glucocorticoid

glucocorticoid /glo̅o̅′kōkôr″təkoid/ [Gk, glykys + L, cortex, bark; Gk, eidos, form] , an adrenocortical steroid hormone that increases gluconeogenesis, exerts an antiinflammatory effect, and influences many body functions. The most important of the three glucocorticoids is cortisol (hydrocortisone). Corticosterone is less active, and cortisone is inactive until converted to cortisol. Glucocorticoids promote the release of amino acids from muscle, mobilize fatty acids from fat stores, and increase the ability of skeletal muscles to maintain contractions and avoid fatigue. These hormones are known to stabilize mitochondrial and lysosomal membranes, increase the production of adenosine triphosphate, promote the formation of certain liver enzymes, and decrease antibody production and the number of circulating eosinophils. A deficiency of glucocorticoids is characterized by hyperpigmentation (bronzing) of the skin, fasting hypoglycemia, weight loss, and apathy. An excess is associated with elevated serum glucose levels, thinning of the skin, ecchymosis, osteoporosis, poor wound healing, increased susceptibility to infection, and obesity. Glucocorticoid secretion is stimulated by the adrenocorticotropic hormone of the anterior pituitary, which in turn is regulated by the corticotropin-releasing hormone of the hypothalamus and circulating cortiosol levels (negative feedback). Synthetic or semisynthetic glucocorticoids, derived chiefly from cortisol, include prednisone, prednisolone, dexamethasone, methylprednisolone, triamcinolone, and betamethasone. Compare mineralocorticoid.