Objective To investigate the toxicity of copper on MES23.5 dopaminergic cells and the probable mechanisms involved in this process. Methods MES23.5 dopaminergic cells were selected as our experimental model. [3-（4, 5-dimethylthiazol2-yl）-2, 5 diphenyltetrazolium bromide] （MTT） assay was used to detect the influence of copper on the cell viability. The semiquantitative reverse transcription polymerase chain reaction （RT-PCR）, Western blotting and the high performance liquid chromatography-electrochemical detection （HPLC-ECD） have been used to detect the tyrosine hydroxlase （TH） mRNA and protein expression and the dopamine content in MES23.5 cells. The flow cytometry have been used to detect the changes of mitochondrial transmembrane potential. Results 100 and 200 μmol/L copper had no effect on the MES23.5 cell viability, whereas 400 and 800 μmol/L of copper could decrease the cell viability （P 〈 0.01）. Treating cells with 200 μmol/L copper for 24 h decreased the TH mRNA expression, the TH expression and the dopamine content compared with the control （P 〈 0.01, P 〈 0.01, P 〈 0.05, respectively）. Besides, the mitochondrial transmembrane potential also decreased with the treatment of 200 μmol/L copper for 24 h （P 〈 0.01）. Condusion Copper could exert the toxic effects on MES23.5 dopaminergic cells and decrease the cell function. The dysfunction of mitochondria may be the mechanism of this toxicity effect.
