Expression of Peroxisome Proliferator-Activated Receptor-γ₁ and Peroxisome Proliferator-Activated Receptor-γ₂ in Visceral and Subcutaneous Adipose Tissue of Obese Women

Abstract

Data regarding the expression of peroxisome proliferator-activated receptor (PPAR)-γ₁ and PPAR-γ₂ in human visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) are conflicting. To clarify this issue, we studied 50 women who had a BMI >35 kg/m² were undergoing gastric reduction surgery. Phenotyping included recording of anthropometric parameters and of a biological profile. Quantification of the expression of PPAR-γ₁ and PPAR-γ₂ in samples of VAT and SAT was performed by real-time RT-PCR. In both SAT and VAT, the level of expression of PPAR-γ₂ were >20-fold that of PPAR-γ₁ (P < 0.001 for both). However, only PPAR-γ₁ was differentially expressed, its levels in SAT being 216 ± 34% those in VAT (P < 0.001). In a stepwise, multivariate regression analysis, the levels of PPAR-γ₁ in both SAT and VAT were the major determinants of waist circumference (R² = 21% for both; P < 0.01). Finally, leptin but not PPARs appeared as the single parameter explaining the largest part of the variability of BMI in our cohort of patients (R² = 22%, P < 0.001). These results are consistent with the putative roles of PPAR-γ₁ and PPAR-γ₂ in carbohydrate metabolism and energy homeostasis, respectively. As such, they constitute an important step toward the identification of potential targets for novel therapeutic strategies in the fields of obesity.