Adrenal cortex function

Omura, T., E. Sanders, D. Y. Cooper, O. Rosenthal, and R. W. Estrabrook Isolation of a non-heme iron protein of adrenal cortex functional as a TPNH-flavoprotein-cytochrome P 50 reductase for hydroxylation reactions. In Non-Heme Iron Proteins Role in Energy Conversion, A. San Pietro, ed., Antioch Press, Yellow Springs, Ohio, pp. 401—412 (1965). 

Correlation with Adenohypophyseal-Adrenal Cortex Function and Stress, Scierwe (1971) 173,1035-1036. 

Overproduction of cortisol by hyperplastic adrenal cortices can result from oversecretion of ACTH (secondary hypercortisolism) due to a defect at the level of the pituitary or median eminence or to ectopic production of ACTH. The former condition is known as Cushing s disease and the latter as ectopic ACTH syndrome. In both conditions, the adrenal cortex functions normally and secretes cortisol in proportion to the level of ACTH. 

As described, in Addison s disease adrenal cortex function is inadequate. The most common cause of Addison s disease is the autoimmune destruction of the adrenal gland. (The major cause of adrenal insufficiency before the 1920s was tuberculosis of the adrenal gland.) Addison s disease also results from prolonged glucocorticoid therapy. (Recall that certain glucocorticoids are used as anti-inflammatory chugs.)... 

The reabsorption of NaCl is under hormonal control by the adrenal cortex insufficient activity of the gland results in drastic losses of Na and Cl . The chief mineral corticoid is aldosterone it also controls K excretion, but in the opposite sense. The Na+ K+ ratio of the urine, therefore, is an indicator of adrenal cortex function. 

The adrenal cortex produces steroidal hormones that are associated with carbohydrate, fat, and protein metabolism, electrolyte balance, and gonadal functions (58). One of these, cortisone [53-06-5] ( ) demonstrated a remarkable ability to relieve the symptoms of inflammatory conditions... 

The adrenal cortex is functionally divided into three zones, the zona glomerulosa, fasciculata, and reticularis. Only the outermost zone, the zona glomerulosa, synthesizes aldosterone. The other zones are responsible for the generation of glucocorticoids and androgens. 

This section of the chapter discusses FSH, LH, GH, and ACTH. FSH and LH are called gonadotropins because they influence the gonads (the organs of reproduction). GH, also called somatotropin, contributes to the growth of the body during childhood, especially the growth of muscles and bones. ACTH is produced by the anterior pituitary and stimulates the adrenal cortex to secrete the corticosteroids. The anterior pituitary hormone, TSH, is discussed in Chapter 51. Prolactin, which is also secreted by the anterior pituitary, stimulates the production of breast milk in the postpartum patient Additional functions of prolactin are not well understood. Prolactin is the only anterior pituitary hormone that is not used medically. 

The major androgen or androgen precursor produced by the adrenal cortex is dehydroepiandrosterone (DHEA). Most 17-hydroxypregnenolone follows the glucocorticoid pathway, but a small fraction is subjected to oxidative fission and removal of the two-carbon side chain through the action of 17,20-lyase. The lyase activity is actually part of the same enzyme (P450cl7) that catalyzes 17tt-hydroxylation. This is therefore a dual function protein. The lyase activity is important in both the adrenals and... 

Neurosteroids differ from nearly all the other transmitters and mediators in that they are lipid-soluble and can easily cross the blood-brain barrier. Thus it is necessary to distinguish those steroids that are produced in the brain from those that find their way there from the circulation after being released from the adrenal cortex or gonads. There are many natural and synthetic steroids that have some effect on neuronal function and can be considered neuroactive but few are actually produced in the brain to act on neurons, i.e. the true neurosteroids. 

Adrenal gland A triangle-shaped organ positioned at the top of the kidney which functions as a double endocrine gland . The larger outer adrenal cortex secretes three classes of steroid hormones glucocorticoids (e.g., cortisol), minerlocorticoids (aldosterone) and small amounts of sex steroids (e.g., testosterone). The inner adrenal medulla secretes catecholamines (e.g., adrenaline and noradrenaline). 

B5. Beigel, F., Function of adrenal cortex in sprue. Helv. Med. Acta 25, 185-207 (1958). 

In relatively recent years, it has become clear that under-nntrition of mother leads to low birth weight of the baby and this can increase the risk of development of degenerative disease in later life, e.g. hypertension, obesity, type 2 diabetes. One hypothesis is that the foetus adapts meta-bolically to deficiencies by increasing the number of cells in organs that perform specific functions that can overcome the deficiency, e.g. an increase in the number of liver cells that carry out gluconeogenesis, an increase in cells in the adrenal cortex to produce more of the chronic stress hormone, cortisol. These changes are carried over into adnlthood which can lead to an inadequate response of the liver to insulin so that insulin resistance develops. So far, however, it is unclear whether deficiencies in specific nntrients or undemutrition per se are responsible for snch changes (Chapter 15). 

Desoxycorticosterone causes an increase in reabsorption of sodium ions and excretion of potassium ions from the renal tubules, which leads to increased tissue hydrophilicity. This facilitates an elevated volume of plasma and increased arterial pressure. Muscle tonicity and work capability are increased. It is used for an insufficiency of function of the adrenal cortex, myasthenia, asthenia, adynamia, and overall muscle weakness. Synonyms of this drug are percorten, docabolin, cortitron, and others. 

Adrenodoxin. Adrenodoxin is the only iron-sulfur protein which has been isolated from mammals. This protein from mitochondria of bovine adrenal cortex was purified almost simultaneously by Kimura and Suzuki (32) and Omura et al. (33). It has a molecular weight of 12,638 (34) and the oxidized form of the protein shows maximal absorbances at 415 and 453 nm. Adrenodoxin acts as an electron carrier protein in the enzyme system required for steroid hydroxylation in adrenal mitochondria. In this system, electron transfer is involved with three proteins cytochrome P. gQ, adrenodoxin and a flavoprotein. Reduced NADP gives an electron to Tne flavoprotein which passes the electron to adrenodoxin. Finally, reduced adrenodoxin transfers the electron to cytochrome Pas shown in Fig. 3. The mechanism of cytochrome P cq interaction with steroid, oxygen and adrenodoxin in mixed-function oxidase of adrenal cortex mitochondria has been reviewed by Estabrook et al. (35). 

The male and female gonads, as well as the placenta of pregnant females and, to a lesser extent, the adrenal cortex, produce a range of steroid hormones which regulate the development and maintenance of reproductive and related functions. As such, these steroid sex hormones have found medical application in the treatment of various reproductive dysfunctions. 

Another major function of the adrenal cortex is the regulation of water and electrolyte metabolism. The principal mineralocorticoid, aldosterone, can increase the rate of sodium reabsorption and potassium excretion severalfold. This will occur physiologically in response to sodium or volume depletion or both. The primary site of... 

Corticotropin (adrenocorticotropic hormone, ACTH) regulates the function of the adrenal cortex and has numerous other effects on metabolism. It contains 39 amino acids in the form of a random coil, owing to the presence of several proline residues that prevent helix formation. Species differences are seen in amino acids 25-39 the rest of the ACTH molecule is identical in all animals and humans. The first 24 amino acids are responsible for all of the biological action of ACTH synthetic human ACTHj 24 is known as cosyntropin. 

---