Protective effects of melatonin against low- and high-LET irradiation.
Protective effects of melatonin against low- and high-LET irradiation.
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DOI：
10.1269/jrr.47.175
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发表时间：
2006-06
影响因子：
2
通讯作者：
Guangming Zhou;T. Kawata;Y. Furusawa;M. Aoki;R. Hirayama;K. Ando;Hisao Ito
中科院分区：
文献类型：
--
作者：
Guangming Zhou;T. Kawata;Y. Furusawa;M. Aoki;R. Hirayama;K. Ando;Hisao Ito
为探讨褪黑素对高LET电离辐射的防护作用，用100 keV/μ m碳束照射中国仓鼠V79细胞。用200 kV X射线进行平行实验。为了避免额外溶剂的影响，将褪黑素直接溶解在培养基中。在照射前将细胞在褪黑激素培养基中培养1小时。用常规集落形成试验检测细胞失活情况，用含6-硫代鸟嘌呤的培养基筛选hprt位点突变体，用流式细胞仪检测细胞周期。碳束和X射线均可剂量依赖性地诱导细胞失活、hprt基因突变和细胞周期G2期阻滞。但碳束显示出更强的效果，如所有三个终点所示，细胞杀伤的相对生物学有效性（RBE）为3.5（10%存活水平），突变诱导的相对生物学有效性（RBE）为2.9（5 × 10（-5）突变体/细胞水平）。褪黑激素对电离辐射具有剂量依赖性的防护作用。在细胞杀伤方面，褪黑激素仅增加暴露于8戈伊或更大的X射线或6戈伊或更大的碳束的那些样品的存活水平。在hprt突变和G2阻滞的诱导中，褪黑激素降低了碳束诱导的这种效应，而不是由X射线引起的。结果表明，褪黑激素减少颗粒与细胞的直接相互作用，而不是间接相互作用。需要进一步的研究来揭示潜在的机制。
To investigate the protective effects of melatonin against high-LET ionizing radiation, V79 Chinese hamster cells were irradiated with 100 keV/microm carbon beam. Parallel experiments were performed with 200 kV X-rays. To avoid the impact from extra solvents, melatonin was dissolved directly in culture medium. Cells were cultured in melatonin medium for 1 hr before irradiation. Cell inactivation was measured with conventional colony forming assay, medium containing 6-thioguanine was used for the selection of mutants at hprt locus, and the cell cycle was monitored by flow cytometry. Both carbon beam and X-rays induced cell inactivation, hprt gene mutation and cell cycle G2 block dose-dependently. But carbon beam showed stronger effects as indicated by all three endpoints and the relative biological effectiveness (RBE) was 3.5 for cell killing (at 10% survival level) and 2.9 for mutation induction (at 5 x 10(-5) mutants/cell level). Melatonin showed protective effects against ionizing radiation in a dose-dependent manner. In terms of cell killing, melatonin only increased the survival level of those samples exposed to 8Gy or larger of X-rays or 6 Gy or larger of carbon beam. In the induction of hprt mutation and G2 block, melatonin reduced such effects induced by carbon beam but not by X-rays. The results suggest that melatonin reduces the direct interaction of particles with cells rather than an indirect interaction. Further studies are required to disclose the underlying mechanisms.