Reproductive Endocrinology

Question 1

What are the dominant hormones during the a) Follicular phase - b) Luteal phase?

Answer 1

a) Oestrogen b) Progesterone

Question 2

What are the names of phases of a female reproductive cycle based of vaginal cytology? What hormones are dominant?

Answer 2

Pro-oestrus (oestrogen) - Oestrus (oestrogen) - Metoestrus (transition) - Dioestrus (progesterone)

Question 3

What is special about the Queen’s cycle?

Answer 3

She is an induced ovulator - only goes into the follicular phase after mating

Question 4

Which animals are polyoestrous?

Answer 4

Cow - Queen - Sow - Rodents

Question 5

Which animals are seasonal polyoestrus short-day?

Answer 5

Ewe - Nanny - Doe - Elk

Question 6

Which animals are seasonal polyoestrus long-day?

Answer 6

Mare

Question 7

Which animals are mono-oestrus?

Answer 7

Bitch - Wolf - Fox - Bear

Question 8

Describe the events of a bitch’s endocrine events

Answer 8

Spontaneous ovulation at the end of variable follicular phase (4-28 days) → Bitch is either pregnant or in dioestrus phase (60days) → Very long Anestrus phase (>90 days)

Question 9

What hormone is essential in Bitches for CL maintainance?

Answer 9

Prolactin

Question 10

Describe LH levels in a Bitch during the follicular phase

Answer 10

Late anestrus = Low levles

1 week before proestrus = increased frequency and amount

Proestrus = lower levels

Late proestrus = reach peak levels of 8-15ng/ml

Question 11

Describe FSH levels in a Bitch during the follicular phase

Answer 11

Late anestrus = increase constantly, high levels

1 week before proestrus = increase (less so than LH)

Proestrus = low levels

Late proestrus = surge 1 days AFTER LH surge

Question 12

Describe the levels of Oestradiol in the Bitch during the follicular phase

Answer 12

Anestrus = low levels (doesn’t respond to FSH)

Proestrus = increased levels from 10pg/ml up to 150pg/ml

Late proestrus = peak levels reached 1-3 days before LH surge

Question 13

Describe the levels of Progesterone in the Bitch during the follicular phase

Answer 13

Anestrus = low levels

Proestrus = slow increase up to time of ovulation

Diestrus = peak values reached AFTER ovulation

Question 14

What does FSH effect in the granulosa cell to generate oestradiol?

Answer 14

Aromatase

Question 15

What does LH do in the Theca cell and the Granulosa cell? What is the final product in each?

Answer 15

Change of cholesterol into pregnenolone (then into progesterone)

Theca = oestradiol - Granulosa = progesterone

Question 16

What is initiated by the decrease of the oestradiol : progesterone ratio?

Answer 16

LH surge - Oestrus sex behaviour

Question 17

What is odd about oocytes just after ovulation? When is this thought to change?

Answer 17

They are immature, not completed their first meiotic division - rise in progesterone?

Question 18

Describe the levels of progesterone during the luteal phase (diestrus) in a Bitch. What happens to it at luteolysis?

Answer 18

Increases and plateaus - Rapid decrease

Question 19

Why would measurement for progesterone levels in a Bitch not determine pregnancy or not?

Answer 19

The luteal phase is the same length as gestation so progesterone would remain high in both cases

Question 20

What begins to regulate progesterone (luteotrophin) levels in the Bitch from day 25?

Answer 20

Prolactin

Question 21

What can be used to induce luteolysis exogenously in the Bitch?

Answer 21

PGF2alpha - Progesterone receptor agonist - GnRH antagonist - continuous GnRH agonist - Dopamine agonist (blocking PRL release)

Question 22

What hormone is used as a diagnostic test for pregnancy in Bitches? How?

Answer 22

Relaxin - it is NON-detectable in non-pregnant animals - sourced from the placenta it rises with PRL rise

Question 23

What can be used to control oestrus in the dog?

Answer 23

Spaying (ovariohysterectomy) - Hormonal control (androgens) - Progesterone - Synthetic progesterones - Testosterone

Question 24

What are the advantages and disadvantages of using A) Progesterone B) Synthetic progesterones C) Testosterone as hormal control in the Bitch?

Answer 24

A) -ve not active orally and short term parenterally

B) +ve longer acting, anti-gonadotrophic, weakly progestagenic, antioestrogenic (proligestone)

-ve increased risk of acromegaly, mammary tumours, diabetes mellitus

C) +ve orally active

-ve affects fertility, protrusion of clitoris and enlarging vulva

Question 25

Define pseudopregnancy

Answer 25

False pregnancy

Question 26

What clinical signs are associated with pseudopregnancy?

Answer 26

Rise in PRL noted 6 weeks after the end of oestrus - Behavioural changs (nest making, etc)

Question 27

How do you treat pseudopregnancy?

Answer 27

Synthetic progesterone suppressing PRL release - oestrogens and androgens to suppress PRL - Dopamine agonist inhibit PRL release

Question 28

Describe the levels of LH in the Queen during it’s cycle

Answer 28

Copulation leads to rapid increase of LH - normally requires multiple copulations to provide enough LH for ovulation

Question 29

Describe the levels of progesterone in a Queen, pointing out differences between pregnant and non-pregnant

Answer 29

Stay at baseline until after ovulation - Increase to peak about 30 days after ovulation - Non-pregnant decreases after this (pregnant queen stays at this level) - Falls to baseline after parturition

Question 30

Describe the levels of PRL in the Queen during pregnancy

Answer 30

Elevated for the last 20 days of pregnancy and throughout lactation (no changes during pseudopregnancy)

Question 31

What are the normal interoestrus and luteal periods of A) Unmated queens B) Mated queens that fail to conceive C) Pregnant queen

Answer 31

A) 21 days (no luteal)

B) 50 days (~45 luteal)

C) luteal phase of ~65 days

Question 32

What can be used to control the oestrus in the Queen?

Answer 32

Spaying (ovariohysterectomy) - Hormone control - hCG - Androgens - Progesterone