Co-exposure of polystyrene microplastics and iron aggravates cognitive decline in aging mice via ferroptosis induction

The objective of this study was to investigate the effects of co-exposure of iron and microplastics (MPs) on the cognitive function of aged humans and animals. It was already known that individual iron or MPs exposure can initiate potential neurotoxicity. However, the combined effect of MPs and iron remained to be elucidated. In this study, the toxicity of iron, MPs, co-treatment of MPs & iron, and the underlying mechanisms were evaluated in vivo. Our findings suggest that 5 µm MPs could enter the aging mice brain and accumulate in cortex and hippocampus. In addition, MPs and iron have a good binding ability, therefore, co-exposure of MPs & iron cause significant iron overload and cognitive deficits as compared to control and individual treatments of iron and MPs. Moreover, the lipid peroxidation and inflammation, which are involved in ferroptosis, get significantly elevated by co-exposure of iron and MPs. Taken together, our results provide compelling evidence that co-exposure of iron and MPs could aggravate the cognitive impairment via disturbing brain iron homeostasis and inducing ferroptosis in cognitive-related brain areas, what's more, the results warn that MPs may act as vectors of pollutants (mostly heavy metals) increasing the health burden on body.