EFFECTS OF IODINE DEFICIENCY ON THYROID HORMONES AND NUCLEAR T_3 RECEPTORS IN RAT CEREBRUM / 中华内分泌代谢杂志

ABSTRACT

We observed the changes of cerebral nuclear T3 and its receptors and T4 5'-deiodinase activity in the fourth or fifth filial generations of the rats with long term iodine deficiency. The cerebrum was dissected on the 20th day postpartum. The results showed that the maximal binding capacity of nuclear T3 receptor was significantly lowered, but the affinity constant was essentially unchanged. Also, the concentration of nuclear T3 and the T4 5'-deiodinase activity were decreased markedly. It was concluded that 1) A decrease of cerebral nuclear T3 receptor was induced by long term iodine deficiency in rats; 2) T4 5'-deiodinase activity rather than serum T3 level could reflect more precisely the cerebral nuclear T3 concentration; and 3) The decrease of T3 receptor may presumably be the initial step of endemic cretinism caused by severe iodine deficiency.