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URO 2 > 3. approach to manipulating reproduction ws > Flashcards

3. approach to manipulating reproduction ws Flashcards

1
Q

where does GnRH come from

A

hypothalamus

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2
Q

how is GnRH produced/controlled

A
  • Pulsatile secretion controlled by tonic centre
  • Suppressed by progesterone
  • Low oestradiol suppresses GnRH release, while high oestradiol
  • stimulates a GnRH surge
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3
Q

what is the taget tissue of GnRH in the female

A

anterior pituitary gland

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4
Q

what is the source of FSH

A

anterior pituitary

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5
Q

how is FSH produced/contolled

A
  • GnRH (stimulatory)
  • Inhibin / oestradiol (inhibitory)
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6
Q

what is the target tissue of FSH in the female

A

follicle (granulosa cells)

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7
Q

where does LH come from

A

anterior pit

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8
Q

how is LH produced/controlled

A
  • GnRH (stimulatory)
  • pulsatile release
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9
Q

what is the target tissue of LH in the female

A
  • follicle (theca cells and granulosa in the dominant follicle)
  • small luteal cells
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10
Q

where does oestradiol come from

A

antral follicles

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11
Q

how is oestradiol produced/controlled

A
  • Co-ordinated action of LH on theca to produce androgens and FSH on granulosa to produce oestradiol via aromatase
  • As follicle grows E2 increases
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12
Q

what are the target tissue of oestradiol in the female

A
  • uterus
  • hypothalamus
  • anteriro pit gland
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13
Q

why might we want to manipulate reproduction and/or use reproductive hormones?

A
  • synchronise the herd
  • helps for ART and to time so all give birth at similar times
  • induce parturition
  • abortion
  • stimulate ovulation
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14
Q

where does progesterone come from

A

CL

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15
Q

how is progesterone produced/controlled

A

LH acting on luteal cells stimulates progesterone production

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16
Q

what is the target tissue of progesterone in the female

A
  • uterus
  • hypothalamus
  • mammary gland
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17
Q

where does oxytocin come from

A
  • CL
  • posterior pit
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18
Q

how is oxytocin produced/controlled

A

pulsatile secretion of pgf2a

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19
Q

what is the target tissue of oxytocin in the female

A
  • uterus
  • mammary gland
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20
Q

where does pgf2a come from

A

epithelial cells in endometrium

21
Q

how is pgf2a produced/controlled

A

oxytocin acting on endometrial oxytocin receptors stimulates pgf2a

22
Q

what is the target tissue of pgf2a in the female

A

CL

23
Q

in which stage of the cycle is this cow. day 30 post mating, no uterine enlargement, no fetal fluids

A

may be pregnant but probably not, should be able to feel a bit of uterine enlargment (def by day 42), should see fetal fluids by day 28

phase: luteal –> has CL
day 9 of cycle (30-21) ish

24
Q

what phase of the cycle is this cow in? she is presented as oestrus has not been observed 60 days after calving. uterus has involuted and no sigsn of endometritis

A
  • we expect her to have come into oestrus. should have started cycling around 25 days post calving
  • left ovary: small, lots of small follicles
  • right ovary: large follicle (maybe too large)

= follicular stage. NO CL
she should be around oestrus now - why not. what can we do to get her back into calf

25
Q

what are the primary actions of GnRH in the female

A

stimulates FSH and LH release

26
Q

what are the primary actions of FSH in the female

A
  • stimulate E2
  • stimulates recruitment of small antral follicles
27
Q

what are the primary actions of LH in the female

A
  • stimulates dominance and growth of large follicles
  • stimulates E2 and ovulation
  • luteal P4 production
28
Q

what are some potential pharmacological effects if in follicular phase there is a dominant follicle and no active CL and GnRH is given

A
  • LH surge
  • ovulation

wont induce oestrus per say, she might happen to be in oestrus but its primary action is inducing oestrus

29
Q

what are some potential pharmacological effects if in follicular phase there is a dominant follicle and no active CL and FSH is given

