Figure 1. Effects of luteolin on 6-OHDA-induced PC12 apoptosis and ROS over-production.

(A) PC12 cells (1×10⁶ cells/ml) were treated with different concentrations of 6-OHDA in serum-free medium for 16 h at 37°C. Cell viability was measured by MTT as described in Materials and Methods. (B) PC12 cells were treated with luteolin in serum-free medium for 30 min before 6-OHDA (100 µM) insult for 16 h. Cell viability was measured by MTT, as described in Materials and Methods. (C) PC12 cells were treated with luteolin in serum-free medium for 30 min before 6-OHDA (100 µM) insult for 12 h. Cell lysates were prepared and immunoblotting was then carried out using an anti-cleaved caspase-3 antibody or anti-α-tubulin antibody. The blots are representative ones from one of three independent experiments. (D) PC12 cells (1×10⁶ cells/ml) were treated with antioxidant for 30 min prior to the addition of 6-OHDA for 30 min at 37°C, and ROS production was measured by H₂DCFDA, as described in the Materials and Methods. (E) PC12 cells were treated with antioxidant for 30 min prior to the addition of 6-OHDA for 16 h at 37°C. Cell viability was determined by Calcein-AM cell viability assay. Data represent the mean ± SD of three independent experiments. *, p<0.05; **, p<0.01 represent significant differences compared with vehicle control (without 6-OHDA).