Cell viability and LDH assays

The viability of neurons was measured by MTT assay. Briefly, the neurons (2,000 cells/well) were cultured in 96-well culture plates for 24 h. Then, MTT (5 mg/ml) was added into each well at 37°C for 4 h. After that, MTT was removed and 150 µl DMSO was added into the well to solubilize purple formazan. Then, absorbance at 570 nm was read using a microplate reader (PLUS 384; Molecular Devices, LLC). LDH cytotoxicity detection kit (cat. no. C0017; Beyotime Institute of Biotechnology) was used as previously described (22).