Adipose Tissue Sex Steroids in Postmenopausal Women with and without Menopausal Hormone Therapy.

CONTEXT: The decrease in serum estrogens after menopause is associated with a shift from a gynoid to an android adipose tissue (AT) distribution. Menopausal hormone therapy (HT) mitigates this change and accompanying metabolic dysfunction, but its effects on AT sex steroid metabolism have not been characterized. OBJECTIVE: We studied effects of HT on subcutaneous and visceral AT estrogen and androgen concentrations and metabolism in postmenopausal women. DESIGN, SETTING, PATIENTS, AND INTERVENTIONS: Serum and subcutaneous and visceral AT from 63 postmenopausal women with (n=50) and without (n=13) per oral HT were analyzed for estrone, estradiol, progesterone, testosterone, androstenedione, dehydroepiandrosterone, and serum estrone sulfate using liquid chromatography-tandem mass spectrometry. Steroid sulfatase activity was measured using radiolabeled precursors. mRNA expression of genes encoding sex steroid-metabolizing enzymes and receptors was performed using real-time reverse transcription quantitative polymerase chain reaction. RESULTS: HT users had 4- to 7-fold higher concentrations of estrone and estradiol in subcutaneous and visceral AT, and 30% lower testosterone in visceral AT compared to non-users. Estrogen-to-androgen ratios were 4- to 12-fold higher in AT of users compared to non-users of HT. In visceral AT, estrogen-to-androgen ratios increased with HT estradiol dose. AT to serum ratios of estrone and estradiol remained high in HT users. CONCLUSIONS: Higher local estrogen to androgen ratios and high AT to serum ratios of estrogen concentrations in HT users suggest that HT may significantly influence intracrine sex steroid metabolism in AT, and these local changes could be involved in the preventive effect of HT on menopause-associated abdominal adiposity.

Adipose tissue estrogen production and metabolism in premenopausal women.

OBJECTIVE: Although the ovaries produce the majority of estrogens in women before menopause, estrogen is also synthesized in peripheral tissues such as adipose tissue (AT). The typical female AT distribution, concentrated in subcutaneous and femoro-gluteal regions, is estrogen-mediated, but the significance of estrogen synthesis in AT of premenopausal women is poorly understood. DESIGN AND METHODS: Serum and subcutaneous and visceral AT homogenates from 28 premenopausal women undergoing non-malignant surgery were analyzed for estrone, estradiol, and serum estrone sulfate (E1S) concentrations with liquid chromatography-tandem mass spectrometry. Isotopic precursors were used to measure enzyme activities of estrone-producing steroid sulfatase and estradiol-producing 17ß-hydroxysteroid dehydrogenases (17ß-HSD). Messenger RNA (mRNA) expression levels of genes for estrogen-metabolizing enzymes were analyzed using real-time reverse transcription quantitative polymerase chain reaction. RESULTS: While estradiol was the predominant circulating active estrogen, estrone dominated in AT, with a higher concentration in visceral than subcutaneous AT (median, 2657 vs 1459 pmol/kg; P = 0.002). Both AT depots converted circulating E1S to estrone, and estrone to estradiol. Median levels of estrone were five to ten times higher in subcutaneous and visceral AT than in serum (P < 0.001) and the estradiol level in visceral AT was 1.3 times higher than in serum (P < 0.005). The local estrone concentration in visceral AT correlated positively with mRNA expression of estrone-producing enzyme aromatase (r = 0.65, P = 0.003). Waist circumference correlated positively with increased estradiol production in subcutaneous AT (r = 0.60, P = 0.039). CONCLUSIONS: Premenopausal AT demonstrated high estrogenic enzyme activity and considerable local estrogen concentrations. This may be a factor promoting female-typical AT distribution in premenopausal women.

Estrogen Metabolism in Abdominal Subcutaneous and Visceral Adipose Tissue in Postmenopausal Women.

Context: In postmenopausal women, adipose tissue (AT) levels of estrogens exceed circulating concentrations. Although increased visceral AT after menopause is related to metabolic diseases, little is known about differences in estrogen metabolism between different AT depots. Objective: We compared concentrations of and metabolic pathways producing estrone and estradiol in abdominal subcutaneous and visceral AT in postmenopausal women. Design, Setting, Patients, and Interventions: AT and serum samples were obtained from 37 postmenopausal women undergoing surgery for nonmalignant gynecological reasons. Serum and AT estrone, estradiol, and serum estrone sulfate (E1S) concentrations were quantitated using liquid chromatography-tandem mass spectrometry. Activity of steroid sulfatase and reductive 17ß-hydroxysteroid dehydrogenase enzymes was measured using radiolabeled precursors. Messenger RNA (mRNA) expression of estrogen-converting enzymes was analyzed by real-time reverse transcription quantitative polymerase chain reaction. Results: Estrone concentration was higher in visceral than subcutaneous AT (median, 928 vs 706 pmol/kg; P = 0.002) and correlated positively with body mass index (r = 0.46; P = 0.011). Both AT depots hydrolyzed E1S to estrone, and visceral AT estrone and estradiol concentrations correlated positively with serum E1S. Compared with visceral AT, subcutaneous AT produced more estradiol from estrone (median rate of estradiol production, 1.02 vs 0.57 nmol/kg AT/h; P = 0.004). In visceral AT, the conversion of estrone to estradiol increased with waist circumference (r = 0.65; P = 0.022), and estradiol concentration correlated positively with mRNA expression of HSD17B7 (r = 0.76; P = 0.005). Conclusions: Both estrone and estradiol production in visceral AT increased with adiposity, but estradiol was produced more effectively in subcutaneous fat. Both AT depots produced estrone from E1S. Increasing visceral adiposity could increase overall estrogen exposure in postmenopausal women.