Steroids Flashcards
What are the main types of steroids?
Glucocorticoids
Mineralocorticoids
Androgens
What are the steroids secreted by?
The adrenal cortex
Where are mineralocorticoids secreted?
Zona glomerulosa of the adrenal cortex
Where are glucocorticoids secreted?
Zona fasciculata of the adrenal cortex
Where are adrenal androgens secreted?
Zona Reticularis of the adrenal cortex
Why are the boundaries between the different types of steroids not absolute?
Synthesised from cholesterol
Additionally, they are also all highly aromatic structures
Due to the steroids having similar structures boundaries are not absolute
Give some examples of glucocorticoids
Corticosterone
Hydrocortisone (Cortisol)
What are the effects of glucocorticoids?
Metabolism.
Negative feedback loops
Anti-inflammatory and immunosuppressive.
What are the metabolic effects of glucocorticoids?
Elevated glucose levels.
Inhibition of protein synthesis (wasting of muscle)
Redistribution of fats
Negative balance of calcium as there is an increased in calcium secretion and decrease in calcium absorption.
What effect does glucocorticoids have on the hypothalamus and pituitary glands?
Hypothalamus releases CRF which stimulates the pituitary gland to release ACTH into the blood.
When these are in the blood it releases steroids which negatively feedback to the hypothalamus and the pituitary gland to inhibit the release of CRF and ACTH.
What are the anti-inflammatory and immunosuppressive effects of glucocorticoids?
Anti-inflammatory:
Reduce redness, swelling and pain (early)
Wound healing, proliferation (late)
Immunosuppressive:
Suppress function of immune cells.
steroids impact both stages of inflammation where as NSAIDs only effect the early
stage
What is the mechanism of action of glucocorticoids?
- Steroid binds to nuclear receptor in cytosol – remember steroids are hydrophobic!
- Translocation of receptor to nucleus
- Receptor act as transcription factor → binds to DNA to initiate lipocortin production
- Also trans represses IL1/TNF-alpha activation
- Lipocortin then inhibits PLA2 thereby inhibiting PG synthesis
What is the function of lipocortin?
Inhibits phospholipase A2 and therefore when steroids are present, this leads to reduced prostaglandin and leukotrienes synthesis.
What are some uses of steroids as drugs?
Replacement therapy (underactive adrenal cortex)
Anti-inflammatory
Immunosuppressive
Emesis
What would the anti-inflammatory effects of steroids be used to treat?
Severe asthma (inhaler beclomethasone)
Severe arthritis
Skin disorders
