Fig. 4.

Stimulation by compound 2 of thyroxine (T4) secretion and thyroidal radioiodide uptake in mice. (A) Mice were given vehicle (PEG300, control), TSH (32 μg), compound 2 (0.5 mg), or the inactive analogue compound 3 (0.5 mg) by i.p. injection. Blood was withdrawn 2 h later and T4 was measured in the serum. The data from 2 independent experiments with 3 mice each are shown. (B) Vehicle (control) or compound 2 (2.5 mg) was given by esophageal gavage and serum T4 was measured 2 h later. The data from 4 independent experiments with 3 mice each are shown. (C) Vehicle (control) or compound 2 (2.5 mg) was given by esophageal gavage on d 1 and 2. On d 3, Na¹²⁵I (20 μCi) was administered by esophageal gavage and the mice were killed 2 h later. The thyroid glands and small pieces of liver were excised and counted for ¹²⁵I radioactivity. The data are presented as the ratio of radioactivity in the thyroid/liver. The data from 2 independent experiments with 2 and 4 mice each are shown.