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Reproduction > Repro Endocrinology SA > Flashcards

Repro Endocrinology SA Flashcards

1
Q

What are the stages of oestrus cycle based on vaginal cytology?

A
  • proestrus (oestrogen dominant)
  • oestrus (oestrogen dominant)
  • OVULATION*
  • metoestrus (transitional)
  • dioestrus (progesterone dominant)
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2
Q

How are the bitch and queen defined reproductively?

A

> bitch
- mono-oestrus, non-seasonal, polytocus, spontaneous ovulatory
queen
- seasonally polyoestrus, polytocous, induced ovulator
- only shows follicular cycles not luteal (as CL required for luteal)

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3
Q

When does the bitch ovulate? What stimulates the initiation of oestrus?

A
  • spontaneously ovulates at end of variable follicular phase (4-28d)
  • no one knows what stimulates bitch to return to oestrus after long anoestrus
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4
Q

What is LH and FSH production dependant upon and what do these act to produce?

A

> dependant on
- GnRH (hypothalamus)
- steroids from ovaries (E2 +-, P4 always -)
LH and FSH act to synthesise OESTRADIOL

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5
Q

How long are the proestrus, estrus, pregnancy/diestrus and anestrus stages in the bitch?

A
  • Proestrus 9d
  • Estrus 9d (long cf. other animals)
  • ovulation->CL*
  • Pregnancy/Diestrus 60d (equivalent length of time so no need for maternal recognition of pregnancy really)
  • CL regresses*
  • Anestrus >90d
  • spontaneous return to proestrus - unknown reason!*
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6
Q

How does LH change throughout the follicular phase?

A 
> mid/late anoestrus
- low LH levels and pulsatility
-  1 week before proestrus
- freq LH pulses ^ -> every 60-90mins, levels also ^
> proestrus
- LH levels  v, pulses v
> late proestrus
- LH reach peak 8-15ng/ml -> oestrus -> ovulation
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7
Q

How does FSH chance throughout the follicular phase?

A 
>mid/late anoestrus 
- high FSH levels
-increase throughout anestrus 
> 1 weeks before proestrus
- modest increases, not as much as LH
> proestrus
- FHS low 
> late proestrus
- peak occours ONE DAY AFTER LH
- modest increase in mean level
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8
Q

Why is the discrepancy between LH and FSH peak times odd?

A

Both driven by GnRH

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9
Q

Which hormone is always present in higher concentration, LH or FSH?

A

FSH

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10
Q

How do oestradiol levels change throughout the follicular phase?

A 
> mid/late anoetrus
- levels remain low
> one week before pro-estrus
- levels remain low
> pro-estrus
- increase 10 fold
> late pro-estrus
- peak reached 1-3d before LH surge 
> diestrus (luteal phase) 
- some secretion
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11
Q

How do progesterone levels change throughout the follicular phase?

A 
> mid/late anoestrus
- low
> 1 week before pro-estrus
- remain low
> proestrus
- increase slowly, small amount
> late proestrus
- small increase from time ofLH surge to time of ovulation
> diestrus
- peak values reached post ovulation
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12
Q

What may be a good measure of pending ovulation in the bitch?

A

progesterone (quick and accurate by ELISA, ovucheck (premate))

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13
Q

Towards the latter stages, which hormone do follicles become dependent solely upon?

A

LH

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14
Q

What else occours at the time granulosa cells acquire LH-Rs?

A

start producing progesterone

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15
Q

what behaviour effects does oestradiol have?

A
  • makes femlaes receptive to male advances
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16
Q

When does the LH surge occour wrt. oestradiol levels?

A

Immediately after peak oestradiol levels

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17
Q

What 2 things are initiated by the decrease in E:P ratio?

A
  • LH surge

- sex behaviour

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18
Q

When does ovulation occours wrt LH surge?

A

~2d after

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19
Q

How does the ovulation of the canid bitch differ to most other species?

A

Ooocytes ovulated are immature and must still undergo 1st meiotic division

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20
Q

What has been suggested as the signal for compelteion of the first meiotic division in the bitch? What is the signal in most animals?

A

Bitch: rising P4 levels during luteinisation
Others: LH surge

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21
Q

How does the difference between ovulation in the canid cf. other spp. affect anything?

A
  • normally environment of the follicle where oocyte grows and matures is important
  • in canid the oviduct environment is important as this is likely where the oocyte will mature and complete 1st meiosis
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22
Q

How does P4 exert effects on cells?

A
  • steroid so intracellular (slow changes)

- also exerts rapid changes (eg. affecting oocyte to -> 1st division) so potentially cell membrane too?

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23
Q

How does the progesterone profile of the pregnant and non prergant bitch differ?

A

IT DOESNT!

  • well it does a tiny bit, slightly higher for slightly longer in pregnant bitch
  • but not useful diagnostically
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24
Q

What is the only source of progesterone in the pregnant bithc?

A

CL

- no placental P4

25
Q

What regulates progesterone secretion during diestrus? After the LH surge?

A
  • LH
  • progesterone itself (autocrine/paracrine) affects CL lifespan negative feedback
  • after LH surge PRL becomes an essential luteotroph and regulates from ~d25
26
Q

What drugs can induce luteolysis in the bitch? What would this cause in the pregnant bitch?

