Some Effects of 3:5:3′-Triiodothyropropionic Acid, Methyl Ether in the Rat

Abstract

In intact rats 3 :5:3′-triiodothyropropionic acid, methyl ether (tripropmethyl ether) exhibited 0.05 the anti-goitrogenic, 0.015 the calorigenic, and 0.05 the plasma total cholesterol-lowering activity of L(+) 3:5:3′-triiodothyronine (L-triiodothyronine). Triprop-methyl ether did not cause a further elevation of the total body oxygen consumption when administered subcutaneously to rats receiving L-triiodothyronine. In addition, triprop-methyl ether was found to be 0.5 and 0.4 as calorigenic as 3:5:3′-triiodothyropropionic acid in intact and thyroidectomized rats, respectively, while the anti-goitrogenic activity of these agents was found to be the same. When given concurrently with thiouracil to rats that had previously received goitrogen for 10 days, triprop-methyl ether inhibited additional thyroid gland hypertrophy. A guinea pig gravimetric assay indicated that the administration of triprop-methyl ether for 30 days to thiouracil-treated rats resulted in a reduction of the thyrotrophin content of the pituitary gland. Triprop-methyl ether displayed a wider separation between its minimum effective anti-goitrogenic and calorigenic doses than any thyromimetic agent yet reported.