Background: Adiponectin is an adipokine with anti-atherogenic and insulin-sensitizing properties. Specific adiponectin receptors, adiponectin receptors 1 (AdipoR1) and 2 (AdipoR2), are present in adipose tissue, indicating adiponectin might have autocrine/paracrine effects on its production or action. In addition, endoplasmic reticulum oxidoreductase 1-Lalpha might mediate regulation of its secretion. The study aim was to determine the subcutaneous adipose tissue (SAT) adiponectin gene and protein expression and their correlation to metabolic parameters during metabolically distinct times after gastric bypass surgery.
Methods: A total of 12 morbidly obese male patients underwent SAT biopsy during gastric bypass surgery, active weight loss (negative energy state), and at weight stabilization (steady state energy). The SAT mRNA and protein content of adiponectin, AdipoR1 and AdipoR2, and endoplasmic reticulum oxidoreductase 1-Lalpha protein levels and the serum levels of adiponectin were assessed.
Results: SAT adiponectin, AdipoR1, and AdipoR2 gene expression increased significantly at the negative energy state, with no further change at steady state energy (P<.05, P<.05, and P=.04, respectively), without significant increases in protein at any stage. Changes in SAT adiponectin protein correlated with changes in AdipoR1 and AdipoR2 during steady state energy (P=.003 and P=.002, respectively). Changes in SAT adiponectin expression did not correlate with those in circulating levels. Changes in endoplasmic reticulum oxidoreductase 1-Lalpha did not correlate with either SAT or circulating levels of adiponectin.
Conclusion: Our data indicate distinct functions of adiponectin receptors, AdipoR1 and AdipoR2, mediate the autocrine/paracrine actions of adiponectin. The lack of correlation between changes in SAT adiponectin gene and protein expression and its circulating levels suggests that adipose tissue synthesis and release of adiponectin are highly regulated pathways.