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|proopiomelanocortin (adrenocorticotropin/ beta-lipotropin/ alpha-melanocyte stimulating hormone/ beta-melanocyte stimulating hormone/ beta-endorphin)|
Adrenocorticotropic hormone (pronounced /əˈdriːnoʊˌkɔrtɪkoʊˈtrɒpɪk ˈhɔrmoʊn/, /-ˈtroʊpɪk/) (ACTH or corticotropin) is a polypeptide hormone produced and secreted by the pituitary gland. It is an important player in the hypothalamic-pituitary-adrenal axis.
ACTH is synthesised from pro-opiomelanocortin (POMC) and secreted from corticotropes in the anterior lobe (or adenohypophysis) of the pituitary gland in response to the hormone corticotropin-releasing hormone (CRH) released by the hypothalamus. It can be produced also by cells of immune system (T cells, B cells and macrophages) as a response to stimuli that go along with stress (including CRH).
ACTH consists of 39 amino acids, the first 13 of which (counting from the N-terminus) may be cleaved to form α-melanocyte-stimulating hormone (α-MSH). (This common structure is one reason that patients with hypocortisolism or Addison's disease, in which ACTH levels are elevated, often present with excessively tanned skin.)
After a short period of time, ACTH is cleaved into α-melanocyte-stimulating hormone (α-MSH) and CLIP, a peptide with unknown activity in humans.
ACTH acts through the stimulation of cell surface ACTH receptors, which are primarily located on the adrenocortical cells. ACTH stimulates the cortex of the adrenal gland and boosts the synthesis of corticosteroids, mainly glucocorticoids but also sex steroids (androgens).
ACTH is also related to the circadian rhythm in many organisms.
The half-life of ACTH in human blood is about ten minutes.
ACTH is available as a synthetic derivative in the forms of cosyntropin,tradename Cortrosyn® and synacthen (synthetic ACTH). Both are very rarely used in place of glucocorticoids to treat secondary adrenal insufficiency in a hospital setting, but are primarily used to conduct the ACTH stimulation test.
- Addison's disease
- Small cell carcinoma (a common cause of ACTH secreted ectopically)
- Congenital adrenal hyperplasia
- Cushing's syndrome
- Nelson's syndrome
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References & BibliographyEdit
|Hormones and endocrine glands - edit|
Hypothalamus: - TRH - CRH - GnRH - GHRH - somatostatin - dopamine | Posterior pituitary: vasopressin - oxytocin - lipotropin | Anterior pituitary: GH - ACTH - TSH - LH - FSH - prolactin - MSH - endorphins - lipotropin
Thyroid: T3 and T4 - calcitonin | Parathyroid: PTH | Adrenal medulla: epinephrine - norepinephrine | Adrenal cortex: aldosterone - cortisol - DHEA | Pancreas: glucagon- insulin - somatostatin | Ovary: estradiol - progesterone - inhibin - activin | Testis: testosterone - AMH - inhibin | Pineal gland: melatonin | Kidney: renin - EPO - calcitriol - prostaglandin | Heart atrium: ANP
Angiotensin - Bombesin/Neuromedin B - Calcitonin gene-related peptide - Carnosine - Delta sleep-inducing peptide - FMRFamide - Galanin - Gastrin releasing peptide - Kinins (Bradykinin, Tachykinins ) - Neuromedin (B, N, U) - Neuropeptide Y - Neurophysins - Neurotensin - Opioid peptide - Pancreatic polypeptide - Pituitary adenylate cyclase activating peptide
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