A comparative experimental study on the impact of radiotherapy dose rate and melatonin pretreatment in tongue and esophageal tissues

AIM: This study aimed to investigate the differential biological responses in tongue and esophageal tissues induced by flattening filter (FF) and flattening filter-free (FFF) beams at varying dose rates, and to assess the radioprotective role of melatonin (MEL) pretreatment. MATERIALS AND METHODS: Forty female Wistar albino rats (6-8 weeks) were divided into five groups: control (G1), FF (16 Gy at 600 MU/min, G2), FF + MEL (G3), FFF (16 Gy at 2400 MU/min, G4), and FFF + MEL (G5). Radiotherapy (RT) was delivered to the head and neck region. MEL (50 mg/kg, intraperitoneal) was administered 15 minutes prior to irradiation. Serum levels of IFN-γ, IL-1β, IL-6, IL-10, caspase-3, and LDH were measured using enzyme-linked immunosorbent assay (ELISA). Histopathological evaluations of tongue and esophageal tissues were performed with hematoxylin and eosin staining, and BCL-2 expression was assessed by immunofluorescence. RESULTS: > .05). CONCLUSIONS: Melatonin pretreatment significantly reduced histopathological tissue damage following irradiation. However, reductions in serum inflammatory and apoptotic markers did not reach statistical significance. No significant differences were observed between FF and FFF beam modalities.