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Reproduction > Applied reproductive endocrinology in SA > Flashcards

Applied reproductive endocrinology in SA Flashcards

1
Q

What does inhibin do?

A

inhibits FSH not LH

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2
Q

How can the oestrous cycle be classified? 2

A

Ovarian secretions - Follicular/luteal

Vaginal cytology - pro-oestrous (E2), oestrous (E2), metoestrous (transitional), dioestrous (P4)

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3
Q

How are the bitch and queen’s cycles classified?

A

BITCH: mono-oestrous, non-seasonal, polytocous, spontaneuous ovulator

QUEEN: seasonally polyoestrous, polytocous, induced ovulator (in N. hemisphere, only non-cycling for one month)

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4
Q

How long is the follicular phase in bitches?

A

variable, 4-28 days

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5
Q

How long is the luteal phase in bitches?

A

60 days

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6
Q 
How long are the phases in bitch cycles?
Proestrous
Estrous
Pregnancy/diestrous
Anoestrous
A

Proestrous - 9 days
Oestrous - 9 days (unusually long for domestics)
Pregnancy/dioestrous - 60 days (CL lasts this time if pregnant or not- problem PDing)
Anoestrous - >90 days (unknown why this happens at all)

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7
Q

Outline bitch LH levels:

Mid/late anoestrous
1 week before proestrous
Proestrous
Late proestrous

A

Mid/late anoestrous: low LH levels/pulsatility, <1ng/ml, occasional LH pulses (2-25 ng/ml) 4-24 hours apart

1 week before proestrous: frequency increases, pulses every 60-90 mins, levels increase to about 3 ng/ml

Proestrous: LH levels become lower and pulses less detectable

Late proestrous: LH reach peak levels, 8-15 ng/ml

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8
Q

Outline bitch FSH levels:

Mid/late anoestrous
1 week before proestrous
Proestrous
Late proestrous

A

Mid/late anoestrous: FSH levels high (near preovulatory), levels increase throughout

1 week before proestrous: modest increase (less pronounced than FSH)

Proestrous: FSH low

Late proestrous: peak occurs about 1 day after LH surge, modest increase in mean level

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9
Q

Outline bitch oestrogen levels:

Mid/late anoestrous
1 week before proestrous
Proestrous
Late proestrous

A

Mid/late anoestrous: remains low

1 week before proestrous: remain low

Proestrous: levels increase throughout from 10pg/ml to 120 pg/ml

Late proestrous: some secretion of oestradiol

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10
Q

True/False: measurement of P4 may be a good measure of impending ovulation.

A

True

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11
Q

Outline bitch progesterone levels:

Mid/late anoestrous
1 week before proestrous
Proestrous
Late proestrous
Dioestrous
A

Mid/late anoestrous: low levels (<0.5ng/ml)

1 week before proestrous: low levels remain

Proestrous: levels increase slowly (0.2 to 0.8 ng/ml)

Late proestrous: 2-4ng/ml at time of LH surge, 4-10ng/ml at time of ovulation

Dioestrous: peak values of 15-90 ng/ml are reached POST-ovulation

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12
Q

What acts on the granulosa cell? What does it produce?

A

FSH and act on it

Produces progesterone and oestradiol (both to blood)

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13
Q

What acts on the theca cell? What does it produce?

A 
LH acts on it
Produces oestradiol  (to blood)
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14
Q

When is oestrous sex behaviour shown? (BITCHES)

A

immediately after peak in oestradiol (suggested to be initiated by decrease in E:P ratio)

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15
Q

When does ovulation occur in relation to LH surge? (BITCHES)

A

2 days after.

Oocytes that are ovulated are immature (i.e. not completed 1st meiotic division). The rising levels of P4 (during luteinisation) could be the signal for completion of first meiotic division.

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16
Q

What happens to P4 in the luteal phase/dioestrous? (BITCHES)

A

P4 increases and plateaus during dioestrous and declines rapidly at luteolysis. This profile occurs in BOTH non-pregnant and pregnant animals

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17
Q

What is the source of P4 in bitches?

A

CL only (NOT placenta)

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18
Q

How are GnRH and luteolysis linked?

A

GnRH agonist (continuous) –> luteolysis

GnRH antagonist –> luteolysis

19
Q

What does P4 do in luteal phase/dioestrous? (BITCHES)

A

regulates CL’s ability to secrete P4 (unusual!).

P4 antagonist (mifeprestone) causes luteolysis
inhibits luteal PGF2a secretion
inhibits PGF-R

20
Q

What does PRL do in luteal phase/dioestrous? (BITCHES)

A

regulates P4 secretion from about day 25 after LH surge

PRL becomes the essential luteotrophin from day 25 after LH surge

It is important to note the PRL levels increase in both pregnant (5 times baseline) and non-pregnant (2-3 times baseline) animals

21
Q

T/F: in bitches, there is no known luteolysin

A

True

22
Q

T/F: in bitches, the PRL/LH -Rs can be expressed throughout luteal phase/dioestrous.

A

True

23
Q

How can luteolysis be endogenously induced in bitches? 5

A
  • PGF2a - high doses
  • P4-R antagonist
  • GnRH anatagonist
  • GnRH agonist (continuously)
  • PRL lowering doses of DA agonist
24
Q

What causes luteolysis in pregnant bitches?

