Quercetin Ameliorates Metabolic Syndrome and Improves the Inflammatory Status in Obese Zucker Rats

Abstract

The aim of this study was to analyze the effects of chronic administration of high doses of quercetin on metabolic syndrome abnormalities, including obesity, dyslipidemia, hypertension, and insulin resistance. For this purpose, obese Zucker rats and their lean littermates were used. The rats received a daily dose of quercetin (2 or 10 mg/kg of body weight) or vehicle for 10 weeks. Body weight and systolic blood pressure (SBP) were recorded weekly. At the end of the treatment, plasma concentrations of triglycerides, total cholesterol, free-fatty acids (FFAs), glucose, insulin, adiponectin, and nitrate plus nitrite (NOx) were determined. Tumor necrosis factor-α (TNF-α) production, inducible nitric oxide synthase (iNOS), and endothelial nitric oxide synthase (eNOS) protein expression were analyzed in visceral adipose tissue (VAT). The raised SBP and high plasma concentrations of triglycerides, total cholesterol, FFA, and insulin found in obese Zucker rats were reduced in obese rats that received either of the doses of quercetin assayed. The higher dose also improved the inflammatory status peculiar to this model, as it increased the plasma concentration of adiponectin, reduced NOx levels in plasma, and lowered VAT TNF-α production in obese Zucker rats. Furthermore, chronic intake of the higher dose of quercetin enhanced VAT eNOS expression among obese Zucker rats, whereas it downregulated VAT iNOS expression. In conclusion, both doses of quercetin improved dyslipidemia, hypertension, and hyperinsulinemia in obese Zucker rats, but only the high dose produced antiinflammatory effects in VAT together with a reduction in body weight gain.

Long-term resveratrol administration reduces metabolic disturbances and lowers blood pressure in obese Zucker rats

“…Various natural molecules found in the human diet have been described as potential 4 agents to treat diabetes and hyperlipidemia [11][12][13][14]. Furthermore, recent studies have shown that some of these compounds strongly stimulate hepatic AMPK [11][12][13], an action that may help to explain some of the antihyperlipidemic effects of these natural derivatives and that provides an avenue for ameliorating hyperlipidemia and accelerated atherosclerosis in diabetes [11].…”

ApoE genotype: from geographic distribution to function and responsiveness to dietary factors

“…Epidemiological studies, together with data from animal models and some clinical trials, suggest a role of dietary flavonoids in the prevention of CVD and other age-related chronic diseases (108)(109)(110) . The flavonol quercetin exhibits a wide range of physiological effects such as inhibition of LDL-oxidation, lowering of arterial blood pressure and platelet aggregation, and improvement of endothelial function as shown in animal models and in human subjects (111)(112)(113)(114)(115)(116)(117) . Furthermore, cell culture and animal studies indicate a potent anti-inflammatory activity of quercetin (116,(118)(119)(120) .…”

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

“…We have chosen the db/db mouse as a model of diabetes because it reliably reflects the development of insulin resistance towards progressive β-cell failure with hyperglycemia as found in human NIDDM. Based on the results from the present study in db/db mice and previous studies in other animal models of obesity [28,29], we conclude that the effects of quercetin are not anti-adipogenic. Rosiglitazone, a member of the thiazolidinediones and a well-established insulin-sensitizing drug, is known to increase body weight [34].…”

“…In vitro studies in 3T3-L1 preadipocytes have indicated anti-adipogenic effects of the flavonol quercetin, suggesting inhibition of differentiation [26,27] and TG accumulation [27]. Oral quercetin supplementation has also been shown to reduce visceral adipose tissue in C56BL/6J mice and obese Zucker rats fed a high-fat/high-sucrose diet for 20 [28] and 10 weeks [29], respectively. However, in the present study, 4 weeks of oral quercetin supplementation in db/db mice had no effect on body weight and rather increased periuterine adipose tissue.…”