低剂量辐射兴奋效应的自由基机制探讨

Low dose radiation induced hormesis and its mechanism of free radicals

目的研究低剂量照射（6cGy）的骨髓细胞悬液，离心后得到的上层相（刺激液）对正常或辐射损伤细胞能否产生低剂量辐射兴奋效应，并探讨其机制。方法刺激液与受0、2或5Gy照射的骨髓细胞悬液进行混合培养，使用MTT比色法检测各组细胞的增殖能力，采用细胞色素c还原法测定细胞中O2^-的浓度。最后，通过加入二亚苯基碘和肉豆蔻醋酸酯实验性、特异地降低或提高细胞中O2^-的浓度，观察此种变化对刺激液产生上述作用的影响。结果正常和受大剂量照射的骨髓细胞与刺激液共培养后，其增殖能力明显高于对照组。减少细胞中O2^-的浓度可降低辐射损伤细胞的增殖活力，而增加细胞中O2^-的浓度可提高辐射损伤细胞的增殖能力。

Objective To investigate whether the supematant （the stimulating fluid） centrifuged from myeloid cells suspension after low dose radiation in vitro can produce hormesis on the normal or radiation damage cells. The mechanism of free radical was probed. Methods Mouse myeloid cell suspension was irradiated respectively by 0, 2 and 5 Gy, and cultured in vitro. MTT method was used to measure the reproductive activity of cells. Meanwhile, Cytochrome C reduction method was used to determine the concentration of O2^- . Lastly, the concentration of O2^- was decreased or increased by adding DPI or PMA, and the effect of such changes on ＂the stimulating fluid＂ was observed. Results Co-cultured with ＂the stimulating fluid＂, the reproductive activity of the myeloid ceils after large dose radiation or the normal myeloid cells were enhanced. Decreasing the concentration of O2^- may degrade the proliferation of the cells after radiation damage ; while increasing it may lead to the opposite result. Conclusions The stimulating fluid can enhance the proliferation of the myeloid cells after radiation damage and also the normal ones. The mechanism of above-mentioned phenomena might be related with the changes of O2^- concentration.