A

rapid pre-partum luteolysis due to feto-placental PGF2a release - essential for onset of parturition

25
Q

What are the clinical signs of pseudopregnancy and what are they associated with?

A

CLINICAL SIGNS: extensive mammary gland development, lactation, behavioural changes typical of pregnancy and lactation

Seem to be associated with an increase in PRL levels

26
Q

What sort of hormone is relaxin?

A

peptide, 2- chain structure, similar to insulin, family of 7 members

27
Q

When are circulating concentrations of relaxin elevated?

A

about 21-24 days after LH surge

28
Q

When is relaxin detectable in bitches?

A

non-detectable in non-pregnant animal - its sole source is the placentra, reaches about 5ng/ml in late pregnancy (days 40-50 gestation). It is the only pregnancy-specific protein identified in the dog. A relaxin enzyme immunoassay is available and has been used for PDing. Levels fall after parturition but remain detectable for at least 30 days during lactation. The increase in relaxin is coincident with the rise in PRL

29
Q

How can oestrous be controlled in bitches?

A

OVH

Hormones - P4 (theoretically possible, not possible because not active orally and short duration of action when given PN). Synthetic progestagens (first generation = MAP, problem of potentially inducing GH secretion –> increased risk of acromegaly, mammary tumours and DM), PROLIGESTONE (PRG) - synthetic progestagen, specifically designed for prevention of oestrous in bitches/queens, strongly anti-gonadotrophic, weakly progestagenic, anti-oestrogenic so effectively controls vulval swelling and bleeding.

Testosterone - active orally BUT affects subsequent fertility and causes protrusion of clitoris and enlargement of vulva.

30
Q

What are the signs of pseudoprenancy?

A

weight gain
mammary development
occasional lactation
from about day 45 after end of oestrous

behavioural signs sometimes - nest making, nursing inaminate objects, occasional false parturition

= clinical/overt pseudopregnancy

Luteal phase duration and concentrations of P4 are normal

Clinical signs associated with rise in plasma PRL and generally noted about 6 weeks after end of oestrous

31
Q

Treatment - pseudopregnancy? 3

A

synthetic progestages - suppress PRL release

Oestrogens and androgens in combination - probably act like progestagens to suppress PRL

DA agonists (bromocriptine) inhibit PRL release (can induce vomiting)

32
Q

True/false, in the queen, there is no proestrous phase and oestral behaviour occurs with few changes of external genitalia

A

True

33
Q

What happens to the LH levels of the queen at copulation?

A

copulation leads to a rapid release of LH from the pituitary - usually multiple copulations are required to produce sufficient LH to induce ovulation

34
Q

When do P4 levels change in the queen?

A

stay at baseline levels until after mating-induced LH surge. levels increase with ovulation and peak after 30 days. if not pregnant, P4 levels then decrease. In pregnant animals, P4 levels are maintained at an elevated level for a further 25-28 days. Queens that have ovulated but aren’t pregnant (pseudopregnant) do NOT return to oestrous until AFTER the levels of P4 have fallen to the baseline

35
Q

Outline PRL in the queen

A

Elevated for the last 20 days of pregnancy and throughout lactation.

No changes in PRL levels during pseudopregnancy.

Theory: PRL drives CL to survive.

36
Q

What is the interoestrous interval in Queens?

A

may be a useful guide as to whethe rovulation or conception has failed to occur.

unmated queens or mated queens that fail to ovulate have an interoesetrous interval of approximately 21 days (no luteal phase)

mated queens that ovulate but fail to conceive have an interoestrous interval of approximately 50 days (luteal phase is 50 days)

mated queens that become pregnant have a luteal phase of about 65 days

37
Q

What is the non-pregnant luteal phase described as in the bitch?

A

pseudopregnancy (after mating or spontaneous ovulation)

Clinical signs = absence of oestrous

Unlike in the bitch, mammary development, lactation and behavioural changes are NOT a feature of pseudopregnancy in the queen (i.e. not due to PRL)

38
Q

How can oestrous be controlled in the cat?

A

OVH

HORMONES: hCG, androgens, progesterone

39
Q

Outline hCG treatment in cats

A

Induces ovulation and delay subsequent calling because Queen goes through period of false pregnancy

40
Q

Outline androgen treatment in cats

A

androgenic anabolic steroids cna be used faily to postpone calling by giving daily oral doses about 30 days before anticipated oestrous - induces masculinsation

41
Q

Outline progesterone treatment in cats

A

PREVENTION - given as soon as signs of calling, suppress the call and prevention of conception should mating occur

TEMPORARY POSTPONEMENT: given during anoestrous will postpone that would follow naturally

PERMANENT POSTPONEMENT: repeat doses given during anoestrous

Only orally administered progestagens are suitable - high doses for a short time (commencing when signs of calling are seen) will result in the queen stopping exhibiting signs of sexual behaviour.

42
Q

How can you hormonally control reproduction in the dog and tom?

A

you can use androgens or anti-androgens to manipulate the system although you tend not to.

43
Q

Outline the bitch’s cycle

A

single very long cycle followed by physiological anoestrous. The dog has no luteolytic mechnaims and the length of the cycle is longer than the length of gestation. multiple ovulations.

44
Q

Outline the Queen’s cycle

A

induced ovulator, highly variabe follicular phase, mating induced luteal phase that is known as pseudo-pregnancy if the mating is infertile

Reproduction (42 decks)

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