title: Melatonin reduces lipid peroxidation and nitric oxide during irradiation-induced oxidative injury in the rat liver.
abstract: Radiation therapy is a popular and useful tool in the treatment of cancer. Melatonin participates in the regulation of a number of important physiological and pathological processes. Melatonin, a powerful endogenous antioxidant, plays a role in the reduction of oxidative damage. Thirty adult rats were divided into five equal groups. On the day of the experiment, groups I and II were injected with 5 or 10 mg/kg melatonin, respectively, while group III received isotonic NaCl solution. Thirty minutes later, groups I, II and III were exposed to 6.0 Gy whole body ionizing radiation in a single fraction. Group IV was injected with 5 mg/kg melatonin but was not irradiated. The final group was reserved as sham treated. Liver malondialdehyde (MDA) and nitric oxide (NO*) levels were measured in all groups. Whole body irradiation caused a significant increase in liver MDA and NO* levels. Hepatic MDA and NO* levels in irradiated rats that were pretreated with melatonin (5 or 10 mg/kg) were significantly decreased. Malondialdehyde and NO* levels were reduced in a dose-related manner by melatonin. The data show that melatonin reduces liver damage inflicted by irradiation when given prior to the exposure to ionizing radiation. The radioprotective effect of melatonin is likely achieved by its ability to function as a scavenger for free radicals generated by ionizing radiation.
authors.affiliation: Departments of Biochemistry, Faculty of Medicine, Atatürk University, Erzurum, Turkey. seytaysi@hotmail.com
authors.forename: Seyithan
authors.initials: S
authors.lastname: Taysi
authors.forename: Mehmet
authors.initials: M
authors.lastname: Koc
authors.forename: Mehmet Emin
authors.initials: ME
authors.lastname: Büyükokuroğlu
authors.forename: Konca
authors.initials: K
authors.lastname: Altinkaynak
authors.forename: Yaşar Nuri
authors.initials: YN
authors.lastname: Sahin
mesh_terms: D000818:Animals; D004305:Dose-Response Relationship, Drug; D015227:Lipid Peroxidation / Q000187:drug effects* / Q000528:radiation effects; D008099:Liver / Q000187:drug effects* / Q000473:pathology / Q000528:radiation effects; D008297:Male; D008315:Malondialdehyde / Q000032:analysis / Q000378:metabolism / Q000528:radiation effects; D008550:Melatonin / Q000494:pharmacology*; D009569:Nitric Oxide / Q000032:analysis / Q000378:metabolism* / Q000528:radiation effects; D018384:Oxidative Stress / Q000187:drug effects* / Q000528:radiation effects; D011837:Radiation-Protective Agents / Q000494:pharmacology*; D051381:Rats
chemical_list: D011837:Radiation-Protective Agents; D009569:Nitric Oxide; D008315:Malondialdehyde; D008550:Melatonin