title: Interplay between up-regulation of cytochrome-c-oxidase and hemoglobin oxygenation induced by near-infrared laser.
abstract: Photobiomodulation, also known as low-level laser/light therapy (LLLT), refers to the use of red-to-near-infrared light to stimulate cellular functions for physiological or clinical benefits. The mechanism of LLLT is assumed to rely on photon absorption by cytochrome c oxidase (CCO), the terminal enzyme in the mitochondrial respiratory chain that catalyzes the reduction of oxygen for energy metabolism. In this study, we used broadband near-infrared spectroscopy (NIRS) to measure the LLLT-induced changes in CCO and hemoglobin concentrations in human forearms in vivo. Eleven healthy participants were administered with 1064-nm laser and placebo treatments on their right forearms. The spectroscopic data were analyzed and fitted with wavelength-dependent, modified Beer-Lambert Law. We found that LLLT induced significant increases of CCO concentration (Δ[CCO]) and oxygenated hemoglobin concentration (Δ[HbO]) on the treated site as the laser energy dose accumulated over time. A strong linear interplay between Δ[CCO] and Δ[HbO] was observed for the first time during LLLT, indicating a hemodynamic response of oxygen supply and blood volume closely coupled to the up-regulation of CCO induced by photobiomodulation. These results demonstrate the tremendous potential of broadband NIRS as a non-invasive, in vivo means to study mechanisms of photobiomodulation and perform treatment evaluations of LLLT.
authors.affiliation: Department of Bioengineering, the University of Texas at Arlington, 500 UTA Blvd, Arlington, TX 76010, USA.
authors.forename: Xinlong
authors.initials: X
authors.lastname: Wang
authors.affiliation: Department of Bioengineering, the University of Texas at Arlington, 500 UTA Blvd, Arlington, TX 76010, USA.
authors.forename: Fenghua
authors.initials: F
authors.lastname: Tian
authors.affiliation: Department of Bioengineering, the University of Texas at Arlington, 500 UTA Blvd, Arlington, TX 76010, USA.
authors.forename: Sagar S
authors.initials: SS
authors.lastname: Soni
authors.affiliation: Department of Psychology and Institute for Neuroscience, the University of Texas at Austin, 108 E. Dean Keeton Stop A8000, Austin, TX 78712, USA.
authors.forename: F
authors.initials: F
authors.lastname: Gonzalez-Lima
authors.affiliation: Department of Bioengineering, the University of Texas at Arlington, 500 UTA Blvd, Arlington, TX 76010, USA.
authors.forename: Hanli
authors.initials: H
authors.lastname: Liu
mesh_terms: D000328:Adult; D003576:Electron Transport Complex IV / Q000378:metabolism* / Q000528:radiation effects; D004734:Energy Metabolism; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D028022:Low-Level Light Therapy / Q000379:methods*; D008297:Male; D010108:Oxyhemoglobins / Q000378:metabolism* / Q000528:radiation effects; D019265:Spectroscopy, Near-Infrared; D015854:Up-Regulation; D055815:Young Adult
chemical_list: D010108:Oxyhemoglobins; D003576:Electron Transport Complex IV