Concentration of Sex Steroids in Adipose Tissue after Menopause

Adipose tissue is a site of uptake, storage, action, and metabolism of sex steroids. After menopause aromatization of androgens to estrogens in adipose tissue is one of the most important sources of estrogen in the circulation and for peripheral tissues. The aim of this study was to estimate local sex steroid concentrations in breast and abdominal subcutaneous (s.c.) adipose tissue, to compare them with plasma concentrations and to investigate possible correlations with body mass index (BMI). The patients were postmenopausal women undergoing surgery for non-oncological reasons (Group A; n = 35) and breast cancer patients (group B; n = 19). The concentrations of estrone, 17β-estradiol, estrone sulfate, 17β-estradiol sulfate, androstenedione, androstenediol (androst-5-ene-3β,17β-diol), testosterone and dehydroepiandrosterone were measured. The method was based on frozen tissue homogenization, extraction with ethanol : acetone, delipidation, extraction of estrogens with ether, and of androgens with iso-octane in toluene, followed by RIA. The mean levels of steroids were higher in fat than in plasma, apart from testosterone. Levels of sulfates of estrogens and androstenediol were higher in breast than abdominal adipose tissue, and levels of estradiol lower. Positive correlations were found between BMI and tissue and plasma concentration of both estrone and androstenedione.