Document Type : Original Article
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
Department of Pathology, Fasa University of Medical Sciences, Fasa, Iran
4Department of Biochemistry, Faculty of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran
5Department of Radiotherapy, Physics Unit, Namazi Hospital, Shiraz University of Medical Sciences, Shiraz, Iran
6Department of Biostatistics, Fasa University of Medical Sciences, Fasa, Iran
7Student Research Committee, Shiraz University of Medical Sciences, Shiraz, Iran
8Young Researchers and Elite Club, Shiraz Branch, Islamic Azad University of Shiraz, Shiraz Iran
9Department of Medical Physics, Fasa University of Medical Sciences, Fasa, Iran
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.
Materials and Methods
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.