Lower expression of adiponectin mRNA in visceral adipose tissue in lean and obese subjects.
Adiponectin is an adipocyte-specific protein suggested to play a role in mediating the metabolic effects of obesity. In the present study, we investigated adiponectin mRNA levels in both visceral and subcutaneous abdominal adipose tissue (AT) from lean and obese subjects. Investigations on both "fresh" fat biopsies and incubations of AT fragments were performed. Regional differences in the effects of the cytokine interleukin-1beta (IL-1beta) were investigated. Adiponectin gene expression was 33% lower in visceral AT than in subcutaneous AT of lean subjects (P < 0.05), and 28% lower in obese subjects, albeit non-significant (P = 0.3). In both lean and obese subjects adiponectin mRNA expression in incubated AT fragments was significantly lower in visceral AT than in subcutaneous AT (lean: P < 0.01; obese: P < 0.05). No difference was found in adiponectin mRNA levels in gluteal compared to abdominal subcutaneous AT. IL-1beta suppressed adiponectin mRNA levels substantially in both subcutaneous and visceral AT. In conclusion, adiponectin gene expression is lower in visceral AT than in subcutaneous abdominal AT, suggesting subcutaneous AT to be more important for circulating adiponectin levels.