Objective: To study the mechanism of the disorder of thyroid hormone metabolism resulted from iodine excess in order to seek suitable selenium intervention dosage.
Methods: 140 Balb/c mice were randomly divided into seven groups, the normal control group, the excessive iodine group (drank the water containing potassium iodate 3000 microg/L) and five selenium intervention groups (drank the water containing 3000 microg/L of potassium iodate and 0.1, 0.2, 0.3, 0.4 and 0.5 mg/L of selenium). All of the mice were cultivated for 16 weeks and the thyroid hormone in plasma were assayed by radioimmunoassay. The iodine in urine and thyroid were analyzed by Cer-Arsenite colormetric method. The activities of glutathione peroxidase, superoxide dismutase and thyroid peroxidase and the level of malondialdehyde in thyroid were analyzed.
Results: The level of thyroid hormone of selenium intervention groups had no significant difference with that of normal control group (P > 0.05). Compared with excessive iodine group, the iodine in thyroid of 0.2 mg/L selenium intervention group increased significantly (P < 0.05). Compared with the normal control group, the activities of glutathione peroxidase and superoxide dismutase and the level of malondialdehyde of 0.2-0.3 mg/L selenium intervention groups in thyroid were not significantly different. Compared with the normal control group, the activity of thyroid peroxidase of 0.1-0.3 mg/L selenium intervention groups were not significantly different.
Conclusion: The results indicated that the optimal dose of selenium could restrain the disorder of thyroid hormone metabolism induced by excessive iodine in mice.