Biochemical changes in injured sciatic nerve of rats after low-level laser therapy (660 nm and 808 nm) evaluated by Raman spectroscopy

• Published in: Lasers in medical science 2019-04, Vol.34 (3), p.525-535
• Main Authors: de Almeida Melo Maciel Mangueira, Melissa, Maciel Mangueira, Nilton, Pereira Gama Filho, Ozimo, Moysés de Oliveira, Márcio, Albuquerque Heluy, Renato, Silveira, Landulfo, Caparelli Moniz de Aragão Dáquer, Egas
• Format: Article
• Language: English
• Subjects: Aluminum; Animals; Biochemistry; Cell proliferation; Collagen; Crushing; Dentistry; Excitation spectra; Female; Glycoproteins; Injuries; Lasers; Levels; Lipids; Low-Level Light Therapy; Medicine; Medicine & Public Health; Myelin; Optical Devices; Optics; Original Article; Phospholipids; Photonics; Principal Component Analysis; Principal components analysis; Proteins; Quantum Optics; Raman spectra; Raman spectroscopy; Rats; Rats, Wistar; Sciatic nerve; Sciatic Nerve - injuries; Sciatic Nerve - metabolism; Sciatic Nerve - radiation effects; Sciatic Nerve - surgery; Sheaths; Spectroscopy; Spectrum analysis; Spectrum Analysis, Raman - methods; Sphingolipids; Surgery; Therapy
• ISSN: 0268-8921; 1435-604X
• DOI: 10.1007/s10103-018-2627-1

The aim of this study was to identify biochemical changes in sciatic nerve (SN) after crush injury and low-level laser therapy (LLLT) with 660 nm and 808 nm by Raman spectroscopy (RS) analysis. A number of 32 Wistar rats were used, divided into four groups (control 1, control 2, LASER 660 nm, and LASER 808 nm). All animals underwent surgical procedure of the SN and groups control 2, LASER 660 nm, and LASER 808 nm were submitted to SN crush damage (axonotmesis). The LLLT in the groups LASER 660 nm and LASER 808 nm was applied daily for 21 consecutive days (100 mW, 30 s, 133 J/cm 2 fluence). The hind paw was removed and the SN was dissected and positioned on an aluminum support to collect dispersive Raman spectra (830 nm excitation, 30 s accumulation). To estimate the biochemical changes in the SN associated with LLLT, the principal component analysis (PCA) was applied. The Raman spectra of the sciatic nerve fragments showed peaks of the major biochemical components of the nerve, especially sphingolipids, phospholipids, glycoproteins, and collagen. The spectral features identified in some of the principal component loading vectors are referred to the biochemical elements present on the SN and were increased in the groups treated with LLLT, mainly lipids (sphingo and phospholipids) and proteins (collagen)—constituents of the myelin sheath. The RS was effective in identifying the biochemical differences in the SN after the crush injury, and LASER 660 nm was more efficient than the LASER 808 nm in cell proliferation and repair of the injured SN.