Thyroid-stimulating hormone regulation

Thilly CH, Swennen B, Bourdoux P, et al. 1993. The epidemiology of iodine-deficiency disorders in relation to goitrogenic factors and thyroid-stimulating-hormone regulation. Am J Clin Nutr 57(2 Suppl) 267S-270S. 

A trophic hormone acts on another endocrine gland to stimulate secretion of its hormone. For example, thyrotropin, or thyroid-stimulating hormone (TSH), stimulates the secretion of thyroid hormones. Adrenocorticotropin, or adrenocorticotropic hormone (ACTH), stimulates the adrenal cortex to secrete the hormone cortisol. Both trophic hormones are produced by the pituitary gland in fact, many trophic hormones are secreted by the pituitary. The pituitary gland is sometimes referred to as the "master gland" because its hormones regulate the activity of other endocrine glands. 

Thyroid hormone is liberated into the bloodstream by the process of proteolysis within thyroid cells. T4 and T3 are transported in the bloodstream by three proteins thyroid-binding globulin, thyroid-binding prealbumin, and albumin. Only the unbound (free) thyroid hormone is able to diffuse into the cell, elicit a biologic effect, and regulate thyroid-stimulating hormone (TSH) secretion from the pituitary. 

Anterior part produces its own hormones in response to hypothalamic releasing hormones, e.g., adrenocorticotropic hormone ACTH, luteinizing hormone LH, follicle-stimulating hormone FSH, prolactin, growth hormone, thyroid-stimulating hormone TSH Thyroid Regulation of metabolism, development, and maturation... 

Somatostatin inhibits secretion of growth hormone and other hormones such as prolactin from the anterior pituitary and is widely distributed in the brain in interneurons and projection pathways. All parts of the cortex contain local circuit somatostatin positive neurons, concentrated in layers V and VI, as does the amygdala and striatum. The nucleus accumbens and adjacent ventral putamen and caudate—designated limbic striatum—have particularly high concentrations of fibres. By contrast, TRH which regulates release of thyroid stimulating hormone and prolactin by the pituitary is generally confined to nuclei in and around the hypothalamus. 

Fig. 6. Hormones of the hypothalamic-pituitary axis and the glands and target organs they regulate (ACTH = adrenocorticotropic hormone LH = luteinizing hormone FSH = follicle stimulating hormone TSH = thyroid stimulating hormone PRL = prolactin GH = growth hormone).

Regulation of synthesis Thyroid function is controlled by a tropic hormone, thyroid-stimulating hormone (TSH, thyrotropin), a glycoprotein synthesized by the anterior pituitary (see Figure 25.2). TSH generation is governed by the hypothalamic thyrotropin-... 

Hormones synthesised by the antei ior pituitary that regulate the activity of various endocrine glands are referred to as tropic hormones (e.g. thyroid-stimulating hormone (TSH), adrenocorticotropic hormone (ACTH), luteinizing hormone (LH), follicle-stimulating hormone (FSH)). 

Morris D D, Garcia M 1983 Thyroid-stimulating hormone response test in healthy horses and effects of phenylbutazone on equine thyroid hormones. American Journal of Veterinary Research 44 503-507 Ralston S L 2002 Insulin and glucose regulation. 

Thyroid-stimulating hormone (TSH) that regulates the growth of the thyroid gland and the iodination of amino acids to produce the thyroid hormones triiodothyronine and thyroxine (see Chapter 52)d... 

---