Fig. 2.

Effects of dopamine on MPP⁺-induced VM dopaminergic neurotoxicity and cell apoptosis. MPP⁺ (20 μM)-treated cells were incubated with two concentrations (100 and 250 μM) of dopamine. a LDH release, b MTT assay, and c quantification of apoptosis in TH-positive neurons were performed 48 h after treatment with MPP⁺. Data are expressed as percent of values in untreated control cells and are means ± S.D. of three independent experiments. All treatments were performed in duplicate and data expressed were averaged values of all cells counted in each condition. The results were compared by one-way ANOVA and Newman–Keuls test. ^$Significant difference to the first column (p < 0.05 vs. control cells treated with saline), ^#significant difference to the first and second column (p < 0.05 vs. control cells treated with saline and vs. saline + dopamine 100 µM), *significant difference to the first, second, third and fourth columns (p < 0.05 vs. control cells treated with saline, vs. control + dopamine 100 µM, vs. control + 250 µM dopamine and vs. MPP⁺ alone)