Antithyroid effect of 2,3-dihydroxypyridine in vivo and in vitro.

Abstract

AbstractThe antithyroid effect of 2,3-dihydroxypyridine (2,3-DHP) was investigated in vivo and in vitro. Thyroid studies were carried out on two groups of rats; one group of 14 rats were fed a low-iodine diet containing 1% 2,3-DHP for 25 days, and a control group of 12 rats received low-iodine diet alone. 2,3-DHP-treated rats had reduced thyroid function with a significant rise in serum thyrotropin (TSH) levels and decreased serum triiodothyronine (T3) levels; thyroxine (T4) and T3 contents of the thyroid gland were 20 and 10%, respectively, lower than those of controls. In vitro, 2,3-DHP inhibited peroxidase activity, and its antiperoxidase potency was similar to the commonly used thioureylene antithyroid drug, propylthiouracil. In addition, 2,3-DHP was a much weaker inhibitor of the thyroid conversion of T4 to T3 in vitro than propylthiouracil. 2,3-DHP represents a new class of antithyroid drug and its main action appears to be inhibition of peroxidase-catalyzed thyroid hormone formation in the thyroid ...