褪黑素对重离子辐射损伤小鼠肺的防护作用研究

目的探讨褪黑素(melatonin,MLT)对重离子辐射损伤小鼠肺的防护作用。方法预先给小鼠腹腔注射10mg/kg的MLT,1h后给予0、0.5、1.0、2.0及4.0Gy的全身12C6+束均匀照射,剂量率约1.4Gy/min,辐射后8h,检测辐射损伤小鼠肺组织的SOD活性和MDA、GSH含量,并通过单细胞凝胶电泳技术检测辐射损伤小鼠肺细胞的拖尾长度和尾距。结果和单纯辐射组相比,10mg/kg的MLT腹腔注射能有效抑制重离子辐射引起的小鼠肺组织SOD活性降低、GSH含量下降和MDA含量提高;同时,MLT还能使受损小鼠肺细胞的拖尾长度和尾距显著降低,且都存在剂量效应关系。结论MIT对重离子全身辐射所致小鼠的抗氧化系统有一定的激活效应,对辐射损伤有一定的防护作用,这可能与对抗膜脂质过氧化、清除自由基及其减轻DNA损伤有一定的关系。

Study on Protective Effect of Melatonin against Radiation Damages of Lung in Mice Induced by Heavy Ion Beams

Objective To evaluate the protective effects of melatonin ( MLT) against the radiation damage of lung induced by heavyions in mice. Methods The mice were whole-body uniformly irradiated with carbon ions at 0、0.5、1.0、2.0 and 4.0 Gy at a dose rate of about 1. 4 Gy/min after an hour to be given intra-peritoneal injection of 10 mg/kg MLT. Then an acute study was performed to determine the alterations in lipid peroxidation [ determined by measuring malondiadehyde ( MDA) level ] , superoxide dismutase ( SOD) activity ( assayed by colorimetric method) and glutathione (GSH) content in lung tissues of irradiated mice. Moreover, the DNA damage (characterized by tail moment and tail length using the single cell gel electrophoresis assay) in lung cells of mice were measured also at 8 h after irradiation. Results Caused by heavy ions irradiation, it was found that in all lung tissue of MLT injected groups (10 mg/kg) compared with irradiation only groups there were dose-related decreases in MDA level, tail moment and tail length, as well as dose-dependent increases in GSH content and SOD activity . Conclusion The MLT has activation effect to antioxidant system of mice induced by whole-body irradiation with heavy ions, and has some protective effect against irradiation injury. This result may be related to the antagonistic effect on membrane lipid peroxidation, scavenging capacity on free radical and reduction of DNA damage.