RESUMO
OBJECTIVE: Radioiodine-131 is a radionuclide that is used for therapeutic purposes in hyperthyroidism and thyroid cancer. The aim of this study was to evaluate apoptotosis and proliferative changes in radioiodine-related kidney damage. MATERIALS AND METHODS: Three groups (n=10/group) of rats were used as follows: the rats were in group 1 untreated, and the rats in groups 2 and 3 were treated once with oral radioiodine (111 MBq). The animals in group 2 were killed at the end of the seventh day and the rats in group 3 were killed at the end of the 10th week. The kidneys were removed and evaluated immunohistochemically. The presence of radioiodine in the kidneys was shown by the Na+/I-symporter antibody and proliferating cell nuclear antigen, Ki-67, caspase-3, caspase-8, caspase-9, and terminal deoxynucleotidyl transferase mediated deoxyuridine triphosphate nick end labeling assay were used to detect cell proliferation and apoptosis. RESULTS: Na+/I-symporter protein accumulation in the kidneys was observed to be significantly greater in group 2 than in group 3 (P<0.05). All the immunohistochemical analyses showed that cell proliferation and apoptosis began on the seventh day and peaked in the 10th week. The proliferating cell nuclear antigen, Ki-67, and caspase expressions and terminal deoxynucleotidyl transferase mediated deoxyuridine triphosphate nick end labeling values were all found to be statistically significantly increased in group 3 compared with the other groups (P<0.05). CONCLUSION: Radioiodine caused cell proliferation and apoptosis as shown by immunohistochemistry.