Lect 19 - Steroid Hormone Metabolism

Question 1

How many carbons do gluco- and mineralo-corticoids have?

Answer 1

21 carbons

Question 2

How many carbons do estrogens have?

Answer 2

18 carbons

Question 3

How many carbons do progestins have?

Answer 3

21 carbons

Question 4

How many carbons do androgens have?

Answer 4

19 carbons

Question 5

How many carbons are in cholesterol?

Answer 5

27 carbons

Question 6

Where are steroid hormones NOT produced ever?

Answer 6

the liver!

Question 7

The first reaction that converts cholesterol to pregnenolone is catalyzed by which enzyme? What are the three names of this enzyme?

Answer 7

1) desmolase
2) cholesterol side-chain cleavage enzyme (CYP450scc)
3) CYP11A

Question 8

How does the body regulate levels of free steroid hormone?

Answer 8

Through binding to binding proteins in the blood

Question 9

Does free steroid hormone or hormone bound to binding protein enter the cell?

Answer 9

free steroid hormone

Question 10

Steroid hormones are degraded where? Excreted where?

Answer 10

Degraded in liver. Excreted in urine.

Question 11

What are the organs where there is de novo synthesis of steroid hormones?

Answer 11

1) testes/ovaries
2) adrenal cortex
3) corpus luteum

Question 12

What hormone is the main glucocorticoid?

Answer 12

cortisol

Question 13

What hormone is the main mineralocorticoid?

Answer 13

aldosterone

Question 14

Cholesterol is turned into pregnenolone by which enzyme?

Answer 14

CYP11A

Question 15

What is another name for CYP11A?

Answer 15

Desmolase or side-chain cleavage enzyme

Question 16

What enzyme turns angiotensin I into angiotensin II?

Answer 16

ACE

Question 17

What enzyme turns angiotensinogen into angiotensin I?

Answer 17

renin

Question 18

What is the rate-limiting enzyme in steroid hormone synthesis? What is the regulated enzyme?

Answer 18

Regulated: StAR

Rate-limited: CYP11A

Question 19

At what point in the day is cortisol synthesis/release the highest?

Answer 19

In the AM right before waking up

Question 20

What are the four major targets of cortisol?

Answer 20

1) liver
2) fat
3) muscle
4) inflammatory response

Question 21

Cortisol affects the liver by stimulating what?

Answer 21

long term gluconeogenesis

Question 22

What activated StAR?

Answer 22

PKA

Question 23

3-beta hydroxysteroid DHG deficiency:

• — DHEA
• — androstenedione
• — aldosterone
• — cortisol

Answer 23

↑ DHEA
↓ androstenedione
↓ aldosterone
↓ cortisol

Question 24

CYP17 deficiency:

• — DHEA
• — androstenedione
• — aldosterone
• — cortisol
• — 11-deoxycorticosterone
• — 11-deoxycortisol

Answer 24

↓ DHEA
↓ androstenedione
↑ aldosterone
↓ cortisol
↑ 11-deoxycorticosterone
↑ 11-deoxycortisol

Question 25

CYP 21 deficiency:

• — DHEA
• — androstenedione
• — aldosterone
• — cortisol

Answer 25

↑ DHEA
↑ androstenedione
↓ aldosterone
↓ cortisol

Question 26

Which is the most common cause of congenital adrenal hyperplasia? What percentage of cases?

Answer 26

CYP21 deficiency, 90-95% of cases

Question 27

What are the symptoms of 3 beta-hydroxysteroid DHG deficiency?

Answer 27

1) low fasting blood glucose
2) natriuresis
3) deficiencies of glucocorticoids and mineralocorticoids
4) ambiguous genitalia may be possible
5) hypotension

Question 28

What are the symptoms of CYP17 defiency?

Answer 28

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

Question 29

What are the symptoms of CYP21 deficiency?

Answer 29

1) hypotension
2) “salt crisis”
3) low fasting blood glucose
4) ambiguous male-like genitalia in females

Question 30

What are the symptoms of CYP11B defiency?

Answer 30

1) mild hypertension
2) low fasting blood glucose
3) male-like genitalia

Question 31

Where does the conversion of tesosterone to DHT take place? Which hormone catalyzes this reaction? What is another name for this hormone?

Answer 31

1) Sertoli cells
2) 5-alpha reductase
3) aromatase

Question 32

Follicular granulosa cells produce _______ by catalysis with ________ under stimulation of _______ receptors.

Answer 32

1) estrogens
2) 5-alpha reductase
3) FSH