|Peripheral deiodination of thyroid hormones: biological significance|
Kühn, E.R.; Mol, K.; Darras, V.M. (1995). Peripheral deiodination of thyroid hormones: biological significance. Neth. J. Zool. 45(1-2): 135-139
In: Netherlands Journal of Zoology. E.J. Brill: Leiden. ISSN 0028-2960, more
|Authors|| || Top |
- Kühn, E.R.
- Mol, K.
- Darras, V.M.
The main secretory of the thyroid gland is thyroxine (T 4), which is a relatively inactive prohormone serving as a substrate for deiodination processes in peripheral presence of outer-ring (ORD) and inner-ring deiodinases (IRD), respectively. During ontogenesis high plasma levels of (T3) occurs in the presence of outer-ring (ORD) and inner-ring deiodinases (IRD), respectively. During ontogenesis high plasma levels of T 3occur at parturition or hatching in precocial mammals and birds and at metamorphic climax in amphibians. These high levels may be obtainedby increased T4 ORD activity and olso by decreased T3 degradation. In mammals, birth and fish growth hormone (GH) has been described as stimulatory agent for ORD activity. In the chick ombryo, GH does not increase the ammount of T4 ORD but inhibits T3IRD activity and T3 degradation.