Mineralocorticoid hormones

Adrenocortical hormone (Section 27.6) A steroid hormone secreted by the adrenal glands. There are two types of adrenocortical hormones mineralocorticoids and glucocorticoids. 

Q2 The adrenal cortex secretes three main groups of hormones mineralocorticoid (e.g. aldosterone), glucocorticoids (e.g. cortisol, cortisone and corticosterone) and gonadocorticoids (mainly androgens with small amounts of progesterone and oestrogen). Aldosterone is a salt-retaining hormone which acts on the kidney to facilitate sodium and water reabsorption. 

See also Figure 19.24, Cortisol, Figure 23.8, Steroid Metabolism, Steroid Hormone Synthesis, Steroid Hormones, Mineralocorticoids, Steroid and Thyroid Hormones - Intracellular Receptors... 

The heart, as an endocrine organ itself, secretes the atrial natriuretic peptide, which has several important influences on the cardiovascular system. In addition to atrial natriuretic peptide, catecholamines, thyroid hormones, mineralocorticoids, sex steroids, and angiotensin II are other hormones also known to exert their effects on the cardiovascular functions and blood pressure. Hormones regulate the contraction and dilatation of the vascular bed. They may also affect the contraction of other smooth muscles other than the vascular smooth muscle. Oxytocin stimulates contraction of the myoepithelium in the mammary gland that is necessary for milk ejection. 

Steroid Hormones and Neurosteroids. Steroids (qv) can affect neuroendocrine function, stress responses, and behavioral sexual dimorphism (78,79) (see Steroids). Mineralocorticoid, glucocorticoid, androgen, estrogen, and progesterone receptors are localized in the brain and spinal cord. In addition to genomic actions, the neurosteroid can act more acutely to modulate the actions of other receptors or ion channels (80). Pregnenolone [145-13-17, ( ) dehydroepiandosterone [53-43-0] C H2 02 (319) are excitatory neurosteroids found in rat brain, independent of adrenal... 

Steroid hormones can be subdivided into sex hormones (androgens, estrogens, and progestins) and corticosteroids (glucocorticoids and mineralocorticoids). 

FIGURE 25.43 The steroid hormones are synthesized from cholesterol, with intermediate formation of pregnenolone and progesterone. Testosterone, the principal male sex hormone steroid, is a precursor to /3-estradiol. Cortisol, a glucocorticoid, and aldosterone, a mineralocorticoid, are also derived from progesterone. 

An endocrine disorder first described by the British Physician Thomas Addison in the mid 1800 s. The adrenal glands fail to produce sufficient amounts of glucocorticoid hormones (cortisol) and sometime mineralocorticoid (aldosterone). If left untreated it is life-threatening, the patient will show muscle weakness, hyperpigmentation and even depression. Typical treatment is hydrocortisone replacement therapy. 

Adrenocorticotrope Hormone (ACTH) Gluco-mineralocorticoid Receptors... 

The renin-angiotensin-aldosterone system (RAAS) generates the peptide hormone angiotensin II and subsequently the mineralocorticoid aldosterone, which both exert considerable impact on blood pressure ( blood pressure control) and fluid homeostasis, and... 

ACE inhibitors do not completely block aldosterone synthesis. Since this steroid hormone is a potent inducer of fibrosis in the heart, specific antagonists, such as spironolactone and eplerenone, have recently been very successfully used in clinical trials in addition to ACE inhibitors to treat congestive heart failure [5]. Formerly, these drugs have only been applied as potassium-saving diuretics in oedematous diseases, hypertension, and hypokalemia as well as in primary hyperaldosteronism. Possible side effects of aldosterone antagonists include hyperkalemia and, in case of spironolactone, which is less specific for the mineralocorticoid receptor than eplerenone, also antiandrogenic and progestational actions. 

The adrenal gland lies on the superior surface of each kidney. It is a double organ composed of an outer cortex and an inner medulla In response to ACTH secreted by the anterior pituitary, the adrenal cortex secretes several hormones (the glucocorticoids, the mineralocorticoids, and small amounts of sex hormones). 

This section of the chapter discusses the hormones produced by the adrenal cortex or the adrenocortical hormones, which are the glucocorticoids and mineralocorticoids. These hormones are essential to life and influence many organs and structures of the body. The glucocorticoids and mineralocorticoids are collectively called corticosteroids. 

The mineralocorticoids consist of aldosterone and des-oxycorticosterone and play an important role in conserving sodium and increasing die excretion of potassium. Because of diese activities, die mineralocorticoids are important in controlling salt and water balance Aldosterone is die more potent of these two hormones. Deficiencies of the mineralocorticoids result in a loss of sodium and water and a retention of potassium. 

Mineralocorticoids. The primary mineralocorticoid is aldosterone. The actions of this hormone include ... 

The steroid hormones known as mineralocorticoids and glucocorticoids are synthesized in the adrenal cortex of mammals [3]. The physiological mineralocorticoid is... 

Steroid hormones are divided into six classes, based on physiological effects estrogens, androgens, progestins, glucocorticoids, mineralocorticoids and vitamin D 847... 

Metyrapone inhibits 11-hydroxylase activity, resulting in inhibition of cortisol synthesis. Initially, patients can demonstrate an increase in plasma ACTH concentrations because of a sudden drop in cortisol. This can cause an increase in androgenic and mineralocorticoid hormones resulting in hypertension, acne, and hirsutism. Nausea, vomiting, vertigo, headache, dizziness, abdominal discomfort, and allergic rash have been reported after oral administration. 

Adrenal cortex Glucocorticoids Mineralocorticoids Sex hormones Steroids... 

Angiotensin II has two effects first, as a vasoconstrictor acting via receptors on vascular smooth muscle cells, and second, it stimulates the adrenal cortex gland to produce aldosterone (a mineralocorticoid steroid hormone, see Chapter 4). Aldosterone promotes the reabsorption of sodium from the renal tubule into the bloodstream and the resulting increase in osmolality (osmotic potential) of the blood causes water reabsorption in the nephrons. The outcome is an increase in blood volume and, therefore, pressure which inhibits (by negative feedback) further renin secretion from the JGA. 

Like all steroids, aldosterone enters the target cell and combines with cytosolic mineralocorticoid receptor. Such receptors are not entirely specific for aldosterone and will also bind cortisol, the principal glucocorticoid hormone. The receptors are protected from cortisol activation by 11 3 hydroxysteroid dehydrogenase which... 

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