PPARγ2 protects against obesity by means of a mechanism that mediates insulin resistance

P>Background Many studies have focused on the physiological parameters and genetic predisposition of subjects presenting both obesity and insulin resistance (IR) and it has been suggested that the peroxisome proliferator-activated receptor gamma 2 (PPAR gamma 2) Pro12Ala variant may contribute to the observed variability in insulin sensitivity. We investigated whether the PPAR gamma 2 mRNA expression levels are associated with IR in morbid obesity in adipose and muscle tissues. Materials and methods In this study, tissue biopsies were obtained from 26 morbidly obese (MO) patients and eight controls. The MO patients were divided into two groups: those with a low homeostasis model assessment of IR (HOMA-IR < 5) (MO-nonIR) and those with a high HOMA-IR (HOMA-IR >= 8) (MO-IR). PPAR gamma 1, PPAR gamma 2 and aP2 mRNA expression levels were measured using quantitative RT-PCR. Results The study found that PPAR gamma 2 mRNA expression in visceral adipose tissue (VAT) was significantly lower in the MO patients (P = 0 center dot 002) than the controls. Moreover, the PPAR gamma 2 mRNA expression was lower in VAT (P < 0 center dot 05) and muscle tissue (P < 0 center dot 01), and higher in subcutaneous adipose tissue (SAT) (P < 0 center dot 01) in the MO-IR than the MO-nonIR group. By contrast, PPAR gamma 1 mRNA expression levels were not dependent on IR. Finally, the MO patients showed a significant negative correlation between PPAR gamma 2 mRNA expression and IR (r = -0 center dot 396, P = 0 center dot 020) in VAT and a positive correlation in SAT (r = 0 center dot 826, P < 0 center dot 001). The variable that best explained the IR was PPAR gamma 2 mRNA expression in SAT (P = 0 center dot 002). Conclusions These data show that PPAR gamma 2 mRNA is expressed differently in the two types of MO patients and is associated with IR.