Trace metal disturbance in mice brain after intranasal exposure of nano- and submicron-sized Fe₂O₃ particles

Trace metals in the brain play an important role in the function of central nervous system (CNS). The objective of this work is to investigate the effects of intranasal exposure of nano- and submicron-sized Fe₂O₃ particles on the homeostasis of trace metals in the brain. After a single intranasal instillation of nano- and submicron-sized Fe₂O₃ particles, the con-tents of Fe, Cu and Zn in the sub-brain regions were determined in the time course from 4 h till to the 30 day post-exposure. Our results indicated that the imbalance of trace metals in the sub-brain regions of mice was induced by the two sizes of Fe₂O₃ particles. The more significant accumulation of Fe in the brain was found in the nano-Fe ₂O₃ treated mice than in the submicron-Fe ₂O₃ treated ones: meanwhile, similar alterations of Zn contents in the brain were observed as well. A strong positive correlation between Fe and Zn levels in the olfactory bulb of nano-Fe₂O ₃ instilled mice and in the hippocampus and cerebral cortex of submicron-Fe₂O₃ instilled mice were found. This is the first trial to investigate the disturbance of trace metals in the brain after exposure to Fe₂O₃ nanoparticles. These results state that much attention should be paid to the potential impact of inhaled Fe ₂O₃ nanoparticles on the CNS.