Assessment of the neurotoxic effect of iron (III) oxide nanoparticles at the subcellular level

Introduction. Both naturally occurring and artificially produced nanoparticles are ubiquitous; their high concentrations can be detected in the environment, thus posing risks of toxic effects in humans. Penetrating the blood-brain barrier by metal nanoparticles has been already proven and is currently of interest from the point of view of toxicology and hygiene. Materials and methods. Female rats were exposed to ferric oxide nanoparticles administered intranasally with a 25 mg/ml suspension at a dose of 50 µl three times a week during six weeks. The experimental and control groups contained seven animals each. Tissue samples for testing were taken from the olfactory bulbs of the rat’s brain. Iron (III) oxide nanoparticles were identified by electron microscopy and energy-dispersive X-ray spectroscopy. The cytotoxic effect of ferric oxide nanoparticles was assessed by ranking mitochondria by mitochondrial membrane morphotypes and comparing their distribution in the experimental and control groups. Results. We confirmed the presence of nanoparticles in tissues of the olfactory bulbs of the exposed rodents. The morphotype pattern of mitochondria showed significant changes following the exposure to ferric oxide nanoparticles: the proportion of mitochondria with normal and vesicular swollen morphotypes decreased by 36.4 and 4.9%, respectively, compared with the control group of animals, the proportion of mitochondria with normal vesicular and vesicular morphotypes increased by 19.8 and 21.8%, while the proportion of vesicular swollen mitochondria decreased from 9.5% to 4.6%. Limitations. The study was limited to examining ultrastructural changes in mitochondria and identifying ferric oxide nanoparticles in tissues. Conclusions. Further studies of the impact of iron-containing nanoparticles on the structure and functions of the mitochondrial apparatus can help to identify their potential harm at the subcellular level and provide information for the development of appropriate health protective measures and new strategies for prevention and treatment of metal toxicity-induced diseases in humans.