Mineralocorticoids vs Glucocorticoids – Function, Disorders, Drugs, Differences

Mineralocorticoids

They are produced in the adrenal cortex. The adrenals are two small glands which look like mushroom caps. These glands weigh only 1.5-2.5 grams and are 1-2 inches long. One adrenal gland sits above each kidney.

In humans, the left adrenal gland is semilunar shaped, while the right adrenal gland is triangular shaped. Even though they are small, they are essential for human health and survival.

For instance, they influence salt and water balances (fluid balance and electrolyte balance) by acting on the minerals, especially potassium and sodium. They mainly act on the kidney, where they cause active excretion of protons and potassium, and water and sodium retention.

Aldosterone

The principal mineralocorticoid is aldosterone, that accounts for most of the activities of this group of hormones. Aldosterone is produced from the precursor corticosterone by the zona glomerulosa of the adrenal cortex in response to angiotensin II. However, recent studies concluded that tissues other than adrenal cortex may also be capable of biosynthesis of this hormone, like – the central nervous and the cardiovascular systems.

Aldosterone plays a crucial role in the regulation of electrolyte and fluid balance in the salivary glands, kidney, large intestine, and sweat glands.

Function

The main effects of the mineralocorticoids are increasing the secretion of potassium and the reabsorption of sodium in the renal tubules. Secondary functions are related to the reabsorption of water, secretion of hydrogen ions, and anion reabsorption. The result of these activities is the maintenance of electrolyte and fluid balance as well as adequate cardiac output.

Moreover, they may mediate the effects of extracellular fluid volume on distal nephron acidification and are an essential determinant of net acid excretion by the kidneys.

Disorders

Disorders of either mineralocorticoid function or production can lead to severe alterations in the potassium, sodium, and water content of the human body.

Elevated levels of aldosterone associated with long-term stimulation of the Renin-Angiotensin-Aldosterone-System is involved in the development of hypertension, hypervolemia, and hypokalemia. In contrast, without sufficient levels of mineralocorticoids, a reduced cardiac output can result in hyperkalemia, hyponatremia, hypotension, dehydration, death, and cardiac arrest. Mineralocorticoid replacement is needed only in primary adrenal insufficiency.

Drugs

Florinef Acetate contains fludrocortisone acetate, a medication that has high glucocorticoid activity and powerful mineralocorticoid effects. Fludrocortisone is used only for its mineralocorticoid effects.

In adrenal insufficiency, it is typically taken together with hydrocortisone, a synthetic hormone which is part of a class of drugs called steroids, that work by activating natural substances in the skin to reduce redness, swelling, and itching.

Glucocorticoids

They are hormones which are produced by the adrenal gland. They regulate the metabolism of proteins, carbohydrates, and fats. The release of glucocorticoids from the adrenal cortex is initially triggered by corticotropin-releasing hormone elaborated by the hypothalamus (a region of the brain composed of many small nuclei with a variety of functions).

The vast majority of glucocorticoid activity is from cortisol, also known as hydrocortisone.

Function

These hormones have potent antiallergic and anti-inflammatory properties. Glucocorticoids inhibit numerous inflammation-associated molecules, like – chemokines, cytokines (produced by immune cells, including – B lymphocytes, macrophages, and mast cells),  adhesion molecules, and arachidonic acid metabolites.

In case of excessive bleeding, they constrict blood vessels to offset the drop in blood pressure due to blood loss. They also increase the blood-glucose (sugar) level by converting fats and proteins into carbohydrates, that in turn is converted to glucose (sugar).

The name “glucocorticoid” derives from early studies showing that this type of hormones was involved in glucose metabolism. During times when no food is consumed, they stimulate a few processes which serve to maintain and increase glucose concentrations in the blood.

Disorders

Addison’s disease occurs when the adrenal glands do not produce a sufficient quantity of the hormone cortisol, and in some patients, the hormone aldosterone. For this reason, Addison’s disease is also referred as hypocortisolism or chronic adrenal insufficiency. The main adrenal insufficiency happens due to the destruction of the adrenal gland. Other causes include – tuberculosis and other diseases infiltrating the adrenal glands.

Drugs

Glucocorticoid drugs are synthetic versions of glucocorticoids, hormones which occur naturally in the human body. Their power to induce lymphocyte apoptosis combined with the potent immunosuppressive and anti-inflammatory activity places these drugs among the most frequently prescribed medicines worldwide.

Examples of these medicines include:

  • prednisone;
  • beclomethasone;
  • prednisolone;
  • methylprednisolone;
  • triamcinolone;
  • hydrocortisone;
  • dexamethasone;
  • cortisone;
  • budesonide;
  • betamethasone.

In people with Duchenne muscular dystrophy (a genetic condition described by progressive muscle weakness and degeneration), treatment with these drugs is associated with considerably reduced risk of losing clinically meaningful mobility as well as reduced risk of death.

In addition, as anti-inflammatory agents, they are commonly used in the treatment of bronchial asthma, an inflammatory disease of the airways which causes periodic attacks of wheezing, coughing, chest tightness, and shortness of breath.

Note – according to a recent study which was issued in AJP, the use of these drugs in the treatment of infections of the lower respiratory tract and chronic obstructive pulmonary disease is linked with an increased risk of neuropsychiatric disorders and suicidal behavior.

Mineralocorticoids vs Glucocorticoids – Differences

Mineralocorticoids are a group of hormones (the most important being aldosterone) which regulate the balance of electrolytes (ions such as potassium and sodium) and water in the human body. Without sufficient supply of these hormones, fatal shock from diminished cardiac output can occur very quickly.

The main glucocorticoid hormone is called cortisol and plays an essential role in the regulation of primary body functions.

In conclusion, mineralocorticoids and glucocorticoids are steroid hormones that are secreted exclusively by the adrenal glands. They produce effects by docking with receptors on the cell’s membrane surface.

Mineralocorticoids control water and electrolyte balance in the body. They do not have any negative impact on the body. The loss of glucocorticoid secretion leads to an inability to deal with stressors, that is fatal.

On the other hand, the chief task for glucocorticoids is to control the fats, carbohydrates, and other proteins within the body. They also have potent anti-allergic and anti-inflammatory effects. The failure to produce these hormones is not acutely life-threatening.

References

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2857982/
https://www.ncbi.nlm.nih.gov/pubmed/17330254
https://www.ncbi.nlm.nih.gov/pubmed/7791815
https://www.ncbi.nlm.nih.gov/pubmed/232834

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