title: Insulin-like factor 3 as a marker of testicular function in obese men.
abstract: OBJECTIVE
  Testicular function declines with obesity as a result of central and peripheral mechanisms, including a primary dysfunction of the Leydig cells. The levels of insulin-like factor 3 (INSL3), a sensitive marker of Leydig cell impairment, have never been evaluated in obese men. To better evaluate the hormonal function of the testis in obese men, we analysed their INSL3 plasma levels and compared them with the obesity status and the other reproductive hormones.
  
  
  METHODS
  Cross-sectional study.
  
  
  METHODS
  Thirty-one obese men [body mass index (BMI) >30 kg/m(2)) aged 22-49 years and 64 age-matched nonobese men.
  
  
  METHODS
  Plasma concentrations of INSL3, testosterone (T), sex hormone-binding globulin (SHBG), oestradiol (E(2)), LH, FSH. Free testosterone (FT) levels were calculated.
  
  
  RESULTS
  Obese men had significantly lower plasma concentrations of total T, SHBG, FT and INSL3, and higher levels of E(2) with respect to nonobese men. LH and FSH values were not different from controls. In obese men, we found a significant negative correlation between BMI and INSL3, and a positive correlation between INSL3 and T. Only one (1/31, 3.2%) obese man had subnormal T levels. On the contrary, 10/31 (32.3%) obese men had low INSL3 values.
  
  
  CONCLUSIONS
  This study showed for the first time that INSL3 levels decrease with obesity, probably as a result of a primary dysfunction of the Leydig cells. INSL3 is a reliable marker of Leydig cell general impairment, whereas T mainly reflects the steroidogenic activity of these cells.
authors.affiliation: Department of Histology, Microbiology and Medical Biotechnologies, Section of Clinical Pathology and Centre for Male Gamete Cryopreservation, University of Padova, Via Gabelli 63, Padova, Italy. carlo.foresta@unipd.it
authors.forename: Carlo
authors.initials: C
authors.lastname: Foresta
authors.forename: Antonella
authors.initials: A
authors.lastname: Di Mambro
authors.forename: Claudio
authors.initials: C
authors.lastname: Pagano
authors.forename: Andrea
authors.initials: A
authors.lastname: Garolla
authors.forename: Roberto
authors.initials: R
authors.lastname: Vettor
authors.forename: Alberto
authors.initials: A
authors.lastname: Ferlin
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000097:blood*; D003430:Cross-Sectional Studies; D004958:Estradiol / Q000097:blood; D006801:Humans; D007328:Insulin / Q000097:blood*; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000097:blood* / Q000378:metabolism* / Q000473:pathology; D011506:Proteins; D012738:Sex Hormone-Binding Globulin / Q000378:metabolism; D013737:Testis / Q000378:metabolism* / Q000473:pathology; D013739:Testosterone / Q000097:blood; D055815:Young Adult
chemical_list: D015415:Biomarkers; D007328:Insulin; C084797:Leydig insulin-like protein; D011506:Proteins; D012738:Sex Hormone-Binding Globulin; D013739:Testosterone; D004958:Estradiol