Figure 2.

Effects of quercetin on the survival of P19 neurons in the presence of excess copper. For the analysis of neuronal survival, P19 neurons (30 × 10³/well) were exposed to the indicated concentrations of CuSO₄ and quercetin in a 96-well plate for 24 h, and for 3 h with MTT afterwards. Precipitated formazan crystals were dissolved with DMSO, and the absorbance was recorded at 570 nm. In moderately injured neurons exposed to 0.5 mM CuSO₄, 150 μM quercetin improved neuronal survival (a). Treatment with 1 mM CuSO₄ induced more severe neuronal death. The presence of 30 μM quercetin further exacerbated the cytotoxic effects of copper, whereas a 150 μM concentration was without effect (b). Data represent the mean ± SD from four independent experiments performed in quadruplets. ^∗P < 0.0001 vs. cont (0 group); ^aP < 0.05 and ^bP < 0.01 vs. the copper-treated group (one-way ANOVA followed by Tukey's test: (a) F_{(4, 39)} = 101.1, P < 0.0001; (b) F_{(4, 31)} = 15.04, P < 0.0001).