Aim: To study the role of dopamine (DA) in rotenone‐induced neurotoxicity in PC12 cells.

Methods: Cell viability was assessed by detecting the leakage of lactate dehydrogenase (LDH) into the medium. Apoptosis rate was measured by flow cytometry. Caspase‐3‐like activity was measured by fluorescence assay using the probe Ac‐DEVD‐AMC. The level of intracellular hydrogen peroxide and other peroxides in PC12 cells were quantified by loading cells with 2′‐7′‐Dichlorodihydrofluorescein diacetate (DCFH‐DA) in fluorescence assay. Lactic acid was measured spectrophotometrically. The DA levels in PC12 cells were determined by HPLC‐ECD.

Results: A 48‐h incubation of PC12 cells with rotenone caused an apoptotic cell death and elevated intracellular reactive oxygen species (ROS) and lactic acid accumulation. Intracellular DA depletion with reserpine significantly attenuated rotenone‐induced ROS accumulation and apoptotic cell death. No change was found in rotenone‐induced ROS accumulation when cells were co‐treated with deprenyl. Brief treatment with reserpine at the end of rotenone treatment had no effect on rotenone‐induced neurotoxicity. However, when cells were first incubated with deprenyl, a monoamine oxidase‐B inhibitor for 30 min then co‐incubated with rotenone plus deprenyl, a brief treatment with reserpine enhanced cell injury.

Conclusion: Rotenone‐induced apoptosis in PC12 cells was mediated by intracellular dopamine oxidation.