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
FSH - gonads

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 of 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

• 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