Melatonin Ameliorates The Production of COX-2, iNOS, and The Formation of 8-OHdG in Non-Targeted Lung Tissue after Pelvic Irradiation

Document Type : Short Communication

Authors

1 Department of Radiology, School of Paramedical Sciences, Shiraz University of Medical Sciences, Shiraz, Iran

2 Ionizing and Non-ionizing Radiation Protection Research Center, Department of Radiotherapy and Oncology, Shiraz University of Medical Sciences, Shiraz, Iran

3 Diagnostic Laboratory Sciences and Technology Research Center, School of Paramedical Sciences, Shiraz University of Medical sciences, Shiraz, Iran

4 4Department of Biomedical Physics and Engineering, Faculty of Medicine, Tehran University of Medical Sciences, Tehran, Iran

5 5Department of Medical Physics, School of Medicine, Iran University of Medical Sciences, Tehran, Iran

Abstract

In this study, we evaluated the bystander effect of radiation on the regulation of cyclooxygenase-2 (COX-2), inducible nitric oxide synthase (iNOS), and 8-hydroxydeoxyguanosine (8-OHdG) in lung tissues of Sprague-Dawley rats with and without pre-administration of melatonin. A 2×2 cm2 area of the pelvis of male Sprague-Dawley rats with and without pre-administration of melatonin (100 mg/kg) by oral and intraperitoneal injection was irradiated with a 3 Gy dose of 1.25 MeV γ-rays. Alterations in the levels of COX-2, iNOS, and 8-OHdG in the out-of-field lung areas of the animals were detected by enzyme immunoassay. The bystander effect significantly increased COX-2, iNOS, and 8-OHdG levels in non-targeted lung tissues (P < 0.05). Melatonin ameliorated the bystander effect of radiation and significantly reduced the level of all examined biomarkers (P < 0.05). The results indicated that the ameliorating effect of a pre-intraperitoneal (IP) injection of melatonin was noticeably greater compared to oral pre-administration. Our findings revealed that the bystander effect of radiation could induce oxidative DNA damage and increase the levels of imperative COX-2 and iNOS in non-targeted lung tissues. Interestingly, melatonin could modulate the indirect destructive effect of radiation and reduce DNA damage in non-targeted cells.

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