Effects of quercetin on serum levels of resistin and IL-18 and on insulin resistance in nonalcoholic fatty liver disease rats / 中华肝脏病杂志

ABSTRACT

<p><b>OBJECTIVE</b>To investigate the effects of quercetin on serum levels of resistin and interleukin (IL)-18 and incidence of insulin resistance (IR) in nonalcoholic fatty liver disease (NAFLD) using a rat model.</p><p><b>METHODS</b>NAFLD was induced in Sprague-Dawley rats by administering a high-fat diet for four weeks. The model rats were then treated with quercetin (oral gavage administration; low dose group 75 mg/kg/day, high dose group 300 mg/kg/day) for eight weeks. Untreated model rats served as controls. Serum levels of resistin, triglyceride (TG), IL-18, fasting plasma glucose (FPG), fasting insulin (FINS), and malondialdehyde (MDA) were measured by standard biochemical assays before and after the quercetin administration. In addition, the insulin resistance index (HOMA-IR) was calculated and pathological changes in liver were observed by histological analysis.</p><p><b>RESULTS</b>Compared to the untreated model rats, the quercetin treated model rats showed significantly lower serum resistin (5.98 vs. 2.70), serum IL-18 (10.93 vs. 8.21), FPG (7.45 vs. 4.99), FINS (12.69 vs. 8.59), and HOMA-IR (4.22 vs. 1.87) (all P less than 0.01). Compared to the untreated model group, the high dose group showed significantly lower TG (t = 4.70) and MDA (t = 5.14) (both P less than 0.01). Serum levels of resistin and IL-18, and levels of TG, FPG and FINS were found to be positively correlated with HOMA-IR and the degree of liver disease (r more than 0, all P less than 0.05). The degree of degeneration was decreased in accordance with the dosages of quercetin, as compared to the untreated model group (U = 4.41 and 2.19, both P less than 0.05), and the pathological degree was less extensive in the high dose group than in the low dose group (U = 2.44, P less than 0.01).</p><p><b>CONCLUSION</b>Quercetin treatment reduces levels of inflammatory cytokines and improves lipid peroxidation and IR in NAFLD rats, and its beneficial effects appear to increase with higher dosage.</p>