title: Low level laser therapy (830nm) improves bone repair in osteoporotic rats: similar outcomes at two different dosages.
abstract: OBJECTIVE
  The goal of this study was to investigate the effects of low level laser therapy (LLLT) in osteoporotic rats by means of subjective histopathological analysis, deposition of collagen at the site of fracture, biomechanical properties and immunohistochemistry for COX-2, Cbfa-1 and VEGF.
  
  
  METHODS
  A total of 30 female Wistar rats (12weeks-old, ±250g) were submitted to ovariectomy (OVX). Eight weeks after the OVX, a tibial bone defect was created in all animals and they were randomly divided into 3 groups (n=10): control bone defect group (CG): bone defects without any treatment; laser 60J/cm(2) group (L60): animals irradiated with LLLT, at 60J/cm(2) and laser 120J/cm(2) group (L120): animals irradiated with LLLT, at 120J/cm(2).
  
  
  RESULTS
  In the laser treated groups, at both fluences, a higher amount of newly formed bone was evidenced as well as granulation tissue compared to control. Picrosirius analysis demonstrated that irradiated animals presented a higher deposition of collagen fibers and a better organization of these fibers when compared to other groups, mainly at 120J/cm(2). COX-2, Cbfa-1 or VEGF immunoreactivity was detected in a similar manner either 60J/cm(2) or 120J/cm(2) fluences. However, no differences were shown in the biomechanical analysis.
  
  
  CONCLUSIONS
  Taken together, our results support the notion that LLLT improves bone repair in the tibia of osteoporotic rats as a result of stimulation of the newly formed bone, fibrovascularization and angiogenesis.
authors.affiliation: Department of Physiotherapy, Federal University of São Carlos (UFSCar), Rodovia Washington Luís (SP-310), Km 235, São Carlos, SP, Brazil. paulobossini@ig.com.br
authors.forename: Paulo Sérgio
authors.initials: PS
authors.lastname: Bossini
authors.forename: Ana Claudia Muniz
authors.initials: AC
authors.lastname: Rennó
authors.forename: Daniel Araki
authors.initials: DA
authors.lastname: Ribeiro
authors.forename: Renan
authors.initials: R
authors.lastname: Fangel
authors.forename: Alessa Castro
authors.initials: AC
authors.lastname: Ribeiro
authors.forename: Manoela de Assis
authors.initials: Mde A
authors.lastname: Lahoz
authors.forename: Nivaldo Antonio
authors.initials: NA
authors.lastname: Parizotto
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D001861:Bone Regeneration / Q000528:radiation effects*; D050659:Core Binding Factor Alpha 1 Subunit / Q000378:metabolism*; D051546:Cyclooxygenase 2 / Q000378:metabolism*; D004307:Dose-Response Relationship, Radiation; D005260:Female; D006614:Hindlimb; D007150:Immunohistochemistry; D028022:Low-Level Light Therapy / Q000379:methods*; D058866:Osteoporotic Fractures / Q000378:metabolism / Q000473:pathology* / Q000532:radiotherapy*; D010052:Ovariectomy; D011879:Radiotherapy Dosage; D011897:Random Allocation; D051381:Rats; D017208:Rats, Wistar; D013977:Tibia / Q000378:metabolism / Q000473:pathology / Q000528:radiation effects; D016896:Treatment Outcome; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism*
chemical_list: D015415:Biomarkers; D050659:Core Binding Factor Alpha 1 Subunit; D042461:Vascular Endothelial Growth Factor A; D051546:Cyclooxygenase 2