A
  • stimulate to grow and produce oestradiol
  • but not going to have any dramatic effect
  • can trigger superovulation but not in this case because we have a dominant follicle (needs to have been given in the luteal phase repeatedly when follicle wave is growing)
30
Q

what are some potential pharmacological effects if in follicular phase there is a dominant follicle and no active CL and LH is given

A

Ovulation of DF;
Luteinisation of follicular cells
At low doses increase E2.
At high doses switch E2 production off

31
Q

what are the potential pharmacological effects if an animal is in the luteal phase (dominant CL and follicles at different stages that can include DF) and GnRH is given

A
  • cause LH surge
  • stimulate more progesterone production from CL
  • ovulate dominant follicle (even though progesterone is supressing ovulation. prog inhibits ovulation through negative feedback on GnRH but we have bypassed and given LH)
  • makes accessory CL
32
Q

what are the potential pharmacological effects if an animal is in the luteal phase (dominant CL and follicles at different stages that can include DF) and FSH is given

A

depends on where we are in stage of luteal
- can increase dominant follicles if given at end of one wave and beginning of another (must be given when we have a growing follicle, NOT when we alreayd have a dominant follicle

33
Q

what are the potential pharmacological effects if an animal is in the luteal phase (dominant CL and follicles at different stages that can include DF) and LH is given

A
  • stimulate more progesterone production from CL
  • ovulate dominant follicle (even though progesterone is supressing ovulation. prog inhibits ovulation through negative feedback on GnRH but we have bypassed and given LH)
  • makes accessory CL
34
Q

what is the primary action of oestradiol in the female

A
  • Oestrus behaviour
  • GnRH release (inhibitory at low concentrations; stimulatory at high)
35
Q

what is the primary action of progesterone in the female

A
  • Uterus: histotroph
  • suppressoestrus
  • Suppress GnRH/ovulation
36
Q

what is the primary action of oxytocin in the female

A
  • pgf2a production if OXTR are present
37
Q

what is the primary action og pgf2a in the female

A

regression of the CL

38
Q

is oestradiol is administered in the follicular phase what happens

A
  • oestrus behaviour
  • GnRH/LH surge
  • ovulation
39
Q

if progesterone is administered in the follicular phase what happens

A
  • would enter luteal phase
  • inhibit ovulation
  • inhibit oestrus
40
Q

is oxytocin is administered in the follicular phase what happens

A

no effect
- might stimulate uterine contraction, might help luteolysis along

41
Q

is pgf2a is administered in the follicular phase what happens

A

no effect
- will increase regression of CL of already regressing CL

42
Q

is oestradiol is administered in the luteal phase what happens

A
  • could induce LH surge
  • but doesnt really do anything. if high does given will induce luteolysis
43
Q

is progesterone is administered in the luteal phase what happens

A

suppression of gonadotrophin and hence follicular maturation
might attenuate luteolysis

44
Q

is oxytocin is administered in the luteal phase what happens

A
  • no effect really.
  • stimulates pgf2a release IF receptors are there (day 15,16,17 of cycle)
  • might help along luteolysis. but will only shorten cycle by about a day. not used to manipulate cyclicity
45
Q

is pgf2a is administered in the luteal phase what happens

A
  • cause regression of CL
  • progesterone declines
  • enters follicular phase/prooestrus
  • come into oestrus within 3-4 days
  • doesnt have much effect though on growing or regressing CL
46
Q

in ruminants and pigs, luteolysis requires hormonal communication between which structures

A

CL and uterine endometrium

47
Q

how is luteolysis initiated

A
48
Q

how can you induce breeding opportunity in the below scenario

A

she is in luteal phase
want to induce luteolysis with pgf2a
- AI her as soon as you notice standing oestrus (3-4 days after admin but maybe 4-5 days as says right ovary only has small follicles. need to give time to grow)
- could then inject GnRH 2-3 days later to ensure ovulation happens
- AI her at 2-3 days whether she is displaying signs of oestrus or not

49
Q

how can you induce breeding opportunity in the below scenario

A
  • she is in follicular phase as DF present
  • might be in or about to be in oestrus (increased uterine tone)
  • so AI her as will be coming into oestrus tomorrow or day after
  • give GnRH/LH to cause LH surge and thus ovulation

URO 2 (107 decks)

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