title: Analysis of the variation in low-level laser energy density on the crushed sciatic nerves of rats: a morphological, quantitative, and morphometric study.
abstract: The objective of this study was to evaluate three energy densities of low-level laser therapy (LLLT, GaAlAs, 780 nm, 40 mW, 0.04 cm2) for the treatment of lesions to peripheral nerves using the sciatic nerve of rats injured via crushing model (15 kgf, 5.2 MPa). Thirty Wistar rats (♂, 200-250 g) were divided into five groups (n = 6): C-control, not injured, and irradiated; L0-injured nerve without irradiation; L4-injured nerve irradiated with LLLT 4 J/cm2(0.16 J); L10-injured nerve irradiated with LLLT 10 J/cm2(0.4 J); and L50-injured nerve irradiated with LLLT 50 J/cm2(2 J). The animals were sacrificed 2 weeks after the injury via perfusion with glutaraldehyde (2.5%, 0.1 M sodium cacodylate buffer). The nerve tissue was embedded in historesin, cut (3 μm), mounted on slides, and stained (Sudan black and neutral red). The morphological and quantitative analysis (myelin and blood capillary densities) and morphometric parameters (maximum and minimum diameters of nerve fibers, axon diameter, G-ratio, myelin sheath thickness) were assessed using the ImageJ software. ANOVA (parametric) or Kruskal-Wallis (nonparametric) tests were used for the statistical analysis. Groups L0, L4, L10, and L50 exhibited diminished values of all the quantitative and morphometric parameters in comparison to the control group. The morphological, quantitative, and morphometric data revealed improvement after injury in groups L4, L10, and L50 (irradiated groups) compared to the injured-only group (L0); the best results, in general, were observed for the L10 group after 15 days of nerve injury.
authors.affiliation: School of Dentistry, University of São Paulo, USP, Ribeirão Preto, Brazil.
authors.forename: Eduardo Keiske Mastuda
authors.initials: EK
authors.lastname: Ziago
authors.affiliation: School of Medicine, University of São Paulo, USP, Ribeirão Preto, Brazil.
authors.forename: Valéria Paula Sassoli
authors.initials: VP
authors.lastname: Fazan
authors.affiliation: School of Dentistry, University of São Paulo, USP, Ribeirão Preto, Brazil.
authors.forename: Mamie Mizusaki
authors.initials: MM
authors.lastname: Iyomasa
authors.affiliation: School of Dentistry, University of São Paulo, USP, Ribeirão Preto, Brazil.
authors.forename: Luiz Gustavo
authors.initials: LG
authors.lastname: Sousa
authors.affiliation: School of Dentistry, University of São Paulo, USP, Ribeirão Preto, Brazil.
authors.forename: Paula Yumi
authors.initials: PY
authors.lastname: Yamauchi
authors.affiliation: School of Medicine, University of São Paulo, USP, Ribeirão Preto, Brazil.
authors.forename: Eunice Aparecida
authors.initials: EA
authors.lastname: da Silva
authors.affiliation: Department of Integral Dentistry, CICO - Research Centre in Dental Sciences, Dental School, Universidad de La Frontera, Temuco, Chile.
authors.forename: Eduardo
authors.initials: E
authors.lastname: Borie
authors.affiliation: Department of Integral Dentistry, CICO - Research Centre in Dental Sciences, Dental School, Universidad de La Frontera, Temuco, Chile.
authors.forename: Ramón
authors.initials: R
authors.lastname: Fuentes
authors.affiliation: School of Medicine, University of São Paulo, USP, Ribeirão Preto, Brazil. fernando.dias@ufrontera.cl.|Department of Integral Dentistry, CICO - Research Centre in Dental Sciences, Dental School, Universidad de La Frontera, Temuco, Chile. fernando.dias@ufrontera.cl.
authors.forename: Fernando José
authors.initials: FJ
authors.lastname: Dias
mesh_terms: D000818:Animals; D002196:Capillaries / Q000473:pathology / Q000528:radiation effects; D028022:Low-Level Light Therapy / Q000379:methods*; D008297:Male; D009186:Myelin Sheath / Q000378:metabolism; D009409:Nerve Crush; D017208:Rats, Wistar; D012584:Sciatic Nerve / Q000098:blood supply / Q000473:pathology* / Q000528:radiation effects*; D020426:Sciatic Neuropathy / Q000473:pathology*
keywords: Energy density; Low-level laser therapy; Morphology and morphometry; Nerve regeneration