Pub

Question 1

What is adrenarche?

Answer 1

A
→first endocrine process of pberty
→Growth of pubic hair, axillary hair
adrenal androgens

Question 2

What is gonadarche?

Answer 2

A
→LH- secondary sex characteristics
→FSH- growth of testes or folliculogenesis

Question 3

When does adrenarche occur?

Answer 3

→6-8 years

Question 4

What hormones are active during adrenarche?

Answer 4

A
→DHEA
→DHEAS

Question 5

What hormones are not affected by adrenarche?

Answer 5

→adrenal hormones
→adrenarche is not a global activation of HPA axis

Question 6

Where are androgens secreted from?

Answer 6

→zona reticularis

Question 7

What causes DHEA/DHEAS secretion?

Answer 7

→inherent maturation of cellular compartments of adrenal cortex

Question 8

At what age does DHEA/DHEAS peak?

Answer 8

20s

Question 9

At what age does DHEA/S secretion stop in infants?

Answer 9

2 years

Question 10

What causes the inactivation of DHEA/S secretion?

Answer 10

foetal zone in adrenal gland shrinks

Question 11

At what age does the zona reticularis becomes fully develop and activate DHEA/S?

Answer 11

inherent maturation of cellular compartments of adrenal cortex6 years

Question 12

What is the precurssor of DHEA/S?

Answer 12

cholesterol

Question 13

What enzyme converts cholesterol to pregnenolone?

Answer 13

CYP11A

increases during adrenarche

Question 14

What happens to mineralocorticoids and glucocorticoids during adrenarche?

Answer 14

mineralocorticoids pathway shuts down to allow for increased production of DHEAS

Question 15

Give examples of mineralocorticoids

Answer 15

Cortisol
Aldosterone

Question 16

What are the functions of DHEA/S?

Answer 16

drives the maturation of hair follicles required for the growth of pubic and auxiliary hair

Question 17

What happens to ACTH is adrenarche?

Answer 17

no change in ACTH levels

Question 18

What were the proposed molecules for instigating adrenarche?

Answer 18

1. POMC
2. ACTH
3. POMC related peptides
4. prolactin, IGF-1, and insulin

Question 19

What is gonadarche?

Answer 19

(Re-)Activation of HPG axis.

Question 20

When does adrenarche occur?

Answer 20

Several years after adrenarche (typically ~11 yrs of age)

Question 21

Which gestational week does activation of HPG occur?

Answer 21

16th

Question 22

When does GnRH switch off in the womb?

Answer 22

just before birth

Question 23

At which scan can the gender of the baby be known?

Answer 23

20th week

Question 24

At what of the day does GnRH rise puberty?

Answer 24

nocturnal

Question 25

What controls the onset of puberty?

Answer 25

Dialogue between our individual genetics and environmental factors

Question 26

What are theories put forward to explain onset of puberty?

Answer 26

→Inherent maturation of CNS
→Body fat/nutrition – Leptin and Ghrelin?
→Hypothalamic hormones - Kisspeptin, other factors?
→Latest theories - Epigenetics?

Question 27

What is the correlation between energy homeostasis and reproduction?

Answer 27

→positive

Question 28

Describe the link between nutrition/ body fat and puberty

Answer 28

→Extremes of energy excess (body fat mass) impact the timing of puberty in both sexes - particularly females

→Under- and over-nutrition in foetal and/or neonates alters the timing of puberty in rodents and humans

Question 29

What can morbid obesity lead to?

Answer 29

→precocious puberty

Question 30

What is the link between obesity and leptin and fertility?

Answer 30

→infertile
→leptin deficient

Question 31

Where is leptin expressed?

Answer 31

→adipose tissue

Question 32

What are the functions of leptin?

Answer 32

→Sensor of energy sufficiency

→Satiety factor - tells brain you’re full

→Stimulates energy expenditure

Question 33

What is the effect of leptin on reproductive system?

Answer 33

high levels of leptin lead to delayed/absent puberty

Question 34

Why does leptin have a permissive role on puberty and not the driver?

Answer 34

Obesity increases leptin and earlier puberty occurs

leptin administration can not stimulate early puberty

No leptin receptors on GnRH neurons

Threshold of leptin required to be reached for puberty but not a driver of puberty itself.

Question 35

What are the functions of Ghrelin?

Answer 35

senses the fasted state, to stimulate feeding and fat deposition

Question 36

What does a bolus of ghrelin stimulate?

Answer 36

stimulates the GH/IGF axis Via GHSR (growth hormone secretagogue receptor)

Question 37

What happens to ghrelin as puberty proceeds

Answer 37

decreases as puberty proceeds

Question 38

What does low levels of leptin and high levels of ghrelin result in?

Answer 38

decreased LH

Question 39

What can we learn from kisspeptin an GnRH neurons?

Answer 39

¾ of the GnRH neurons co-express Kiss1R mRNA

Question 40

What are the hypothalamic sites of importance in reproduction?

Answer 40

AVPV- anteroventral periventricular nucleus

Arcuate nucleus

Question 41

What do we know about kisspeptin and GPR54 during puberty?

Answer 41

→not much change in receptors
→mainly kisspeptin regulation increases

Question 42

What is the effect of continuous kisspeptin infusion of LH in juvinile mokeys?

Answer 42

→Gradual response and then complete shut down

Question 43

What are the effects of starvation on expression of kisspeptin in the hypothalamus?

Answer 43

less Kisspeptin in puberty but not that much change in adults

Question 44

What are the links between kisspeptin-GnRH system and metabolic cues?

Answer 44

→Reduced leptin in starvation, decreased GnRH secretion
→Leptin directly excites Kiss1 neurones in ARC
→Leptin deficiency »↓Kiss 1 mRNA in ARC
→But only 10-40% of Kiss1 neurones express LepR