Suppression of hypothalamic deiodinase type II activity blunts TRH mRNA decline during fasting
Open Access
- 2 August 2005
- journal article
- Published by Wiley in FEBS Letters
- Vol. 579 (21) , 4654-4658
- https://doi.org/10.1016/j.febslet.2005.07.035
Abstract
Fasting is characterized by disrupted thyroid feedback, with suppressed levels of thyroid hormones and paraventricular thyrotropin releasing hormone (TRH). We found that third ventricle administration of the deiodinase inhibitor, iopanoic acid, dose‐dependently reduced deiodinase type II (DII) activity selectively in the hypothalamus. This suppression of DII by iopanoic acid during fasting prevented elevated DII activity and blunted the decline in hypothalamic TRH mRNA levels. Because fasting‐induced elevation in hypothalamic DII activity is paralleled by increased hypothalamic T3 concentration, our study suggests that T3 formation by DII in the hypothalamus is the cause of disrupted thyroid feedback during fasting.Keywords
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