Context:

Obesity is associated with increased circulating 17β-estradiol (E2), but less is known about E2 concentrations in adipose tissue. In addition to E2, adipose tissue synthesizes E2 fatty acyl esters (E2-FAE).

Objective:

The aim was to compare estrogen concentrations and expression of estrogen-converting enzymes in adipose tissue between severely obese men and women.

Design and Setting:

Tissue samples were obtained during elective surgery in University Central Hospital in the years 2008 through 2011.

Patients:

We studied 14 men and 22 premenopausal women undergoing bariatric surgery and 10 control women operated for nonmalignant reasons.

Interventions:

Paired samples were taken from abdominal sc and visceral adipose tissue and serum and analyzed for E2 and E2-FAE by fluoroimmunoassay and liquid chromatography-tandem mass spectrometry. mRNA expression of genes was analyzed by quantitative PCR.

Results:

Compared with men, E2 levels in sc adipose tissue in obese women were higher, along with higher relative mRNA expression of steroid sulfatase and 17β-hydroxysteroid dehydrogenases 1, 7, and 12. In men, E2-FAE concentrations in adipose tissue were similar to E2 but in women significantly lower compared with E2. Adipose tissue E2-FAE and serum E2-FAE levels correlated positively in obese subjects. Serum E2 did not significantly correlate with E2 concentration or mRNA expression of genes in adipose tissue in obese men or women.

Conclusions:

The production of E2 by the large adipose mass was not reflected by increased circulating E2 concentrations in severely obese men or women. However, adipose tissue may contribute to concentrations of serum E2-FAE.

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