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Fluoride exposure decreased neurite formation on cerebral cortical neurons of SD rats in vitro

Abstract

Fluoride, a geochemical element, can damage the brain and result in dysfunction of the central nervous system. In recent years, fluoride-induced neurotoxicity has become one of research focuses of environmental toxicology. Our previous study showed that fluoride could induce the structural damages of the cerebral cortex and reduce the learning and memory abilities of mice offspring. However, the underlying mechanisms of these effects remain unclear. In this study, primary neurons were isolated from the cerebral cortices of postnatal 1-day SD rats. The primary cultured cerebral cortical neurons were adherent and the cellular network was obvious. Neurons were identified by Nissl’s staining and were used for experiments. Different concentrations of sodium fluoride (0.5, 1.0, 1.5, 2.0 and 2.5 mM) were chosen to explore its toxic effects on neuron of SD rats in vitro. Results showed that neuronal morphology was obviously damaged in 2.0 and 2.5 mM, but was not adversely affected in 0.5 and 1 mM. Further studies revealed that the neurites of neuron were shrunken and even became fractured with the increase in NaF dose, which have been detected by scanning electron microscopy (SEM). Meanwhile, TEM showed marginated chromatin, widened nuclear gaps, damaged nuclei and swollen or even absent mitochondria in 1.5, 2 and 2.5 mM group. The cytoskeletal staining was consistent with the above results. The number of neurites of cerebral cortical neuron significantly decreased after fluoride exposure by immunofluorescent assay. In summary, high fluoride (1.5, 2 and 2.5 mM) concentrations exerted a significant toxic effect on the cellular morphologies and neural formation of primary cultured cortical neurons. These findings provide new insights into the roles of NaF in neuronal damage and can contribute to an improved understanding of fluoride-induced neurotoxicity.

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All data generated or analysed during this study are included in this published article.

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Funding

This work was supported by the National Natural Science Foundation of China (No. 32002352), Scientific and Technological Foundation of Henan Province in China (202102310629, 202300410165, 192102110080) and the China Postdoctoral Science Foundation (Grant No. 2019M652548).

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Authors

Contributions

Hongmei Ning conceived the study. Lingli Chen designed experiments and drafted the manuscript. Chong Li, Zhihong Yin and Dongfang Hu carried out the experiments and collected and analysed the data. Yaming Ge and Lingli Chen revised the manuscript. All authors read and approved the final manuscript.

Corresponding authors

Correspondence to Yaming Ge or Lingli Chen.

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Ethics approval

All of the procedures involving the rats were approved by and performed according to the guidelines of the Animal Ethics Committee of the Henan Institute of Science and Technology.

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All authors have read and approved this version of the article and consent to publish.

Conflict of interest

The authors declare no competing interests.

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Responsible Editor: Mohamed M. Abdel-Daim

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Ning, H., Li, C., Yin, Z. et al. Fluoride exposure decreased neurite formation on cerebral cortical neurons of SD rats in vitro. Environ Sci Pollut Res 28, 50975–50982 (2021). https://doi.org/10.1007/s11356-021-13950-2

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  • DOI: https://doi.org/10.1007/s11356-021-13950-2

Keywords

  • Fluorosis
  • Neurotoxicity
  • Cerebral cortical neurons
  • Neurite