Analysis of Brain Tissue Metabolites in Rats Following Chronic Exposure to Cerium Oxide via the Gastrointestinal Tract

In this study, twenty SD rats were randomly divided into a control group and experimental group (500 mg/kg CeO₂NPs), with 10 rats in each group. The rats were expose to the toxin by gavage every other day for a duration of 90 days. Behavioral tests in the water maze were conducted on day 84th day of exposure. Brain tissue samples were collected 24 h allowed by ICP-MS analysis to detect the presence of Ce element in rat brain tissue, and metabolomics analysis was performed on brain tissue samples. The study revealed a statistical significant weight loss in the experimental group compared to the control group, at 6 and 20 days during gavage, with stastical significance (<italic>P</italic>&lt;0.05). The content of Ce element in the brain tissue of rats in the experimental group was 4.6600 mg/kg±0.0466 mg/kg. There were no significant differences in the behavioral experiments between the two groups. A total of 350 metabolites were detected by metabolomics, and there were six differential metabolites compared with the control group, all down regulated. The above research results indicate that CeO₂NPs with a particle size &lt;50 nm are capable of traversing the blood-brain barrier and penetrating the brain tissue. According to the water maze behavioral analysis and brain tissue metabolomics analysis, long term (90 days) exposure of the gastrointestinal tract to a high dose (500 mg/kg) of CeO₂NPs had no effect on the learning and memory of rats, and the metabolism of brain tissue was normal down-regulated.