Titanium dioxide nanoparticle affects motor behavior, neurodevelopment and axonal growth in zebrafish (Danio rerio) larvae

More attention has been recently paid to the ecotoxicity of titanium dioxide nanoparticles (nano-TiO2) owing to its common use in many fields. Although previous studies have shown that nano-TiO2 is neurotoxic, the mechanism is still largely unknown. In the present study, zebrafish embryos were exposed to 0.01, 0.1, and 1.0 mg/L nano-TiO2 and 1.0 mg/L micro-TiO2 for up to 6 days post-fertilization (dpf). Exposure to 1.0 mg/L nano-TiO2 significantly decreased the body length and weight of zebrafish larvae; however, the hatching and mortality rate of zebrafish embryos did not change. Behavioral tests showed that nano-TiO2 exposure significantly reduced the swimming speed and clockwise rotation times of the larvae. The results revealed that nano-TiO2 treatment adversely affected motor neuron axon length in Tg (hb9-GFP) zebrafish and decreased central nervous system (CNS) neurogenesis in Tg (HuC-GFP) zebrafish. Additionally, real-time polymerase chain reaction analysis demonstrated that genes associated with neurogenesis (nrd and elavl3) and axonal growth (alpha 1-tubulin, mbp, and gap43) were significantly affected by nano-TiO2 exposure. In conclusion, our study demonstrated that early life stage exposure of zebrafish to nano-TiO2 causes adverse neural outcomes through the inhibition of neurodevelopment and motor neuron axonal growth. (C) 2020 Published by Elsevier B.V.

Automated summary

The study revealed that early life stage exposure of zebrafish to nano-TiO2 adversely affects neural outcomes by inhibiting neurodevelopment and motor neuron axonal growth.