Original ContributionTitanium dioxide nanoparticles induce strong oxidative stress and mitochondrial damage in glial cells
Section snippets
Materials
Dulbecco׳s modified Eagle׳s medium (DMEM), antibiotic–antimycotic 100× solution, minimal essential medium (MEM) nonessential amino acids and pyruvate solutions (100×), 0.25% trypsin–EDTA solution, and newborn calf serum (NBCS) were purchased from Gibco/BRL (Grand Island, NY, USA). Sterile plastic material for tissue culture was from Corning (Corning, NY, USA). Flow cytometry reagents were purchased from Becton–Dickinson Immunocytometry Systems (San Jose, CA, USA).
TiO2 NPs induced oxidative stress
To determine if TiO2 NPs could induce damage in glial cells, we determined the changes in the cellular redox state caused by oxidative stress mediating the oxidation of H2DCFDA. TiO2 NPs induced a strong increase in H2DCFDA oxidation in C6 and U373 cells, in comparison with the negative control (Fig. 1). This rise was observed from 2 h after treatment, with a maximal increase at 6 h and a decrease at 24 h in both cell lines.
Considering that TiO2 NPs induce a strong oxidative stress, the expression
Discussion
Because TiO2 NPs can translocate into the CNS, we evaluated their possible toxic effect on glial cells, which are the principal component of the CNS and provide support and protection to neurons. Several toxicity studies on astrocytes (astrocytic glial cells or astroglia) using cultures of primary, subcultured, or permanent cell lines (astrocytomas), have been extremely valuable in toxicity evaluation and to understand the mechanisms of action of a number of neurotoxic substances [32];
Conclusions
In conclusion, TiO2 NPs induced a strong oxidative stress, mediated by change in the redox state as well as by a decrease in genes of antioxidant enzymes, lipid peroxidation, reduction in mitochondrial membrane potential, and mitochondrial depolarization, in glial cells in vitro. These findings suggest that the exposure of brain cells in vivo to TiO2 NPs could cause brain injury, contribute to the development of neurodegenerative diseases [58], and be hazardous to health.
Acknowledgments
We thank to CONACyT, for providing financial support to Elizabeth Huerta-García, Sandra Gissela Márquez-Ramírez, and José Antonio Pérez-Arizti, graduate students from the Posgrado en Investigación en Medicina, Escuela Superior de Medicina, Instituto Politécnico Nacional and from the Posgrado en Ciencias Biológicas, Universidad Nacional Autónoma de México, Scholarship Nos. 227281, 175962, and 294521, respectively. We also thank CONACyT for economical support of this work and Project 182341.
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2022, ToxicologyCitation Excerpt :Oxidative stress can be caused by an increase in ROS production accompanied by an impairment of the antioxidant enzymic defense. In this regard, an increase in the activity of antioxidant enzymes such as glutathione reductase (GR), glutathione peroxidase (GPx), and catalase can be detected in glial cells exposed to titanium dioxide nanoparticles (Huerta-García et al., 2014). Then, we hypothesized that exposure to E171 causes cellular alterations in colon cells through the E171 internalization and the formation of ROS that could remain even if the exposure is suspended.
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These authors contributed equally to this work.