Oral Quercetin Supplementation Lowers Plasma sICAM-1 Concentrations in Female db/db Mice

Silvia Wein,Gerald Rimbach,Siegfried Wolffram,Eva Schrader

doi:10.4236/pp.2013.41011

Abstract

Background: Flavonoids are documented for their potential anti-adipogenic, anti-inflammatory and anti-diabetic effects. Quercetin, one of the most abundant flavonoids in edible plants, was investigated for these effects in a diabetic mouse model (db/db, leptin receptor mutation) exerting early relevant clinical signs of non-insulin dependent diabetes mellitus, such as hyperglycemia, hyperinsulinemia, hypertriglyceridemia, hypoadiponectinemia and obesity. Materials & Methods: Female db/db mice (n = 24) were fed a flavonoid-poor maintenance diet without (C) or with the addition of quercetin (0.3 g/kg diet, Q) or rosiglitazone (4 mg/kg diet, TZD). Food and water were freely available during the 4 week feeding period. Thereafter, blood samples (fasted) were analyzed for glucose, insulin, triacylglycerols, non-esterified fatty acids, cholesterol, adiponectin and soluble intercellular adhesion molecule-1 (sICAM-1). Adiponectin mRNA levels were measured in adipose tissue. Furthermore, sICAM-1 release was investigated using tumor necrosis factor alpha stimulated EAhy926 cells. Results: Only TZD treatment reduced fasted plasma glucose, triacylglycerols and cholesterol and increased plasma adiponectin concentrations compared to groups C and Q. Adiponectin mRNA levels after quercetin treatment were not different from TZD-treatment or controls. Only quercetin treatment reduced sICAM-1 release in vitro and in vivo. Conclusions: Quercetin effectively reduced sICAM-1 release in the progressive diabetic state, revealing its anti-inflammatory potential in vivo.

Highlights

Obesity is associated with endocrine dysfunction of adipose tissue resulting in elevated secretion of pro-inflammatory cytokines [1], oxidative stress [2], and hypoadiponectinemia [3] contributing to the pathogenesis of insulin resistance [4]
Four weeks of oral quercetin treatment of female db/db mice reduced plasma soluble intercellular adhesion molecule-1 (sICAM-1) concentrations compared to controls (Table 3). sICAM-1 concentrations tended (P < 0.058) to be lower in the quercetin-treated group compared to in the TZD-treated group (Table 3)
In contrast to TZD treatment, quercetin treatment did not result in reduced fasting plasma glucose, TG or cholesterol levels compared to controls (Table 3)

Summary

Introduction

Obesity is associated with endocrine dysfunction of adipose tissue resulting in elevated secretion of pro-inflammatory cytokines [1], oxidative stress [2], and hypoadiponectinemia [3] contributing to the pathogenesis of insulin resistance [4]. Cytokines, such as tumor necrosis factor alpha (TNF-α), induce the expression and release of adhesion molecules (ICAM-1) in different cell types [5]. Conclusions: Quercetin effectively reduced sICAM-1 release in the progressive diabetic state, revealing its anti-inflammatory potential in vivo

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Conclusion