17 terms

The Adrenal Hormones

Which hormones are released by the adrenal cortex?
cortisol (glucocorticoids), testosterone, aldosterone (mineralocorticoids). (steroid hormones)
Which hormones are released by the adrenal medulla?
epinephrine and norepinephrine. (catecholamines)
Adrenocortical hormones
-mineralocorticoids and glucocortocoids (aldosterone and cortisol)
-act on intracellular nuclear receptors
-receptor plus hormone unfolds and binds to DNA at HORMONE RESPONSE ELEMENTS-leads to transcription of genes
-increases RNA polymerase activity and production of specific mRNAs
-increases protein synthesis
Nuclear Receptors
Receptors for lipophilic hormones - function within the cell nucleus to activate genetic transcription (production of mRNA). Must be activated by binding to its hormone ligand before it can bind to a specific region of DNA.
Which drugs activate nuclear receptors?
• Oestrogen Receptor Agonists - for hormone
replacement therapy in postmenopausal women

• Glucocorticoid Receptor Agonist - for inflammation
Which drugs antagonize nuclear receptors?
-SPIRONOLACTONE. mineralocorticoid receptor antagonists-for oedema due to liver cirrhosis and for heart failure.

-TAMOXIFEN. oestrogen receptor antagonists-for prevention and treatment of breast cancer.

-BICALUTAMIDE/CASODEX. androgen receptor antagonists-treatment of prostrate cancer.
Aldosterone (mineralocorticoids)
-aids in regulating electrolytes and water balance.
-retain Na in exchange for K
-retains water
-production mainly regulated by renin/angiotensin system.
-aldosterone antagonist-spironolactone-used as a K sparing diuretic.
-aldosterone acts on distal renal tubes to increase Na reabsorption and increased excretion of K and H.
-aldosterone nuclear receptors occur only in kidneys.
-spironolactone is a competitive antagonist of aldosterone at these receptors.
-the effect of the aldosterone-receptor complex interaction with DNA is to increase the number of Na channels in the membrane of the renal cell.
-negative feedback on anterior pituitary/hypothalamus
-anti-inflammatory and immunosuppressive effects
Glucocorticoids (metabolic actions)
-CBH decreased uptake of glucose but increased breakdown of protein to glucose-HYPERGLYCAEMIA
-Proteins increased breakdown and reduced synthesis
-Fat increased breakdown, redistribution
-Raise plasma glucose levels to provide energy to combat stress.
Glucocorticoids (anti-inflammatory and immunosuppressive effects)
-blood vessel dilation/leakage
-production of mediators
-inflammatory and immune cell activity
-glucocorticoids inhibit phopholipase A2
-this blocks production of arachidonic acid, prostaglandins and leukotrienes from cell membrane phospholipid.
-taken orally
-replacement cortisol
-taken orally
-inflammatory and
-taken orally
-skin inflammation
Adverse effects of glucocorticoids include...
-suppression of response to infection
-suppression of synthesis endogenous glucocorticoid
-metabolic effects
Catecholamines (adrenal medulla hormones)
-adrenaline and noradrenaline (to a lesser extent) secreted in response to the sympathetic nervous system (fight or flight)
-Stimulation releases glucose from the liver and fatty acids from adipose tissue
-actions of epinephrine (adrenaline) in these tissues are mediated by elevations in cyclic AMP levels.
-also maintain BP through ionotropic effects on the heart and vasoconstrictor actions
-people with hypertension can be treated with beta-adrenoreceptor antagonists to reduce cardiac rate
-failure of adrenal medulla is rare but causes hypotension
-tumours of adrenal medulla secrete catecholamines causing hypertension and must be removed surgically.