The thyroid hormone decarboxylation product, 3,5,3'-triiodothyronamine (T3AM), 
has been shown to inhibit the cAMP production stimulated by isoproterenol in 
turkey erythrocytes. This adrenergic receptor binding inhibition was not shown 
by the thyroid hormones nor by tyramine, but was observed for 
3,5-diiodotyramine, 3,5-diiodothyronamine, and thyronamine. T3AM also inhibits 
prolactin secretion in cultured pituitary cells as well as domperidon binding in 
rat corpora striata membranes. T3AM has no thyromimetic activity at the nuclear 
level. The molecular structure of T3AM, determined as a borosalicylate salt by 
X-ray diffraction techniques, is the first report of a decarboxylated thyroid 
hormone analogue.