corticotropina

Corticotropina, known in English as adrenocorticotropic hormone (ACTH), is a peptide hormone produced by the anterior pituitary gland. In humans, ACTH is a 39-amino-acid peptide derived from the larger precursor protein proopiomelanocortin (POMC).

ACTH's primary role is to stimulate the adrenal cortex to produce and release glucocorticoids, mainly cortisol, as well as androgens. It binds to the melanocortin receptor MC2R on adrenal cortex cells, triggering a cAMP-mediated signaling cascade that promotes steroidogenesis and the synthesis of enzymes involved in cortisol production.

Regulation occurs through the hypothalamic-pituitary-adrenal axis. Corticotropin-releasing hormone (CRH) from the hypothalamus stimulates ACTH secretion, while circulating glucocorticoids provide negative feedback. ACTH levels exhibit diurnal variation and increase in response to stress.

Clinical notes: The ACTH stimulation test uses a synthetic form, cosyntropin (ACTH 1-24), to assess adrenal function. Therapeutically, high-dose ACTH has been used to treat certain inflammatory and autoimmune conditions and is still employed in some contexts, such as infantile spasms, though its use is limited by adverse effects and the availability of alternative therapies.

Structure and genetics: The ACTH sequence is encoded within the POMC gene, located on human chromosome 2. Processing of POMC yields ACTH along with other peptides, including melanocyte-stimulating hormones (MSH). The hormone's production and action are part of the broader stress response and endocrine regulation.