Measurement of Cell Viability

Cell viability was measured with the MTT assay (Gibco). Briefly, primary cortical neurons were seeded in 96-well plates and subjected to various treatments as described above. MTT solution (5 mg/ml) was added to each culture well, and the cells were incubated for 4 h at 37°C. The medium was carefully aspirated, and 200 μl DMSO per well was added to dissolve the blue formazan products. The values of absorbance at 490 nm were measured using a microplate reader. The results of the absorbance of the test wells were expressed as cells alive. Cell survival rates were expressed as percentages of the value of cells without any treatment. The experiment was repeated three times.