EFFECT OF GRADED DOSES OF PROPYLTHIOURACIL ON BIOSYNTHESIS OF THYROID HORMONES1
- 1 April 1961
- journal article
- other
- Published by The Endocrine Society in Endocrinology
- Vol. 68 (4) , 582-588
- https://doi.org/10.1210/endo-68-4-582
Abstract
Graded doses of PTU (0.001–180 mg.) were administered subcutaneously once daily to rats for three days. I131 was given immediately following the last dose of PTU; twenty-four hours later the thyroids were removed. Relative amounts of DIT and of T3+T4 decreased with increasing doses of PTU. No DIT nor T3+T4 were found with doses greater than 0.1 mg. The relative amount of MIT increased with the amount of PTU, attained its maximum at a dose of 5 mg., then declined. Even with 180 mg. of PTU, MIT formation was not blocked completely. The absolute amount of radioiodide declined sharply with doses greater than 0.01 mg. Formation of DIT from MIT is thus inhibited by very small doses of PTU, whereas organic binding of iodide into MIT is not completely blocked even with very large doses. Coupling to form iodinated thyronines is depressed by smaller amounts of PTU than the other biosynthetic mechanisms studied.Keywords
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