title: Modulation of SHBG binding to testosterone and estradiol by sex and morbid obesity.
abstract: OBJECTIVE
  Sex hormone-binding globulin (SHBG) binds and transports testosterone and estradiol in plasma. The possibility that SHBG is a mixture of transporting proteins has been postulated. We analyzed in parallel the effects of obesity status on the levels and binding capacity of circulating SHBG and their relationship with testosterone and estradiol.
  
  
  METHODS
  Anthropometric measures and plasma were obtained from apparently healthy young (i.e. 35 ± 7 years) premenopausal women (n =32) and men (n =30), with normal weight and obesity (BMI >30 kg/m2).
  
  
  METHODS
  SHBG protein (Western blot), as well as the plasma levels of testosterone, estradiol, cortisol and insulin (ELISA) were measured. Specific binding of estradiol and testosterone to plasma SHBG was analyzed using tritium-labeled hormones.
  
  
  RESULTS
  Significant differences in SHBG were observed within the obesity status and gender, with discordant patterns of change in testosterone and estradiol. In men, testosterone occupied most of the binding sites. Estrogen binding was much lower in all subjects. Lower SHBG of morbidly obese (BMI >40 kg/m2) subjects affected testosterone but not estradiol. The ratio of binding sites to SHBG protein levels was constant for testosterone, but not for estradiol. The influence of gender was maximal in morbid obesity, with men showing the highest binding/SHBG ratios.
  
  
  CONCLUSIONS
  The results reported here are compatible with SHBG being a mixture of at least two functionally different hormone-binding globulins, being affected by obesity and gender and showing different structure, affinities for testosterone and estradiol and also different immunoreactivity.
authors.affiliation: Department of Biochemistry and Molecular Biomedicine; Faculty of BiologyUniversity of Barcelona, Barcelona, Spain.|Institute of BiomedicineUniversity of Barcelona, Barcelona, Spain.|CIBER Obesity and NutritionBarcelona/Girona, Spain.
authors.forename: María Del Mar
authors.initials: MDM
authors.lastname: Grasa
authors.affiliation: Department of Biochemistry and Molecular Biomedicine; Faculty of BiologyUniversity of Barcelona, Barcelona, Spain.
authors.forename: José
authors.initials: J
authors.lastname: Gulfo
authors.affiliation: Department of Biochemistry and Molecular Biomedicine; Faculty of BiologyUniversity of Barcelona, Barcelona, Spain.
authors.forename: Núria
authors.initials: N
authors.lastname: Camps
authors.affiliation: Department of Biochemistry and Molecular Biomedicine; Faculty of BiologyUniversity of Barcelona, Barcelona, Spain.
authors.forename: Rosa
authors.initials: R
authors.lastname: Alcalá
authors.affiliation: Department of Biochemistry and Molecular Biomedicine; Faculty of BiologyUniversity of Barcelona, Barcelona, Spain.
authors.forename: Laura
authors.initials: L
authors.lastname: Monserrat
authors.affiliation: University Hospital 'Dr. Josep Trueta'Girona, Spain.|Girona Institute of Biomedical Researchand Hospital of Girona 'Dr. Josep Trueta', Spain.|CIBER Obesity and NutritionBarcelona/Girona, Spain.
authors.forename: José María
authors.initials: JM
authors.lastname: Moreno-Navarrete
authors.affiliation: University Hospital 'Dr. Josep Trueta'Girona, Spain.|Girona Institute of Biomedical Researchand Hospital of Girona 'Dr. Josep Trueta', Spain.|CIBER Obesity and NutritionBarcelona/Girona, Spain.
authors.forename: Francisco José
authors.initials: FJ
authors.lastname: Ortega
authors.affiliation: Department of Biochemistry and Molecular Biomedicine; Faculty of BiologyUniversity of Barcelona, Barcelona, Spain.|Institute of BiomedicineUniversity of Barcelona, Barcelona, Spain.|CIBER Obesity and NutritionBarcelona/Girona, Spain.
authors.forename: Montserrat
authors.initials: M
authors.lastname: Esteve
authors.affiliation: Department of Biochemistry and Molecular Biomedicine; Faculty of BiologyUniversity of Barcelona, Barcelona, Spain.|Institute of BiomedicineUniversity of Barcelona, Barcelona, Spain.|CIBER Obesity and NutritionBarcelona/Girona, Spain.
authors.forename: Xavier
authors.initials: X
authors.lastname: Remesar
authors.affiliation: Department of Biochemistry and Molecular Biomedicine; Faculty of BiologyUniversity of Barcelona, Barcelona, Spain.|Institute of BiomedicineUniversity of Barcelona, Barcelona, Spain.|CIBER Obesity and NutritionBarcelona/Girona, Spain.
authors.forename: José Antonio
authors.initials: JA
authors.lastname: Fernández-López
authors.affiliation: University Hospital 'Dr. Josep Trueta'Girona, Spain.|Girona Institute of Biomedical Researchand Hospital of Girona 'Dr. Josep Trueta', Spain.|CIBER Obesity and NutritionBarcelona/Girona, Spain.
authors.forename: José Manuel
authors.initials: JM
authors.lastname: Fernández-Real
authors.affiliation: Department of Biochemistry and Molecular Biomedicine; Faculty of BiologyUniversity of Barcelona, Barcelona, Spain.|Institute of BiomedicineUniversity of Barcelona, Barcelona, Spain.|CIBER Obesity and NutritionBarcelona/Girona, Spain.
authors.forename: Marià
authors.initials: M
authors.lastname: Alemany
mesh_terms: D000293:Adolescent; D000328:Adult; D004958:Estradiol / Q000097:blood / Q000378:metabolism*; D005260:Female; D005916:Globulins / Q000378:metabolism; D006801:Humans; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000378:metabolism* / Q000503:physiopathology; D017697:Premenopause / Q000097:blood; D011485:Protein Binding; D012737:Sex Factors; D012738:Sex Hormone-Binding Globulin / Q000378:metabolism*; D013739:Testosterone / Q000097:blood / Q000378:metabolism*; D055815:Young Adult
chemical_list: D005916:Globulins; D012738:Sex Hormone-Binding Globulin; D013739:Testosterone; D004958:Estradiol