Lecture 15: Pituitary Hormones Flashcards by Brooke Thornburg

Anterior pituitary hormones

-gonadotropins
-GnRH

How well did you know this?

Not at all

Perfectly

Pituitary gland

-master gland
-hypophysis
-size of a pea

How well did you know this?

Not at all

Perfectly

Anterior pituitary hormones

-grwoth hormone (GH), prolactin
-TSH, FSH, LH
-Adrenocorticotropic hormone (ACTH)

How well did you know this?

Not at all

Perfectly

GH and prolactin

-single-chain protein hormones
-activate JAK/STAT pathway

How well did you know this?

Not at all

Perfectly

Thyroid stimulating hormone (TSH), FSH, LH

-dimeric protein hormones
-share common a chain
-activate GPCRs

How well did you know this?

Not at all

Perfectly

adrentocorticotropic hormone (ACTH)

-single-chain peptide
-activates a GPCR

How well did you know this?

Not at all

Perfectly

Gonadotropins

-FSH
-LH
-hCG

How well did you know this?

Not at all

Perfectly

Follicle-stimulating hormone (FSH)

-stimulate conversion of testosterone to estrogens

-ovarian follicle development in women
-regulate spermatogenesis in men

How well did you know this?

Not at all

Perfectly

Lutenizing hormone (LH)

-stimulates androgen production
-only in follicular phase for women
-controls estrogen and preogesterone production in luteal phase

How well did you know this?

Not at all

Perfectly

Human chorionic gonadotropin (hCG)

-produced in placenta during pregnancy
-nearly identical with LH (B-chain)
-binds LH receptors
-controls estrogen and progesterone production during pregnancy

How well did you know this?

Not at all

Perfectly

Gonadotropin structure

-heterodimeric proteins
-common a chain
-distinct B-chain confers specificity
-B-chain of LH and hCG nearly identical
-SC, IM
-10-40 hour half life

How well did you know this?

Not at all

Perfectly

Gonadotropin clinical products

-menotropins
-urofollitropin (uFSH)
-follitropin a and B
-Lutotropin a
-hCG
-Choriogonadotropin a

How well did you know this?

Not at all

Perfectly

Menotropins

-human menopausal gonadotropins (hMG)
-1st product
-from urine of postmenopausal women
-FSH and LH but lower potency

How well did you know this?

Not at all

Perfectly

Urofollitropin (uFSH)

-FSH purified from urine of postmenopausal women
-LH activity removed during purification

How well did you know this?

Not at all

Perfectly

Follitropin a and Follitropin B

-recombinant FSH forms
-identical amino acid seq to FSH
-differ in carbohydrate chains
-more expensive than uFSH

How well did you know this?

Not at all

Perfectly

Lutotropin a

-recombinant LH form
-combo with follitropin a for follicular development in women with LH deficiency
-discontinued

How well did you know this?

Not at all

Perfectly

hCG clinical product

-extracted from urine of pregnant women

Choriogonadotropin a (rhCG)

-recombinant hCG

Gonadotropic ovulation induction

-in women with anovulation secondary to hypogonadotropic hypogonadism, pcos, etc
-controlled ovarian hyperstimulation in reproductive technology procedures
-protocols based on physiology of normal menstrual cycle
-high cost
-need close monitoring during admin
-reserved for patients who fail other treatments

Ovulation induction protocol

FSH preparations (hMG, uFSH) during follicular phase
admin of hCG = ovulation = insemination or oocyte retrieval
hormonal support during luteal phase (exogenous progesterone)

How to prevent LH surge in ovulation induction

-endogenous GnRH needs to be blocked by continous admin of GnRH or GnRH antagonist

Male infertility treatment protocol

injection of hCG for 8-12 weeks (initial phase)
injection of hMG for months

Use of gonadotropins for male infertility treatment

-LH and FSH
-introduction of intracytoplasmic sperm injection (ICSI) reduces the minimume requirement of spermatogenesis

Adverse effects of gonadtropin fertility treatment

-ovarian hyperstimulation syndrome
-multiple pregnancy (15-20%)

ovarian hyperstimulation syndrome

-0.5-4% -overproduction of estrogen and progesterone = vascular hyperpermeability -ovarian enlargement, ascites, hydrothorax, hypovolemia

Gonadotropin-releasing hormone (GnRH)

-decapeptide hormone -secreted by hypothalmus -binds GPCR on gonadotrope cells in anterior pituitart -gonadorelin

Gonadorelin

-acetate salt of synthetic GnRH -4 min IV -3 hr SC

Synthetic analogs of GnRH products

-goserelin -histrelin -leuprolide -nafarelin -triptorelin

synthetic analogs of GnRH features

-D-amino acid at position 6 -ethylamide substituted for glycine at position 10 (except nafarelin) -more potent -longer lasting

Pulsatile secretion of GnRH

-only way that stimulates LH and FSH release -IV every 1-4 hr

Nonpulsatile admin of GnRH

-INHIBITS release of FSH and LH =hypogonadism

GnRH to treat female infertility

-IV -pulsatile using portable pump -less likely to cause multiple pregnancies and hyperstimulation -inconvienent and expensive

GnRH to treat male infertility

-hypothalmic hypogonadism -PULSATILE IV using pump (months) -gonadotropin treatment favored

GnRH as a suppressant treatment

-ovarian hyperstimulatino -endometriosis -prostate cancer -central precocious puberty

continuous GnRH agonist treatment

=suppression of gonadotropin release

GnRH treatment of Controlled ovarian hyperstimulation

-suppression of endogenous LH surge that causes premature ovulation -SC of leuprolide -nasal application of nafarelin

GnRH treatment of endometriosis

-suppress gonadotropin release =suppress ovaries =reduce estrogen and progesterone production

GnRH treatment of prostate cancer

-combo with androgen agonist =reduction of testosterone levels and effects

GnRH antagonists

-Ganirelix -Cetrorelix -Abarelix -Degarelix

use of GnRH ANTAgonists

-ovarian hyperstimulation (shorter duration of treatment) -advanced prostate cancer