Puberty

Question 1

Hormonal changes that lead to puberty 1

Answer 1

• First thing that changes is an increase in gonadotropin pulse frequency
• This leads to increased steroid hormone production (mostly during sleep) which accounts for development of secondary sex characteristics seen in puberty
• Before puberty the brain and pituitary are hyperresponisve to negative feedback from steroid hormones, leading to infrequent pulses of GnRH/FSH/LH
• Upon reaching a certain age this sensitivity to steroid hormones is decreased and thus there is greater pulse frequency of GnRH/FSH/LH leading to a rise in steroid hormones

Question 2

Hormonal changes that lead to puberty 2

Answer 2

• The mechanism for which hyper responsiveness to steroid hormones decreases is not known
• Likewise, steroid-independent inhibition (which accounts for majority of early-pubertal changes) is unknown
• Adrenarche: adrenal glands produce androgens before gonadotrophs rise, leading to pubic and axillary hair
• Growth is accomplished by action of both GH and sex steroids
• Leptin on puberty: doesn’t control onset of puberty by itself, but can contribute to puberty as other process initiate it

Question 3

Hormonal changes that occur with precocious or delayed puberty

Answer 3

• Precocious puberty: can be due to elevated GnRH levels in individuals who should have more suppressed GnRH levels (i.e. GnRH secreting tumor)
• Can also be due to inappropriate activation of LH receptors in the gonads
• One way to Rx is give continuous infusion of GnRH to suppress pulses and gonadotrophic hormones
• Delayed puberty: can be from hypogonadotropic hypogonadism (problem is in the ant pit/hypothal, not in gonads)
• Often due to inability of GnRH neurons to pass thru cribiform plate during development and thus a lack of GnRH cells in hypothal later in life
• Rx: women put on OCPs, men give supplemental T