Objectives: It has been reported that near-infrared (NIR) laser irradiation is effective in cerebral ischemia. We examined the effect of 808 nm laser diode irradiation on CBF in mice. The potential of NIR laser irradiation in the treatment of cerebral ischemia was also investigated.
Methods: Male C57BL/6J mice were used. An 808 nm CW diode laser was applied to the hemisphere transcranially. CBF was measured with a non-contact laser Doppler blood perfusion imager. We measured directly nitric oxide in the brain tissue during NIR laser irradiation. To confirm the effect of pretreatment by NIR laser irradiation, we conducted the 1.6 W/cm2 NIR laser irradiation to the hemisphere transcranially for 30 minutes before bilateral common carotid artery occlusion (BCCAO). The control mice were also subjected to BCCAO without pretreatment by NIR laser irradiation.
Results: Transcranial NIR laser irradiation increased local CBF by 30% compared to control value in mice. NIR laser irradiation also provoked a significant increase in cerebral NO concentration. Pretreatment by NIR laser irradiation improved residual CBF following bilateral carotid occlusion in mice.
Conclusions: Our data suggest that targeted increase of CBF is available by NIR laser irradiation and it is concerned in NOS activity and NO concentration. Besides, NIR laser irradiation may have a protective effect for transient ischemia.
