Omental Gene Expression of Adiponectin Correlates with Degree of Insulin Sensitivity Before and After Gastric Bypass Surgery

Abstract

Background and Aim 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 (RT-PCR) was used for analysis of the adipose tissues. Adiponectin expression was normalized for GAPDH 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 5-fold higher in subjects after GB when compared with age matched morbidly obese subjects before GB (P<0.01). There were not 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. Conclusion Omental adiponectin gene expression significantly increase 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.

Effect of adiposity on tissue-specific adiponectin secretion

“…In another study of 25 women undergoing elective gynecological surgeries, adiponectin expression was higher in SAT compared to omental AT in both lean and overweight women [ 22 ]. Furthermore, Chen and colleagues found that omental expression of adiponectin was much higher after weight loss with gastric bypass surgery when compared to age-matched obese controls undergoing the same surgery and matched non-obese controls [ 23 ]. Our study evaluated AT (in contrast to adipocytes) secretion of adiponectin in a relatively large sample size of both men and women (in contrast to studies limited to women).…”

Does bariatric surgery improve adipose tissue function?

“…These findings point strongly towards adipose tissue regaining its endocrine capacity after surgery. It has also been reported that SAT expression of leptin goes down after RYGB whereas adiponectin gene expression in primarily SAT was reported to increase in only one out of five studies . In the context of these findings it is worth mentioning the novel hypothesis that adiponectin is produced in significant amounts by adipocytes in the bone marrow .…”

Ekspresja adiponektyny w otyłości trzewnej jest istotnym wyznacznikiem insulinooporności w otyłości olbrzymiej

“…Similar results were recently reported by Chen et al, who analysed adiponectin gene expression in the omental adipose tissue in 40 patients, of whom 25 were obese and showed an inverse correlation with HOMA-IR. In the same study, adiponectin gene expression was significantly increased (by about five times) after gastric bypass intervention, paralleling the improvement in insulin resistance [26].…”