Glucocorticoids

Glucocorticoids are one of the corticosteroids, or steroid hormones, released from the adrenal gland. Corticosteroids are also known as adrenal cortical steroids. Glucocorticoids are synthesized and released when corticotropin, or adrenocorticotropic hormone, is released from the anterior pituitary. They bind to glucocorticoid receptors, which are present in almost every cell in vertebrate animals and are essential for the use of carbohydrate, fat and protein by the body. Glucocorticoids are necessary for the body’s normal response to stress, and they also have anti-inflammatory effects, regardless of whether they occur naturally or are synthesized.

Cortisol, or hydrocortisone, is the most important glucocorticoid in humans.

Glucocorticoid effects

There are two major categories of glucocorticoid effects: immunological and metabolic. Conditions that cause inflammation or overactive immune response such as allergies, asthma, autoimmune diseases and sepsis are often treated by glucocorticoids. Glucocorticoids also have demonstrated an ability to interfere with some of the abnormal mechanisms in cancer cells.

Regarding the metabolic effects of glucocorticoids, cortisol stimulates several processes that increase and maintain glucose concentrations in the blood. Other metabolic effects include the stimulation of glucogenesis in the liver; the mobilization of amino acids in extrahepatic tissues; inhibition of glucose uptake in muscle and adipose tissue; and stimulation of fat breakdown.

Low doses of glucocorticoids may be used to treat renal insufficiency.

The development and homeostasis of T lymphocytes may be affected by glucocorticoids, and glucocorticoids may also effect fetal development by promoting lung function.

When glucocorticoids are administered as a drug, or when hyperadrenocorticism occurs, excessive levels of the hormones may affect bone formation, suppression of calcium absorption, delayed wound healing, muscle weakness and increased risk for infections.

Mechanisms of action

The two mechanisms of action of glucocorticoids include transactivation and transrepression. They act on the hippocampus, amygdala and frontal lobes. These help regulate metabolic and cardiovascular functions.

Treatment with glucocorticoids

Glucocorticoids inhibit swelling and are used to treat inflammation in diseases such as asthma, rheumatoid arthritis, inflammatory bowel disease, multiple sclerosis, psoriasis and eczema. Both natural and synthetic glucocorticoids are used in treatment.

However, long-term use of oral glucocorticoids has been associated with osteoporosis, metabolic disease and a heightened risk for cardiovascular disease.

Glucocorticoids also slow immune responses and have been used in the treatment of autoimmune diseases and in preventing graft rejection. Those taking medications that weaken the immune system, like corticosteroids, can be at greater risk for fungal infection.

Neutrophilia may occur with acute or chronic use of corticosteroids. Other adverse effects include hyperglycemia, increased skin fragility, negative calcium balance, steroid-induced osteoporosis, weight gain, adrenal insufficiency, muscle breakdown, growth failure, increased amino acids, glaucoma or cataracts.

Additional information may be found at these websites:

http://bloodjournal.hematologylibrary.org/cgi/collection/gene_expression

http://www.nlm.nih.gov/medlineplus/ency/article/003706.htm

http://www.mayoclinic.com/health/metabolism/WT00006/

http://www.nature.com/jcbfm/index.html

http://www.nutritionandmetabolism.com/

http://www.hormone.org/Public/endocrinologist.cfm

http://www.nlm.nih.gov/medlineplus/ency/article/002257.htm

http://www.ncbi.nlm.nih.gov/books/NBK22/?depth=10

http://endo.endojournals.org/

http://www.mayoclinic.org/medicalprofs/glucocorticoid-induced-diabetes.html

http://www.nlm.nih.gov/medlineplus/steroids.html