Mechanism of glucocorticoid action.

Glucocorticoids are steroid hormones synthesized by the adrenal cortex that are important in regulating many physiological and developmental processes. Because of anti-inflammatory and immunosuppressant effects, they are widely used to treat a variety of disorders. Their action occurs because of binding to the receptor in responsive cell types. The receptor protein consists of specific domains, each required for specific functions. The steroid: receptor complex migrates to the nucleus, binds to specific regions of DNA called glucocorticoid response elements, and either stimulates or inhibits the expression of specific genes. A cell's response depends upon the availability of hormone, transport proteins, affinity and number of intracellular receptors. Several mechanisms that in vivo appear to influence the number of functional receptors within a responsive cell have been defined. These are autoregulation of receptor synthesis, modulation of receptor phosphorylation, and regulation of receptor levels by factors that mediate other signal transduction pathways.