Investigation of the protective effects of intraperitoneal melatonin in rats receiving laryngeal radiotherapy

Abstract

Objectives: To examine the protective effects of melatonin on laryngeal radiation damage. Materials and methods: 31 rats were divided into 4 groups as follows: 1) the control (C) group (n = 7), was only injected with intraperitoneal ethanol solution; 2) the melatonin (M) group (n = 8), was injected intraperitoneal melatonin solution with 5 mg/kg; 3) the radiotherapy (RT) group (n = 8) was given laryngeal radiation after intraperitoneal injection of ethanol solution; 4) the M + RT group (n = 8), RT was given 30 minutes after 5 mg/kg dose of melatonin solution was injected. Drug and radiation applications were continued for 5 days. The weight changes of the rats were recorded. At the end of the study, inflammation, neutrophil migration and lym-phoid aggregates, collagen distribution, laryngeal glandular structures and biochemical analysis of laryngeal tissues [malondialdehyde (MDA), total oxidant status (TOS) and total antioxidant status (TAS)] were determined. Results: In the M +RT group, the first day and the 30th weight differences were significantly increased when compared with the RT group (p = 0.050). Inflammation, neutrophil migration, lymphoid aggregate, disorganized collagen distribution and loss of glandular tissues were found statistically more in the RT group than in the C group (p < 0.05). MDA and TOS levels were in the M + RT group exhibited better values than they did in the RT group (p < 0.05). TAS levels was markedly increased in the M + RT group than in the RT group (p < 0.001). Conclusion: Administration of melatonin to rats prior receiving laryngeal radiation, decreases the level of oxidative stress markers and increases the level of anti-oxidative markers. (c) 2022 Japanese Society of Otorhinolaryngology-Head and Neck Surgery, Inc. Published by Elsevier B.V. All rights reserved.