Hellekant Adrenal Cortex Physiology and Pharm Flashcards
What zone of the adrenal cortex produces aldosterone?
Glomerulosa
What zone of the adrenal cortex produces glucocorticoids?
Fasiculata
What zone of the adrenal cortex produces androgens?
Reticularis
What causes the release of CRH? Where is it released from?
Stress and circadian rhythm cause CRH release from hypothalamus
What promotes the production of aldosterone?
Angiotensin II (due to low BP), high K+, and high levels of ACTH
What is the difference between aldosterone and cortisol in the HPA axis?
Cortisol has a negative feedback; aldosterone does not
What cells does CRH bind? What is the receptor type CRH binds?
Binds Gs receptor on corticotrophs in the anterior pituitary
CRH increases synthesis of what?
Preprohormone POMC - which is cleaved into ACTH and MSH and lipotropin
What is POMC cleaved into?
ACTH, MSH, lipotropin
How do melanocytes in the skin cleave POMC?
Into MSH, but not ACTH
What cells synthesize ACTH?
Corticotrophs
ACTH binds what receptor in adrenal cortical cells?
Melanocortin-2 receptor (MC2R)
What kind of receptor is melanocortin receptor type 2? What binds it?
Gs coupled receptor; ACTH binds it
ACTH binding MC2R promotes what?
Synthesis of side-chain cleavage enzyme (CYP11A) in adrenal cortex
What is the function of the enzyme CYP11A1?
Conversion of cholesterol to pregnenolone
What is the rate limiting step in adrenal steroid synthesis?
CYP11A - p450scc enzyme converting cholesterol to pregnenolone
What receptor can ACTH bind on melanocytes?
Melanocortin 1 receptor
Where in the cell are glucocorticoid receptors found?
Cytosol
Where are mineralocorticoid receptors found?
Kidney, colon, sweat glands, heart, hippocampus, brown adipose
Mineralocorticoid receptor has affinity for what?
Equal affinity for mineralocorticoid and glucocorticoids
How to mineralocorticoid responsive tissues regulate the equal affinity of glucocorticoids and mineralocorticoids for the MR?
Mineralocorticoid responsive tissues (eg kidney) convert cortisol to inactive cortisone so there is no effect from cortisol
What is the inactive form of cortisol?
Cortisone
What is the active form, cortisol or cortisone?
Cortisol
What increases the level of corticotropin binding globulin?
Estrogens and pregnancy
What is the function of 11 beta hydroxylase 2?
Converts active glucocorticoid to inactive steroid (eg cortisol converted to cortisone)
What tissues convert active glucocorticoids to inactive steroids?
Kidney, colon, salivary glands, placenta, fetus
What enzyme can convert inactive steroids to active steroids?
11 beta hydroxylase type 1
What tissues convert inactive steroid to active steroids?
Liver adipose, lung, vascular tissue, CNS, macrophages