Corticotropin

Corticotropin is a pituitary peptide hormone secreted by the anterior pituitary. It acts on the melanocortin type 2 receptor (MC2R) on the surface of adrenal cortical cells. This receptor is a Gs protein-coupled receptor. When corticotropin binds to MC2R, it activates adenylate cyclase, increases cAMP levels, and then activates protein kinase A (PKA). This promotes the transport of cholesterol into the mitochondrion, where cholesterol side-chain cleavage enzyme (CYP11A1), located in the mitochondrion, converts cholesterol into pregnenolone. Through this pathway, corticotropin stimulates the zona fasciculata of the adrenal cortex to secrete cortisol, thereby increasing gluconeogenesis, raising blood glucose and blood pressure, and producing systemic anti-inflammatory and immunoregulatory effects.