Paraquat is a cationic herbicide that causes acute cell injury by undergoing redox cycling. Oxidative stress is thought to be the crucial mechanism invoked by this redox-cycling compound. The cytotoxicity of paraquat was examined in an immortalized human mesencephalic neuron-derived cell line. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide reduction activity was examined as cytotoxicity indicator. Cells were seeded with densities at inoculation of 5 × 10(4)cells/ml and 10 × 10(4)cells/ml, and paraquat was added 24h later to give final concentrations from 10 to 500 μM. At 24 and 48 h of treatment, mitochondrial activity was determined with the MTT assay. To further understand the effect of paraquat exposure on human mesencephalic neuron-derived cells, the cells were differentiated and similar experiments were carried out. Supplementation of culture medium with dibutyryl cyclic AMP and GDNF significantly increased the resistance of the cultures to the paraquat-mediated cytotoxicity. These results confirm that GDNF confers protection against paraquat-mediated cytotoxicity and show that immortalized human mesencephalic neuron-derived cells are an adequate in vitro system for evaluating the cytoprotective effects of GDNF on oxidative injury caused by xenobiotics.
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