adrenokortikotroopse

Adrenokortikotroopse, in English known as adrenocorticotropic hormone (ACTH), is a peptide hormone produced by the anterior pituitary gland. It stimulates the adrenal cortex to synthesize and secrete glucocorticoids, principally cortisol, and to a lesser extent androgens, by promoting adrenal steroidogenesis.

Production and regulation occur in response to hypothalamic signals. ACTH secretion is driven by corticotropin-releasing hormone (CRH) and, to some extent, vasopressin released from the hypothalamus. Cortisol exerts negative feedback on both the hypothalamus and the pituitary to regulate ACTH levels. ACTH release follows a circadian rhythm, typically peaking in the early morning.

Mechanism and targets: ACTH acts on the melanocortin 2 receptor (MC2R) on adrenal cortex cells, activating pathways that increase the synthesis of cortisol and promote growth and maintenance of the adrenal cortex. The result is a rise in circulating glucocorticoids, which influence metabolism, immune function, stress response, and other physiological processes.

Clinical relevance: ACTH levels help diagnose and differentiate adrenal disorders. In primary adrenal insufficiency (Addison’s disease), ACTH is elevated due to loss of cortisol feedback. In secondary or tertiary adrenal insufficiency, ACTH is low or inappropriately normal due to pituitary or hypothalamic dysfunction. The ACTH stimulation test (cosyntropin test) assesses adrenal reserve by measuring cortisol response to synthetic ACTH. In Cushing’s disease, excess ACTH from a pituitary adenoma drives elevated cortisol; conversely, exogenous glucocorticoids suppress ACTH production through negative feedback.

Pharmacology and related biology: synthetic ACTH (cosyntropin) is used diagnostically to test adrenal function; ACTH is derived from the precursor protein POMC.