoxin, Hooker Antony M, Bhat Madhava, Scott Bobby R, Turner David R, Sykes Pamela J
Department of Haematology and Genetic Pathology, Flinders University & Flinders Medical Centre, Bedford Park, SA, Australia.
Radiat Res. 2007 Jun;167(6):682-92. doi: 10.1667/RR0764.1.
Adaptive responses are induced by stress such as X radiation and result in a lower than expected biological response. Two-dose adaptive response experiments typically involve a low priming dose followed by a subsequent high radiation dose. Here, we used a sensitive in vivo chromosomal inversion assay to demonstrate for the first time an adaptive response when a low dose (0.01-1 mGy) was given several hours after a high 1000-mGy radiation dose. The adaptive responses in this study were of similar magnitude to the two-dose adaptive responses previously observed in this test system when the low dose was given first. A chromosomal inversion adaptive response was also induced by two 1000-mGy doses and when a 1-mGy dose was preceded or followed by a dose of 0.01 mGy, but not by two 4000-mGy doses. This is also the first example of an adaptive response when both doses are low. Our data agree with previous reports of an on-off mechanism of adaptive response. The induction of an adaptive response by a low dose after a high damaging dose provides evidence that the mechanisms underlying radiation adaptive responses are not due to prevention of damage induced by the high dose but to modulation of the cellular response to this damage.
适应性反应由诸如X射线等应激诱导产生，并导致低于预期的生物学反应。两剂量适应性反应实验通常包括一个低预照射剂量，随后是一个高辐射剂量。在此，我们首次使用一种灵敏的体内染色体倒位分析方法，来证明在给予1000 mGy高辐射剂量数小时后再给予低剂量（0.01 - 1 mGy）时的适应性反应。本研究中的适应性反应幅度与该测试系统先前观察到的先给予低剂量时的两剂量适应性反应相似。两个1000 mGy剂量也能诱导染色体倒位适应性反应，当1 mGy剂量之前或之后给予0.01 mGy剂量时也能诱导，但两个4000 mGy剂量则不能。这也是两个剂量都低时出现适应性反应的首个实例。我们的数据与先前关于适应性反应开关机制的报道一致。高损伤剂量后低剂量诱导适应性反应，这表明辐射适应性反应的潜在机制并非由于防止高剂量诱导的损伤，而是由于调节细胞对这种损伤的反应。
