Endocrine Abstracts

In 2004, we reported the discovery of a new signaling molecule chemically related to thyroid hormones called 3-iodothyronamine (T₁AM). T₁AM is formally a decarboxylated and deiodinated derivative of thyroxine (T₄) and was detected in tissues and circulation of rodents. Single-dose administration of T₁AM to mice resulted in unique biological activities including hypothermia, bradycardia, and hyperglycemia. The T₁AM-induced hyperthermia could have useful therapeutic applications as T₁AM has been found to be neuroprotective against stroke in mice. In hibernating rodents single-dose T₁AM induces a dramatic shift in energy utilization away from carbohydrates and toward lipids. T₁AM does not bind to or activate thyroid hormone receptors (TRα, TRβ), yet does bind and/or activate a few G protein-coupled receptors (GPCRs) of the biogenic amine receptor family including trace amine-associated receptor 1 (TAAR1), α-adrenergic receptor 2a (Adra2a), and serotonin receptor 2c (5HT2c). This lecture will cover the developments in this area and highlight recent work on T₁AM serum protein binding and distribution, and biological effects from chronic T₁AM treatment in normal and diet-induced obese mice.