Lanthanum Oxide Nanoparticles Distribution in Wistar Rats after Oral Exposure and Respective Effects

Abstract

Adult Wistar rats were exposed to lanthanum oxide nanoparticles (La2O3-NPs). Animals were initially treated with single doses of La2O3-NPs suspensions at 5.0, 50, 300 and 2000 mg kg-1 per body weight (bw), which were orally administered. Behavior changes, symptoms of intoxication and mortality were not observed for individuals treated with the La2O3-NPs. However, the histological analysis of different organs of the treated rats revealed that 300 mg kg-1 and 2000 mg kg-1 bw La2O3-NPs caused hepatic lesions. Subsequently, 40 individuals were divided in four groups with 10 individuals in each group and daily treated with water only (control) and with 1.0, 10 and 100 mg kg-1 bw La2O3-NPs. After 30 days, it was observed that the La2O3-NPs did not affect the body weight and organs weight of the animals. The La2O3-NPs also did not change the levels of creatinine, urea, glutamyl transferase (γ-GT), alanine aminotransferase (ALT), aspartate aminotransferase (AST) and thiobarbituric acid reactive substances (TBARS) in blood serum. Neurotoxicity, evaluated by the acetylcholinesterase (AChE) activity, was not observed as well. An increase of reactive oxygen species (ROS) was found in kidney of rats treated with 100 mg kg-1 bw La2O3-NPs. Conversely, protein oxidation decreased in the liver of those animals. The catalase (CAT) activity was not affected by La2O3-NPs and that of superoxide dismutase (SOD) was in the liver of animals treated with 10 mg kg-1 bw La2O3-NPs. Lanthanum was determined in organs and blood of the treated animals. The element was not detected in the blood but was in the organs, in higher concentration in liver, kidneys, and heart. Lanthanum present in the form of NPs or as free ion could not be detected. As such, it is worth investigating possible transformation of La2O3-NPs in the organism, their elimination routes, and effects of longer exposure times.