. Scientific Frontline: Iron Nanoparticles Neurotoxic Even at Low Doses

Tuesday, March 21, 2023

Iron Nanoparticles Neurotoxic Even at Low Doses

Scientists discovered this by studying the brains of rats
Photo Credit: Aleksandr Gusev

Iron oxide nanoparticles, which pollute the air, are toxic to the central nervous system even in low doses. To find out, Ural scientists injected rats intranasally with suspensions containing iron oxide particles and studied functional and structural changes in their brains. The data may help to develop measures to prevent neurodegenerative diseases. The study was conducted at the Ekaterinburg Medical Research Centre of Rospotrebnadzor, and the analysis and synthesis of the data was carried out as part of the Priority 2030 program. The results have been published in the International Journal of Molecular Sciences.

"Many technological processes can produce nanoparticles in the metallurgical industry. Inhalation of nanoparticles is harmful to human health, because even at low concentrations they can penetrate directly into the brain: through the nasal cavity, through the olfactory tract, directly into various brain structures", - says Ilzira Minigalieva, Doctor of Biological Sciences and Head of the UrFU Laboratory "Stochastic transport of nanoparticles in a living organism".

To understand exactly how low doses of iron oxide affect the central nervous system, scientists conducted an experiment on rats and injected each rat intranasally with a suspension containing 0.45 mg of nanoparticles. This amount was not chosen at random because the main purpose of the study was to see if such low doses could have a neurotoxic effect.

It turned out that when the rats were exposed to this substance, their exploratory behavior changed and their general motor activity decreased. The scientists' hypothesis was that this inhibition was due to the impairment of conductivity in the central nervous system (CNS). This was confirmed at the ultrastructural level by electron microscopy. The Urals scientists found not only the presence of nanoparticles themselves in some structures of the brain, but also a large number of axons with damaged myelin sheaths. The researchers also found an increase in pathologically altered mitochondria in the brain cells of rats.

"All of this points to manifestations of the neurotoxic effect of iron nanoparticles at the ultrastructural level and at the sub-cellular level. It is interesting that we did not find any pronounced changes at the cellular and biochemical level", - explains Ilzira Minigalieva.

The conclusion that nanoparticles are able to penetrate the structures of the rat brain and distribute themselves irregularly in its sections requires further research. Scientists need to find out the distribution patterns and factors influencing them (such as nanoparticle physical properties, exposure dose and time, injection method). In the future, researchers plan to investigate the correlation between the presence of nanoparticles in tissues, cells or organelles and ultrastructural damage to the biological objects studied.

Reference: The neurotoxic effects of high doses of iron nanoparticles have been repeatedly demonstrated. For example, changes in motor activity and spatial memory, blood-brain barrier permeability and accumulation of nanoparticles in the brain were observed in mice exposed to iron oxide at doses of 25 and 50 mg/kg bw for four weeks. It is also known that nanoparticles can be deposited in brain tissue and damage the striatum, which regulates muscular and visceral tone and produces conditioned reflexes. Oral exposure to iron nanoparticles at a total dose of 5 mg/kg resulted in an increase in the oedema of the brain tissue. 

Published in journalInternational Journal of Molecular Sciences

Source/CreditUral Federal University

Reference Number: ns032123_01

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