As a diagnostic aid (adrenocortical function), corticotropin combines with a specific receptor on the adrenal cell plasma membrane. In patients with normal adrenocortical function, it stimulates the initial reaction involved in the synthesis of adrenal steroids (including cortisol, cortisone, weak androgenic substances, and a limited quantity of aldosterone) from cholesterol by increasing the quantity of cholesterol within the mitochondria. Corticotropin does not significantly increase serum cortisol concentrations in patients with primary adrenocortical insufficiency (Addison's disease). The mechanism of action of corticotropin in the treatment of infantile myoclonic seizures is unknown.
Corticotropin acts through the stimulation of cell surface ACTH receptors, which are primarily located on the adrenocortical cells. Corticotropin stimulates the cortex of the adrenal gland and boosts the synthesis of corticosteroids, mainly glucocorticoids but also sex steroids (androgens). Corticotropin is also related to the circadian rhythm in many organisms.