title: Radio-protective effects of melatonin against irradiation-induced oxidative damage in rat peripheral blood.
abstract: During radiotherapy, ionizing irradiation interacts with biological systems to produce free radicals, which attacks various cellular components. The hematopoietic system is well-known to be radiosensitive and its damage may be life-threatening. Melatonin synergistically acts as an immunostimulator and antioxidant. In this study we used a total of 120 rats with 20 rats in each group. Group 1 did not receive melatonin or irradiation (Control group), Group 2 received only 10 mg/kg melatonin (Mel group), Group 3 exposed to dose of 2 Gy irradiation (2 Gy Rad group), Group 4 exposed to 8 Gy irradiation (8 Gy Rad group), Group 5 received 2 Gy irradiation plus 10 mg/kg melatonin (Mel +2 Gy Rad group) and Group 6 received 8 Gy irradiation plus 10 mg/kg melatonin (Mel+8 Gy Rad group). Following exposure to radiation, five rats from each group were sacrificed at 4, 24, 48 and 72 h. Exposure to different doses of irradiation resulted in a dose-dependent decline in the antioxidant enzymes activity and lymphocyte count (LC) and an increase in the nitric oxide (NO) levels of the serum. Pre-treatment with melatonin (10 mg/kg) ameliorates harmful effects of 2 and 8 Gy irradiation by increasing lymphocyte count(LC) as well as antioxidant enzymes activity and decreasing NO levels at all time-points. In conclusion 10 mg/kg melatonin is likely to be a threshold concentration for significant protection against lower dose of 2 Gy gamma irradiation compared to higher dose of 8 Gy. Therefore, it seems that radio-protective effects of melatonin are dose-dependent.
authors.affiliation: Department of Medical Physics and Biomedical Engineering, Faculty of Medicine, Tehran University of Medical Sciences, Keshavarz Blvd., Poursina Ave., Tehran 468, Iran. shirazia@tums.ac.ir
authors.forename: Alireza
authors.initials: A
authors.lastname: Shirazi
authors.forename: Ehsan
authors.initials: E
authors.lastname: Mihandoost
authors.forename: Mehran
authors.initials: M
authors.lastname: Mohseni
authors.forename: Mahmoud
authors.initials: M
authors.lastname: Ghazi-Khansari
authors.forename: Seied
authors.initials: S
authors.lastname: Rabie Mahdavi
mesh_terms: D000818:Animals; D001769:Blood / Q000187:drug effects* / Q000378:metabolism / Q000528:radiation effects*; D002374:Catalase / Q000378:metabolism; D005979:Glutathione Peroxidase / Q000378:metabolism; D018655:Lymphocyte Count; D008297:Male; D008550:Melatonin / Q000494:pharmacology*; D009569:Nitric Oxide / Q000378:metabolism; D018384:Oxidative Stress / Q000187:drug effects* / Q000528:radiation effects*; D011837:Radiation-Protective Agents / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D013482:Superoxide Dismutase / Q000378:metabolism; D013997:Time Factors; D014916:Whole-Body Irradiation / Q000009:adverse effects*
chemical_list: D011837:Radiation-Protective Agents; D009569:Nitric Oxide; D002374:Catalase; D005979:Glutathione Peroxidase; D013482:Superoxide Dismutase; D008550:Melatonin