%0 Journal Article
%T Associations between Tissue Visfatin/Nicotinamide, Phosphoribosyltransferase (Nampt), Retinol Binding Protein-4, and Vaspin Concentrations and Insulin Resistance in Morbidly Obese Subjects
%A Zeynep Goktas
%A Shannon Owens
%A Mallory Boylan
%A David Syn
%A Chwan-Li Shen
%A Debra B. Reed
%A Susan San Francisco
%A Shu Wang
%J Mediators of Inflammation
%D 2013
%I Hindawi Publishing Corporation
%R 10.1155/2013/861496
%X Visfatin/Nampt, vaspin, and retinol binding protein-4 (RBP-4) play an important role in insulin resistance. The objectives of this study were to measure visfatin/Nampt, vaspin, and RBP-4 concentrations in blood, liver, muscle, subcutaneous, omental, and mesenteric adipose tissues in morbidly obese subjects and investigate their relationship to insulin resistance. Blood and tissue samples were collected from 38 morbidly obese subjects during Roux-en-Y surgery. Insulin resistance biomarkers were measured using standard kits. Visfatin/Nampt, vaspin, and RBP-4 gene expression levels in tissues were measured using real-time PCR. Their protein concentrations in blood and tissues were measured using ELISA kits. Diabetic subjects had significantly higher homeostasis model of assessment-insulin resistance and age and lower blood HDL-cholesterol concentrations than nondiabetic and prediabetic subjects. Diabetic and prediabetic subjects had significantly higher blood concentrations of visfatin/Nampt and vaspin than nondiabetic subjects. Liver RBP-4 concentrations were positively associated with blood glucose concentrations. Blood insulin resistance biomarker levels were positively associated with visfatin/Nampt concentrations in omental adipose tissue and liver, and vaspin concentrations in mesenteric adipose tissue. In conclusion, the correlations of visfatin/Nampt, vaspin, and RBP-4 with insulin resistance are tissue dependent. 1. Introduction Obesity is a multifactorial disease, which is linked to many chronic diseases including cardiovascular disease and type 2 diabetes [1, 2]. Many research studies indicate that obesity is a low-grade inflammatory condition [3, 4]. Expanded adipose tissue functions as an endocrine organ, which produces and secretes a number of hormones and cytokines known as adipokines [5, 6]. Visfatin/Nampt, vaspin, and retinol binding protein-4 (RBP-4) are novel adipokines and may play important roles in insulin resistance development. Increased visceral fat mass was positively associated with insulin resistance [7, 8]. Visfatin was identified as an adipokine in 2005 by Fukuhara and colleagues [9]. Early research suggested that this peptide adipokine produces insulin-mimetic effects by binding to the insulin receptors and activating downstream insulin signaling pathways [9¨C11]. However, due to failure to reproduce these data, Fukuhara and colleagues retracted their findings in 2007 [12]. The relationship between insulin resistance and blood or tissue visfatin/Nampt concentrations is not clear. Some studies indicate that blood visfatin/Nampt
%U http://www.hindawi.com/journals/mi/2013/861496/