Omental gene expression of adiponectin correlates with degree of insulin sensitivity before and after gastric bypass surgery

Background: Circulating adiponectin is known to correlate negatively with insulin resistance in patients with obesity and diabetes. The aim of this study was to assess the effect of gastric bypass (GB) surgery on adiponectin gene expression in subcutaneous and omental adipose tissues. Methods: Adipose tissues and plasma were obtained from 25 subjects undergoing GB surgery, 15 non-obese subjects, and 12 subjects after GB surgery. Real-time quantitative reverse transcription polymerase chain reaction was used for analysis of the adipose tissues. Adiponectin expression was normalized for glyceraldehyde 3-phosphate dehydrogenase and expressed as percentage of subject-matched subcutaneous expression which was given an arbitrary value of 100%. Insulin resistance was assessed by the homeostatic model assessment (HOMA). Circulating adiponectin was assayed by ELISA. Results: Omental adiponectin gene expression was fivefold higher in subjects after GB when compared with age-matched morbidly obese subjects before GB (P<0.01). There were no statistical differences in omental adiponectin gene expression observed in subjects after GB and age-matched non-obese subjects. For the entire cohort of subjects, there was a significant negative correlation between omental adiponectin expression and insulin resistance expressed by HOMA values (r=-0.62, P<0.001). Circulating adiponectin was significantly lower (P<0.05) in the obese group than in the non-obese and post-GB groups. Conclusions: Omental adiponectin gene expression significantly increases after GB surgery reaching levels equal to age-matched non-obese subjects. Omental adiponectin expression has a significant negative correlation with the insulin resistance status.