Corticosterone is a steroid hormone produced in the adrenal cortex. Among other things, it serves to synthesize aldosterone.
What is corticosterone?
Just like cortisone, corticosterone belongs to the steroid hormones. Steroid hormones are hormones that are built from a steroidal backbone. This skeleton is derived from cholesterol. Cholesterol is an alcohol that belongs to the lipid group. Steroid hormones such as corticosterone therefore also belong to the lipid hormones. Because they are lipophilic, they can easily penetrate the cell wall and can just as easily bind to their specific receptors inside the cell. Just like most other steroid hormones, corticosterol is produced in the adrenal cortex. The lipophilic hormones are poorly soluble in water, so they must bind to plasma proteins for transport in the blood.
Function, effects, and roles
Corticosterone is basically an intermediate produced during the production of other steroid hormones. For example, the hormone aldosterone is synthesized from corticosterone via several intermediate steps. Aldosterone is a so-called mineralocorticoid. It belongs to the group of corticosteroids and causes an increased recovery of water and sodium in the kidney. Another hormone formed from corticosterone is pregnenolone. On the one hand, pregnenolone functions as a neurotransmitter, and on the other hand, it is a precursor for various steroid hormones. Current studies show that pregnenolone has a neuroprotective and neuroregenerative effect. It therefore not only protects the nerve sheaths, but also ensures the restoration of damaged nerve cells. In addition, pregnenolone has a positive effect on sleep behavior by activating GABA receptors in the brain. Furthermore, the hormone seems to have an influence on women’s sexuality. Women with low pregnenolone levels suffer significantly more frequently from libido disorders. In addition, the male sex hormone testosterone and the female sex hormone estradiol are formed from pregnenolone via several intermediate pathways. In the human body, corticosterone also has a minor glucocorticoid and a minor mineralocorticoid effect. Glucocorticoids increase blood glucose levels by stimulating cellular glucose production, by stimulating glucagon secretion, and by inhibiting insulin secretion. They also inhibit inflammatory responses at various levels of the body. Mineralocorticoids affect, among other things, electrolyte balance in the body.
Formation, occurrence, properties, and optimal levels
Corticosterol is formed in the adrenal cortex. The starting product in its production is cholesterol. This may originate from lipoproteins in the blood plasma, from the hydrolysis of cholesterol esters, or from the de novo synthesis of activated acetic acid. Progesterone is then formed from the cholesterols via a twofold hydroxylation. This requires 21-hydroxylase and 11β-hydroxylase. Several intermediate steps then lead to the production of corticosterone. The normal range of corticosterone in blood is between 0.1 and 2 micrograms per 100 milliliters. After administration of ACTH, the level should be less than 6.5 micrograms per 100 milliliters.
Diseases and disorders
The formation of corticosterone is stimulated by the release of ACTH. ACTH is a hormone produced in the anterior lobe of the pituitary gland, the pituitary gland. In various diseases, the production and secretion of ACTH can be disturbed. Increased ACTH levels are seen, for example, in cold, stress, adrenocortical insufficiency, or paraneoplastic syndrome. Increased ACTH secretion leads to increased production of corticosterone and thus also to increased formation of aldosterone. This disease state is called hyperaldosteronism. Hyperaldosteronism manifests itself in the form of a classic triad. First, affected individuals suffer from hypertension. As an excessive amount of aldosterone is secreted and produced, the rate of reabsorption at the kidneys increases. Sodium and water are increasingly brought back into the body. As a result, the blood volume increases and the pressure in the blood vessels rises. At the same time, hypokalemia develops. Potassium ions are lost during the recovery of sodium ions in the tubular system of the kidneys. In the course of the disease, metabolic alkalosis also develops.In this case, the blood pH rises above the normal value of 7.45 due to the loss of hydrogen ions. Conversely, hypoaldosteronism can occur due to reduced production of corticosterone. As a result, patients excrete more water and sodium. Hyponatremia develops, accompanied by nausea, vomiting, and seizures. Changes in demeanor, lethargy and disorientation are also possible symptoms of sodium deficiency. When more sodium is excreted, more potassium remains in the body. Hyperkalemia thus develops. Characteristic symptoms of such hyperkalemia are muscle weakness and paralysis. In addition, cardiac complications may develop. In the worst case, life-threatening ventricular fibrillation occurs. Moreover, with increased production of corticosterone, glucocorticoid effects may be enhanced. An excess of glucocorticoids leads to Cushing’s syndrome. Typical signs of Cushing’s syndrome include obesity, fatigue, weakness, sleep disturbances, hypertension, and very thin skin (parchment skin). Secondary diabetes mellitus (diabetes) may develop due to the increased mobilization of glucose. If the glucocorticoid effect is absent, the affected persons suffer from nausea, vomiting, weight loss and fatigue. They feel weak and have difficulty concentrating. If too little corticosterone and too few glucocorticoids are produced in the adrenal cortex, the pituitary gland secretes more ACTH. Together with this, there is usually a release of melanin, so that there is an increase in pigment in the skin. As a result, patients develop brown skin. In contrast to a vacation tan, this tan also involves the palms of the hands and the soles of the feet.
