title: Dose-dependent increase in intratesticular testosterone by very low-dose human chorionic gonadotropin in normal men with experimental gonadotropin deficiency.
abstract: OBJECTIVE
  In men with infertility secondary to gonadotropin deficiency, treatment with relatively high dosages of human chorionic gonadotropin (hCG) stimulates intratesticular testosterone (IT-T) biosynthesis and spermatogenesis. Previously we found that lower dosages of hCG stimulated IT-T to normal. However, the minimal dose of hCG needed to stimulate IT-T and the dose-response relationship between very low doses of hCG and IT-T and serum testosterone in normal men is unknown.
  
  
  METHODS
  We induced experimental gonadotropin deficiency in 37 normal men with the GnRH antagonist acyline and randomized them to receive one of four low doses of hCG: 0, 15, 60, or 125 IU sc every other day or 7.5 g daily testosterone gel for 10 d. Testicular fluid was obtained by percutaneous aspiration for steroid measurements at baseline and after 10 d of treatment and correlated with contemporaneous serum hormone measurements.
  
  
  RESULTS
  Median (25th, 75th percentile) baseline IT-T was 2508 nmol/liter (1753, 3502 nmol/liter). IT-T concentrations increased in a dose-dependent manner with very low-dosage hCG administration from 77 nmol/liter (40, 122 nmol/liter) to 923 nmol/liter (894, 1017 nmol/liter) in the 0- and 125-IU groups, respectively (P<0.001). Moreover, serum hCG was significantly correlated with both IT-T and serum testosterone (P<0.01).
  
  
  CONCLUSIONS
  Doses of hCG far lower than those used clinically increase IT-T concentrations in a dose-dependent manner in normal men with experimental gonadotropin deficiency. Assessment of IT-T provides a valuable tool to investigate the hormonal regulation of spermatogenesis in man.
authors.affiliation: Department of Medicine, University of Washington, 1959 NE Pacific Street, Box 357138, Seattle, Washington 98195, USA. mylang@u.washington.edu
authors.forename: M Y
authors.initials: MY
authors.lastname: Roth
authors.forename: S T
authors.initials: ST
authors.lastname: Page
authors.forename: K
authors.initials: K
authors.lastname: Lin
authors.forename: B D
authors.initials: BD
authors.lastname: Anawalt
authors.forename: A M
authors.initials: AM
authors.lastname: Matsumoto
authors.forename: C N
authors.initials: CN
authors.lastname: Snyder
authors.forename: B T
authors.initials: BT
authors.lastname: Marck
authors.forename: W J
authors.initials: WJ
authors.lastname: Bremner
authors.forename: J K
authors.initials: JK
authors.lastname: Amory
mesh_terms: D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D006063:Chorionic Gonadotropin / Q000494:pharmacology*; D002853:Chromatography, Liquid; D004305:Dose-Response Relationship, Drug; D015200:Fluoroimmunoassay; D005640:Follicle Stimulating Hormone / Q000097:blood / Q000172:deficiency*; D006801:Humans; D007986:Luteinizing Hormone / Q000097:blood / Q000172:deficiency*; D008297:Male; D013058:Mass Spectrometry; D008875:Middle Aged; D018579:Patient Selection; D012661:Semen / Q000737:chemistry / Q000187:drug effects*; D013737:Testis / Q000187:drug effects*; D013739:Testosterone / Q000032:analysis*
chemical_list: D006063:Chorionic Gonadotropin; D013739:Testosterone; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone