corticosterone, steroid hormone secreted by the outer layer, or cortex, of the adrenal gland. Classed as a glucocorticoid, corticosterone helps regulate the conversion of amino acids into carbohydrates and glycogen by the liver, and helps stimulate glycogen formation in the tissues. Corticosterone is similar in structure, although somewhat less potent, than the other glucocorticoids cortisol and cortisone. It is produced in response to stimulation by the pituitary substance adrenocorticotropic hormone (ACTH). In some species, but not in humans, corticosterone is the predominant glucocorticoid secreted by the adrenal. It is a precursor in the synthesis of aldosterone, another adrenal cortical steroid.