Dietary exposure to silver nanoparticles in Sprague-Dawley rats: effects on oxidative stress and inflammation

Due to undesirable hazardous interactions with biological systems, we evaluated the effect of silver nanoparticles (AgNPs) intake on oxidative stress and inflammation. Rats received for 81 days a standard diet (Controls) or a standard diet plus 500 mg/d/kg BW AgNPs. We assayed plasma lipids, and oxidative stress was assessed by measuring liver and heart superoxide anion production (O₂°⁻) and liver malondialdehyde levels (MDA). Antioxidant status was appraised using plasma paraoxonase activity (PON), plasma antioxidant capacity (PAC) and liver superoxide dismutase activity (SOD). Liver inflammatory cytokines TNFα and IL-6 levels and plasma alanine aminotransferase (ALT) were assayed. Compared with Controls, AgNPs raised cholesterolemia (9.5%), LDL-cholesterol (30%), and lowered triglycerides (41%). They also increased liver (30%) and cardiac (41%) O₂°⁻ production, reduced PON activity (15%) and raised liver TNFα (9%) and IL-6 (∼12%). Plasma ALT activity rose (12%) after treatment with AgNPs. However, PAC and liver MDA and SOD activity were unchanged. These features indicate that exposure to 500 mg/d/kg BW of AgNPs results in liver damage by a dysregulation of lipid metabolism, highlighting liver and heart as the most sensitive organs to the deleterious effects. Our findings also demonstrate for the first time the oxidative and inflammatory effects of dietary AgNPs.