Melatonin prevents possible radiotherapy-induced thyroid injury.

ABSTRACT

PURPOSE: We aimed to investigate the protective effect of melatonin in radiotherapy-induced thyroid gland injury in an experimental rat model. MATERIALS AND METHODS: Thirty-two rats were divided into four groups the control group, melatonin treatment group, radiotherapy group and melatonin plus radiotherapy group. The neck region of each rat was defined by simulation and radiated with 2 Gray (Gy) per min with 6-MV photon beams, for a total dose of 18 Gy. Melatonin was administered at a dose of 50 mg/kg through intraperitoneal injection, 15 min prior to radiation exposure. Thirty days after the beginning of the study, rats were decapitated and analyses of blood and thyroid tissue were performed. RESULTS: Tumor necrosis factor-α (TNF-α), interleukin-1 beta (IL-1ß), thiobarbituric acid reactive substances (TBARS) and nitric oxide (NO) levels in the radiotherapy group were significantly higher than those in the melatonin plus radiotherapy group (p < .05), whereas interleukin-10 (IL-10) and glutathione (GSH) values were higher in the melatonin plus radiotherapy group (p < .05). The infiltration of inflammatory cells and percentage of apoptosis in the radiotherapy group were significantly higher than those in the melatonin plus radiotherapy group (p < .05). CONCLUSIONS: Melatonin helped protect thyroid gland structure against the undesired cytotoxic effects of radiotherapy in rats.