Abstract
Low-reactive level laser therapy and photo-dynamic therapy have become popular in many clinical fields. Herein, the possible application of these techniques to the central nervous system is discussed. Low-reactive level laser irradiation with a wavelength of 830 nm has been shown to suppress neuronal activities in the rodent brain and increase tissue ATP levels. Such effects of lasers may facilitate the protection of neurons from ischemic brain insults. In addition to these techniques, we have demonstrated that photo-oxidation of the cerebral cortex by photo-irradiation following the injection of photosensitizing dye induces spreading depression, the propagation of neuronal membrane depolarization throughout the cortical hemisphere. Spreading depression potently induced the proliferation of progenitor cells, which have multipotency in cellular differentiation. Thus, this photo-dynamic technique may facilitate the regeneration of brain tissue. We believe that these phototherapeutic techniques will usher in a new frontier in the medical science of the central nervous system.
