Distribution of exogenous [125I]-3-iodothyronamine in mouse in vivo: relationship with trace amine-associated receptors
- Grazia Chiellini1,
- Paola Erba2,
- Vittoria Carnicelli1,
- Chiara Manfredi2,
- Sabina Frascarelli1,
- Sandra Ghelardoni1,
- Giuliano Mariani2 and
- Riccardo Zucchi1
- 1Dipartimento di Scienze dell'Uomo e dell'Ambiente
2Dipartimento di Oncologia, University of Pisa, Via Roma 55, 56126 Pisa, Italy
- (Correspondence should be addressed to G Chiellini; Email: g.chiellini{at}bm.med.unipi.it)
Abstract
3-Iodothyronamine (T1AM) is a novel chemical messenger, structurally related to thyroid hormone, able to interact with G protein-coupled receptors known as trace amine-associated receptors (TAARs). Little is known about the physiological role of T1AM. In this prospective, we synthesized [125I]-T1AM and explored its distribution in mouse after injecting in the tail vein at a physiological concentration (0.3 nM). The expression of the nine TAAR subtypes was evaluated by quantitative real-time PCR. [125I]-T1AM was taken up by each organ. A significant increase in tissue vs blood concentration occurred in gallbladder, stomach, intestine, liver, and kidney. Tissue radioactivity decreased exponentially over time, consistent with biliary and urinary excretion, and after 24 h, 75% of the residual radioactivity was detected in liver, muscle, and adipose tissue. TAARs were expressed only at trace amounts in most of the tissues, the exceptions being TAAR1 in stomach and testis and TAAR8 in intestine, spleen, and testis. Thus, while T1AM has a systemic distribution, TAARs are only expressed in certain tissues suggesting that other high-affinity molecular targets besides TAARs exist.
- Received in final form 8 March 2012
- Accepted 22 March 2012
- Made available online as an Accepted Preprint 22 March 2012
- © 2012 Society for Endocrinology
