Abstract: Objective To investigate the degeneration of dopaminergic neurons induced by MPP⁺ in mouse mesencephalic dissociated culture. Methods OF1/SPF　mouse embroys of 14 d were used to make mecsencephalic dissociated culture, and the culture was divided into control and MPP⁺ -treated group. On the 10th day in vitro, different concen Trations of MPP⁺ (final concentrations of 0.1,1,10 and 15 μmol•L^-1) were added into the culture and incubated for 48 h. Dopaminergic neurons were identified and counted by using tyrosine hydroxylase (TH) immunochemistry under microscope. In order to investigate the time course effect of MPP⁺ on the degeneration of doapminergic neurons, 10 μmol•L^-1MPP⁺ was used and incubated for different time (2,4,8,24,48,72 and 96 h) on the 10th day in vitro. Results The numbers of dopaminergic neurons per well in the 0.1,1,10 and 15 μmol•L^-1 MPP⁺ groups were (70.30±6.38)%,(67.39±4.92)%,(51.68±2.95)%, and (50.91±5.60)% of control level, respectively. The cell death of dopaminergic neurons induced by 10 μmol•L^-1 MPP⁺ presented in two different ways. Loss of fibers and terminals of dopaminergic neurons was common way of damage, only few degenerated dopaminergic neurons presented as the loss of cell body. The number of dopaminergic neurons in the control group was (839.8±15.5) per well;meanwhile (677.2±6.1),(411.5±26.6),(229.0±20.3), and (191.3±15.2) were found in MPP⁺-treated groups 24, 48, 72 and 96 h after administration, respectively, which were lower significantly than that in control group（P<0.05）. Conclusion MPP⁺ with different concentrations（0.1,1,10 and 15 μmol•L^-1） could induce the damage and dead of dopaminergic neurons.The degeneration and death are both dose-and time-dependency. And two different mechanism may exist in the damage and death of dopaminergic neurons induced by MPP⁺.

Key words: 6-tetrahydropyridine, parkinson disease, mesencephalon, neurons, cell culture