Related Experiment Video
Updated: Jul 19, 2026

Colorimetric Assessment of Deiodinase 1 Activity in Human Liver Microsomes Using the Sandell-Kolthoff Reaction
Published on: April 10, 2026
The nuclear receptor constitutively active/androstane receptor regulates type 1 deiodinase and thyroid hormone
Eric S Tien1, Kenji Matsui, Rick Moore
1Pharmacogenetics Section, Laboratory of Reproductive and Developmental Toxicology, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709, USA.
Abstract:
We observed that the level of reverse triiodothyronine (rT3) was significantly increased after partial hepatectomy (PH) in both wild-type and constitutively active/androstane receptor (CAR) knockout (KO) mice, and treatment with phenobarbital (PB), a CAR activator, after PH decreased rT3 to restore its original level only in wild-type mice. On the other hand, no significant changes in the level of total T3 or free T3 in the serum were observed in either wild-type or CAR KO mice after PH or treatment with PB. Type 1 deiodinase (D1) activity and expression were significantly reduced by PH and up-regulated by PB in a CAR-dependent manner. In addition, known T3-regulated genes [tyrosine aminotransferase (TAT) and basic transcription element binding protein (BTEB)] were also significantly decreased by PH and induced by PB. Injection of rT3 into normal mice revealed that rT3 is capable of repressing the known thyroid hormone-regulated genes Tat, Bteb, and Cpt-1 in the liver. Our results suggest that PH decreases D1 activity leading to increased rT3 level, resulting in the repression of T3 target genes. Subsequent treatment with PB decreases rT3 in a CAR-dependent manner through the up-regulation of the D1 gene.
Related Concept Videos
Transducer Mechanism: Nuclear Receptors
About 48 different soluble family members of nuclear receptors are identified that can be divided into two main classes:
Intracellular Hormone Receptors
Synthesis and Regulation of Thyroid Hormones
Upon reaching the thyroid gland, TSH stimulates the follicular cells' active uptake of iodide ions from the blood. The ions diffuse to the apical surface of the cells and are oxidized to iodine. The iodine is then...
Functions of Thyroid Hormones
TH is indispensable for the normal development and maturation of the skeletal, muscular, and nervous systems during fetal and childhood growth. It facilitates bone mineral turnover and regulates protein synthesis in developing tissues, contributing significantly to overall growth and...
Co-activators and Co-repressors
Master Transcription Regulators

