title: Increased sensitivity of the thyroid in iodine-depleted rats to the goitrogenic effects of thyrotropin.
abstract: The present studies demonstrate that iodine depletion increases the sensitivity of the thyroid to the goitrogenic effects of thyrotropin. Iodine depletion was induced by feeding rats a low iodine diet containing propylthiouracil for 10-14 days before hypophysectomy. Accumulation of iodine in the thyroid after hypophysectomy was prevented by continuing the antithyroid drugs in the diet. Doses of thyrotropin as low as 3 mU/100 g of body weight per day produced significant thyroid enlargement in 3-7 days in iodine-depleted rats. Adding propylthiouracil or perchlorate to the diet during treatment with thyrotropin did not reduce or augment the goitrogenic response to thyrotropin in iodine-depleted rats. Increasing the level of circulating iodide also did not reduce the goitrogenic response to thyrotropin. The increased sensitivity of the iodine-depleted thyroid gland may provide an explanation for the development of thyroid enlargement without requiring an increased level of circulating thyrotropin.
mesh_terms: D000818:Animals; D003677:Deficiency Diseases; D004032:Diet; D006042:Goiter / Q000139:chemically induced* / Q000378:metabolism; D007016:Hypophysectomy; D007455:Iodine / Q000378:metabolism*; D010472:Perchlorates / Q000494:pharmacology; D010902:Pituitary Gland / Q000502:physiology; D011441:Propylthiouracil / Q000494:pharmacology; D051381:Rats; D013961:Thyroid Gland / Q000187:drug effects* / Q000378:metabolism; D013972:Thyrotropin
chemical_list: D010472:Perchlorates; D011441:Propylthiouracil; D013972:Thyrotropin; D007455:Iodine