Format

Send to

Choose Destination
Eur J Endocrinol. 2017 Apr;176(4):393-404. doi: 10.1530/EJE-16-0834. Epub 2017 Jan 11.

Modulation of SHBG binding to testosterone and estradiol by sex and morbid obesity.

Author information

1
Department of Biochemistry and Molecular Biomedicine; Faculty of BiologyUniversity of Barcelona, Barcelona, Spain.
2
Institute of BiomedicineUniversity of Barcelona, Barcelona, Spain.
3
CIBER Obesity and NutritionBarcelona/Girona, Spain.
4
University Hospital 'Dr. Josep Trueta'Girona, Spain.
5
Girona Institute of Biomedical Researchand Hospital of Girona 'Dr. Josep Trueta', Spain.
6
Department of Biochemistry and Molecular Biomedicine; Faculty of BiologyUniversity of Barcelona, Barcelona, Spain malemany@ub.edu.

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.

DESIGN:

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.

PMID:
28077498
DOI:
10.1530/EJE-16-0834
[Indexed for MEDLINE]

Supplemental Content

Full text links

Icon for Sheridan PubFactory
Loading ...
Support Center