Registration Dossier

Administrative data

Endpoint:
neurotoxicity
Remarks:
other: in vivo and in vitro studies
Type of information:
experimental study
Adequacy of study:
other information
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: special investigation

Data source

Reference
Reference Type:
publication
Title:
Neurotoxic potential of iron oxide nanoparticles in the rat brain striatum and hippocampus
Author:
Wu J, Ding T, Sun J
Year:
2013
Bibliographic source:
NeuroToxicology 34 (2013) 243–253

Materials and methods

Principles of method if other than guideline:
The study focuses on the effects of Fe3O4-NPs on the striatum and hippocampus, including oxidative injury and the accumulation and retention of Fe3O4-NPs. The study also explores the molecular mechanism of oxidative damage in dopaminergic neurons.
GLP compliance:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
solid: nanoform
Details on test material:
The Fe3O4-NPs employed in this study were measured by TEM to be 30 nm in size (Fig. 2A) and remained spherical after being labelled with 125I. The hydrodynamic diameters of the Fe3O4-NPs and 125I-Fe3O4-NPs in physiological saline were 496+/- 86 nm and 462+/-75 nm, respectively. Zeta potential determination revealed that the Fe3O4-NPs and 125I-Fe3O4-NPs were 9.1+/- 2.2 mV and 8.4+/- 2.1 mV in physiological saline, respectively. Statistical comparisons showed no significant increases in size or zeta potential in the labelled particles (p > 0.05).

Test animals

Species:
rat
Strain:
other: SD
Sex:
male

Administration / exposure

Route of administration:
other: intranasal
Vehicle:
physiological saline
Duration of treatment / exposure:
The rats in our studies were divided into four groups:
(1) intranasally instilled with 125I-Fe3O4-NPs for 1 day (In1d, euthanised at 1 d);
(2) intranasally instilled with 125IFe3O4-NPs for 7 days (In7d, euthanised at 8 d);
(3) 7 days postinstillation (post in 7d, euthanised at 14 d);
(4) 14 days postinstillation (post in 14d, euthanised at 21 d)
Frequency of treatment:
The rats in our studies were divided into four groups:
(1) intranasally instilled with 125I-Fe3O4-NPs for 1 day (In1d, euthanised at 1 d);
(2) intranasally instilled with 125IFe3O4-NPs for 7 days (In7d, euthanised at 8 d);
(3) 7 days postinstillation (post in 7d, euthanised at 14 d);
(4) 14 days postinstillation (post in 14d, euthanised at 21 d)
No. of animals per sex per dose:
Six animals were euthanised at each time point (2 d, 8 d, 14 d, and 21 d)

Results and discussion

Any other information on results incl. tables

A regional distribution of Fe3O4-NPs was observed in rat brains after the particles were intranasally instilled for seven days. The particles were found to be deposited at particularly high concentrations in the rat striata and hippocampi. Over half of the Fe3O4-NPs were retained in the striata for a minimum of 14 days, and may have induced oxidative damage to the region. However, no injuries were observed in the hippocampi. These in vitro studies demonstrate that Fe3O4-NPs may decrease neuron viability, trigger oxidative stress, and activate JNK- and p53-mediated pathways to regulate the cell cycle and apoptosis. These results also suggest that environmental exposure to Fe3O4-NPs may play a role in the development of neurodegenerative diseases.

Applicant's summary and conclusion

Executive summary:

This study focuses on the effects of Fe3O4-NPs on the striatum and hippocampus, including oxidative injury and the accumulation and retention of Fe3O4-NPs. This study also explores the molecular mechanism of oxidative damage in dopaminergic neurons.

A regional distribution of Fe3O4-NPs was observed in rat brains after the particles were intranasally instilled for seven days. The particles were found to be deposited at particularly high concentrations in the rat striata and hippocampi. Over half of the Fe3O4-NPs were retained in the striata for a minimum of 14 days, and may have induced oxidative damage to the region. However, no injuries were observed in the hippocampi. These in vitro studies demonstrate that Fe3O4-NPs may decrease neuron viability, trigger oxidative stress, and activate JNK- and p53-mediated pathways to regulate the cell cycle and apoptosis. These results also suggest that environmental exposure to Fe3O4-NPs may play a role in the development of neurodegenerative diseases.