Question

Thyroid hormones exert their effects on cells in a manner similar to steroid hormones; describe the mechanism of action of thyroid hormones (hint: they are an amine hormone).

Answer 1

Thyroid hormones are produced by the thyroid gland and they are responsible for the regulation of metabolism. Deficiency in iodine will result into decrease production of T3 and T4 because they are partially produced of iodine. Binding of thryroid hormone receptor and corepressor molecules to DNA regions called thyroid hormone response element near genes will form a complex (receptor-corepressor-DNA) and this complex will block gene transcription.

However, the binding of triiodothyronine (T3) to the receptor will induce a conformational change in the receptor displacing the corepressor from the complex. This mechanism will result into recruitment of coactivator protein and RNA polymerase.

Answer 2

Answer & explanation:

Thyroid hormones are essential for regulating metabolism, they are T3 (triiodothyronine) and T4 (thyroxine).

The mechanism of action of the thyroid begins in the hypothalamus, an area of the brain that controls the thyroid (and other glands). The hypothalamus produces TSH (thyroid stimulating hormone), this hormone signals the thyroid to produce T3 and T4.

Then, iodine from food is taken up by the thyroid cells, oxidized and associated with thyroglobulin (protein produced in the thyroid itself), and this association finally results in the production of T3 and T4, which will be directed to various organs through of the bloodstream.