Effects of melatonin on wortmannin-induced tau hyperphosphorylation

Aim: To explore the underlying mechanism of tau hyperphosphorylation in an Alzheimer's-affected brain and the possible arresting strategies. Methods: MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl-tetrazolium bromide), crystal violet assay, phase-contrast, dead end colorimetric apoptosis detection system (TUNEL) and electron microscopy were used to detect cell viability, morphology and apoptosis. Western blot, P-32-labeling and the detection of malondialdehyde level and super, oxide dismutase activity were used respectively for the phosphorylation level of tau, the activity of glycogen synthase kinase (GSK-3), and oxidative stress measurement. Results: Exposure of the cells to wortmannin resulted in an obvious lipid peroxidation, reduction of cell viability, cell process retraction, and plasma vacuolation, but with no obvious cell apoptosis. We also found that preincubation of the cells with melatonin or vitamin E attenuated differentially wortmannin-induced oxidative stress as well as GSK-3 overactivation and tau hyperphosphorylation. Conclusion: Wortmannin is an effective tool for reproducing Alzheimer-like tau hyperphosphorylation cell model and melatonin/vitamin E can effectively protect the cells from wortmannin-induced impairments.