Aug28 M1,2-Male Reproductive System Flashcards
HPT (testicular) axis with hormones
- h: GnRH (gonadotropin releasing H)
- p: LH and FSH (gonadotropins)
- t: steroids and inhibin
- Feedback
what ntr controls pulsatile secretion of GnRH
kisspeptin, 10 aa peptide
GnRH charact
- susceptible to proteases
- analogs used for infertility tx, contraception, etc.
(imp?) main use of GnRH today
prostate cancer
how to use GnRH analog as an agonist
give in pulsatile fashion (every 60-90 min) (like phgy)
how to use GnRH analog as an antagonist
give constant long lived dose (inhibits the gonadotropes = cells in pit making LH, FSH)
2 parts of LH and FSH (gonadotropins)
- alpha subunit (same in LH and FSH). same gene
- beta subunit (makes the bio specif): two diff genes
half life of FSH vs LH
FSH very much longer half life than LH
why FSH half life long
need constant exposure to stim the dev of germ cells
why LH half life short
comes out in pulsatile fashion (resp to GnRH pulse).
FSH fct
stim dev of germ cells
LH fct
stim steroidogenesis
R of gonadotropins are what
GPCRs with 7 parts TM prot. (classic)
precursor to all sex steroids
cholesterol. 5 areas of substitutions to make the diff steroids (prog, androgens, CS, estrogen)
steroid binding Rs parts and are where
- nuclear. are TFs. turn on-off many genes
- steroid binding domain. area of dimerization. zinc finger (to bind DNA)
cells making testo
Leydig cells
how to make DHT (dihydrotesto)
5 alpha reductase reduces the double bond of testo
how to make estradiol
aromatase aromatizes double bond of testo
pro hormone concept in steroid action
testo pro hormone. depending on tissue, will find testo OR a derivative (DHT, estradiol)
is estrogen a pro hormone (like testo)
no
cell membrane steroid hormone Rs (SHRs) where and diff
allow faster response of transcription (1-5 min). nuclear SHRs = hours
*membrane SHRs in brain for sleep, etc
inhibin origin
testes Sertoli cells
inhibin fct
inhibit FSH release by gonadotropes of pit
inhibin structure
Inhibin A: alpha + betaA subunits
Inhibin B: alpha + betaB subunits