2: Steroid Biosynthesis Flashcards
Mineralocorticoid receptors (MRs)
Group of nuclear receptors (ligands bind in nucleus)
Five steroid hormones that bind MRs and which ones have the highest binding efficacy
- Aldosterone: highest
- 11-deoxycorticosterone: very high
- Testosterone, cortisol, cortisone
What is common about all hormones that bind MRs
Increase Na retention -> cause hypertension
Reminder of the HPA axis
CRH from hypothalamus -> ACTH from anterior pituitary -> adrenal cortex
What can mutations in 17,20 lyase cause? How?
Prostate cancer; major sex hormones are not made -> steroid synthesis shifts towards corticosterone -> excess corticosterone causes adrenal hyperplasia
Where is 25-hydroxycholecalciferol exclusively produced?
Liver
Aldosterone function
Balances Na and K in blood
Conn Syndrome / Primary Aldosteronism
Adrenal glands produce too much aldosterone -> loss of K + retention of Na
What does loss of K and retention of Na cause in Conn Syndrome?
Body holds too much water -> HTN
Mechanism of adrenal hyperplasia
Increased production from adrenal gland of cortisol precursors and androgens
What two enzymes can be mutated in adrenal hyperplasia?
21-hydroxylase, 11B-hydroxylase
Mutation in 21-hydroxylase causes increase in which hormone?
Progesterone
Mutation in 21-hydroxylase causes decrease in which four hormones?
Deoxycorticosterone, 11-deoxycortisol, cortisol, aldosterone
Mutation in 11B-hydroxylase causes increase in which hormone?
Deoxycorticosterone
Mutation in 11B-hydroxylase causes decrease in which three hormones?
Corticosterone, cortisol, aldosterone
