Gonadotropins Flashcards
gonadotropin definitions
three types: FSH, LH and hCG; all have the same alpha subunit, made by ant. pit. or placenta, and have unique beta subunits (but LH and hCG are very similar)
mechanism of action for the gonadotropins
act via GPCRs that are coupled to G-alphas (upreg cAMP);
LH and hCG both through the LH-receptor
LH and FSH target gonads (and corpus luteum @ females)
FSH targets and function males and females
males: sertoli cells promotes spermogenesis, stimulates inhibin secretion
females: granulosa cells; support follicular growth, stimulate inhibin, stimulate estrogen
LH targets and functions males and females
males: leydig cells, promotes test. synth.
females: theca, corpus luteum, follicles; stim. estro. and progesterone
hCG targets and functions females only
corpus luteum; stim progesterone
feedback mechanism for FSH, LH and hCG
dependent on prog. estro. androgens and inhibin
hypothalamic control of gonadotropins
exquisite pulsatility, half life of 2-4 minutes GnRH, 1x per hour
anterior pit control
can desensitize to excess GnRH if exposed
gonadotropin regulation (physiological)
GABA, Norepi, opioids, dopamine
follicular phase of menstrual cycle
estrogen still inhibitory and gonadotropin pulses small and frequent
ovulation phase
estrogen is now positive feedback, and at high levels, resultant LH surge induces ovulation
luteal phase
progesterone feedback increases amplitude of pulses of GnRH but also increases the interval
fertizilations
trophoblastic production of hCG compensates for the placenta until it is mature (week 9)
hCG diagnosis
pregnancy, certain tumors (in urine)
LH diagnosis
timing intercourse properly for pregnancy
FSH and LH diagnosis
diagnostic for precocious puberty
Fertility treatment (IVF and intermediate)
FSH for maturation followed by hCG to induce ovulation
IVF adds harvesting
indications for treatment males
cryptorchidism (hCG) fertility treatment (both FSH and LH)
adverse effects of gonadotropin therapy
multiple gestations; Ovarian hyperstimulation syndrome: increased vascular permeability, hypotension, coagulopathies
leuprolide definition
GnRH agonist; depot IM
indications for leuprolide
central precocious puberty (desensitization of GnRH receptor)
hormone dependent cancer
endometriosis (no longer than six months due to bone density loss)
fertility treatment
ganirelix definition
GnRH antagonist
indications for ganirelix
control over fertilization cycles
hormone responsive cancer
