Abstract
As described in our previous paper, prolonged intake of excess iodide results in thyroid enlargement in mice. The present experiments were undertaken to determine whether a different metabolism of iodide exists between the mouse and rat when the animal was acutely and chronically given large doses of iodide. The present data indicated that over a wide range (1 to 50μg/mouse) of acute iodide doses, total organic iodination was greatly increased without detectably altering the pattern of hormonal products synthesized. While, the release of hormone from newly iodinated thyroglobulin was inhibited. In a chronic iodide load experiment, mice were injected 125I for 15 days and then given daily injection of 50μg 127I labeled with 2μCi of 131I for 5 to 15 days. From the analysis of thyroidal radioactivity of 125I and 131I and plasma PBI and BEI, iodidetreated thyroid of mice given large doses of iodide chronically synthesized increased quantities of organic iodine and released less quantities of thyroidal radioiodine than the control animal. It is suggested that excess iodide apparently does stimulate the organification of idodide and conversely inhibits thyroidal radioiodine release in mice.
