title: Melatonin ameliorates ionizing radiation-induced oxidative organ damage in rats.
abstract: This study was designed to study the effects of the potential radioprotective properties of pharmacological doses of melatonin against organ damage induced by whole-body irradiation (IR) in rats. A total of 32 male Sprague-Dawley rats were exposed to irradiation performed with a LINAC producing 6 MV photons at a focus 100 cm distant from the skin. Under ketamine anaesthesia, each rat received a single whole-body dose of 800 cGy. Immediately before and after IR, rats were treated with either saline or melatonin (20 mg/kg and 10 mg/kg, i.p.) and decapitated at 12-h after exposure to irradiation. Another group of rats was followed for 72-h after IR, where melatonin (10 mg/kg, i.p.) injections were repeated once daily. Tissue levels of malondialdehyde (MDA)--an index of lipid peroxidation--, glutathione (GSH)--a key to antioxidant--and myeloperoxidase (MPO) activity--an index of neutrophil infiltration--were estimated in liver, lung, colon and intestinal tissues. The results demonstrate that both 12-h and 72-h following IR, tissue levels of MDA were elevated (p<0.05-0.001), while GSH levels were reduced (p<0.05-0.001) in all organs. On the other hand, melatonin, reduced the levels of MDA and increased the GSH levels significantly, (p<0.05-0.001). MPO activity was increased significantly in the colonic tissue at the both 12-h and 72-h, and in the hepatic tissue at the 72-h following IR, which were reduced by melatonin (p<0.01-0.001). In the lung tissue enzyme activity was decreased at 72nd h of post-irradiation. In conclusion, the increase in MDA levels and MPO activity and the concomitant decrease in GSH levels demonstrate the role of oxidative mechanisms in irradiation-induced tissue damage, and melatonin, by its free radical scavenging and antioxidant properties, ameliorates irradiation-induced organ injury. Thus, supplementing cancer patients with adjuvant therapy of melatonin may have some benefit for successful radiotherapy.
authors: Department of Pharmacology, Marmara University, School of Pharmacy, Istanbul, Turkey.
authors: Göksel
authors: G
authors: Sener
authors: Nermina
authors: N
authors: Jahovic
authors: Osman
authors: O
authors: Tosun
authors: Beste Melek
authors: BM
authors: Atasoy
authors: Berrak C
authors: BC
authors: Yeğen
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000494:pharmacology*; D003106:Colon / Q000187:drug effects / Q000473:pathology / Q000528:radiation effects; D005978:Glutathione / Q000378:metabolism; D007082:Ileum / Q000187:drug effects / Q000473:pathology / Q000528:radiation effects; D008099:Liver / Q000187:drug effects / Q000473:pathology / Q000528:radiation effects; D008168:Lung / Q000187:drug effects / Q000473:pathology / Q000528:radiation effects; D008297:Male; D008315:Malondialdehyde / Q000378:metabolism; D008550:Melatonin / Q000494:pharmacology*; D010084:Oxidation-Reduction; D009195:Peroxidase / Q000378:metabolism; D011837:Radiation-Protective Agents; D051381:Rats; D017207:Rats, Sprague-Dawley; D014916:Whole-Body Irradiation
chemical_list: D000975:Antioxidants; D011837:Radiation-Protective Agents; D008315:Malondialdehyde; D009195:Peroxidase; D005978:Glutathione; D008550:Melatonin