Salicylates and Thyroid Function. II. The Effect on the Thyroid-Pituitary Interrelation

Abstract

The effect of salicylate on some thyrotropin-dependent functions of the thyroid gland was investigated in man and rats. Salicylates retard the rate of release of I131 from the human or rat thyroid gland, and salicylate administration in the rat leads to a partial inhibition of goiter production in the propylthiouracil treated animal. However, the thyroid of salicylate-treated patients still responds to exogenous thyrotropin with an increase in the uptake of I131, and elevation of the serum protein bound iodine concentration, and an acceleration of the rate of release of radioiodine from the thyroid gland. Salicylate-C14 did not appear to be significantly concentrated in the pituitary, hypothalmus, thyroid, or adrenal. It was concluded that the inhibition of thyroid function produced by salicylate administration is mediated via an inhibition of thyrotropin stimulation at a pituitary or higher level. This inhibition did not appear to be related to uncoupling of oxidative phosphorylation, pyrogenesis, chelating ability of the ortho-substituted phenols, or adrenal stimulation.