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23.05.2013 | 10:36 PM

The thyroid axis is wired to preserve and defend circulating T3.

Triiodothyronine (T3) is the active form of thyroid hormone. Most T3 is produced outside the thyroid gland via deiodination of T4, with less than 20% being secreted directly from the thyroid. It is estimated that healthy adults produce about 30 ug T3/day, of which about 5 ug are secreted directly from the thyroid and the […]

23.05.2013 | 8:27 PM

Local thyroid hormone activation plays critical metabolic role.

Thyroid hormone acts in virtually all tissues accelerating the rate of energy expenditure and production of heat. The importance of thyroid hormone in temperature regulation is illustrated by the fact that hypothyroid patients frequently exhibit cold intolerance and, in some cases, can also experience hypothermia. In small rodents (and perhaps humans as well) this is […]

14.05.2013 | 12:39 AM

Type 2 deiodinase (D2) is inactivated by ubiquitination.

The thyroid hormone activating deiodinase, D2, is a type I endoplasmic-reticulum (ER)-resident thioredoxin fold-containing selenoprotein. It is anchored to the ER membrane in close proximity to the cell nucleus through a single transmembrane domain. The D2 globular domain containing the catalytic active site is in the cytosol whereas only a few amino acids exist in […]

06.05.2013 | 5:03 PM

Nutrient availability and thyroid hormone activation.

In mammals, body energy expenditure decreases with caloric restriction as well as prolonged starvation. This is an adaptive response driven by the hypothalamus that includes behavioral as well as metabolic modifications. During fasting, the hormonal milieu is dominated by low levels of insulin and thyroid hormones, which might explain the slow-down in weight loss after […]