Canal

Question 1

What part of the brain develops slower during puberty and what is its function

Answer 1

the prefrontal cortex, rational thinking

Question 2

What sex steroids are active in the HPG axis

Answer 2

hypothalamus - GnRH
Pituitary - LH
gonads - FSH

Question 3

Steps in menstruation

Answer 3

• FSH stimulates egg maturation and oestrogen release
• Oestrogen stops FSH production and stimulates LH release
• LH causes mature egg release
• Progesterone maintains uterus lining

Question 4

What is the result of the menopause

Answer 4

• increased risk of CV disease
• loss of bone mass, higher risk of fractures

Question 5

history of kisspeptin

Answer 5

‘96 - Kiss1 gene discovered
‘99 - GPR 54 gene identified
‘01 - Kisspeptin protein is a high-affinity ligand for GPR54 (kiss1R)
‘03 - mutations in KISS1R means defecit in reproductive function

Question 6

What is function of kisspeptin

Answer 6

Kisspeptin signalling, via Kiss1R, essential for proper pubertal development and reproductive function

Question 7

what does a GPR54 mutation lead to

Answer 7

sexual immaturity, failure or gonadal function and hypogonadotropism

Question 8

Difference between preoptic and arcuate ksispeptin

Answer 8

• low levels of kisspeptin in preoptic, high in arcuate because effect of oestrogen is lost
• Arcuate has neurokynin B and dynorphin, Preoptic has galanine and tyrosine
• Arcuate receives from metabolic, Preoptic from gonads
• preoptic +, arcuate -

Question 9

What happens to GnRH inputs during perinatal

Answer 9

receive inputs from:
- developing neural GABA-glutatmate innervations and glia
- Arcuate kiss neurons

Question 10

Postnatal GnRH neural network

Answer 10

• sexual differences in AVPV kiss1 neurons, more in females
• differences happen in development and then stay this way

Question 11

organisational hypothesis

Answer 11

• increase in testosterone results in masculinisation of kiss1 expression, leads to deletion of kiss/AVPV neurons
• Decrease in oestrogen necessary for feminisation of Kiss1 neurons in AVPV

Question 12

what could explain slump in GnRH expression in juveniles

Answer 12

suppression of stimulatory ARC kiss neuronal input

Question 13

What triggers puberty

Answer 13

• before puberty, kisspeptin decreases, less GnRH, less sex steroids
• just before, brakes come off! high kisspeptin and GnRH leads to egg/sperm

Question 14

What enables pubertal period in females

Answer 14

late development of kisspeptin neurons from preoptic to GnRH cell bodies enables generation of GnRH surge in pubertal period
Surge is vital

Question 15

Leptin

Answer 15

• signal of energy abundance
• secreted in body fat stores
• stimulates activation of GnRH
• kiss2 neurons in Arc express leptin receptors
• leptin treatment partially rescues defective Kiss1 levels
• reason for premature puberty in obese

Question 16

HPG axis senescence

Answer 16

• in puberty, increase in gonadal hormones = sexual maturation
• also permanent sensitisation neural circuits, leads to social reproductive behaviours and incentive seeking behaviours

Question 17

What is imprinting? how does it happen?

Answer 17

parental origin-specific differential gene expression
- in eutherian mammals, marsupials and flowering plants
- happens through epigenetic instructions laid down in parental germ cells

Question 18

what does 2x copies of the maternal genome result in? what does it mean?

Answer 18

decrease in placenta size, means that maternal genome contributes to development of foetus

Question 19

what does 2x copies of paternal genome result in? what does it mean?

Answer 19

extra-embryonic tissue, means some cells are selectively switched off in testis, others in ovaries

Question 20

Why does imprinting occur?

