Amifostine and melatonin attenuate radiation-induced oxidative stress, inflammation, and fibrotic remodeling in the vocal folds and subglottic glands of rats

Head and neck radiotherapy is an effective treatment for cancer but often causes collateral injury to adjacent laryngeal tissues, leading to complications such as impaired voice production and mucosal dysfunction. This study examined whether pretreatment with amifostine or melatonin could mitigate radiation-induced morphological and molecular alterations in the vocal fold (VF) lamina propria and subglottic glands (SGs). Twenty-four male Sprague Dawley rats were randomly assigned to control, radiation only (RT), RT plus amifostine (RT+AMI), or RT plus melatonin (RT+MEL) groups. A single 15 Gy dose was delivered to the head and neck, and tissues were collected on day 10. Radiation induced early fibrotic remodeling in the VFs, characterized by increased collagen I/III deposition and TGF-β1 expression, and caused pronounced SG structural damage, including ductal dilation, acinar atrophy, and elastin fiber disorganization. Both agents attenuated collagen accumulation, preserved elastin architecture, and reduced fibrotic marker expression, with melatonin showing a greater effect in the VFs. Despite these structural improvements, mRNA levels of AQP5, AMY1, and hyaluronic acid synthase remained unchanged, suggesting that functional decline had not yet fully manifested at this early stage. These findings indicate that amifostine and melatonin provide partial radioprotection against acute fibrotic and structural damage in laryngeal tissues, supporting their potential as adjunctive agents for preserving vocal and mucosal functions during radiotherapy.