A
  • GnRH continuously
  • GnRH antagonist
  • PR antagonist (eg. mifepristone)
    *inhibit luteal PGF2a secretion
  • Inhibit PGF-R (FP) * look these up - don’t understand?
    > abortion
27
Q

In which spp is PRL the principle luteotroph?

A

Rodents

28
Q

Which spp produce placental P4?

A

Sheep and humans

29
Q

Do PRL levels increase in the non-pregnant bitch?

A

Yes (but not as much as pregnant bitch)

30
Q

How are PRL and relaxin levels linked?

A

Both increase dramatically ~d25 after LH surge (and ovulation)
- PRL remains high where relaxin drops off around d60

31
Q

What receptors are expressed thorughout CL life?

A
  • PRL and LH

- PGF2a (hence can cause abortion at any time, just no endogenous luteolysins present naturally)

32
Q

What can induce luteolysis exogenously?

A
  • PGF2a
  • P4-R ant
  • GnRH ant
  • GnRH agonist continuously
  • DA ag (at high levles, as will v PRL)
33
Q

What is the only time an endogenous luteolysin is produced by the bitch?

A

feto-placental PGF2a release pre-partum to induce parturition

34
Q

Which is the ONLY pregnancy specific hormone in the bitch? Where is this produced? How can it be tested?

A

Relaxin

  • produced in the placenta only
  • enzyme immunoasssay available
35
Q

What pathogy may PRL cause?

A

Pseudopregnancy

36
Q

What does relaxin cause in males?

A

Testicle descent

37
Q

When are relaxin levels increased in the bitch?

A

~21-24d after LH surge

38
Q

How long post-parturition can relaxin be detected?

A

Levels drop at parturition but can be detected for 30d during lactation

39
Q

Where does Relaxin act?

A
  • pituitary cells -> PRL -> P4

- Luteal cells -> P4

40
Q

What are the 2 options for control of oestrus in the bitch?

A
  • OVH

- Hormonal (steroids) control

41
Q

Which hormones may be used exogenously to control oestrus in the bitch? Which are NOT useful?

A

> Progesterone not useful as poor bioavailablitly orally and short t1/2
- Synthetic progestagens effective
- 1st gen (eg. MAP) potentially induce GH secretion -> acromegaly, mammary tumour, DM
- Proligestone - strong anti-gonadotrophic, weak progestagen, antioestrogenic (controls vulval swelling and bleeding)
Testosterone
- active by mouth
- BUT affects subsequent frertility
- causes vulval and clitoral enlargement

42
Q

When will a pseduo pregnancy be seen?

A

~45d (6weeks) after end of estrus

43
Q

What hormonal changes are asscoated with psedopregnancy?

A
  • Progesterone NORMAL

- Associated with rise in PRL

44
Q

What potentiates the development of a pseudopregnancy?

A

Any event causing rapid fall in progesterone

  • OVH
  • lysis of CL
  • termination of pregnancy
45
Q

How can pseudopregnancy be ended?

A
  • usually regresses spontaneously
    Tx
  • synthetic progestagens suppress PRL release
  • oestrogens and androgens combo (probable act = P4)
  • DA-ags (eg. bromocriptine) - but some old ones can induce vomiting
46
Q

How do oestradiol levels change during the follicular phase of the queen?

A
  • relatively high but variable
47
Q

What regulates LH release in the queen?

A

Copulation -> massive LH release from pituitary

usually multiple copulations needed to produce sufficient LH for ovulation

48
Q

When do progesterone levels rise in the queen? When do they fall?

A
  • stay at baseline until ovulation after the mating-induced LH surge
  • peak after 30 days
  • in NON-preg animal, levels decrease from this point
  • in PREG, maintained for 25-28 d
  • if ovulation occours, even if mating is not succesful (pseudopregnancy) the queen will not return to estrus until after the levles of progesterone have fallen to baseline
49
Q

When are PRL levels elevated in the queen?

A

Last 20d of pregnancy and throughout lactation

NOT in pseudopregnancy

50
Q

What is the normal interoestrus interval of the queen? Mated queen? Pregnant queen?

A

Unmated or unovulatory: 21d (no luteal phase)
Mated, ovulate, NOT pregnant: 50d (luteal phase ~45d)
Mated, pregnant: ~65d

51
Q

What is the interestrus interval determined by?

A

When P4 levels fall

52
Q

When may pseudopregnancy occour in the queen?

A
  • any non-pregnant luteal phase

- after sterile mating or spontaneously

53
Q

What are the clinical signs of pseudopregnancy in the queen?

A
  • lack of estrus

- NO physical signs (mammary development, lactation, behavioural change)

54
Q

What causes the CL to persist beyond the usual 45d in a pregnant queen?

A

PRL (extra 20d)

55
Q

How may oestrus be controlled in the queen?

A

> OVH
Hormones
- hCG: induces ovulation, delays subsequent oestrus as cat enters pseudopregnant state
- androgens: anabolic steroids daily 30d pre suspected estrus ,but induces masculinisation
- progesterone: ORALLY administered only. High doses, short time
- prevention (given as soon as calling begins) prevents conception and calling
- posteponement (given in anoestrus) may be temporary or permenant if repeated

56
Q

Which endocrinology is better understood - the tom or the dog?

A

Dog

57
Q

What is the action of LH in the male?

A

Stimulates Leydig cells to produce testosterone

58
Q

What is the biological activity of relaxin?

A
  • produced by placenta

- activity unknown but useful Dx of pregnancy

Reproduction (30 decks)

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