Answer 20

imprinted genes thought to influence transfer of nutrients to foetus and newborn from the mother - Selfish gene

Question 21

Parental conflict of kinship hypothesis

Answer 21

1991:
- in polygynous mammals, mothers bear offspring for multiple fathers
- paternally-derived genomes compete with other males, selection facours those that extract most maternal resources
- its why imprinted paternal genomes are in the placenta

Question 22

co-adaptaion hypothesis

Answer 22

2006:
- imprinted genes act co-adaptively to optimise foetal development and maternal provisioning and nurturing
- only a subset of genes fit, mainly paternal in both placenta and hypoT

Question 23

What is Peg3

Answer 23

‘paternal expressed gene 3’
- maternal copy is imprinted to be silenced
- expressed in maternal hypoT, palcenta and foetal hypoT
- example of co-adaptation

Question 24

How is Peg3 expressed?

Answer 24

only if inherited paternally

Question 25

What is Peg3's function?

Answer 25

it effects maternal care: - milk release in adults - suckling in newborns - causes crouching over pups and nest building in females - allows males to find fertile mates

Question 26

what does Peg3 KO do?

Answer 26

causes impair in growth and puberty

Question 27

Why is Peg3 an example of co-adaptation

Answer 27

because converging actions of Peg3 in mother and foetus illustrate its functional co-adaptation for hypoT and placenta

Question 28

Turner syndrome

Answer 28

- 1/2000 female babies - XO happens when conceived - 70% have female X, 30% male

Question 29

physical characteristics of Turner's

Answer 29

- short - ovarian female --> no sex steroids - no secondary sex characteristics - potentially autism

Question 30

treatments for turner's

Answer 30

- no cure - hormone replacement therapy - growth hormone therapy - heart/kidney checkups

Question 31

cognitive features of turner's

Answer 31

- likely X-linked - ovarian failure = impaired neuro development - executive function effected, impairments in attention, working memory, cognitive flexibility, abstract reasoning - moderate social impairment

Question 32

Impact of Skuse's study

Answer 32

- some genes involved in behavioural and social cognitive skills are imprinted - resulted in search for genes in X chromosomes - data suggest there are non-primary factors contributing to the difference between sexes - caused research into autism

Question 33

autism spectrum disorder

Answer 33

- prevalence increasing - strong familial link - strong sex bias - threshold higher for females --> males have higher chance

Question 34

how did Skuse's study relate to autism?

Answer 34

- Skuse proposed female protection lies within the X chromosome in an imprinted X-linked gene - expressed only on paternal X-chromosome, which would only be inherited by a girl, hence why threshold is higher

Question 35

How does the HPA axis regulate stress?

Answer 35

- PVN of hypothalamus: CRH and AVP - Pituitary gland: ACTH - Adrenal gland: glucocorticoids and catecholamines - Negative feedback to brain: GR and MR

Question 36

What behaviours in mothers are measured to assess future stress of offspring?

Answer 36

licking and grooming (LG) arched back nursing (ABN)

Question 37

What do offspring of high LG/ABN mothers show?

Answer 37

- reduced plasma ACTH and corticosterone responses to stress - increase hippocampal GR expression --> low adulthood stress

Question 38

Why do poor mothers produce more stressed offspring

Answer 38

low GR levels, weak feedback on CRH, elevated glucocorticoid secretion

Question 39

what mechanisms underlie long-term effects of maternal care

Answer 39

Epigenetic mechanisms: - DNA methylation - histone modification - small non-coding RNAs

Question 40

How does DNA methylation work?

Answer 40

- high levels of DNA methylation result in repressive chromatin - low levels results in permissive chromatin

Question 41

histone modifications

Answer 41

- histone H3K9 acetylation and H4K4 methylation both present at actively transcribed regions of genome - basically pups from low LG mothers have high DNA methylation, low histone modification

Question 42

human stress data

Answer 42

- childhood trauma alters HPA stress response, decreased GR response, increased risk of antisocial behaviour

Question 43

holocaust victims

Answer 43

- low urinary cortisol - increased risk of anxiety/depression

Question 44

Is PTSD maternally or paternally linked

Answer 44

maternally

Question 45

mismatch hypothesis

Answer 45

high levels of stress in childhood means you can deal with it later in life

Question 46

cumulative hypothesis

Answer 46

opposite of mismatch

Question 47

MAOa in stress

Answer 47

boys with low MAOa activity have increased risk of adolescent and adult antisocial behaviour