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Flashcards in Renal 2 Pharmacology 2 Deck (48)
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1

Male Hypothalamic-Pituitary-Gonadal Axis

-release/secretion of hypothalamic and anterior pituitary hormone is pulsatile
-GnRH in hypothalamus stimulates pituitary to Release FSH and LH which stimulates sertoli cells and leydig cells

2

Anterior pituitary LH stimulates

Leydig cells testosterone biosynthesis and secretion

3

Testosterone + pituitary FSH stimulates

sertoli cells-->sperm maturation

4

Sperm maturation in Sertoli cells

-depends on FSH and testosterone, but also on precisely controlled estrogen levels
-Aromatase in sertoli cells uses testosterone to make estradiol

5

GnRH (LHRH)

-released by hypothalamus
-stimulates anterior pituitary to produce and secrete FSH and LH

6

FSH

-released by anterior pituitary
-stimulates sertoli cells and sperm maturation

7

LH

-released by anterior pituitary
-stimulates testosterone hormone synthesis and secretion by leydig cells

8

Continual high concentrations of LH result in

reduced secretion of testosterone due to down regulation of LH receptors in Leydig cells

9

Androgens, testosterone

-released by adrenals and testes
-stimulates Sertoli cells (other cells responsive to androgens, e.g. prostate epithelium)

10

Estrogens, estradiol

-released by adrenals and testes
-formed by aromatase catalyzed conversions of androgens to estrogens

11

Aromatase

-converts androstenedione to estrone and testosterone to estradiol

12

Synthesis of dihydrotestosterone

-androstenedione converted to testosterone by 17B-hydroxylase
-testosterone converted to DHT by 5a-reductase

13

Synthesis of estradiol in males

-estrone converted to estradiol by 17B-hydroxylase or testosterone converted to estradiol by aromatase

14

High concentrations of testosterone in the circulation

-inhibit the release of GnRH, FSH, and LH, by negative feedback control

15

When circulating concentrations of testosterone are low,

-higher levels of GNRH, FSH, and LH are released

16

Testicular levels of testosterone are

100-500x greater than those found in blood

17

An in crease in PSA level over time may indicate

prostate cancer

18

Androgens stimulate

prostate cancer cells to grow
-lowering androgen levels or stopping androgens from signaling in prostate cancer cells often makes tumors shrink or grow more slowly for a time.
-Androgen deprivation therapy alone does not cure prostate cancer

19

GnRH antagonist

Degarelix

20

GnRH agonist

Leuprolide
-Nafarelin (nasal)

21

Natural replacement of GnRH

Gonadorelin

22

Degarelix

-GnRH antagonist (blocks receptor on pituitary)
-reduces testosterone levels below detectable levels quickly (2-3 days)
-used to treat advanced prostate cancer
-given subcutaneously as a monthly injection
-counters reflex to try to produce more T because receptor is blocked

23

Degarelix Side effects

-problems at injection site (pain, redness, swelling) and increased levels of liver enzymes on lab tests

24

Continuous administration fo a GnRH agonist (Leuprolide)

-eventually desensitizes receptors for GnRH and LH after an initial 'surge' in androgen biosynthesis

25

Leuprolide

-causes circulating testosterone to surge initially, then drop later due to desensitization of GnRH and LH receptors
-cause testicles to shrink over time (chemical castration)
-other GnRH agonists include goserelin, triptorelin, and histrelin

26

How to manage testosterone flare that coincides with administration of GnRH receptor agonists

-concurrent administration of androgen receptor antagonists

27

Androgen receptor antagonists include

Bicalutamide
Flutamide
Nilutamide

28

Bicalutamide

-used with leuprolide or other GnRH agonists
-favored
-1x a day

29

Flutamide

used with GnRH/LHRH agonists

30

Nilutamide

-used in combination with surgical castration