Glucocorticoids: chemical structure, target-cells, mechanism of action, physiological effects

Adrenal cortex is source of gluco- and mineralocorticoids. Glucocorticoids are cortisol (hydrocortizone), cortizone and corticosterone. They are formed in zona fasciculata of adrenal cortex.

Chemical structure: All glucocorticosteroids are derivatives of cholesterol, have double bond between C4 and C5 and ketogroup in C3. Cortisol has OH-groups in C11 and C17; cortizone has got OH group in C17; corticosterone in C11.

Target-cells are cells of skin, liver, thimus, splen, adipose, muscular and connective tissues

Mechanism of action – 2-nd one

Physiological action:

I. The influence on Protein metabolism: 1) cleavage of muscular proteins; 2) synthesis of enzymes in liver

II. The influence on Carbohydrates metabolism: 1) gluconeogenesis from amino acids (main effect on the level of glucose in blood plasma); 2) increase of glycogenogenesis (but this effect is less than gluconeogenesis therefore the level of glucose in blood plasma is increased); 3) decrease of permeability of plasma membranes of peripheral tissues for glucose; 4) decrease of usage of glucose in tissues because glycolysis is decreased

III. The influence on lipids metabolism: 1) glucocorticoids decrease lipogenesis in legs and lower part of the body, but increase lipogenesis in face and upper part of the body; 2) they cause lipolysis and subsequent ketogenesis

IV. Antiinflammatory and antiallergic action because they inhibit cyclooxigenase which is a key enzyme of prostanoids formation. Prostanoids are mediators of inflammation and allergy. Beside of this they supress immune system and cause aging involution of thimus

Mineralocorticoids: chemical structure, target-cells, mechanism of action, physiological effects

Mineralocorticosteroids are formed in zona glamerulosa of adrenal cortex. There are next mineralocorticosteroids: 1) aldosterone and 2) deoxycorticosterone

Chemical structure: they are derivatives of cholesterol, have double bond between C4 and C5, ketogroup in C3 and aldehyde group in C13

Target-cells: are cells of kidneys, intestinal mucosa, salivary glands, sweat glands, urinary tract, urinary bladder, skin, myocardium and liver

Physiological effects they influence on synthesis of oxireductase and Na-K-ATP-ase. Therefore synthesis of ATP and its cleavage with production of energy for reabsorption of Na and water is increased. Pottassium and protons are excreted. Thus, aldosterone regulates osmotic pressure and acidic-base balance