Protective effects of melatonin and diclofenac against high dose radiation-induced acute brain injury in rats

The aim of this study was to determine the preventive effects of melatonin and diclofenac against oxidative stress and acute inflammation induced by high-dose radiation in rat brain. Adult male (180-220 g) albino Wistar rats were randomly divided into five groups. Control group did not receive any administration. In radiation group, rats were subjected to dose of 70 Gy from LINAC. In melatonin group, five days prior to irradiation, animals received melatonin daily (100 mg/kg body weight i.p.). Diclofenac group received diclofenac daily (8 mg/kg body weight orally), five days prior to irradiation. Melatonin+diclofenac group received melatonin along with diclofenac, five days prior to irradiation. Tissue and blood samples were collected 48 hours after irradiation. Oxidative stress was assessed by determining reduced glutathione (GSH), thioredoxin (Trx) and thiobarbituric acid reactive substances (TBARS) levels, and alteration in antioxidant enzymes such as glutathione peroxidase (GSH-Px), glutathion reductase (GSH-R) and thioredoxin reductase (Trx- R) in brain tissues of all groups. Serum C-reactive protein levels were determined to assessment of acute inflammation. Also, brain tissues were investigated histopathologically. A significant increase in the TBARS levels was observed in the irradiated animals (p<0,05). Melatonin treatment significantly prevented the increasing of TBARS content in rat brain tissue. GSH-Px and GSH-R levels had been significantly increased in melatonin group (p<0,05). Statistically significant alterations in the levels of GSH, Trx, CRP and the activity of Trx-R were not observed. In conclusion; melatonin showed a protective role against oxidative damage induced by high-dose radiation in rat brain. Diclofenac showed an antioxidative effect too. According to histopathological evaluation, diclofenac supressed acute inflammation induced by radiation. But there is not correlation between CRP results and histopathological findings. Keywords: Melatonin, Diclofenac, Radiation, Oxidative stress