The Plant Flavonoid, Quercetin, Reduces Some Forms of Dioxin Toxicity by Mechanism Distinct from Aryl Hydrocarbon Receptor Activation, Heat-Shock Protein Induction and Quenching Oxidative Stress

Abstract

To clarify the relationship between heat shock protein (Hsp) 70 expression and dioxin toxicity, we studied the effect of quercetin, which is an inhibitor of the biosynthesis of Hsp70, on the acute toxicity of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in C57BL/6J mice. Contrary to our expectation, results showed that continuous administration of quercetin could attenuate the reduction in body weight gain produced by TCDD (100 μg/kg, p.o.). In addition, the hepatomegaly was also significantly reduced by treatment with quercetin for 1 and 30 day(s) after TCDD treatment in spite of having no effect on thymic atrophy. On the other hand, quercetin showed no notable effects on TCDD-induced changes in hepatic Hsp70.1 mRNA, ethoxyresorufin O-deethylase activity and lipid peroxidation. Although we failed to clarify the exact protective mechanisms, our data suggest that quercetin has a protective effect against some forms of dioxin toxicity.