Dietary Intervention with Quercetin Attenuates Diesel Exhaust Particle-Instilled Pulmonary Inflammation and Behavioral Abnormalities in Mice

Exposure to diesel exhaust particles (DEPs) is inevitable and closely linked with increased health hazards, causing pulmonary abnormalities by increasing inflammation, hypoxia, and so on. Moreover, long-term exposure to DEPs may trigger whole-body toxicity with behavioral alterations. Therefore, nutritional intervention with natural components may be desirable to prevent and/or ameliorate DEP-inducible pathophysiology in mammals. Quercetin has been demonstrated to reduce metabolic complications by possessing antioxidative, anti-inflammatory, and antimutagenic effects. In this study, we investigated the effects of quercetin on pulmonary inflammation and behavioral alteration in male C57BL/6 mice against DEP instillation. The experimental mice were separated into four treatment groups (n = 8 per group), which include: vehicle control, DEP instillation, dietary intervention with a low dose of quercetin (20 mg/kg) for 14 days with DEP instillation for 7 days, or dietary intervention with a high dose of quercetin (100 mg/kg) for 14 days with DEP instillation for 7 days. Compared with the DEP-instilled group, dietary intervention with quercetin significantly attenuated eosinophils in the bronchoalveolar lavage fluid analysis, pulmonary cytokine, and hypoxic mRNA expressions regardless of quercetin concentrations. DEP instillation triggered hyperactivities in the experimental mice, while quercetin pretreatment successfully normalized DEP-inducible abnormalities regardless of the dosage. Therefore, dietary intervention with quercetin may be an applicable means to prevent DEP-triggered pulmonary and behavioral abnormalities.