L20: Puberty and Menopause Flashcards

You may prefer our related Brainscape-certified flashcards:
1
Q

What is Kallman’s syndrome? What does it appear like?

A
  • GnRH deficiency goes together with anosmia (loss of smell):
    i) Because GnRH neurons start off at the back of the nose (not in the hypothalamus) and migrate through to the hypothalamus, if they don’t develop men and women can’t smell properly alongside Kallmann’s syndrome
  • Kallmann’s syndrome more often in males than females
  • Kallmann’s results in sexual imaturity
  • Also gets unicoid structure (long arms and legs)
    i) Without GnRH didn’t go through puberty, so bones didn’t stop growing
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the stages of sexual maturation?

A
  1. Adrenarche (activation of adrenal gland) – around age of 8
  2. Puberty
    i) HPG axis activation
    ii) Females: menarche (first menstrual cycle) – definitive (can record)
    iii) Males: 1st ejaculation (imprecise)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is adrenarche?

A

awakening of adrenal gland

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is menarche?

A

first menstrual period in female adolescent

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

When does adrenarche take place?

A

adrenal cortex activated ~8 yo

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

How does adrenarche happen?

A
  • Increased secretion of steroids from zona reticularis (DHEA, androstenedione, testosterone)
  • ?role – pubic/axillary hair – people with impaired gonadal function will still show some hair
  • **not associated with timing of puberty
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What are the differences in gonadotrophin secretion in pre-puberty, early puberty, mid-late puberty, adult (post puberty)?

A

Testosterone
- Birth: high in boys, then declines (very high for first few months, then completely switched off)
- Early puberty: secretion increases at night in boys
- Mid-late puberty: increased during day as well

Oestradiol
- Birth: very high, then declines (very high for first few months, then completely switched off)
- Puberty: secretion increases

AMH
- Neonate: high and rises steadily through childhood
- Puberty: ‘wobble’

Measured by LH levels
- pre-puberty: more or less steady and low
- early puberty: initially switched on as night pulses
- mid-late puebrty: even higher pulses, during the day as well
- adult: less pulsatility, levels more steady

check slide 8

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the general pattern of gonadotrophin secretion in early teens and mid-late puberty?

A

Gonadotrophin secretion
- In early teens: nocturnal switching on, all driven from the brain, not sure why, but culminates in increased LH/FSH secretion
- Mid-late puberty: nocturnal progresses until its continuous throughout the whole day

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is hypothalamic maturation theory? How was it proven?

A

Hypothalamic maturation theory
- In castrated female monkeys: one does not get the high gonadotrophins, that one would get in adulthood, they do not respond, GnRH is not there to switch them on

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is menarche? what is its pattern throughout female’s life?

A

Menarche
- over first couple of years system is dysregulated, it is normal to have anovulatory cycles for the first couple of years after puberty
- afterwards they become regular
- towards the menopause it’s dysregulated again

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is the role of kisspeptin? What is the evidence? How is kisspeptin related to puberty?

A
  • stimulates GnRH neurons, increases reproductive function
  • transgenic mice with deleted kisspeptin receptor (GPR54) fail to progress through puberty
  • peripheral administration of kisspeptin to prepubertal rats stimulates LH secretion and induces ovulation
  • increase in KiSS-1 mRNA and/or GPR54 mRNA expression during puberty
  • the electrophysiological response of GnRH neurons to kisspeptin increases at puberty
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What happens to LH levels when kisspeptin experimentally is added?

A
  • more pulsatility
  • higher levels of LH
  • Kisspeptin generates pulses of GnRH that then drive secretion of LH
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

How is age of puberty and body weight related?

A

there are two critical ranges:
- critical weight range for initiation of adolescent spurt
- critical weight range for menarche

  • Weight range to hit puberty: humans- 47kg for girls, 55kg for boys, a critical range to hit puberty, can also observe this in hypothalamic amenorrhea, were women lose weight, and reproductive system switches off –> thought to be largely related to leptin
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is the role of leptin? How is it important in puberty? what is the evidence?

A
  • secreted by fat cells
  • regulates appetite and energy expenditure
  • metabolic signal - control of HPG axis
  • mice: homozygous mutants (-/-) are infertile, reversed by leptin treatment
  • humans: leptin receptor signalling failure = obese and infertile (no GnRH secretion)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

How is leptin hypothesized to be related to kisspeptin?

A
  • Leptin has positive feedback on KiSS neurons
  • Fasting decreases kiss1 mRNA? Lack of leptin?
  • Where people have leptin receptor activation mutations –> get early puberty
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what is menopause? What are the symptoms? what is it defined as?

A
  • Exhaustion of ovarian reserve
  • Decreased oestrogen levels
  • Permanent cessation of menses following loss of ovarian activity
  • Usually defined as >12 months of amenorrhoea (with high FSH level – key diagnostic)
  • Menopause does not mean you have zero eggs, it means you do not have enough to maintain that supply that then will be driven by gonadotrophins to produce ovulation and therefore menstruation
17
Q

What happens to menstrual regularity across life?

A
  • normal ovulatory cycles rise till 30 years, and start declining at around 40 years
  • anovulatory cycles decline till 30 years
  • incomplete cycles rise till 18, then decline and start rising again at age of 35
  • There’s a decrease in reproductive success as women get older, quality of eggs gets lower
  • Cycles get irregular towards menopause
  • However if you use donated egg, reproductive success does not fall

see slide 30 for summary

18
Q

What are the hormones needed for growing follicles?

A
  • AMH at peak at preantral stage, then declines completely till antral
  • Inhibin B and oestradiol starts being produced from preantral and is at its peak at preovulatory stage

check slide 33 for diagramm

19
Q

What are the perimenopausal changes in hormones?

A
  • oestradiol falls
  • FSH increases
  • inhibin B decreases
    • Serum AMH levels are highly correlated with AFC, AMH falls down as women get older
20
Q

What is the study done to prove AMH and prediction of menopause?

A
  • Study by Broer et al, 2011, found out that there is a slight trend that women with lower AMH levels, tend to go through menopause earlier, than women with higher levels of AMH
21
Q

What is the SWAN study regarding AMH?

A
  • Followed women AMH levels right up to the menopause
  • But they were already 47.5 years when they started
  • What they showed, even if you are in your later fourties, having a low AMH level wasn’t a good predictor of whether you are going to stop the periods and go through menopause in the next 12 months
22
Q

What are the clinical symptoms of menopause?

A
  • menstrual cycle changes (irregular)
  • hot flushes
  • night sweats
23
Q

What are the consequences of menopause?

A
  • amenorrhoea
  • osteoporosis
  • cardio/cerbrovascular disease
24
Q

What is the possible treatment of menopause?

A
  • hormone replacement therapy
25
Q

What is the novel treatment for hot flashes during menopause?

A
  • Neurokinin antagonist has a dramatic effect on hot flashes