Male Sex Hormones

Question 1

What is the most potent androgen?

Answer 1

5alpha-DHT

Question 2

How potent is testosterone?

Answer 2

Moderately

Question 3

What is the least potent androgen?

Answer 3

DHEA

Question 4

At what age does plasma testosterone start to decline?

Answer 4

50

Question 5

What enzyme converts testosterone to DHT?

Answer 5

5alpha-reductase

Question 6

What % testosterone is unbound?

Answer 6

2%

Question 7

What % testosterone is bound to SHBG?

Answer 7

65%

Question 8

What % testosterone bound to albumin

Answer 8

33%

Question 9

Where is testosterone converted to DHT?

Answer 9

Target tissues, not the blood since most is bound

Question 10

Where is testosterone converted to estrodiol?

Answer 10

Adipose and liver

Question 11

What enzyme converts testosterone to estrodiol?

Answer 11

Aromatase

Question 12

What hormones bind to androgen receptor?

Answer 12

Testosterone and DHT

Question 13

What is the co-activator of androgen receptor?

Answer 13

ARA70, must bind to receptor complex for androgen receptor to function

Question 14

What are the physiological effects of testosterone?

Answer 14

• Male sex drive and performance
• Muscle mass inc
• Penile and scrotal growth
• Vocal cord thickening
• Spermatogenesis

Question 15

What are the physiological effects of DHT?

Answer 15

• Inc facial and body hair
• Acne
• Scalp hair recession
• Prostate enlargement
• Skeletal growth and epiphyseal closure
• Stimulate lean body mass
• Stimulate erythropoietin and clotting factor production
• Dec HDL

Question 16

Are the effects of testosterone and DHT general or tissue specific?

Answer 16

Tissue specific

Question 17

What are some therapeutic uses of synthetic androgens?

Answer 17

• Androgen replacement therapy for hypogonadism or aging males
• Protein anabolic effects for catabolic disorders
• Anemia via EPO
• Anabolic steroids in athletes

Question 18

What are synthetic androgens?

Answer 18

Full androgen agonists can be esterified or alkylated

Question 19

Potency of esterified synthetic androgens?

Answer 19

Similar to testosterone

Question 20

Potency of alkylated synthetic androgens?

Answer 20

more pronounced anabolic properties so they are more specific for things like catabolic disorders

Question 21

What are the risks in male athletes associated with anabolic steroids?

Answer 21

• Inhibit LH/FSH
• Withdrawal=infertility (azoospermia)
• Loss of libido/impotence
• Feminization (T–>E)
• Liver toxicity
• CV toxicity

Question 22

What are the benefits in male and female athletes associated with anabolic steroids?

Answer 22

-Anabolic and EPO effects

Question 23

What are the risks in female athletes associated with anabolic steroids?

Answer 23

• Inhibit LH/FSH
• Menstruation effects
• Anovular cycles/infertility
• Loss of libido
• Virilization
• Liver tox
• CV tox

Question 24

What is a drug used for synthesis inhibition/anti-androgen therapy?

Answer 24

Finasteride

Question 25

What is the MOA of Finesteride?

Answer 25

Competitive inhibition of 5alpha-reductase type II-->blocks DHT formation in prostate gland, reducing serum DHT levels by 70%

Question 26

What are the two 5alpha-reductase isoforms and where are they located?

Answer 26

Type I -low expression in prostate, hair follicles. High in sebaceous glands (acne) and is only weakly inhibited by finasteride Type II -High expression in prostate, hair follicles, low in sebaceous glands, potently inhibited by finasteride

Question 27

What is finasteride approved for?

Answer 27

- Benign prostatic hyperplasia (BPH)-->dec prostate volume because prostate enlargement is dependent on DHT formation via type II - Male pattern baldness: bald men have more DHT in hair follicles.

Question 28

What is an example of an androgen receptor antagonist?

Answer 28

Flutamide

Question 29

What is the MOA of flutamide?

Answer 29

Pure androgen receptor antagonist (prevents ARA70 binding?)

Question 30

What are the therapeutic uses of flutamide?

Answer 30

- Hormone sensitive prostate cancer. Block DHT binding, reduce gene transcription and androgen effects on tumor growth - Precocious puberty - Female virilization (dev of male characteristics)