Lect 19 - Steroid Hormone Metabolism Flashcards
Jan 28, 2019
How many carbons do gluco- and mineralo-corticoids have?
21 carbons
How many carbons do estrogens have?
18 carbons
How many carbons do progestins have?
21 carbons
How many carbons do androgens have?
19 carbons
How many carbons are in cholesterol?
27 carbons
Where are steroid hormones NOT produced ever?
the liver!
The first reaction that converts cholesterol to pregnenolone is catalyzed by which enzyme? What are the three names of this enzyme?
1) desmolase
2) cholesterol side-chain cleavage enzyme (CYP450scc)
3) CYP11A
How does the body regulate levels of free steroid hormone?
Through binding to binding proteins in the blood
Does free steroid hormone or hormone bound to binding protein enter the cell?
free steroid hormone
Steroid hormones are degraded where? Excreted where?
Degraded in liver. Excreted in urine.
What are the organs where there is de novo synthesis of steroid hormones?
1) testes/ovaries
2) adrenal cortex
3) corpus luteum
What hormone is the main glucocorticoid?
cortisol
What hormone is the main mineralocorticoid?
aldosterone
Cholesterol is turned into pregnenolone by which enzyme?
CYP11A
What is another name for CYP11A?
Desmolase or side-chain cleavage enzyme
What enzyme turns angiotensin I into angiotensin II?
ACE
What enzyme turns angiotensinogen into angiotensin I?
renin
What is the rate-limiting enzyme in steroid hormone synthesis? What is the regulated enzyme?
Regulated: StAR
Rate-limited: CYP11A
At what point in the day is cortisol synthesis/release the highest?
In the AM right before waking up
What are the four major targets of cortisol?
1) liver
2) fat
3) muscle
4) inflammatory response
Cortisol affects the liver by stimulating what?
long term gluconeogenesis
What activated StAR?
PKA
3-beta hydroxysteroid DHG deficiency:
- — DHEA
- — androstenedione
- — aldosterone
- — cortisol
↑ DHEA
↓ androstenedione
↓ aldosterone
↓ cortisol
CYP17 deficiency:
- — DHEA
- — androstenedione
- — aldosterone
- — cortisol
- — 11-deoxycorticosterone
- — 11-deoxycortisol
↓ DHEA ↓ androstenedione ↑ aldosterone ↓ cortisol ↑ 11-deoxycorticosterone ↑ 11-deoxycortisol
CYP 21 deficiency:
- — DHEA
- — androstenedione
- — aldosterone
- — cortisol
↑ DHEA
↑ androstenedione
↓ aldosterone
↓ cortisol
Which is the most common cause of congenital adrenal hyperplasia? What percentage of cases?
CYP21 deficiency, 90-95% of cases
What are the symptoms of 3 beta-hydroxysteroid DHG deficiency?
1) low fasting blood glucose
2) natriuresis
3) deficiencies of glucocorticoids and mineralocorticoids
4) ambiguous genitalia may be possible
5) hypotension
What are the symptoms of CYP17 defiency?
1) no cortisol or weak androgens
2) hypertension (due to build up of the mineralocorticoid 11-deoxycorticosterone)
3) low fasting blood glucose
4) female-like genitalia
What are the symptoms of CYP21 deficiency?
1) hypotension
2) “salt crisis”
3) low fasting blood glucose
4) ambiguous male-like genitalia in females
What are the symptoms of CYP11B defiency?
1) mild hypertension
2) low fasting blood glucose
3) male-like genitalia
Where does the conversion of tesosterone to DHT take place? Which hormone catalyzes this reaction? What is another name for this hormone?
1) Sertoli cells
2) 5-alpha reductase
3) aromatase
Follicular granulosa cells produce _______ by catalysis with ________ under stimulation of _______ receptors.
1) estrogens
2) 5-alpha reductase
3) FSH
