Steroid hormones (2-1) Flashcards
Role of PNMT? What increases transcription of PNMT?
Converts epinephrine to norepinephrine; cortisol increases transcription. A decrease in cortisol leads to a decrease in epinephrine (Addison’s dx)
Role of StAR protein?
To transport cholesterol into the inner mitochondrial membrane
After cholesterol is synthesized to pregnenolone, to which organelle is it transported to, to continue the pathway?
Smooth ER
Androstenedione is a precursor to _____
Testosterone (via 17-ketoreductase)
Describe electron flow, from NADPH to cytochrome P-450 hydroxylase
NADPH transfers 2 electrons to adrenodoxin reductase. Then, the electrons are passed on to adrenodoxin. Finally, Adrenodoxin passes them on to cytochrome P-450 hydroxylase.
Describe 5 alpha-reductase deficiency
Testosterone cannot be converted to DHT; a genetic male looks like a female, from birth until puberty. After puberty, testosterone production is ramped up, returning the phenotype to normal.
Describe the overall actions of glucocorticoids
To increase production of glucose while inhibiting all other pathways not involved in glucose production. This causes HYPERGLYCEMIA and HYPERINSULINEMIA.
What is characteristic of people with Addison’s disease / hypocortism?
Plasma adrenaline levels have been shown to be reduced
Cause of Cushing’s dx?
Elevated levels of cortisol! May also lead to increased amounts of male sex hormone, because of overactive adrenal glands
What is the obesity and hyperglycemia in people with Cushing’s dx, due to?
Due to the insulin-resistant muscle and liver, and also due to hyperinsulinemia (down-regulates insulin receptors)
What is the HTN in Cushing’s dx, due to?
Due to the activation of the aldosterone receptor by excess amounts of cortisol
How does 11-beta-HSD protect mineralocorticoid receptors from the high concentrations of glucocorticoids?
11-B-HSD converts cortisol, which binds the mineralocorticoids, to cortisone, which doesn’t bind them.
What are the effects of increased aldosterone, on Na+ and K+?
An increase in K+ excretion and Na+ reabsorption is seen; thus, an increase in BP is also seen.
How is renin production stimulated?
It is stimulated in the kidneys, when there is a decrease in BP
What causes congenital adrenal hyperplasia, and why?
An excess amount of ACTH in the blood causes CAH because there are low levels of epinephrine and a lack of (-) feedback inhibition
3-beta hydroxysteroid dehydrogenase deficiency (CAH)
- Highest on the overall pathway; perhaps the most pathologic.
- AR dx with no gluco/mineralocorticoids, androgens or estrogens
- Salt excretion in urine
- Patients have female-like genitalia
17-alpha hydroxylase deficiency (CAH)
- No sex hormones or cortisol are produced
- Increased production of mineralocorticoids (aldosterone) -> Na+ and fluid retention; thus, hypertension.
21-alpha hydroxylase deficiency (CAH)
- Most common form of CAH
- Gluco- and Mineralocorticoids are absent
- Overproduction of androgens -> masc. of external genitalia in females / early virilization in males
11-beta-1 hydroxylase deficiency (CAH)
- Decrease in cortisol, aldosterone and corticosterone
- Increase in fluid retention, which suppresses the renin/angiotensin system, causing low-renin hypertension
3-beta hydroxysteroid dehydrogenase deficiency
- Requires NAD+ and is NOT a cytochrome p450 enzyme (while the rest are)
- Deficiency affects production of:
- – Cortisol: hypoglycemia, epi deficiency
- – Aldosterone: low BP
- – Androgens: female genitalia in males, female infertility
17-alpha hydroxylase / 17,20-lyase deficiency
- Aldosterone levels will be high, so HTN is seen
- Overproduction of ACTH causes adrenal hyperplasia
- Males and females will be sterile; feminization of males, seen
21-alpha hydroxylase deficiency
- No cortisol is produced, leading to hypoglycemia
- No aldosterone produced, leading to hypotension
- Adrenal glands produce excess androgens
11-beta hydroxylase deficiency
- Adrenal glands produce excess androgens
- Although both sexes will be virilized (males, prematurely so), both sexes will be infertile.
