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Evaluation of low level laser therapy on the neuromuscular regeneration in axonotomized rats


Nerve injuries are very common in clinical-like situations. They mainly affect nerves on limbs generating incapacity. Low level laser therapy (LLLT) is indicated to induce nerve regeneration. One recent study of our laboratory showed that LLLT (wave length 660 nm and energy density around 10, 60 and 120 J/cm2) is effective to promote neuromuscular recovery, avoid skeletal muscle atrophy and activate extracellular matrix enzymes inducing remodeling in both nerve and muscles. The present study considered these first results, and it will characterize the temporal effects and molecular mechanisms of LBP (660 nm 60 J/cm2) on neuromuscular regeneration. Thus, the aim of this project is to evaluate the effects of LBP, applied over the crushed sciatic nerve, on neuromuscular recovery of rats after 7, 15 and 21 days of injury. Seventy Wistar male rats (250g) will be used. Sciatic nerves will be crushed using a controlled pinch which will generate an axonotmesis. Groups will be divided into: normal; nerve injury+LLLT simulated 7, 15 and 21 days after injury; and nerve injury+LLLT 660 nm 60J/cm2 daily irradiated during 7, 15 and 21 days after lesion. For functional analysis the walking-track test will be considered. Electrical indexes (rheobase, chronaxie and accommodation) will be measured to investigate neuromuscular excitability through experimental period. Animals will be euthanized at 7, 15 or 21 days after nerve injury according group description. Sciatic nerves and tibialis anterior muscles (TA) will be removed and processed. Histological sections from nerves and muscles will be stained using Masson's Thricomio and toluidine blue for routine morphological evaluation. Morphometric analyses will be performed in both nerve and muscles. Muscle fibers from the middle belly will be measured. Nerve and muscle fragments will be used to evaluate genic (real time-PCR) and proteic (Western Blot and zymography) expressions. The brain derived neurotrophic factor (BDNF) and neurotrophin-4 expressions, both important for neuron survival and muscle trophism maintenance will be investigated, as well as the matrix metalloproteinases (MMP-2 and -9), remodeling enzymes of extracellular matrix which allow axonal growing. For statistical analysis, data will be submitted to Levene's and Shaipro-Wilk's test to confirm data homogeneity and normality, respectively. After that, parametric data will be submitted to Anova one-way test followed by Tukey's test. A level of 5% will be considered as significant. (AU)

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Scientific publications
(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)
ALCANTARA, CAROLINA C.; GIGO-BENATO, DAVILENE; SALVINI, TANIA F.; OLIVEIRA, ALEXANDRE L. R.; ANDERS, JUANITA J.; RUSSO, THIAGO L. Effect of Low-Level Laser Therapy (LLLT) on Acute Neural Recovery and Inflammation-Related Gene Expression After Crush Injury in Rat Sciatic Nerve. Lasers in Surgery and Medicine, v. 45, n. 4, p. 246-252, APR 2013. Web of Science Citations: 23.
SILVA-COUTO, MARCELA A.; GIGO-BENATO, DAVILENE; TIM, CARLA R.; PARIZOTTO, NIVALDO A.; SALVINI, TANIA F.; RUSSO, THIAGO L. Effects of low-level laser therapy after nerve reconstruction in rat denervated soleus muscle adaptation. BRAZILIAN JOURNAL OF PHYSICAL THERAPY, v. 16, n. 4, p. 320-327, JUL-AUG 2012. Web of Science Citations: 5.

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