Influence of cadmium contamination on brain glial cells: consequences and bioindication possibilities

Abstract

Cadmium (Cd) is a heavy metal that currently presents in almost all components of the environment. Cd is a ubiquitous pollutant that is constantly entering the environment from industry and agriculture, mining, forest fires and many more sources. Some occupational diseases have aftereffects associated with Cd cytotoxicity. Despite long-term studies of the toxic effects of Cd, its cytotoxicity of low doses and the chronic effects on the nerve tissue cells remain undiscovered. The results of determining the Cd neurotoxicity indicate a disturbance of the permeability of the blood-brain barrier, the accumulation of Cd in the brain and the deterioration of the functional activity of the central nervous system. One of the main cellular targets for Cd in the brain are astrocytes. Astrocytes provide nutrition and functional activity of neurons, as well as recovery of physical and metabolic damage. The cytoskeleton of astrocytes is built of glial fibrillary acidic protein (GFAP). GFAP participates in important functions of astrocytes and its condition reflects the astrocytes reactivity. The molecular mechanisms of the neurotoxic effects of Cd on the glial cytoskeleton remain unknown. Glioblastomas are widely used to study the cytotoxic mechanisms of various compounds, including heavy metals, as cellular models of astrocytes. Taking into account the role of oxidative stress in a cell damage, as well as the reactive response of glial cells, we study the influence of low doses of Cd on oxidative stress and expression of GFAP and glucose-6-phosphate dehydrogenase (G6PD) in U373GM cells. Doses of 2-10 μM Cd induced a dose-dependent increase in reactive oxygen species and lipid peroxidation products. The same doses inhibited the expression of the cytoskeletal marker of astrocytes (GFAP) and metabolic marker of glucose utilization (G6PD). The obtained results indicate a pronounced cytotoxic effect of low doses of Cd in the astrocytic cell model U373GM. In addition, the astroglial cytotoxicity of Cd may be mediated by oxidative damage, inhibition of glial intermediate filament expression, and glucose utilization disorders. These parameters can be promising biomarkers of toxic effects both for the assessment of human and animal health and for determining the state of the environment as a whole.