Cortisol

Cortisol is a steroid hormone, more specifically a glucocorticoid, which is produced by the zona fasciculata of the adrenal cortex.^[1] It is released in response to stress and a low level of blood glucose.

Its functions are to increase blood sugar through gluconeogenesis, to suppress the immune system, and to aid the metabolism of fat,protein, and carbohydrate.^[2] It also decreases bone formation.^[3]

Hydrocortisone (INN, USAN, BAN) is a name for cortisol when it is used as a medication. Hydrocortisone is used to treat people who lack adequate naturally generated cortisol. It is on the World Health Organization's List of Essential Medicines needed in a basichealth system.

Main functions in the body[edit]

Metabolic response[edit]

In the early fasting state, cortisol stimulated gluconeogenesis (formation of glucose, in the liver, from certain amino acids, glycerol, lactate, and/or propionate), and activates anti-stress and anti-inflammatory pathways.^[5] Cortisol (as well as epinephrine and/or norepinephrine) also plays an important, but indirect, role in liver and muscle glycogenolysis, the breaking down of glycogen to glucose-1-phosphate and glucose. This is done through its passive influence on glucagon. Additionally, Cortisol facilitates the activation of glycogen phosphorylase, which is necessary for epinephrine to have an effect on glycogenolysis.^[6][7]

In the late fasting state, the function of cortisol changes slightly and actually increases glycogenesis. This response is a conservatory process that allows the liver to take up any glucose that is not being used by peripheral tissue and turn it into liver glycogen stores to be used incase the body moves into the starvation state.

Elevated levels of cortisol, if prolonged, can lead to proteolysis (breakdown of proteins) and muscle wasting.^[8] Several studies have shown a lipolytic (breakdown of fat) effect of cortisol, although, under some conditions, cortisol may somewhat suppress lipolysis.^[9]

Immune response[edit]

Cortisol prevents the release of substances in the body that cause inflammation. It is used to treat conditions resulting from over activity of the B-cell-mediated antibody response. Examples include inflammatory and rheumatoid diseases, as well as allergies. Low-potency hydrocortisone, available as a non-prescription medicine in some countries, is used to treat skin problems such as rashes, and eczema.

It inhibits production of interleukin (IL)-12, interferon (IFN)-gamma, IFN-alpha and tumor-necrosis-factor (TNF)-alpha by antigen-presenting cells (APCs) and T helper (Th)1 cells, but upregulates IL-4, IL-10, and IL-13 by Th2 cells. This results in a shift toward a Th2 immune response rather than general immunosuppression. The activation of the stress system (and resulting increase in cortisol and Th2 shift) seen during an infection is believed to be a protective mechanism which prevents an over activation of the inflammatory response.^[10]