How is growth hormone regulated

Although multiple second messengers have been implicated, the adenylate cyclase-cyclic AMP-protein kinase A system appears to exert a predominant role.

The developmental regulation of the somatotropes and of GH gene expression is also of importance in determining the GH responses to releasing and inhibiting hormones. The availability of several rodent strains with genetic disorders of growth associated with impaired GH secretion, along with the development of transgenic models, has permitted a more detailed analysis of the role of cytokines and growth factors on both somatotrope biology and hormone secretion.

Growth hormone is also of considerable interest as a drug used in both humans and animals. A critical concept in understanding growth hormone activity is that it has two distinct types of effects:. Keeping this distinction in mind, we can discuss two major roles of growth hormone and its minion IGF-I in physiology. Growth is a very complex process, and requires the coordinated action of several hormones. The major role of growth hormone in stimulating body growth is to stimulate the liver and other tissues to secrete IGF-I.

IGF-I stimulates proliferation of chondrocytes cartilage cells , resulting in bone growth. Growth hormone does seem to have a direct effect on bone growth in stimulating differentiation of chondrocytes. IGF-I also appears to be the key player in muscle growth. It stimulates both the differentiation and proliferation of myoblasts. It also stimulates amino acid uptake and protein synthesis in muscle and other tissues. Growth hormone has important effects on protein, lipid and carbohydrate metabolism.

In some cases, a direct effect of growth hormone has been clearly demonstrated, in others, IGF-I is thought to be the critical mediator, and some cases it appears that both direct and indirect effects are at play.

Production of growth hormone is modulated by many factors, including stress, exercise, nutrition, sleep and growth hormone itself. However, its primary controllers are two hypothalamic hormones and one hormone from the stomach:.

Growth hormone secretion is also part of a negative feedback loop involving IGF-I. High blood levels of IGF-I lead to decreased secretion of growth hormone not only by directly suppressing the somatotroph, but by stimulating release of somatostatin from the hypothalamus.

Home Hormones Growth hormone. Growth hormone Growth hormone is produced by the pituitary gland. It has many functions including maintaining normal body structure and metabolism. How is growth hormone controlled? What happens if I have too much growth hormone? What happens if I have too little growth hormone? Last reviewed: May Prev. Gonadotrophin-releasing hormone. Growth hormone-releasing hormone. Related Glands. Pituitary gland Hypothalamus View all Glands.

Related Endocrine Conditions. Gigantism Hypopituitarism Acromegaly Adult-onset growth hormone deficiency Childhood-onset growth hormone deficiency Diabetes mellitus View all Endocrine conditions. Related Hormones. Growth hormone-releasing hormone Somatostatin View all Hormones. Related Glossary Supplements.