The Potential Radioprotective Role Of Selenium On GAMMA Irradiated Rats' Salivary Glands

This study was conducted to evaluate the radioprotective efficacy of selenium, a naturally occurring antioxidant nutrient, against gamma radiation damage in rats' salivary glands by histological, histochemical and immunohistochemical assessments. A total of 48 male Albino rats were equally divided into 6 groups: Groups I and II were subjected to single gamma irradiation doses of 4Gy and 6Gy, respectively. Group III was injected with an intraperitoneal daily dose of sodium selenite (15 μg/kg) for three weeks. Groups IV and V were injected intraperitoneally with Se for one week before exposure to gamma rays at doses of 4 Gy and 6 Gy, respectively, and for two weeks after. The control group received neither radiation nor selenium. Animals were sacrificed 1 day, 2 weeks, 4 weeks and 8 weeks after radiation exposure. Paraffin sections of the submandibular and sublingual glands were stained by hematoxylin and eosin, alcian/PAS stain and Feulgen reaction, in addition to proliferating cell nuclear antigen (PCNA) immunostaining. The Feulgen and PCNA reactivity was estimated by an image analyzer computer system. Histological examination of the irradiated groups revealed intra cytoplasmic vacuoles in the acinar cells of both glands. A reduction in the number and content of secretory granules was noted in the submandibular granular convoluted tubules (GCT). In the 6 Gy group, some acini appeared atrophied or completely degenerated. A decreased alcian/PAS and Feulgen histochemical staining was noted in both glands one day and 2 weeks after irradiation. A milder degree of these changes was noted in the selenium treated groups. Two months post irradiation, the glandular tissue appeared normal in both the irradiated and the selenium treated irradiated groups. PCNA immunostaining revealed an initial decline in the number of proliferating cells in all glandular compartments 1 day post-irradiation in both glands followed by a subsequent increase after 14 days. The same pattern was generally detected in the selenium treated irradiated groups.The results revealed that the selenium treatment prevented some of the deleterious effects of radiation and helped maintaining the normal histological appearance of the salivary glands and their contents of carbohydrates and nucleic acids.