Effects of subchronic dietary exposure to the engineered nanomaterials SiO and CeO in C57BL/6J and 5xFAD Alzheimer model mice.

Background: There is an increasing concern about the neurotoxicity of engineered nanomaterials (NMs). To investigate the effects of subchronic oral exposures to SiO and CeO NMs on Alzheimer's disease (AD)-like pathology, 5xFAD transgenic mice and their C57BL/6J littermates were fed ad libitum for 3 or 14 weeks with control food pellets, or pellets dosed with these respective NMs at 0.1% or 1% (w/w). Behaviour effects were evaluated by X-maze, string suspension, balance beam and open field tests. Brains were analysed for plaque load, beta-amyloid peptide levels, markers of oxidative stress and neuroinflammation.

Results: No marked behavioural impairments were observed in the mice exposed to SiO or CeO and neither treatment resulted in accelerated plaque formation, increased oxidative stress or inflammation. In contrast, the 5xFAD mice exposed to 1% CeO for 14 weeks showed significantly lower hippocampal Aβ plaque load and improved locomotor activity compared to the corresponding controls.

Conclusions: The findings from the present study suggest that long-term oral exposure to SiO or CeO NMs has no neurotoxic and AD-promoting effects. The reduced plaque burden observed in the mice following dietary CeO exposure warrants further investigation to establish the underlying mechanism, given the easy applicability of this administration method.