Effect of Iodine on Thyroid Tumors Induced in the Rat by a Low-Iodine Diet2

Publisher Website
Google Scholar
Abstract
Neoplastic thyroid nodules were induced in rats by feeding them a low-iodine diet for 1 year. Then the rats were supplemented with iodine for 2, 4, 8, 16, 32, and 64 days, respectively, and killed. Controls not receiving iodine were killed at the same intervals. The number and the volume of the thyroid nodules were estimated quantitatively. Iodine treatment produced a reappearance of thyroid hormone in the blood and brought the level of thyrotrophic hormone back to a normal range. It caused a regression in the size of the thyroid gland and a considerable increase in the number of “light cells.” Two main types of nodules were observed; namely, type-β, formed of polarized cells having some resemblance to the cells lining the lumen of the thyroid follicles and probably originating from these cells, and type-γ, a solid mass of unpolarized cells probably originating from the “light cells” of the thyroid. Except, perhaps, for the very small ones, most type-β nodules persisted throughout the 2-month iodine treatment period, but they decreased in size. Iodine strongly stimulated the formation of type-γ nodules; after 2 months there were twice as many nodules in the iodine-treated group as in the controls. The formation of the new nodules probably resulted from a progressive growth of the light cells accompanied by a progressive disappearance of follicular cells.

This publication has 6 references indexed in Scilit: