Methylmercury at low doses modulates the toxicity of PCB153 on PC12 neuronal cell line in asynchronous combination experiments

Me–Hg and PCB153 are known neurotoxic contaminants which tend to accumulate in food, particularly in fish. Aim of this study was to perform asynchronous and combined exposure to Me–Hg and PCB153 in a neuronal rat cell line (PC12) to better characterise the antagonism observed at some combination concentrations.PC12 cells were treated with three concentrations of Me–Hg (0.1–0.5–1.0 μM) and PCB153 at one concentration (175 μM) in single and combined asynchronous exposures, using viability (MTT assay) as end-point.At all concentrations used, a statistically significant antagonistic effect was observed when Me–Hg preceded PCB153 exposure, while effect was additive when PCB153 preceded Me–Hg exposure. The antagonism is particularly evident at low concentrations of Me–Hg (0.1 μM).In conclusion, combined asynchronous exposure showed that whereas Me–Hg can modulate PCB153 toxicity, the opposite seems not to be true. Therefore, the use of asynchronous exposure could be a promising approach to study the mechanisms of toxicity of binary mixtures.