Response of serum inhibin B and pro-alphaC levels to gonadotrophic stimulation in normal men before and after steroidal contraceptive treatment.
BACKGROUND
Testicular regulation of inhibin B may be influenced by the germ cell complement.


METHODS
We examined the effects of gonadotrophin stimulation on serum inhibin B and pro-alphaC in 25 normal men at (i) control (stimulation test 1), (ii) after spermatogenic suppression induced by testosterone plus progestin treatment (stimulation test 2), and (iii) during spermatogenic recovery induced by FSH and/or hCG treatment (stimulation test 3). For each test, subjects received a single injection of 1200 IU FSH or 5000 IU hCG or both.


RESULTS
Inhibin B and pro-alphaC fell with spermatogenic suppression (75 and 51% of pre-treatment baseline respectively, P < 0.05). Inhibin B response to FSH (130-144%) was similar in controls and after germ cell suppression. Pro-alphaC response after germ cell suppression compared with control was significantly increased (P < 0.05) with both FSH (210-229% versus 140-185%) and hCG (254-261% versus 145%). All treatments partially restored spermatogenesis with no clear relationship apparent between inhibin B and sperm count.


CONCLUSIONS
We conclude that: (i) serum inhibin B and pro-alphaC are only partially gonadotrophin dependent, (ii) spermatogenic suppression does not modify inhibin B response to FSH but enhances pro-alphaC response to both FSH and hCG, and (iii) inhibin B is a poor marker of spermatogenesis in this model of gonadotrophic manipulation in normal men.
Matthiesson
Kati L
KL
Prince Henry's Institute of Medical Research, Monash Medical Centre, Monash University, Clayton, Victoria 3168, Australia.
Robertson
David M
DM
Burger
Henry G
HG
McLachlan
Robert I
RI
D000328:Adult; D015415:Biomarkers / Q000097:blood; D006063:Chorionic Gonadotropin / Q000009:adverse effects / Q000494:pharmacology*; D003272:Contraceptive Agents, Male / Q000494:pharmacology*; D005640:Follicle Stimulating Hormone / Q000009:adverse effects / Q000494:pharmacology*; D006062:Gonadotropins / Q000097:blood; D006801:Humans; D007265:Inhibins / Q000097:blood*; D008297:Male; D011498:Protein Precursors / Q000097:blood*; D012016:Reference Values; D013091:Spermatogenesis / Q000502:physiology; D013739:Testosterone / Q000097:blood
D015415:Biomarkers; D006063:Chorionic Gonadotropin; D003272:Contraceptive Agents, Male; D006062:Gonadotropins; D011498:Protein Precursors; C422364:inhibin B; C095971:inhibin-alpha subunit precursor; D013739:Testosterone; D007265:Inhibins; D005640:Follicle Stimulating Hormone