Pharmacological Manipulation in Males

Question 1

HPT Axis General Principles

Answer 1

1. Hypothalamus produces GnRH
2. GnRH acts on anterior pituitary
3. Anterior pituitary produces LH and FSH
4. LH acts on Leydig cells leading to testosterone production
5. FSH acts on Sertoli cells leading to spermatogenesis
6. Testosterone has -ve feedback effect on Hypothalamus and anterior pituitary
7. Sertoli cell produce inhibin which has -ve feedback effect on anterior pituitary

Question 2

What effect will sex steroids have on HPT axis?

Answer 2

All will have -ve feedback effect and reduce reproductive function
Androgens have anabolic effect

Question 3

Progestogen effect

Answer 3

Decreases testosterone via -ve feedback
suppresses spermatogenesis

Question 4

Why give progestogen depot to animal with testosterone stimulated tumour?

Answer 4

Progestogen has -ve feedback effect on testosterone
Drive for tumour is removed
Don’t use testosterone because ether drives tumour
Don’t use oestrogens because they cause bone marrow suppression

Could also castrate and remove source of testosterone production

Question 5

Effect of GnRH agonist

Answer 5

○ Negative feedback effect
Works like GnRH antagonist
No subsequent stimulation of pituitary
No release of FSH or LH
○ Reduces testosterone production from Leydigs
○ Reduces libido
○ Spermatogenesis reduced

Question 6

GnRH/Lh use in males

Answer 6

Can’t buy LH - can buy hCG (LH-like in activity)
Used to confirm presence of testicular tissue
* Rig test

If testicular tissue is present - exogenous GnRH/hCG will stimulate testosterone production