The metabolic syndrome is related to β3-adrenoceptor sensitivity in visceral adipose tissue

Abstract

The metabolic syndrome is a well-known risk for the development of cardiovascular disease. In the present study the possible importance of an altered visceral adipocyte β-adrenoceptor function in this syndrome was investigated. In 65 subjects of both sexes undergoing elective surgery for non-malignant-disorders, the metabolic syndrome phenotype and the lipolytic sensitivity for various β-adrenoceptor subtype agonists in omental adipocytes were determined. The study group represented a wide range of abdominal adipose tissue distribution (waist-to-hip ratios 0.76-1.13), but was otherwise apparently healthy. The subjects were divided into three subgroups according to their waist-to-hip (WHR) ratios: 1) WHR < 0.92; 2) WHR 0.92-1.04; 3) WHR > 1.04. The subgroups demonstrated significant differences regarding body mass index, sagittal diameter, systolic and diastolic blood pressures, plasma concentrations of glucose, insulin, triglycerides and HDL-cholesterol (p = 0.005-0.0001). Furthermore, in omental adipocytes β3-adrenoceptor sensitivity, but not β1- and β2-adrenoceptor sensitivities, differed significantly between the WHR subgroups (p = 0.0001). β3-adrenoceptor sensitivity was also related to the other components of the metabolic syndrome, although a strong covariation between WHR and β3-adrenoceptor sensitivity vs blood pressure and the metabolic parameters was found. The present data provide evidence of a relationship between upper body obesity and its associated metabolic complications and also, an increased visceral fat β3-adrenoceptor sensitivity. We suggest that the latter finding results in an augmented release of non-esterified fatty acids from the visceral fat depot to the portal venous system. This may in turn contribute to the development of the metabolic syndrome.