11β-hydroxysteroid dehydrogenase 2 activity is elevated in severe obesity and negatively associated with insulin sensitivity

Abstract

Alterations in glucocorticoid (GC) metabolism may contribute to the development of obesity and insulin resistance. We aimed to study the role of 11β-hydroxysteroid dehydrogenase type 2 (11β-HSD2) in human adiposity, paying special attention to the association between altered GC metabolism and insulin sensitivity. In 24-h urine samples of 72 extremely obese (mean BMI 45.5 ± 1.1 kg/m2), but otherwise healthy patients urinary free cortisol (UFF), urinary free cortisone (UFE), tetrahydrocortisol (THF), 5α-tetrahydrocortisol (5α-THF), and tetrahydrocortisone (THE) were quantified by radioimmunoassay. The sum of the three major tetrahydrometabolites is an estimate for daily GC secretion, and the sum of UFF and UFE represents potentially bioactive-free-GCs. Thirty healthy lean subjects (BMI 22.3 ± 0.3 kg/m2) served as controls. In obese subjects, absolute daily GC secretion and the potentially bioactive-free-GCs were significantly (P < 0.005) higher than in lean controls (11.8 ± 0.7 vs. 8.0 ± 0.6 mg/d; and 171.8 ± 11.2 vs. 117.6 ± 9.2 μg/d, respectively). However, when these values were corrected for body surface area (BSA), significant differences were no longer detectable. While enzyme activity indices for 5α-reductase and 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) were similar in lean and obese subjects, 11β-HSD2 was markedly elevated in adiposity (3.7 ± 0.2 vs. 2.1 ± 0.1; P < 0.0001). This increase was accompanied by a significant reduction in UFF excretion corrected for BSA (16.5 ± 1.2 vs. 21.7 ± 2.0 μg/d/m2; P = 0.0222). Besides, 11β-HSD2 activity was significantly correlated with insulin sensitivity (P = 0.0262). When body size is accounted for, both adrenal GC secretion and potentially bioactive-free-GCs are indistinguishable between lean and extremely obese subjects. However in obesity, the kidney appears to intensify its supply of the direct substrate cortisone for extrarenal 11β-HSD1, which may fuel visceral adiposity and insulin resistance. © 2008 The Obesity Society.