ARCHIVE

24.01.2006 | 11:01 AM

Differential Effects of Central Leptin, Insulin, or Glucose Administration during Fasting on the Hypothalamic- Pituitary-Thyroid Axis and Feeding-Related Neurons in the Arcuate Nucleus.

The reductions in circulating levels of leptin, insulin, and glucose with fasting serve as important homeostasis signals to neurons of the hypothalamic arcuate nucleus that synthesize neuropeptide Y (NPY)/agouti-related protein (AGRP) and -MSH/cocaine and amphetamine-regulated transcript. Be- cause the central administration of leptin is capable of pre- venting the inhibitory effects of fasting on TRH […]

03.08.2005 | 11:05 AM

Adaptive Activation of Thyroid Hormone and Energy Expenditure.

The mechanisms by which thyroid hormone accelerates energy expenditure are poorly understood. In the brown adipose tissue (BAT), activation of thyroid hormone by type 2 iodothyronine deiodinase (D2) has been known to play a role in adaptive energy expenditure during cold exposure in human newborns and other small mammals. Although BAT is not present in […]

19.06.2005 | 11:13 AM

The Hedgehog-inducible ubiquitin ligase subunit WSB-1 modulates thyroid hormone activation and PTHrP secretion in the developing growth plate.

WSB-1 is a SOCS-box-containing WD-40 protein of unknown function that is induced by Hedgehog signalling in embryonic structures during chicken development. Here we show that WSB-1 is part of an E3 ubiquitin ligase for the thyroid-hormone- activating type 2 iodothyronine deiodinase (D2). The WD-40 propeller of WSB-1 recognizes an 18-amino-acid loop in D2 that confers […]

01.06.2005 | 1:36 PM

The Type 2 Deiodinase A/G (Thr92Ala) Polymorphism Is Associated with Decreased Enzyme Velocity and Increased Insulin Resistance in Patients with Type 2 Diabetes Mellitus.

Despite the well-established role of liver X receptors (LXRs) in regulating cholesterol homeostasis, their contribution to lipid homeostasis remains unclear. Here we show that LXR null mice are defective in hepatic lipid metabolism and are resistant to obesity when challenged with a diet containing both high fat and cholesterol. This phenotype is dependent on the […]

23.04.2005 | 1:42 PM

Dopaminergic and Somatostatinergic Pathways Decrease Serum Thyrotropin in Rats Bearing the 256-Walker Mammary Carcinoma.

The hypothalamus-pituitary-thyroid axis was studied in rats with the “low T3 syndrome” caused by the implantation of the Walker-256 mammary carcinoma. Male adult rats were injected s.c. with 1 x 106 viable tumoral cells and killed 10 days later. The tumor development was associated with decreased thyroid activity characterized by a ~15% reduction in the […]

23.04.2005 | 1:29 PM

LXRs regulate the balance between fat storage and oxidation.

Despite the well-established role of liver X receptors (LXRs) in regulating cholesterol homeostasis, their contribution to lipid homeostasis remains unclear. Here we show that LXR null mice are defective in hepatic lipid metabolism and are resistant to obesity when challenged with a diet containing both high fat and cholesterol. This phenotype is dependent on the […]

30.03.2005 | 1:59 PM

Type 2 Iodothyronine Selenodeiodinase Is Expressed throughout the Mouse Skeleton and in the MC3T3-E1 Mouse Osteoblastic Cell Line during Differentiation.

Thyroid hormone affects multiple aspects of bone metabolism, but little is known about thyroid hormone deiodination in bone cells except that cultures of skeletal cells and bone organ express types 1 and 2 iodothyronine deiodinases (D1 and D2) mRNAs. In the present study, outer ring deiodination (ORD) activity was detected in bone extracts of multiple […]

30.03.2005 | 1:50 PM

Type 1 Iodothyronine Deiodinase Is a Sensitive Marker of Peripheral Thyroid Status in the Mouse.

Mice with one thyroid hormone receptor (TR) -1 allele en- coding a dominant negative mutant receptor (TR 1PV/ ) have persistently elevated serum T3 levels (1.9-fold above normal). They also have markedly increased hepatic type 1 iodothyro- nine deiodinase (D1) mRNA and enzyme activity (4- to 5-fold), whereas other hepatic T3-responsive genes, such as Spot14 […]

23.07.2004 | 2:12 PM

Chronic Cardiac-Specific Thyrotoxicosis Increases Myocardial – Adrenergic Responsiveness.

Whereas many cardiac symptoms of thyrotoxico- sis resemble those of the hyperadrenergic state, circulating catecholamines are reduced or normal in this condition. To test the hypothesis that the thyrotoxic heart is hypersensitive to catechol- amines, we studied -adrenergic signaling in a transgenic (TG) mouse in which the human type 2 iodothyronine deiodinase (D2) gene is […]

23.04.2004 | 2:21 PM

Lipopolysaccharide Induces Type 2 Iodothyronine Deiodinase in the Mediobasal Hypothalamus: Implications for the Nonthyroidal Illness Syndrome.

To determine whether the type 2 iodothyronine deiodinase (D2), the principal central nervous system enzyme converting T4 to biologically active T3, is regulated in tanycytes by im- mune activation, D2 activity was measured in the mediobasal hypothalamus (MBH) 4, 12, and 24 h after administration of bacterial lipopolysaccharide (LPS) and compared with D2 lev- els […]