Adrenal cortex

Glucocorticoid release is controlled by secretion of adreno-corticotrophic hormone (ACTH) from the anterior pituitary gland into the circulation. Mineralocorticoid secretion is stimulated by the renin-angiotensin mechanism.

Hormones produced from the adrenal cortex are all derived from cortisone and are based on the cyclopentano-perhydrophenanthrene nucleus. This nucleus contains 19 carbon atoms. At the C-17 position there is a side chain. Those with two carbon atoms in the side chain are known as C-21 steroids and those with no carbon atoms are known as C-19 steroids. C-19 steroids with an oxygen atom at the side chain are 17-ketosteroids and those with a hydroxyl group are 17-hydroxy corticosteroids. C-19 steroids are androgenic.

C-21 steroids have either a mineralocorticoid or glucocorti-coid effect depending on whether their primary effect is on sodium-potassium excretion or predominantly on glucose and protein metabolism respectively.

The predominant steroids produced by the adrenal cortex are as follows:

• Glucocorticoids: cortisol and corticosterone.

• Mineralocorticoid: aldosterone.

• Androgens: predominatly androstenedione, 11-hydroxy-androstenedione, testosterone, and the inactive precursor dehydroepiandrostenedione sulphate(DHA-S)

Small amounts of progesterone and oestrogens are also synthesised.

Individual tumours may arise which produce an excess of each of these hormones:

• Cushing's syndrome or Cushing's disease - glucocorticoids;

• Conn's syndrome - mineralocorticoids;

• adrenogenital syndrome - sex hormones.

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