Effects of low-level laser therapy on regulation of genic expression of myogenic regulatory factos and proteins related to muscle trophism during skeletal muscle regeneration of aged rats

• Grant number: 16/21204-1
• Support type: Scholarships in Brazil - Scientific Initiation
• Effective date (Start): June 01, 2017
• Effective date (End): May 31, 2018
• Field of knowledge: Health Sciences - Physiotherapy and Occupational Therapy
• Principal Investigator: Raquel Agnelli Mesquita Ferrari
• Grantee: Eric Moreno Ramos Magalhães
• Home Institution: Universidade Nove de Julho (UNINOVE). Campus Vergueiro. São Paulo , SP, Brazil

Abstract

Aging is characterized by the loss of the function in the elderly (physiological, biochemical, morphological and cellular) and are related to the progressive muscle mass decline compromising the strength and quality of movement. These factors increase the incidence of muscle injuries generating strong interest from professionals in understanding its mechanisms and study resources that can be used to improve this process. The low level laser therapy (LLLT) have shown positive effects on skeletal muscle regeneration such as an increased in adenosine triphosphate (ATP) production, stimulation of angiogenesis, activation and proliferation of satellite cells, modulation in production of cytokines and growth factors during the process, reducing their settling time and by improving their quality. The objective of this study is to evaluate the effect of LLLT on myostatin, calcineurin and myogenic regulatory factors (MRFs) mRNA expression in skeletal muscle of aged rats following cryoinjury on tibialis anterior muscle. Wistar aged rats will be divided randomly into 4 groups (n = 50): Control (n=5), Cryoinjured (n = 15); Cryoinjured with LLLT (n = 15); LLLT (n = 15). LLLT will be performed 2 hours after induction of injury and consist of daily applications until the day of sacrifice using the parameters (» = 780nm, 1000mW / cm2 power density, power 40mW; 3,2J total energy, time 10s). The animals of groups 2 to 4 will be euthanized after 1, 3 and 7 days. For the analysis of gene expression, total RNA from muscle samples will be obtained using TRIZOL reagent and will be subsequently obtained the cDNA using the High Capacity kit for performing the quantitative PCR. The data will be analyzed using the Bioestat 5.0 software (PA, Brazil). The distribution of the normality of the data will be evaluated by the Kolmogorov-Smirnov test. The data with parametric distribution will be submitted to the One-way ANOVA followed by Tukey test for comparison between groups. The data distribution not parametric will be submitted to the One-way ANOVA on Ranks followed by Dunn's test for comparison between groups. Confidence levels will be adjusted to 95% (p <0.05).