Forskolin stimulation of 3, 5, 3'-triiodothyronine release from perifused rat thyroids

In a perifusion system in the presence of 3-isobutyl-1-methylxanthine, forskolin stimulated secretion of not only cAMP but also 3, 5, 3'-triiodothyronine (T3) from rat thyroid glands. The increases in both cAMP and T3 were dose-dependent at forskolin concentrations of 2.0 X 10(-7)M to 2.0 X 10(-5)M. After perifusion for 4 h, tissue concentrations of cAMP also increased as a result of forskolin treatment. Since forskolin is regarded as a specific activator of the cAMP generating system, this observed forskolin stimulation of T3 secretion from perifused rat thyroid glands indicates that cAMP is involved in regulating thyroid hormone secretion.