Adipose tissue diacylglycerol acyltransferase activity and blood lipoprotein triglyceride enrichment in women with abdominal obesity

Abstract

Previous studies have suggested altered triglyceride (TG) storage in patients with abdominal obesity and blood lipid disorders. ObjectiveWe hypothesized that women with abdominal obesity and a dysmetabolic profile have low DGAT activity in their abdominal fat compartments. MethodsPaired omental (OM) and subcutaneous (SC) adipose tissue samples were obtained surgically from 39 women undergoing abdominal hysterectomies. Body composition and fat distribution were measured by dual energy x-ray absorptiometry and computed tomography. DGAT activity was measured by acylation of sn-l,2-diacylglycerol with [14C] oleoyl-CoA in microsomal fractions isolated from whole adipose tissue homogenates. DGAT activity was calculated on the basis of picomoles (pmol) TG synthesized in the assay per min per mg lipid, per μg protein or per 1000 cells. ResultsNo depot differences were found when DGAT activity was reported per μg microsomal protein or per 1000 cells. DGAT activity in either depot was not associated with adipocyte diameters and blood lipid profile variables. DGAT activity per mg lipid was higher in OM than in abdominal SC adipose tissue (0.43 ± 0.20 vs. 0.34 ± 0.18 pmol/min/mg lipid, p < 0.05). OM DGAT activity was negatively correlated with OM adipocyte diameter and visceral adipose tissue area (r = −0.43, p < 0.01 and r = −0.38, p < 0.05 respectively). Plasma total, LDL and HDL TG levels were negatively associated with OM DGAT activity independent of total body fat mass (r = −0.39, p < 0.05, r = −0.46, p < 0.001 and r = −0.40, p < 0.05 respectively). ConclusionA defect in adipose tissue DGAT activity is predictive of adiposity and blood lipoprotein TG enrichment only when considering activity per tissue lipid mass.