Reproductive Endocrinology Flashcards
What are the dominant hormones during the a) Follicular phase - b) Luteal phase?
a) Oestrogen b) Progesterone
What are the names of phases of a female reproductive cycle based of vaginal cytology? What hormones are dominant?
Pro-oestrus (oestrogen) - Oestrus (oestrogen) - Metoestrus (transition) - Dioestrus (progesterone)
What is special about the Queen’s cycle?
She is an induced ovulator - only goes into the follicular phase after mating
Which animals are polyoestrous?
Cow - Queen - Sow - Rodents
Which animals are seasonal polyoestrus short-day?
Ewe - Nanny - Doe - Elk
Which animals are seasonal polyoestrus long-day?
Mare
Which animals are mono-oestrus?
Bitch - Wolf - Fox - Bear
Describe the events of a bitch’s endocrine events
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)
What hormone is essential in Bitches for CL maintainance?
Prolactin
Describe LH levels in a Bitch during the follicular phase
Late anestrus = Low levles
1 week before proestrus = increased frequency and amount
Proestrus = lower levels
Late proestrus = reach peak levels of 8-15ng/ml
Describe FSH levels in a Bitch during the follicular phase
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
Describe the levels of Oestradiol in the Bitch during the follicular phase
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
Describe the levels of Progesterone in the Bitch during the follicular phase
Anestrus = low levels
Proestrus = slow increase up to time of ovulation
Diestrus = peak values reached AFTER ovulation
What does FSH effect in the granulosa cell to generate oestradiol?
Aromatase
What does LH do in the Theca cell and the Granulosa cell? What is the final product in each?
Change of cholesterol into pregnenolone (then into progesterone)
Theca = oestradiol - Granulosa = progesterone
What is initiated by the decrease of the oestradiol : progesterone ratio?
LH surge - Oestrus sex behaviour
What is odd about oocytes just after ovulation? When is this thought to change?
They are immature, not completed their first meiotic division - rise in progesterone?
Describe the levels of progesterone during the luteal phase (diestrus) in a Bitch. What happens to it at luteolysis?
Increases and plateaus - Rapid decrease
Why would measurement for progesterone levels in a Bitch not determine pregnancy or not?
The luteal phase is the same length as gestation so progesterone would remain high in both cases
What begins to regulate progesterone (luteotrophin) levels in the Bitch from day 25?
Prolactin
What can be used to induce luteolysis exogenously in the Bitch?
PGF2alpha - Progesterone receptor agonist - GnRH antagonist - continuous GnRH agonist - Dopamine agonist (blocking PRL release)
What hormone is used as a diagnostic test for pregnancy in Bitches? How?
Relaxin - it is NON-detectable in non-pregnant animals - sourced from the placenta it rises with PRL rise
What can be used to control oestrus in the dog?
Spaying (ovariohysterectomy) - Hormonal control (androgens) - Progesterone - Synthetic progesterones - Testosterone
What are the advantages and disadvantages of using A) Progesterone B) Synthetic progesterones C) Testosterone as hormal control in the Bitch?
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
