Acute changes in murine hippocampus and olfactory bulb after nasal instillation of varying size cerium dioxide particles

ABSTRACT

Cerium (Ce)-containing compounds are now widely applied in medicine, agriculture, and animal breeding. However, the effects of Ce on humans, especially on the central nervous system (CNS), remain to be determined. In order to investigate whether Ce exposure affected the CNS, the aim of this study was to expose female ICR mice to varying nanoparticle sizes of 35 nm and 300 nm, and to a mixture of 1–5 µM cerium dioxide (CeO₂) particles through intranasal (i.n.) instillation at daily dose of 40 mg/kg body weight. Immunohistochemical data showed that glial fibrillary acidic protein expression (GFAP) increased significantly in the hippocampus and olfactory bulb in all Ce-administered groups. The ultrastructure of olfactory bulb cells displayed chromatin reduction. In the hippocampus decreased chromatin was associated with ribosome shedding as evidenced from transmission electron microscopy (TEM). No significant differences in immunohistochemistry were noted between varying sizes of CeO₂ groups. The results of inductively coupled plasma–mass spectroscopy (ICP-MS) analysis group exposed to 1–5 µM demonstrated that Ce levels were significantly higher in whole brain (0.17 ng/mg) than for the control (0.04 ng/mg). Data thus demonstrated that i.n. instillation of different sized CeO₂ particles induced damage in the olfactory bulb and hippocampus and that CeO₂ particle size did not appear to play a role in the observed adverse responses.

FUNDING

This study was funded by National Natural Science Foundation of China (81160341).

Additional information

Funding

This study was funded by National Natural Science Foundation of China (81160341).