Photobiomodulation by LED 660 nm and Taurine against H2O2 oxidative stress in SH-SY5Y cells

Alzheimer's Disease (AD) is a progressive uncurable neurodegenerative pathology affecting millions worldwide. Photo- biomodulation and Taurine are promising alternatives for preventing and reducing the rapid progression of neurodegenera- tion, stimulating the reconstructing of neural tissue structures, especially improving mitochondrial activity, which is highly impaired in AD. In this study, the mitochondrial effects of Taurine combined with light emitting diode (LED) irradiation were evaluated on human neuroblastoma cells (SH-SY5Y), under oxidative stress condition by hydrogen peroxide (H2O2) exposure, a considerable modulator in AD. We evaluated LED irradiation at the wavelength of 660 nm and Taurine under different concentrations before and together with exposing SH-SY5Y cells to different concentrations of H2O2, assessing mitochondrial activity by the MTT colorimetric test and labeling live cells mitochondria by the fluorescent probe MitoTracker. Cell viability was also evaluated by the trypan blue exclusion assay, and cellular morphological structures were imaged by scanning electron microscopy (SEM). Neuroprotective effects were achieved by both LED irradiation and LED irradia- tion + Taurine when cells were exposed to them before H2O2-induced stress. Comparing both agents, LED irradiation at 660 nm is sufficient to improve mitochondrial activity, however, healthy mitochondrial morphology was only observed when cells were treated with Taurine together with LED irradiation, representing affordable candidates that act in synergy against oxidative stress, one of the main contributors to neurodegeneration.