Ultrastructural assessment of the radioprotective effects of sodium selenite on parotid glands in rats.

The aim of this study was to assess the radioprotective effects of sodium selenite on parotid glands in rats by ultrastructural analysis of acinar cells. Four experimental groups were assessed; control, irradiated, selenium, and selenium/irradiated. The sodium selenite dose was 0.5 mg/kg, administered intraperitoneally 24 h before irradiation in the head and neck region with a single 15-Gy dose of gamma radiation. At 4, 8, 12, 48 and 72 h after irradiation, all animals were sacrificed and the parotid glands were removed. Radiation caused cellular changes from 4 h, and the organelles that presented the greatest alterations were the mitochondria and the secretion glands; nuclear alterations were also observed. Sodium selenite was found to have a radioprotective action, as the selenium/irradiated group presented with less damage when compared to the irradiated group. However, sodium selenite caused cellular alterations that were evident after 8 h, but with less damage when compared to those caused by radiation, which demonstrates a favorable risk-benefit for its use as a radioprotector. Thus, this research shows that sodium selenite has an effective radioprotective action in the parotid gland, which may contribute to the reduction of the adverse effects brought by the radiotherapy.