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PHAR300 > L16 Male Contraception > Flashcards

L16 Male Contraception Flashcards

1
Q

What are the 3 parts of the male reproductive shown in class

A

testis, epididymis, vas deferens

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2
Q

Describe the inside of a testis

A

Comprised of seminiferous tubules and Leydig cells (surround the tubules)

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3
Q

What is the function of Leydig cells

A

they produce high local testosterone (5-7mg/day)

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4
Q

TF: Leydig cells are found inside the seminiferous tubules

A

False, Leydig cells are found outside the tubules, while Sertoli cells are found inside

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5
Q

What is the function of Sertoli cells

A

they embed and support maturing sperm cells

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6
Q

what is the daily sperm production in humans

A

34g

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7
Q

what is the sperm concentration in most fertile men

A

greater or equal to 15 million/ml (range of 15-200 million/ml)

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8
Q

What sperm concentration results in only 1% pregnancy risk

A

lesser or equal to 1 million/ml

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9
Q

How long is spermatogenesis for humans

A

64 days (2 months)

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10
Q

TF: Sertoli cells produce testosterone and estradiol

A

False

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11
Q

Which molecule serves as a building block for steroids

A

cholesterol

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12
Q

which hormone primarily regulates testosterone production

A

LH

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13
Q

TF: progesterone is a precursor for testosterone

A

True

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14
Q

Which chromosome is the human androgen receptor gene located on

A

X

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15
Q

TF: the ligand-binding domain for hAR (human androgen receptor) protein is at the NH2-terminal domain

A

False, its at the C terminal

The N-terminal domain = transcriptional activation

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16
Q

Describe the mechanism of action for androgen

A
  • Testosterone and Dihydrotestosterone (DHT) enter the cell
  • T is converted to DHT by 5alpha-reductases using NADPH
  • DHT binds to androgen receptors along with coregulators to move into the nucleus
  • Transcription is activated
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17
Q

Which enzyme converts T into estradiol?

A

aromatase

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18
Q

Which enzyme converts T into DHT?

A

5alpha-reductase

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19
Q

What does T act on? DHT? estradiol?

A

T: muscle, bone marrow, bone, brain
DHT: external genitalia, prostate, skin, hair
Estradiol: Bone, brain, breast

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20
Q

What behaviors are associated with low estrogen

A

increased sex drive and increased activity

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21
Q

What behavior(s) is/are associated with high estrogen

A

decreased eating

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22
Q

What behavior is associated with high DHT

A

increased eating

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23
Q

What does 5alpha-reductase do?

A

converts T into DHT

24
Q

What does aromatase do?

A

It converts T into estradiol

25
Q

TF: testosterone causes an individual to be calmer

A

False, it causes aggression

26
Q

What are the 4 contraceptive methods for men

A

Male vasectomy, male condom, withdrawal, spermicide

27
Q

TF: Most of the population relies on male contraceptives

A

False, only 40% of the population relies on male contraceptives

28
Q

TF: Condoms are only used to prevent pregnancies

A

False, they are important to prevent STDs

29
Q

How does male vasectomy work?

A

The vas defends is cut

30
Q

What is vasovasotomy

A

It is the reverse process of male vasectomy

31
Q

What are potential male contraceptive methods that are being developed

A

Hormonal (injections/implants/creams), non-hormonal, immunocontraception

32
Q

What is the negative feedback mechanism operating in male gametogenesis

A

Testosterone and estradiol (leydig cells) + inhibit-B (sertoli cells)

*inhibin-B only acts at the level of the pituitary and primarily acts on FSH

33
Q

TF: administering sustained doses of testosterone to rabbits for 3 months increases plasma testosterone

A

True

34
Q

Does administering testosterone increase spermatogenesis? Why?

A

No, spermatogenesis is triggered by production of endogenous testosterone or local testosterone levels in the germ cells.

