Tahamtan Raziyeh, Shabestani Monfared Ali, Tahamtani Yasser, Tavassoli Alireza, Akmali Maasoomeh, Mosleh-Shirazi Mohammad Amin, Naghizadeh Mohammad Mehdi, Ghasemi Danial, Keshavarz Mojtaba, Haddadi Gholam Hassan
Department of Biophysics and Biochemistry, Cellular and Molecular Biology Research Centre, Babol University of Medical Sciences, Babol, Iran.
Department of Stem Cells and Developmental Biology at Cell Science Research Center, Royan Institute for Stem Cell Biology and Technology, ACECR, Tehran, Iran.
Cell J. 2015 Spring;17(1):111-20. doi: 10.22074/cellj.2015.517. Epub 2015 Apr 8.
Free radicals generated by ionizing radiation attack various cellular components such as lipids. The lung is a very radiosensitive organ and its damage is a doselimiting factor in radiotherapy treatments. Melatonin (MLT), the major product of the pineal gland acts as a radioprotective agent. This study aims to investigate the radioprotective effects of MLT on malondialdehyde (MDA) levels and histopathological changes in irradiated lungs.
In this experimental study, a total of 62 rats were divided into five groups. Group 1 received no MLT and radiation (unT), group 2 received oral MLT (oM), group 3 received oral MLT and their thoracic areas were irradiated with 18 Gy (oMR), group 4 received MLT by intraperitoneal (i.p.) injection and their thoracic areas were irradiated with 18 Gy (ipM-R), group 5 received only 18 Gy radiation in the thoracic area (R). Following radiotherapy, half of the animals in each group were sacrificed at 48 hours for evaluation of lipid peroxidation and early phase lung injuries. Other animals were sacrificed in the eighth week of the experiment for evaluation of the presence of late phase radiation induced lung injuries.
Pre-treatment of rats with either i.p injection (p<0.05) and oral administration of MLT (p<0.001) significantly reduced MDA levels in red blood cell (RBC) samples compared to the R group. Furthermore, i.p. injection of MLT decreased MDA levels in plasma and tissue (p<0.05). In the early phase of lung injury, both administration of MLT significantly increased lymphocyte (p<0.05) and macrophage frequency (p<0.001). MLT reduced the lung injury index in the lungs compared to the R group (p<0.05).
The result of this study confirms the radioprotective effect of MLT on lipid peroxidation, and in both early and late phases of radiation induced lung injuries in an animal model.
电离辐射产生的自由基会攻击各种细胞成分，如脂质。肺是对辐射非常敏感的器官，其损伤是放射治疗中的剂量限制因素。褪黑素（MLT）是松果体的主要产物，具有辐射防护作用。本研究旨在探讨MLT对受照射肺组织中丙二醛（MDA）水平和组织病理学变化的辐射防护作用。
在本实验研究中，将62只大鼠分为五组。第1组未接受MLT和辐射（未处理组），第2组接受口服MLT（口服组），第3组接受口服MLT并对其胸部区域进行18 Gy照射（口服MLT+照射组），第4组通过腹腔注射MLT并对其胸部区域进行18 Gy照射（腹腔注射MLT+照射组），第5组仅对胸部区域进行18 Gy辐射（照射组）。放射治疗后，每组一半的动物在48小时处死，以评估脂质过氧化和早期肺损伤。其他动物在实验的第八周处死，以评估晚期辐射诱导的肺损伤情况。
与照射组相比，腹腔注射（p<0.05）和口服MLT（p<0.001）预处理大鼠可显著降低红细胞（RBC）样本中的MDA水平。此外，腹腔注射MLT可降低血浆和组织中的MDA水平（p<0.05）。在肺损伤早期，两种MLT给药方式均显著增加淋巴细胞（p<0.05）和巨噬细胞频率（p<0.001）。与照射组相比，MLT降低了肺组织的肺损伤指数（p<0.05）。
本研究结果证实了MLT在动物模型中对脂质过氧化以及辐射诱导的肺损伤早期和晚期均具有辐射防护作用。
