Fuel homeostasis and reproduction function

Question 1

how would you describe the interaction between fuel homeostasis and reproductive function

Answer 1

bi-directional

Question 2

why is nutrition status relevant to reproductive function

Answer 2

reproduction requires a lot of energy

Question 3

what effect does obesity have on reproductive function

Answer 3

impairs it

Question 4

what effect does fasting have on reproductive function

Answer 4

impairs it

Question 5

how does fasting impair reproductive function

Answer 5

• regular LH pulses become disrupted

- low leptin levels means POMC isnt stimulated and NPY isnt inhibited

Question 6

what does low levels of POMC mean for reproduction

Answer 6

low POMC means GnRH and kisspeptin arent stimulated and so puberty isnt stimulated

Question 7

what does high NPY mean for reproduction

Answer 7

inhibits GnRH and kisspeptin and so puberty isnt stimulated

Question 8

how does leptin help reproductive function

Answer 8

in normal state, leptin levels are sufficient to stimulate POMC and inhibit NPY
this combination aloows GnRH and kisspeptin to stimualte puberty

Question 9

what inhibits GnRH and kisspeptin

Answer 9

High NPY and low POMC

Question 10

How is LH affected by obesity

Answer 10

pulses of LH keep their frequency by their amplitude is reduced

Question 11

how does obesity affect reproduction

Answer 11

• LH surges are smaller

- leptin resistance develops which means POMC is low and NPY is high

Question 12

main signalling mechanisms for communcating health energy status to HPG axis

Answer 12

leptin

Question 13

other signals involved in energy homeostasis

Answer 13

insulin, ghrelin, PYY

Question 14

under normal circumstances how does reproductive function effect fuel homestasis

Answer 14

very little effects, just slight changes in insulin sensitivity and energy homesostasis across the female reproductive cycle and at puberty

Question 15

when does reproductive function have an effect on fuel homeostasis

Answer 15

pregnancy - reproductive axis has a big effect on energy homeostasis

Question 16

Why does pregnancy effect energy homeostasis

Answer 16

there are many circulating hormones and signals involved in pregnancy. All women become insulin resistance during pregnancy

Question 17

when is it normal for insulin resistance to occur

Answer 17

pregnancy

Question 18

when does insulin resistance have protective effects

Answer 18

pregnancy

Question 19

how does insulin resistance occur in pregnancy

Answer 19

post receptor signalling is inhibited by progesterone and cortisol

Question 20

is inuslin binding affected in pregnancy

Answer 20

no. although progesterone and cortisol inhibit insulin binding, this is balanced by the stimulatory effects of oestrogen

Question 21

what stimulates insulin binding

Answer 21

oestrogen

Question 22

what inhibits insulin binding

Answer 22

progesterone and cortisol

Question 23

is insulin resistance consistant in pregnancy

Answer 23

no, it increases across pregnancy when hormone levels increase

Question 24

how is insulin resistance benificial

Answer 24

there is more glucose available for the foetus

Question 25

how does foetus get glucose when mother has normal insulin sensitivity

Answer 25

some glucose in maternal blood is transported across placenta via GLUT3 transporters

Question 26

transporter for glucose from maternal blood to placenta

Answer 26

GLUT3

Question 27

What must adapt to maternal insulin resistance

Answer 27

Islet cells must adapt to prevent development of gestational diabetes

Question 28

how do islets adapt to insulin resistance in pregnancy

Answer 28

- increased glucose-stimulated insulin secretion - increased beta cell mass - increased insulin synthesis - increased gap junctions between beta cells - increased cAMP synthesis

Question 29

what tells islet cells to adapt to insulin resistance in pregnancy

Answer 29

prolatin and placental lactogen

Question 30

where is prolactin released from

Answer 30

pituitary

Question 31

functions of prolaction

Answer 31

regulates immune system, growth factor, anti-apoptopic, signals to islets to adapt

Question 32

what does prolactin act on

Answer 32

PRL receptor

Question 33

where is placental lactogen from

Answer 33

placenta

Question 34

function of placental lactogen

Answer 34

stimulates development of mammary glands in late pregnancy and similar functions as prolactin

Question 35

what does placental lactogen bind to

Answer 35

PRL receptor

Question 36

what acts on the PRL receptor

Answer 36

prolactin and placental lactogen

Question 37

what happens when islets fail to adapt to insuin resistanace in pregnancy

Answer 37

gestational diabetes

Question 38

gestational diabetes is caused by

Answer 38

failure of the islet cells to adapt to insuin resistance in pregnancy

Question 39

why is gestational diabetes a problem in pregnancy

Answer 39

risks to the mother and the baby

Question 40

risks to mother from gestational diabetes

Answer 40

- high BP - pre eclampsia - UTI - c-section

Question 41

risks to baby from gestational diabetes

Answer 41

- macrosoia = big baby - risk of birth injury - hypoglycaemia - respiratory problems

Question 42

why doe some beta cells fail to adapt to insulin resistance

Answer 42

Not becuse of low levels of prolactin or placental lactogen becuase studies show levels are the same, although may be more resistance

Question 43

risk factors for developing gestational diabetes

Answer 43

same as those of T2DM - race - high BMI - age - family history

Question 44

why does fuel homeostasis matter during pregnancy

Answer 44

to supply foetus with eneryg for growth whilst keeping mother healthy

Question 45

what other syndroms are strongly linked to insulin resistance and hyperinsulinemi in pregnancy

Answer 45

PCOS and hyperandrogenemia

Question 46

insulin and LH

Answer 46

high insulin works with LH to stimulate theca cells to produce more androgens this exacerbates the problem of antral cells already producing excess androgens in PCOS

Question 47

insulin and FSH

Answer 47

high insulin impairs action of FSH on granulosa leading to follicular arrest

Question 48

how does excess androgens effect insulin

Answer 48

normally, androgens and oestrogen balance eachother to allow for normal insulin binding. Excess androgens inhibit inuslin binding and so resistance occurs both in inulsin binding and in post-receptor signalling

Question 49

cycle of high androgens on insulin

Answer 49

high androgens = increased insuline resistance in muscle and adipose = increased plasma insulin

Question 50

how is PCOS a viscous bi-directional cycle

Answer 50

PCOS is characterised by postive loop between androgens and insulin. unsure which is the inial cause, but may be mutlple factors

Question 51

what does hyperinsulinemia cause in terms of PCOS

Answer 51

- increased androgen release from theca cells - impaired follicle development - possible increased GnRH pulses = hyperandrogenaemia

Question 52

what does hyperandrogenaemia cause in terms of PCOS

Answer 52

- increased insulin resistance in muscle and adipose | = hyperinsulinemia