Effect of iodide, methimazole, and thyroxine on thyroidal accumulation of radioiodide in immature domestic fowl [Gallus domesticus]

Accumulation of radioiodide by the thyroids of individual domestic fowl was measured with the technique described by T. F. Davison, J. G. Rowell, and J. Rea, [1981) J. Endocrinol. 89, 371-378). Radioiodide uptake was markedly decreased in birds given an excess of iodide in the drinking water (60 mg KI/liter) or injections of thyroxine (T4: 5 X 50 micrograms T4/kg body wt), in agreement with published findings. Treatment with a goitrogen (250 mg methimazole/liter drinking water) decreased 125I uptake for at least 8 days but thereafter uptake increased and this was accompanied by gross thyroidal enlargement. The results indicate that the thyroid partly compensates for goitrogenic inhibition.