Transport of intranasally instilled fine Fe2O3 particles into the brain: micro-distribution, chemical states, and histopathological observation.
It has been demonstrated that inhaled fine (d < 2.5 microm) and ultrafine (d < 100 nm) particles produce more severe toxicity than coarse particles. Some recent data support the concept that the central nervous system (CNS) may be a target for the inhaled fine particulates. This work describes initial observation of the transport of intranasally instilled fine ferric oxide (Fe2O3) particles in animal brain. The iron micro-distribution and chemical state in the mice olfactory bulb and brain stem on day 14 after intranasal instillation of fine Fe2O3 particle (280 +/- 80 nm) suspension at a single dose of 40 mg/kg body weight were analyzed by synchrotron radiation x-ray fluorescence and x-ray absorption near-edge structure (XANES). The micro-distribution map of iron in the olfactory bulb and brain stem shows an obvious increase of Fe contents in the olfactory nerve and the trigeminus of brain stem, suggesting that Fe2O3 particles were possibly transported via uptake by sensory nerve endings of the olfactory nerve and trigeminus. The XANES results indicate that the ratios of Fe (III)/Fe (II) were increased in the olfactory bulb and brain stem. The further histopathological observation showed that the neuron fatty degeneration occurred in the CA3 area of hippocampus. Such results imply an adverse impact of inhalation of fine Fe2O3 particles on CNS.
Wang
Bing
B
Laboratory for Bio-Environmental Effects of Nanomaterials and Nanosafety and Key Laboratory of Nuclear Analytical Techniques, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, China.
Feng
Wei Y
WY
Wang
Meng
M
Shi
Jun W
JW
Zhang
Fang
F
Ouyang
Hong
H
Zhao
Yu L
YL
Chai
Zhi F
ZF
Huang
Yu Y
YY
Xie
Ya N
YN
Wang
Hai F
HF
Wang
Jing
J
D000818:Animals; D001692:Biological Transport; D001921:Brain / Q000378:metabolism*; D001933:Brain Stem / Q000378:metabolism; D002490:Central Nervous System / Q000378:metabolism*; D005290:Ferric Compounds / Q000737:chemistry*; D006624:Hippocampus / Q000378:metabolism; D008297:Male; D051379:Mice; D009297:Nasal Mucosa / Q000378:metabolism; D009830:Olfactory Bulb / Q000378:metabolism; D013050:Spectrometry, Fluorescence / Q000379:methods; D013052:Spectrometry, X-Ray Emission; D013997:Time Factors; D014965:X-Rays
D005290:Ferric Compounds; C000499:ferric oxide