16 - Adrenal Hormones Flashcards
(40 cards)
Where are steroid hormones synthesized?
- Adrenal cortex (adrenocorticoids)
- Ovaries, testes (sex steroids)
Steroid secretion is controlled by _____ secreted from the _____
- Peptides
- Hypothalamus and pituitary
What are the general effects of glucocorticoids?
- Modulation of carbohydrate metabolism
- Increase levels of glycogen in liver and circulating glucose
- Early effects stimulate immune system
- Prolonged secretion leads to immune suppression and cell death
When does secretion of glucocorticoids increase?
During periods of stress
What are the general effects of adrenocorticoids?
- Modulation of water balance (control of water reabsorption)
- Promotes Na+ uptake in tubular epithelial cells
- Modulation of K+ ion transport
When are adrenocorticoids secreted?
During periods of stress
Secretion of ___ during stress is essential for life
Cortisol
Can glucocorticoids interact w/ mineralocorticoid receptors and vice versa?
Yes
Describe the humoral pathway response to stress
- Visceral brain activates limbic system
- Limbic system causes anterior pituitary to stimulate adrenal cortex to release cortisol
- Cortisol is converted into glycogen or interacts w/ GR receptor to produce anti-inflammatory effects and cell death
Describe the RAS pathway response to stress
- Visceral brain releases norepinephrine, which stimulates renin release
- Renin -> angiotensin 1 and 2 -> adrenal cortex -> aldosterone
- Aldosterone effects sodium uptake, which causes increased BP
Which factors increase cortisol levels?
- Stress
- Hypothyroidism
- Liver disease
What happens to circulating cortisol?
- 90% is bound to corticosteroid-binding globulin
- Remainder is free or loosely bound to albumin, allowing it exert its effect on target cells
What does increased transcription of glucocorticoids cause?
Production of anti-inflammatory or inhibitory cytokines (IL-10, IL-12, IL-1 receptor antagonists)
What does decreased transcription of glucocorticoids cause?
Production of inflammatory cytokines (IL-2, 3, 4, 5, 6, 13, and 15) and inflammatory enzymes (iNOS, COX-2)
What does increased serum glucose levels cause?
- Increased insulin release
- Decrease glucose uptake by muscle cells
What does increased insulin secretion cause?
- Increased lipogenesis
- Decreased lipolysis (to a lesser degree)
What is the effect of glucocorticoids in lymphoid and connective tissue, muscle, peripheral fat, and skin?
- Decreased muscle mass
- Weakness and thinning of skin
What is the effect of glucocorticoids on bone?
- Causes osteoporosis in Cushing’s syndrome and imposes a major limitation in the long-term therapeutic use of glucocorticoids
- Reduce growth in children
What are the GENERAL effects of glucocorticoids?
- Catabolic
- Anti-anabolic
- Anti-inflammatory
- Immunosuppressive
How are glucocorticoids anti-inflammatory?
- Effect concentration, distribution, and function of peripheral leukocytes
- Suppress inflammatory cytokines, chemokines, and other mediators of inflammation (increase neutrophils and decrease lymphocytes, monocytes, eosinophils, and basophils)
How are glucocorticoids immunosuppressive?
- Down regulate T-lymphocyte proliferation
- Inhibit T-lymphocyte activation
- Down regulate plasma cells
- Inhibit inflammatory cell migration
- Inhibit antigen phagocytosis by macrophages
- Suppress antibody production
Do glucocorticoids inhibit or activate phospholipase A2? How do they do this?
- Inhibit
- Decrease synthesis of arachidonic acid
- Decrease prostaglandins, leukotrienes, and platelet-activating factor
Do glucocorticoids increase or decrease expression of COX-2? How?
Decrease by decreasing prostaglandins
What is the effect of glucocorticoids on mast cell and basophil secretion?
Cause vasoconstriction and decrease capillary permeability, so depress mast cell and basophil secretion
