A COMPARISON OF THE EFFECTS OF GOITROGENS ON THYROID ACTIVITY IN TRITURUS VIRIDESCENS AND DESMOGNATHUS FUSCUS

¹ Biology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, Department of Biology, University of Virginia, Charlottesville, Virginia, and Department of Biology, Catholic University of America, Washington, D. C.

1. Specimens of Triturus viridescens and Desmognathus fuscus were injected on alternate days with 0.1 ml. of 1.0% thiourea. Others were injected on alternate days with 0.1 ml. of 0.2% potassium perchlorate. Histological study was made of the thyroid glands of both experimental and control animals after 30 days and 46 days of treatment. Measurements of uptake and turnover of injected I¹³¹ were made on the animals treated for 46 days.

2. Evidence was obtained from the histological observations and from the use of radioiodine to show that although the thyroids of control specimens of Desmogna-thus were physiologically active, those of Triturus controls were rather inactive.

3. Both thiourea and potassium perchlorate inhibited thyroidal function in Desmognathus, as evidenced by both histological changes and changes in radioiodine uptake.

4. In Triturus, thiourea brought about only a slight hyperemia and potassium perchiorate produced no detected histological change in the thyroid. Radiological measurements after the injection of ¹³¹, however, indicated that the same physiological responses taking place in Desmognathus also occurred in Triturus but at a lower level of thyroidal function.

5. Measurements of radioactivity in the heart region demonstrated that iodine was readily excreted from all the specimens of Desmognathus and from the individuals of Triturus treated with potassium perchlorate. Elimination of iodine was relatively slow in the other specimens of Triturus.