Objective: We tested the hypothesis that women with adipocyte hypertrophy in either omental (OM) or subcutaneous (SC) adipose tissue are characterized by alterations in adipocyte lipolysis and adipose tissue expression of genes coding for proteins involved in adipocyte metabolism or inflammation, independent of overall adiposity and fat distribution.
Methods: OM and SC fat samples were obtained surgically in 44 women (age: 47.1±5.0years, BMI: 27.7±5.3kg/m(2)). In a given depot, women with larger adipocytes than predicted by the regression of adipocyte size vs. total and regional adiposity measurements were considered as having adipocyte hypertrophy, whereas women with smaller adipocytes than predicted were considered as having adipocyte hyperplasia.
Results: Women with OM adipocyte hypertrophy had significantly lower SC GLUT4 mRNA abundance (p≤0.05), higher SC CEBPB mRNA expression (p≤0.05) as well as higher mRNA expression of OM PLIN (p≤0.05), CD68 (p≤0.10), CD14 (p≤0.10), CD31 (p≤0.05) and vWF (p≤0.05) compared to women with OM adipocyte hyperplasia. OM adipocyte isoproterenol- (10(-10) to 10(-5)mol/L), forskolin- (10(-5)mol/L) and dibutyryl cAMP- (10(-3)mol/L) stimulated lipolysis was higher in women with hypertrophic OM adipocytes (p≤0.05, for all). Women with SC adipocyte hypertrophy had lower SC mRNA expression of GLUT4 (p≤0.10), higher SC mRNA expression of CEBPB (p≤0.05), lower plasma adiponectin concentrations (p≤0.05) and higher SC adipocyte isoproterenol- (10(-9) to 10(-5)mol/L) stimulated lipolysis (p≤0.05) compared to women with SC adipocyte hyperplasia.
Conclusion: Hypertrophic adipocytes in both fat compartments are characterized by alterations in adipocyte lipolysis and adipose tissue expression of genes coding for proteins involved in adipocyte metabolism or inflammation.
Keywords: Adipocyte; Gene expression; Hyperplasia; Hypertrophy; Inflammation; Lipolysis.
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