Visceral adiposity, increased adipocyte lipolysis, and metabolic dysfunction in obese postmenopausal women.

Abstract

This study determines whether there are regional differences in lipolysis and whether adipocyte lipolysis is associated with the degree of visceral adiposity and its metabolic complications in 32 obese (28-37 kg/m2), nondiabetic, postmenopausal women. In vitro lipolysis was measured in the basal state and after addition of epinephrine (Epi), Epi plus yohimbine, Epi plus propranolol, and N6,2'-O-dibutyryl adenosine 3',5'-cyclic monophosphate (DBcAMP) in abdominal (ABD) and gluteal (GLT) adipocytes. Upper body obese [UBO, waist-to-hip ratio (WHR) > or = 0.80, n = 19] women had a greater intra-abdominal fat area (IA, 199 +/- 50 vs. 142 +/- 28 cm2) and Epi-stimulated lipolysis (ABD: 1.60 +/- 1.10 vs. 0.95 +/- 0.54 mumol glycerol.10(6) cells-1.2h; GLT: 1.14 +/- 0.70 vs. 0.66 +/- 0.42 mumol glycerol.10(6) cells-1.2 h) than lower body obese (LBO, WHR < 0.80, n = 13) women. The UBO women also had lower high-density lipoprotein cholesterol (1.39 +/- 0.40 vs. 1.64 +/- 0.39 mmol/l, P < 0.05), higher plasma triglycerides (1.89 +/- 0.48 vs. 1.44 +/- 0.56 mmol/l, P < 0.05), and higher fasting insulin levels (154 +/- 57 vs. 118 +/- 33 pmol/l, P < 0.05) than LBO women. Basal, adrenergic receptor-mediated, and DBcAMP-stimulated lipolytic rates in ABD and GLT adipocytes were positively correlated with IA (r = 0.44-0.76, P < 0.05, n = 28). In both UBO and LBO women, Epi-stimulated lipolysis was higher (+30%, P < 0.05) in ABD than GLT adipocytes. These results show that, in postmenopausal women, visceral obesity is associated with increased rates of lipolysis in both ABD and GLT subcutaneous adipocytes. The findings also indicate that Epi-stimulated lipolysis is greater in ABD than GLT adipocytes regardless of fat distribution.