Increasing serum testosterone levels actually deters spermatogenesis since the body will stop producing testosterone

35
Q

TF: Testosterone injection could potentially be used as a contraceptive method

A

True

36
Q

How does testosterone affect LH and FSH production

A

Testosterone is a negative feedback regulator that acts on the hypothalamus and the anterior pituitary glands, signalling them to stop producing LH and FSH

37
Q

Why is testosterone used in combination with estradiol to suppress spermatogenesis

A

Combining testosterone and estradiol aims to suppress sperm production effectively while minimizing the side effects associated with higher doses of testosterone alone. Estradiol is believed to enhance the contraceptive effect by further suppressing gonadotropin-releasing hormone (GnRH) and follicle-stimulating hormone (FSH) from the pituitary gland.

38
Q

TF: Hormonal implants for men such as T-E implants are effective immediately

A

False, it takes 64 days (time for sperm to mature)

39
Q

What are options for hormonal contraception for men other than exogenous testosterone administration

A

Exogenous Progesterone, GnRH antagonists

40
Q

How do hormonal male contraceptives work? What is their aim?

A

To inhibit FSH and LH secretion/production

41
Q

What is Dimethandrolone undecanote

A

Male hormonal contraceptive
Androgen and progesterone receptor agonist

Not aromatized I.e. no estrogen in activity/feminizing side effects

Not a substrate for 5alpha-reductase (which converts T to DHT)

42
Q

What is 11beta-MNTDC

A

A male hormonal contraceptive that suppresses serum gonadotropins (LH and FSH)

43
Q

What are some non-hormonal methods of contraception

A

Thermal contraceptives (hot baths, heating devices, heating underwear, silicone ring, ultrasound)

Drugs that cause azoospermia (prevents mitosis but non-selective, used in cancer, cytotoxic)

Gossypol, retinoids acid deprivation, BRDT inhibition, spin inhibition, inhibition of soluble adenyl Cyclades (sAC)

44
Q

What is gossypol?

A

Non hormonal male contraceptive, daily pill that suppresses sperm production, permanent/irreversible in 10-20% of men

Cotton seed oil extract

45
Q

What is an important consideration when targeting retinoic acid for spermatogenesis inhibition

A

Retinoic acid inhibitors like WIN 18,446 induce a disinformation/disinhibition reaction in men who drink alcohol

It blocks the action of an alcohol metabolizing enzyme

46
Q

How does BRDT (a bromodomanin protein) work

A

BRDT is required for meiosis

Current inhibitor JQ1 also inhibits other bromodomanin proteins leading to toxicity

Completely reversible

47
Q

Why is the epididymis a target for male contraception? What are some examples

A

It is involved in the maturation process for the sperm
It is perhaps reversible

Steroid 5alpha-reductive inhibitors
Calcium channel blocker (prevents enzyme action needed for fertilization - not specific)
Sperm mobility as a target (mifepristone)

48
Q

What is eppin

A

Human sperm surface protein, important for sperm motility

49
Q

What are the advantages of inhibiting soluble adenyl cyclase (sAC)

A

It is specific and reversible (targets sperm motility)

50
Q

What are the general trends for testosterone concentrations throughout male life span

A

Lowers with age
Increases during puberty
Increased during fetal and neo-natal development as well
Minimum during pre-pubertal (near zero)

51
Q

What are symptoms associated with T deficiency (4)

A

Sexual dysfunction (decreased libido, erectile dysfunction)
Adverse metabolic effects (CRA, coronary artery disease)
Decreased bone density
Potentially affects cognitive function

52
Q

Hormonal replacement therapy benefits include:

A

Preserve/improve bone mass, muscle mass, strength, physical functions, libido, well-being, mood, cognition

53
Q

Why is hormonal replacement therapy for men only useful in cases of androgen deficiency

A

There are adverse affects since the hormones target many cells throughout the body

54
Q

What are three examples of androgen abuse

A

Rejuvenation, sports, body building

55
Q

What are potential negative side effects to androgen abuse

A

Inhibition of spermatogenesis
Feminization since T can be hydrolyzed into estrogen (specifically estradiol) by aromatase

*aromatase is usually found in granulosa cells and Sertoli cells

PHAR300 (13 decks)

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