Effect of low dose L-DOPA with or without CD39 inhibitor pre-treatment on the oxidative stress (χ±σ, n = 10).

PC12 cells were seeded into 96-well plates (5×10³/well; 200 µl/well) and divided into two groups: L-DOPA treatment group and CD39 inhibitor pre-treatment group (cells were pre-incubated with 0.5 mM ARL 67156 for 30 min or 10 µM H89 for 1 h before L-DOPA treatment). Cells were incubated with L-DOPA at different concentrations (0, 1, 5, 10 and 20 µmol/L) for 3 days. On the fourth day, cells were incubated with 100 µmol/L H₂O₂ for 8 h. MTT assay and LDH assay were performed to determine the viability of PC12 cells. (A) The cell viability with or without CD39 inhibitor pretreatment was detected by MTT assay. Results showed the viability increased as compared to untreated group, while H89 and ARL eliminated this effect. (B) The cell viability was detected by LDH assay. Results showed that the LDH content in L-DOPA treated groups was lower than that in untreated group, while H89 and ARL eliminated this effect. (C) Intracellular ROS level was measured. H₂O₂ could induce oxidative stress. **P<0.01, *P<0.05 vs 0 µmol/L L-DOPA group.