Abstract
It is recognized currently that irradiation of low-energy laser light has a specific effect on biological systems, so called bio-stimulation effect. We have been studied bio-stimulation effect on head regeneration in decapitated hydra caused by low-energy laser irradiation. This paper reports for the first time the experimental results especially the dependence on laser wavelengths. The bio-stimulation effect of laser light is estimated by comparing regenerated tentacle numbers in irradiated group with non-irradiated controls. We used linearly polarized Ar and dye lasers for light source, and changed energy density between 0.1 and 2J/cm2. It was found that the effect on head regeneration in hydra varies with the laser wavelength. For the wavelengths lower than 600nm and 600-640nm, inhibition and activation effects were observed, respectively. However, in the region of 650-670nm, no effect was measured. Also a large difference of the effect between the wavelengths of 514.5nm and 610nm was found at the laser energy density of 1J/cm2.
