Neurotoxicity of aluminum oxide nanoparticles and their mechanistic role in dopaminergic neuron injury involving p53-related pathways

The central nervous system is a potential target for Al2O3 nanoparticles (Nano-Al2O3). Here, we investigated the effects of intranasal instillation of Nano-Al2O3 on the distribution and damage in crucial functional sub-brain regions of rats. In vivo results show that Nano-Al2O3 was translocated into the brain via the olfactory nerve pathway. Nano-Al2O3 accumulated in the hippocampus, olfactory bulb, cerebral cortex, and striatum, causing ultrastructural changes, oxidative damage, inflammatory responses, and histopathological damage in sub-brain regions. As indicated by in vitro studies, cell viability decreased with the addition of Nano-Al2O3, which increased the levels of lactate dehydrogenase and oxidative stress. Nano-Al2O3 also impaired mitochondrial function, disturbed the cell cycle and induced apoptosis. In addition, Nano-Al2O3 decreased the expression of cyclin D1, bcl-2, Mdm2, and phospho-Rb and increased the expression of p53, p21, Bax, and Rb. Therefore, oxidative stress, mitochondrial dysfunction, and p53-related pathways might be important in the process of dopaminergic neurotoxicity induced by Nano-Al2O3. The current study establishes a striatum damage model and identifies molecular biomarkers of dopaminergic neuron damage induced by Nano-Al2O3. In brief, our study demonstrates that Nano-Al2O3 exposure can be a risk factor for neurodegenerative diseases and may negatively impact the hippocampus, striatum, and dopaminergic neurons.