Reproductive Hormones

Question 1

What is the result of GnRh release from the hypothalamus?

Answer 1

Cause gonadotrophs to release FSH and LH

Question 2

What happens with sustained GnRH?

Answer 2

Inhibit FSH/LH release

Question 3

What is the half life of GnRH?

Answer 3

degraded by peptidases in about 4 min.

Question 4

What inhibits GnRH?

Answer 4

Negative feedback from sex steroids and GnIH

Question 5

What does LH do in females?

Answer 5

Released in a pulsitive manner and stimulates production of corpus luteum

Question 6

What is the targets for LH?

Answer 6

Females: Theca cells
Males: Leydig cells

Question 7

What is the main cause of ovulation?

Answer 7

Large increases in LH

Question 8

What inhibits LH?

Answer 8

Sustained release of GnRH and negative feedback from sex steroids

Question 9

What is the structure of LH and where is it made?

Answer 9

Alpha and beta chains and made by gonadotrophs in the pituitary

Question 10

What does FSH do in females?

Answer 10

Stimulate the growth of Graafian follicles

Question 11

What is the structure and where is FSH made?

Answer 11

Alpha and Beta chain made by gonadotrophs in the anterior pituitary

Question 12

What activates FSH?

Answer 12

GnRH released in a pulsative manner and activin

Question 13

What inhibits FSH?

Answer 13

Sustained release of GnRH and inhibin and negative feedback

Question 14

What is the half life of FSH?

Answer 14

30-100 minutes

Question 15

What is the targets of FSH?

Answer 15

Females: granulosa cells
Males: Sertoli cells

Question 16

What is prolactin?

Answer 16

Protein hormone made in the anterior pituitary by lactotrophs. Similar to growth hormone

Question 17

What does prolactin do in females?

Answer 17

• Mammogenesis
• Lactogenesis
• Galactopoeisis
• Repro and body effects

Question 18

What does prolactin do in males?

Answer 18

Sensitize leydig cells to LH potentiating testosterone

Question 19

What regulates prolactin?

Answer 19

Negatively regulated by dopaminergic neurons in the arcuate nucleus

Question 20

What is oxytocin?

Answer 20

Peptide hormone made in the hypothalamus and released in the posterior pituitary

Question 21

What does Oxytocin do in females>

Answer 21

• Smooth muscle contraction in repro organs
• Prostaglandin synthesis
• CNS effects

Question 22

What does Oxytocin in males?

Answer 22

Contraction of the epididymis and vas deferens and prostaglandin synthesis

Question 23

What regulates oxytocin?

Answer 23

Neural sensory pathways and positive feedback loop

Question 24

What is melatonin?

Answer 24

Monoamine hormone made by pineal gland at nigh

Question 25

What is the purpose of melatonin?

Answer 25

Functions in circadian rhythm and core for seasonal breeders through the KISS system controlling GnRH and direct stimulation of pars tuberalis

Question 26

What is the effect of melatonin on KISS neurons in short day breeders?

Answer 26

Inhibits

Question 27

What is the effect of melatonin on KISS neurons in long day breeders?

Answer 27

Stimulates

Question 28

What does 17B- hydroxysteroid dehydrogenase do?

Answer 28

Synthesize testosterone or estradiol from weaker androgens or estrogens

Question 29

What does Aromatase do>

Answer 29

Needed for synthesis of all estrogens

Question 30

What does 5a-reductase do?

Answer 30

Needed for synthesis of Dihydrotestosterone

Question 31

WHere is testosterone produced?

Answer 31

C19 androgen steroid made in leydig cells in testis (small amount in the adrenal glands and ovaries)

Question 32

How is testosterone made?

Answer 32

Reduced from adrostenedione by 17bHSD and controlled by LH

Question 33

What is the half life of testosterone?

Answer 33

30-40min

Question 34

What are the carrier proteins for testosterone?

Answer 34

SHBG and ABP

Question 35

What is dihydrotestosterone?

Answer 35

C19 hormone made by reducing testosterone with 5a-reductase

Question 36

What androgen is more potent?

Answer 36

DHT

Question 37

What is the half life of DHT?

Answer 37

50-60min

Question 38

Why are circulating levels of DHT low?

Answer 38

Usually made at the site of action

Question 39

What is estradiol?

Answer 39

C18 estrogen made from androtenedione with 17b-HSD and aromatase

Question 40

Where is aromatase found?

Answer 40

Males: sertoli cells Females: Granulosa cells

Question 41

What are non repro effects of estradiol?

Answer 41

- Bone maintenance | - Closure of epiphyseal plate (why women are usually shorter)

Question 42

What is the carrier protein for estradiol?

Answer 42

SHBG

Question 43

What is the strongest estrogen?

Answer 43

Estradiol

Question 44

What are other estrogens?

Answer 44

Estrone, estriol, and equilin

Question 45

What receptors do estrogens bind to?

Answer 45

Estrogen receptors but some differentiate to cause different effects on different tissues

Question 46

What is progesterone?

Answer 46

C21 progestin secreted by granulosa luteal cells in CL during luteal phase of estrous

Question 47

What is the effect of progesterone?

Answer 47

-pro-gestational (pause estrous cycle during pregnancy and support pregnancy)

Question 48

What receptors do progesterones bind to?

Answer 48

- Nuclear progesterone receptors | - Membrane receptor

Question 49

How is progesterone made?

Answer 49

Is an intermediate in almost all steroid making tissues. Only secreted in absence of advanced steroid enzymes

Question 50

What is the structure of activins?

Answer 50

dimers of inhibin beta subunits

Question 51

What is the structure of inhibins?

Answer 51

dimers of alpha and beta subunit

Question 52

What receptor do inhibins/activins bind to?

Answer 52

Activin receptors

Question 53

What cells secrete activin and inhibins?

Answer 53

Males: Sertoli Female: granulosa cells

Question 54

What regulates activin/inhibin?

Answer 54

Follistatin. Binds to activin to prevent activin binding

Question 55

What is the role of prostaglandins in the male repro tract?

Answer 55

- regulate immune response to sperm in males and females | - regulate activity of ductal system

Question 56

What is the role of prostaglandins in females?

Answer 56

- Contractions - Control luteolysis - signaling for sperm

Question 57

What is hCG and eCG(PMSG)

Answer 57

produced by placenta in humans and horses respectively (LH receptor agonists)