The study of superoxide dismutase in thyroid of rats with iodine deficiency by immunohistochemistry and immunoelectron microscopy

Objective To study the relationship between free radical and iodine deficiency by means of observing iodine deficiency, morphological damage and superoxide dismutase (SOD) in rat thyroid. Methods Immunohistochemical and immunoelectron microscopy techniques were performed to show the location of SOD and the ultrastructure of the epithelial cell of thyroid in rats with different iodine deficiency. Stereological parametes were obtained by image processing. Results SOD of thyroid in normal rats was located in the rough endoplasmicreticulum,theboundaryofmicrovilliandcolloid lumin, and cytoplasm of top of follicular epithelia. The thyroid of iodine deficiency showed the poor distribution of SOD. In the group of low iodine intake for 4 months (LI 4), many epithelial cells were obviously damaged, and the content of SOD was significantly lower. Only very few epithelial cells had a positive reaction of SOD. In the group of low iodine intake for 6 months, SOD was very poor and the structure was damaged seriously following the process of iodine deficiency. Conclusions Iodine deficiency induces the reduction of SOD, the increase of free radicals and damaging structure and function of membrane and results in the further aggravation of damage by iodine deficiency.