Radioprotective effect of resveratrol for early and late ionizing radiation-induced damages on colon and rectum in rats

Radiotherapy, which is routinely used to treat a wide range of oncological disorders, primarily affects the malignant tissue in the targeted area, but also have negative effects in the surrounding tissues. Pelvic radiotherapy causes early and late effects on the colon and rectum. Resveratrol (RVT) has been revealed to have a number of pharmacological effects in a variety of experimental models and clinical circumstances, therefore it has piqued the interest of scientists in recent years. In this study, we aimed to investigate the potential protective effects of resveratrol (RVT), a strong antioxidant, anti-inflammatory and anti-mutagenic agent, against toxicity of colonic and rectal tissues seen in the early and late stages after pelvic radiation. The treatment durations of the current study were designed as one week and ten weeks interval by following radiation exposure. Sprague Dawley rats were divided into 5 groups (8 animals/group) as the control, radiation-early effects (Rd-E), radiation-late effects (Rd-L), and RVT-treated Rd-E (Rd-E+RVT) and RVT-treated Rd-L (Rd-L+RVT) groups. Ionizing radiation was performed to the pelvic area that covers colon and rectum in single fraction of 20 Gy in a linear accelerator using with 6 MV photon energy. RVT was orally administered (10 mg/kg/day) immediately following the radiation exposure and continued daily for 1 and 10 weeks for early and late groups, respectively. Pelvic radiation caused a significant decrease in glutathione level, while malondialdehyde levels, myeloperoxidase activity and 8-hydroxydeoxyguanosine were increased in both Rd-E and Rd -L groups in the colon and rectum tissues. Additionally, light microscopic evaluations (H & E staining) revealed degeneration of epithelium and inflammatory cell infiltration in the colonic and rectal tissues in radiation groups. RVT treatment reversed all conducted biochemical parameters and ameliorated histomorphological changes following early and late effects of pelvic radiation in tissues. In conclusion, resveratrol may be a candidate as a radioprotector for normal tissues during and after radiotherapy.