Adrenal Cortex Flashcards
Describe the parent molecule that all adrenal steroids are derived.
Cholesterol; Is modified by enzymes to make other steroid hormones
List the major actions of glucocorticoids
You don’t want lots of glucocorticoids floating around all of the time. Rise in glucocorticoids during periods of reduced food availability will help maintain serum glucose concentrations for CNS function at the expense of fat and protein; CNS only uses glucose Physiological function of glucocorticoids: Metabolic: Glucose “sparing – promotes gluconeogenesis, Stimulates lipolysis, Promotes protein degradation, Stimulates glycogen formation, Inhibits glucose uptake by many tissues, Catabolic for most tissues Response to stress Immune- Potent anti-inflammatory role (used clinically), Immunosuppression (at higher doses), Potential for infections Blood- Increases neutrophils, decrease lymphocytes Skeletal- Can promote bone breakdown, Inhibits vitamin D
List stimuli that alter ACTH secretion
cortisol inhibits secretion of CRH and ACTH; CRH stimulates the production of ACTH
Describe the actions of aldosterone on ion metabolism
not regulated by the pituitary; promotes Na retention and K elimination, involved in water retention and H ion elimination
Describe with diagrams the regulatory system that controls the secretion rate of aldosterone
Describe with diagrams the regulatory system that controls the secretion rate of cortisol
List the major symptoms of Cushing’s disease in the dog
PU/PD, hyperphagia, abdominal enlargement (pendulous), alopecia, muscle weakness, lethargy
Describe the effect of ACTH on the adrenal cortex
acts on the 2 inner zones, promotes the secretion of glucocorticoids (cortisol/corticosterone)
Describe the mechanism of ACTH action
acts via cAMP, negative feedback system loop
Describe the role glucorticoids play in regulating ACTH secretion
negative feedback loop, high levels of cortisol suppress CRH/ACTH production
Name two species where cortisol is the most critical glucocorticoid
cats, horses
Name two species where corticosterone is the most critical glucocorticoid
rats, mice
Name a species where both cortisol and corticosterone are major glucocorticoids
dogs
Describe why administration of synthetic glucocorticoid causes atrophy of the adrenal zones that normally make glucocorticoid
exogenous cortisol in system, decrease CRH/ACTH (feedback), decrease endogenous cortisol secretion, atrophy of cells
Describe why a hypoglucocorticoid state frequently results following cessation of exogenous glucocorticoid treatment
atrophy of cells, ACTH stimulation of endogenous cortisol not as effective
Define and describe iatrogenic Cushing’s.
Clinical caused by treatment of other disorders by high doses of cortisol; ex.- use of glucocorticoids in immune suppression can lead to a short term Cushnoid state
Explain what sex steroids are produced by the adrenal cortex
Zona reticularis- DHEA: primary androgen; androstenedione
Explain the actions of sex steroids produced by the adrenal cortex
DHEA/androstenedione- development of secondary sex characteristics at puberty; serve as substrates for production of estrogens; may play role in preventing degenerative changes in ageing
Describe why production of high levels of adrenal steroids sometimes leads to estrogenic effect
Because they can serve as substrates for the production of estrogens
Describe the effect of glucocorticoids on the immune system
high doses can cause immunosuppression
- inhibits inflammation/T-lymphocytes production
Understand the mechanism of action and principle toxicities of the adrenolytic drug o,p’-DDD (mitotane) and appropriate approaches to its use for the treatment of hyperadrenocorticism
selective necrosis of inner zone cells (mechanism unknown); used in treatment of secondary or PDH (pituitary-dependent hyperadrenocorticism)
DHEA
primary androgen, sex steroid produce by the adrenal gland (zona reticularis)
androstenedione
sex steroid produced by the adrenal gland (zona reticularis)
glucocorticoid
cortisol/corticosterone; produced by adrenal gland; diurnal variation, can be influenced by stress
