Adrenocorticotropic hormone (ACTH or corticotropin) is a polypeptide hormone synthesised from pre-opiomelanocortin and secreted from corticotropes in the anterior lobe of the pituitary gland in response to the corticotropin-releasing hormone released by the hypothalamus. ACHT consists of 39 amino acids. It stimulates the cortex of the adrenal gland, resulting in the synthesis of corticosteroids: mainly glucocorticoids, but also mineralcorticoids and, to a lesser extent, androgens. ACTH secretion is also modulated by the circadian rhythm.
Synthetic ACTH has been used to manage asthma, and can be used during acute attacks of gout, because it stimulates the body to produce and release corticosteroids (cortisol) that naturally reduce inflammation. Synthetic ACTH has also been used for patients with multiple sclerosis, West’s syndrome, ulcerative colitis and tumoral cerebral oedema (1).
Synthetic ACTH is available as cosyntropin (. Cortrosyn®), containing only the first 24 amino acids of ACTH but retaining full function; and tetracosactide (. Synacthen®, which was previously known as tetracosactrin in the UK).
Synthetic ACTH is also used for adrenal function testing. A single injection of synthetic ACTH should result in a rise in blood cortisol concentration in 30 minutes. The test assists with determining whether the adrenal glands are diseased or damaged or whether there is a lack of pituitary ACTH secretion.
The thymus is a soft, triangular-shaped organ found in the chest posterior to the sternum. The thymus produces hormones called thymosins that help to train and develop T-lymphocytes during fetal development and childhood. The T-lymphocytes produced in the thymus go on to protect the body from pathogens throughout a person’s entire life. The thymus becomes inactive during puberty and is slowly replaced by adipose tissue throughout a person’s life.
Other Hormone Producing Organs
In addition to the glands of the endocrine system, many other non-glandular organs and tissues in the body produce hormones as well.
As indicated above, ACTH is a cleavage product of the pro-hormone, proopiomelanocortin (POMC), which also produces other hormones including α-MSH that stimulates the production of melanin . A family of related receptors mediates the actions of these hormones, the MCR, or melanocortin receptor family. These are mainly not associated with the pituitary - adrenal axis. MC2R is the ACTH receptor . While it has a crucial function in regulating the adrenal, it is also expressed elsewhere in the body, specifically in the osteoblast , which is responsible for making new bone, a continual and highly regulated process in the bodies of air-breathing vertebrates.  The functional expression of MC2R on the osteoblast was discovered by Isales et alia in 2005.  Since that time, it has been demonstrated that the response of bone forming cells to ACTH includes production of VEGF , as it does in the adrenal. This response might be important in maintaining osteoblast survival under some conditions.  If this is physiologically important, it probably functions in conditions with short-period or intermittent ACTH signaling, since with continual exposure of osteoblasts to ACTH, the effect was lost in a few hours.