3-Iodothyronamine (T1AM) is an endogenous thyroid hormone derivative with unknown biosynthetic origins. Structural similarities have led to the hypothesis that T1AM is an extrathyroidal metabolite of T 4. This study uses an isotope-labeled T4 [heavy-T 4 (H-T4)] that can be distinguished from endogenous T 4 by mass spectrometry, which allows metabolites to be identified based on the presence of this unique isotope signature. Endogenous T 1AM levels depend upon thyroid status and decrease upon induction of hypothyroidism. However, in hypothyroid mice replaced with H-T4, the isotope-labeled H-T3 metabolite is detected, but no isotope-labeled T1AM is detected. These data suggest that T1AM is not an extrathyroidal metabolite of T4, yet is produced by a process that requires the same biosynthetic factors necessary for T4 synthesis.
Biosynthesis of 3-Iodothyronamine (T1AM) is dependent on the sodium-iodide symporter and thyroperoxidase but does not involve extrathyroidal metabolism of T4
SABA, ALESSANDRO;ZUCCHI, RICCARDO;
2012-01-01
Abstract
3-Iodothyronamine (T1AM) is an endogenous thyroid hormone derivative with unknown biosynthetic origins. Structural similarities have led to the hypothesis that T1AM is an extrathyroidal metabolite of T 4. This study uses an isotope-labeled T4 [heavy-T 4 (H-T4)] that can be distinguished from endogenous T 4 by mass spectrometry, which allows metabolites to be identified based on the presence of this unique isotope signature. Endogenous T 1AM levels depend upon thyroid status and decrease upon induction of hypothyroidism. However, in hypothyroid mice replaced with H-T4, the isotope-labeled H-T3 metabolite is detected, but no isotope-labeled T1AM is detected. These data suggest that T1AM is not an extrathyroidal metabolite of T4, yet is produced by a process that requires the same biosynthetic factors necessary for T4 synthesis.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
