Effect of Iodine Deficiency and Iodine Excess on Antioxidation of Rat Thyroid / 环境与健康杂志

ABSTRACT

Objective To study the effect of different iodine intake on the antioxidation of rat thyroid. Methods The rats were divided into 6 groups, low iodide (LI), normal iodine (NI), high iodide including five fold (5HI), ten fold (10HI), fifty fold (50HI), one hundred fold (100HI) and given potassium iodide (KI) at different dosages through food respectively. After 6 and 12 months of treatment, the rats were sacrificed respectively and the activity of glutathione peroxidase (GPx), superoxide dismutase (SOD), the content of malondialdehyde (MDA) in the thyroid were determined. Results The activity of GPx , SOD and the MDA content in LI group were significantly higher than those in NI group. There was no difference in the SOD and GPx activity and MDA content among NI, 5HI and 10HI groups. The MDA content in 50HI group was lower than that in NI group after treated for 12 months, but no difference was found between them after treated for 6 months. Compared with NI group, the GPx activity, SOD activity and MDA content in 100HI group increased after 6 months of treatment, however, decreased after 12 months of treatment. Conclusion Low iodine intake can induce oxidative damage of the thyroid gland in normal rats, high iodine (100 fold) intake for a long period (12 months) may decrease the activity of anti-oxidases in thyroid without obvious oxidative damage, that shows the anti-oxidative system of rat thyroid has a tolerance to high iodine intake.