Evaluation of endocrine testing of Leydig cell function using extractive and recombinant human chorionic gonadotropin and different doses of recombinant human LH in normal men.
BACKGROUND
The functional testing of endocrine testis uses extractive human chorionic gonadotropin (ehCG). Recombinant human hCG (rhCG), avoiding any contamination, should replace ehCG. Moreover, a functional evaluation with recombinant human LH (rhLH) would be closer to physiology than a pharmacological testing with hCG.


METHODS
The study was conducted in normal men. We first evaluated the dose-effect of ehCG on plasma testosterone and estradiol levels, before and after injection of either hCG or vehicle. Secondly, the responses to the optimal dose of ehCG were compared with those of rhCG. Thirdly, we investigated the dose-effect of rhLH, on steroid hormone secretion. LH, testosterone, and estradiol plasma levels were measured after the injection of either rhLH or placebo.


RESULTS
ehCG induced dose-dependent increases in plasma estradiol and testosterone levels. They respectively peaked at 24 and 72 h after the injection. The most potent dose of ehCG (5000 IU) induced results similar to those observed with 250 microg (6500 IU) rhCG. By comparison with placebo, rhLH induced a significant and dose-dependent increase in plasma testosterone levels 4 h after the injection. Peak response of testosterone to rhLH and rhCG was significantly correlated. rhLH did not induce significant change in plasma estradiol level.


CONCLUSIONS
In normal men, a single i.v. injection of 150 IU rhLH induces a 25% rise in plasma testosterone levels by comparison with placebo. At the moment, the dynamic evaluation using hCG remains the gold standard test to explore the Leydig cell function. The use of 250 microg rhCG avoiding any contamination should be recommended.
Cailleux-Bounacer
Anne
A
Department of Endocrinology and INSERM CIC 204, Rouen University Hospital, 76000 Rouen, France.
Reznik
Yves
Y
Cauliez
Bruno
B
Menard
Jean François
JF
Duparc
Céline
C
Kuhn
Jean Marc
JM
D000293:Adolescent; D000328:Adult; D006063:Chorionic Gonadotropin / Q000627:therapeutic use*; D003940:Diagnostic Techniques, Endocrine; D004305:Dose-Response Relationship, Drug; D004958:Estradiol / Q000097:blood; D006801:Humans; D007248:Infertility, Male / Q000097:blood / Q000175:diagnosis*; D007985:Leydig Cells / Q000187:drug effects / Q000502:physiology*; D007986:Luteinizing Hormone / Q000008:administration & dosage* / Q000097:blood; D008297:Male; D010919:Placebos; D011994:Recombinant Proteins / Q000627:therapeutic use; D016037:Single-Blind Method; D013739:Testosterone / Q000097:blood
D006063:Chorionic Gonadotropin; D010919:Placebos; D011994:Recombinant Proteins; D013739:Testosterone; D004958:Estradiol; D007986:Luteinizing Hormone