Hormone, adrenal cortex sources

The adrenal glands are located anatomically above the kidneys. They comprise a three-layer cortex and a medulla. The medulla is the source of catecholamines such as epinephrine, the fight-or-flight hormone. The cortex is the source of aldosterone, the primary mineralocorticoid that is involved in the regulation of sodium reabsorption in the kidneys. In addition, the cortex is also the source of steroids known as glucocorticoids, of which cortisol is the principal endogenous representative. Synthesis and release of cortisol is under the control of adrenocorticotropic hormone (ACTH). 

The last important steroidal hormone of the adrenal cortex to be characterized was aldosterone la. This substance was only available in minute amounts from natural sources and the determination of structure by Reichstein and his colleagues1-2 was a masterpiece of collaboration between University (Basel) and Industry (Ciba-Geigy). The masked aldehyde group at C18 is an unusual feature for a steroidal molecule and at once posed interesting problems of synthesis. There are very few natural steroids which are substituted at C18, so a partial synthesis did not, at first, seem very practical. 

Our study on the distribution of electron transferring proteins in animal sources is still in progress. From present knowledge, adrenodoxin can be found in adrenal cortexes from pig, beef, and rat. Further, a similar protein was isolated from pig testis (see II-A-2), and it was also found in the ovary. However, brain, heart, liver, kidney, and pancreas appear to lack adrenodoxin-like protein. If this is correct, the proteins of the ferredoxin family are located solely in the glands which directly act in the biosynthesis of steroid hormones. It is of interest that adrenodoxin-like protein does not participate in the steroid hydroxylation involved in cholesterol and cholic acid biosyntheses. All of these reactions without the participation of adrenodoxin are similar to enzymes responsible for microsomal non-specific hydroxylation, which consist of the following sequence of electron transfer ... 

The hormones of (he adrenal glands are essential for survival. The adrenal cortex is the source of the two important steroid hormones, aldosterone and cortisol (Fig. 1). The adrenal medulla is embryologically and histologically distinct from the cortex anil is part of the sympathetic nervous system. Medullary cells synthesize, store and secrete adrenaline, along with noradrenaline and dopamine. The adrenal medullary hormones arc discussed further on pages 126-127. 

Infrared spectroscopy has been applied in identifying and determining the structures of steroids isolated from natural sources, for example, testis, ovary, placenta, adrenal cortex, bile, and blood. The technique has been used to identify compounds along the biosynthetic routes of, for example, cholesterol, pregnenolone, androgens, adrenal hormones, aldosterone, and estrogens. 

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