title: Low-level laser therapy for closed-head traumatic brain injury in mice: effect of different wavelengths.
abstract: OBJECTIVE
  Traumatic brain injury (TBI) affects millions worldwide and is without effective treatment. One area that is attracting growing interest is the use of transcranial low-level laser therapy (LLLT) to treat TBI. The fact that near-infrared light can penetrate into the brain would allow non-invasive treatment to be carried out with a low likelihood of treatment-related adverse events. LLLT may treat TBI by increasing respiration in the mitochondria, causing activation of transcription factors, reducing inflammatory mediators and oxidative stress, and inhibiting apoptosis.
  
  
  METHODS
  We tested LLLT in a mouse model of closed-head TBI produced by a controlled weight drop onto the skull. Mice received a single treatment with continuous-wave 665, 730, 810, or 980 nm lasers (36 J/cm(2) delivered at 150 mW/cm(2)) 4-hour post-TBI and were followed up by neurological performance testing for 4 weeks.
  
  
  RESULTS
  Mice with moderate-to-severe TBI treated with 665 and 810 nm laser (but not with 730 or 980 nm) had a significant improvement in Neurological Severity Score that increased over the course of the follow-up compared to sham-treated controls. Morphometry of brain sections showed a reduction in small deficits in 665 and 810 nm laser treated mouse brains at 28 days.
  
  
  CONCLUSIONS
  The effectiveness of 810 nm agrees with previous publications, and together with the effectiveness of 660 nm and non-effectiveness of 730 and 980 nm can be explained by the absorption spectrum of cytochrome oxidase, the candidate mitochondrial chromophore in transcranial LLLT.
authors.affiliation: Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, MA 02114, USA.
authors.forename: Qiuhe
authors.initials: Q
authors.lastname: Wu
authors.forename: Weijun
authors.initials: W
authors.lastname: Xuan
authors.forename: Takahiro
authors.initials: T
authors.lastname: Ando
authors.forename: Tao
authors.initials: T
authors.lastname: Xu
authors.forename: Liyi
authors.initials: L
authors.lastname: Huang
authors.forename: Ying-Ying
authors.initials: YY
authors.lastname: Huang
authors.forename: Tianghong
authors.initials: T
authors.lastname: Dai
authors.forename: Saphala
authors.initials: S
authors.lastname: Dhital
authors.forename: Sulbha K
authors.initials: SK
authors.lastname: Sharma
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Whalen
authors.forename: Michael R
authors.initials: MR
authors.lastname: Hamblin
mesh_terms: D000818:Animals; D019540:Area Under Curve; D001921:Brain / Q000473:pathology; D001930:Brain Injuries / Q000145:classification / Q000473:pathology / Q000532:radiotherapy*; D004195:Disease Models, Animal; D016489:Head Injuries, Closed / Q000145:classification / Q000473:pathology / Q000532:radiotherapy*; D028022:Low-Level Light Therapy; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D015599:Trauma Severity Indices; D016896:Treatment Outcome