Mineralocorticoids

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Mineralocorticoids , also mineralocorticoids , belong to the corticosteroids , a class of steroid hormones from the adrenal cortex . The name refers to their role in regulating the potassium / sodium balance and therefore blood pressure . The two most important natural mineralocorticoids are aldosterone (activating) and deoxycorticosterone (inactivating). Like the glucocorticoids , the mineralocorticoids are descendants of progesterone (Δ4-pregnene-3,20-dione).

Mineralocorticoids are similar to glucocorticoids, but they mainly affect the body's water and mineral balance.

physiology

By activating the mineralocorticoid receptor, mineralocorticoids increase the reabsorption of sodium in the distal tubule of the kidney and increase the excretion of potassium . The water excretion follows the sodium, therefore the mineralocorticoids (to a lesser extent also other corticoids) increase the water content in the body.

biosynthesis

As with all steroids , the biosynthesis of the corticoids starts with cholesterol , which is either ingested with food or (in much larger quantities) is formed from mevalonate . The intermediate product is pregnenolone , which is converted to corticosterone in two ways and this is converted to aldosterone in two steps .

Dismantling

Like other corticoids, the mineralocorticoids are inactivated in the liver and mainly excreted in the bile, 10% also in the urine , in the form of inactive conjugates.

Mineralocorticoid metabolism pathology

Overproduction of mineralocorticoids, caused for example by hormone-producing tumors or an ACTH overfunction, lead to chronic potassium deficiency ( Conn syndrome ).

Of the enzymes involved in the biosynthesis and breakdown of mineralocorticoids, four can be affected by rare hereditary diseases that result in a deficiency in the respective enzyme:

There is also a hereditary disease in which the activity of CYP11B2 is increased and leads to hyperaldosteronism .

Applications

The only synthetic mineralocorticoid is fludrocortisone , which is used clinically for primary insufficiency of the adrenal cortex in adrenogenital syndromes . It is easier and more common in practice to influence the natural aldosterone effect by antagonizing diuretics (water tablets), which are summarized as " potassium-sparing diuretics ". In contrast to thiazide diuretics , there is no insulin resistance . Other uses are for high blood pressure and after a heart attack .

Web links

Wikibooks: Biochemistry and Pathobiochemistry: Steroid Hormone Metabolism  - Learning and Teaching Materials

Individual evidence

  1. ^ EP Gomez-Sanchez, CE Gomez-Sanchez: Central regulation of blood pressure by the mineralocorticoid receptor. In: Molecular and cellular endocrinology. Volume 350, Number 2, March 2012, pp. 289-298, doi : 10.1016 / j.mce.2011.05.005 . PMID 21664417 . PMC 3189429 (free full text).
  2. ^ PJ Fuller, Y. Yao, J. Yang, MJ Young: Mechanisms of ligand specificity of the mineralocorticoid receptor. In: The Journal of endocrinology. Volume 213, Number 1, April 2012, pp. 15-24, doi : 10.1530 / JOE-11-0372 . PMID 22159507 .
  3. ^ UA Hawkins, EP Gomez-Sanchez, CM Gomez-Sanchez, CE Gomez-Sanchez: The ubiquitous mineralocorticoid receptor: clinical implications. In: Current hypertension reports. Volume 14, Number 6, December 2012, pp. 573-580, doi : 10.1007 / s11906-012-0297-0 . PMID 22843494 . PMC 3491176 (free full text).
  4. ↑ AM Dorrance: Interfering with mineralocorticoid receptor activation: the past, present, and future. In: F1000prime reports. Volume 6, 2014, p. 61, doi : 10.12703 / P6-61 . PMID 25165560 . PMC 4126546 (free full text).
  5. ^ MR Seawell, F. Al Darazi, V. Farah, KB Ramanathan, KP Newman, SK Bhattacharya, KT Weber: Mineralocorticoid receptor antagonism confers cardioprotection in heart failure. In: Current heart failure reports. Volume 10, number 1, March 2013, pp. 36-45, doi : 10.1007 / s11897-012-0120-x . PMID 23114591 . PMC 3568253 (free full text).