Control of Growth

Question 1

What factors influence puberty?

Answer 1

Genetics
Hormones
Nutrition
Environment

Question 2

How does GnRH release change during puberty?

Answer 2

Pulsatile increase

Question 3

Why does low nutrition intake result in a delayed onset of fertility?

Answer 3

Reproductive function is sensitive to the state of energy reserves
Initiation of puberty is strongly influenced by the nutritional level received during the prepubertal period after weaning

Question 4

What hormone signals energy reserves?

Answer 4

Leptin

Question 5

How does leptin deficiency affect fertility - how?

Answer 5

Causes a lack of puberty
Lack of GnRH pulsatility
Variable degree of hypogonadotropic hypogonadism & infertility

Question 6

What 3 hormones are needed to initiate & maintain puberty?

Answer 6

Sex steroids
Melatonin
Leptin

Question 7

How does the combination of sex steroids, melatonin & leptin lead to puberty?

Answer 7

1. Light acts on suprachiasmatic nucleus, which activates pineal gland
2. Pineal gland releases melatonin
3. Leptin released from body fat
4. Sex steroids released from gonads
5. All 3 hormones activate Kiss1 neurone, which activates GnRH neurone, causing pulsatile release of GnRH (>pulsatile release of LH + FSH/testoserone)