Figure 1.

Camptothecin (CPT) induced hormetic effect in PC12 cells and protected against hydrogen peroxide (H₂O₂)-induced cell death. A, The PC12 cells were treated with indicated concentrations of CPT for 24 hours. B, PC12 cells were treated with 2 μmol/L H₂O₂ alone or in combination with CPT (0.05, 0.11, 0.22, and 0.44 μmol/L) for 24 hours. *P < .05, **P < .01, compared to control (CTL) or H₂O₂ alone. Cell viability was determined by MTT assay as described in Materials and Methods section. Data are represented as means ± SD of 3 to 5 independent experiments. C, PC12 cells were treated with 2 μmol/L H₂O₂ alone or in combination with 0.11 μmol/L CPT for 24 hours. Cells were photographed using the InCell 2000 confocal microscope.