1.3.3 Male Reproductive Endocrinology Flashcards
Name three factors that stimulate GnRH release
Leptin, norepinephrine (NE), neuropeptide Y (NPY)
Where is the majority of estradiol produced? How?
Adipose; aromatization of testosterone
What does inhibin level correlate with?
total sperm count and testicular volume
index of spermatogenesis
What is the main function of inhibin B from sertoli cells?
Suppress FSH secretion from pituitary
ABP produced and released?
Produced by sertoli cells and released into the lumen of the seminiferous tubules
What are the three principal hormones produced by the gonads?
Testosterone and Estradiol (Leydig cells)
Inhibin B (Sertoli)
What is andropaus
Along with secondary sex characteristic development, what occurs during puberty?
Growth
What do sertoli cells release in the negative feedback loop on FSH?
Inhibin B
What factors inhibit the release of GnRH? (5)
GABA, dopamine (DA), IL-1, beta-endorphin, prolactin
How does gonadotrophins (LH and FSH) work?
Bind G protein receptors, activate AC, production of cAMP, activation of protein kinase A (PKA)
What does testosterone control?
What is activin?
locally (pituitary) produced peptide that antagonizes inhibin B resulting in the stimulation of FSH release
What are the key steps in testerone synthesis and metabolism?
Draw out the pituitary axis of LH/FSH with the reproductive system
Shortly after birth, what happens to newborn baby boys?
Huge stimulation of LH leading to high levels of testosterone
What receptors are present on sertoli cells? (2)
FSH and androgen receptors
How does testerone act?
Passively diffuses through cells
Inactivate cytosolic androgen receptor
Ultimately, activate gene txn
What type of cells responds to LH?
Leydig cells
What are some of the characteristics of someone with Klinefelter’s syndrome?
What could cause precocious puberty?
What does degradation occur?
Liver
What protein plays a key role in the first step of steriod hormone biosynthesis?
Steriodogenic acute regulatory (StAR) protein
When does androgen production peak during fetal development?
2nd trimester
Leydig cells produce what which has negative feedback on LH/FSH production?
Testosterone
What typically binds to testosterone?
SHBG (sex hormone binding globulin) and albumin
Describe the pattern of testosterone production?
Diurnal pattern with early morning peak
What are the two classes of testosterone deficiency?
What are the two types of precocious puberty?
Gonadotrophin dependent/independent
What transcription factor (peptide) upregulates LH/FSH?
GnRH
What is Finasteride? What is its usage?
5-alpha-reductase inhibitor; BPH and prostate cancer
What are some of the products of Sertoli cells? (3)
Anti-Mullerian hormone, androgen binding protein, inhibin B
What is the effect of testosterone on the bone?
Strengthens bone
What type of cells respond to FSH?
Sertoli
What is adrenarche?
early sexual maturation (b/t 6-11 y/o), often associated with puberty
What occurs during puberty?
The amount of testosterone rise and will stay high for rest of life
During the pubertal stage, when does LH levels primarily begin to surge?
Nocturnally, leading to morning wood
What is an important enzyme in testosterone metabolism?
aromatase or 5-DHT/5 alpha-reductase
