Omental and subcutaneous adipose tissue steroid levels in obese men

Abstract

We examined plasma and fat tissue sex steroid levels in a sample of 28 men aged 24.8–62.2 years (average BMI value of 46.3 ± 12.7 kg/m 2). Abdominal adipose tissue biopsies were obtained during general or obesity surgery. Omental and subcutaneous adipose tissue steroid levels were measured by gas chromatography and chemical ionization mass spectrometry after appropriate extraction procedures. BMI and waist circumference were negatively correlated with plasma testosterone ( r = −0.49 and −0.50, respectively, p < 0.01) and dihydrotestosterone ( r = −0.58 and −0.56, respectively, p < 0.01), and positively associated with estrone levels ( r = 0.64 and 0.62, respectively, p < 0.001). Regional differences in adipose tissue steroid levels were observed for dihydrotestosterone ( p < 0.005), androstenedione ( p < 0.0001) and dehydroepiandrosterone levels ( p < 0.05), which were all significantly more concentrated in omental versus subcutaneous fat. Positive significant associations were found between circulating level of a steroid and its concentration in omental and subcutaneous adipose tissue, for estrone ( r = 0.72 and 0.57, respectively, p < 0.01), testosterone ( r = 0.66 and 0.58, respectively, p < 0.01) and dihydrotestosterone ( r = 0.58 and 0.45, respectively, p < 0.05). Positive correlations were observed between plasma dehydroepiandrosterone-sulfate and omental ( r = 0.56, p < 0.01) as well as subcutaneous adipose tissue dehydroepiandrosterone level ( r = 0.38, p = 0.05). Positive significant associations were found between omental adipocyte responsiveness to positive lipolytic stimuli (isoproterenol, dibutyryl cyclic AMP and forskolin) and plasma or omental fat tissue androgen levels. In conclusion, although plasma androgen or estrogen levels are strong correlates of adipose tissue steroid content both in the omental and subcutaneous fat depots, regional differences may be observed. Androgen concentration differences in omental versus subcutaneous adipose tissue suggest a depot-specific impact of these hormones on adipocyte function and metabolism.