Effects of photobiomodulation on gene expression of calcineurin and myostatin in skeletal muscle after peripheral nerve injury in wistar rats

• Grant number: 16/16753-6
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Effective date (Start): October 01, 2016
• Effective date (End): July 31, 2017
• Field of knowledge: Health Sciences - Physiotherapy and Occupational Therapy
• Principal Investigator: Raquel Agnelli Mesquita Ferrari
• Grantee: Patrick Raoul Vicente de Matos
• Host Institution: Universidade Nove de Julho (UNINOVE). Campus Vergueiro. São Paulo , SP, Brazil

Abstract

Clinically, a peripheral nerve injury (PNI) is not a risk of life to the individual but can have a negative impact on the quality of life in cases where there is a complete regeneration that results in motor or sensory disturbances. The literature highlights the constant search for effective therapies in the upregulation of post-PNI neuromuscular repair. In this context, photobiomodulation has shown positive effects in treating LNP however restricted studies using especially low-level laser therapy (LLLT) which is applied only at the site of nerve injury. Objective: To analyze the effects of LLLT applied at the site of nerve damage (LLLTn) and / or the affected muscle for this injury (LLLTmm) on the morphology and gene expression of myostatin and calcineurin in muscle tissue after sciatic nerve crush in Wistar rats. Methods: 85 Wistar rats will be used (200-250 g) and will be divided randomly into 5 groups: control, Injury, Injury+LLLTn, Injury+LLLTmm and Injury+LLLTn+LLLTmm (n = 20 / group) analyzed after 1, 2, 3 and 4 weeks. The left sciatic nerve injury procedure performed by the crushing technique using a flat hemostat with lock (6.3Mpa) through compression of 30s. Laser treatment will be started after 2 hours with LLLT (780nm, 0.04cm², 1W/cm², 3.2J) in nerve lesion area (20J/cm², 0.8J by point, 4 points), and / or the tibialis anterior muscle ( 10 J/cm², 0.4J by point, 8 points). At the end of the experimental period, TA muscles will be carefully removed and weighed to determine the degree of atrophy and muscle mass ratio. This tissue will be also subjected to histological analysis of morphological (diameter of muscle fiber cross-sectional area, core location, and a total number of vessels) using hematoxylin & eosin (HE). For the analysis of gene expression, Total RNA from muscle samples will be obtained using Trizol reagent, cDNA will be synthesized using "High Capacity® kit" and qPCR will be performed using specific primers: calcineurin, myostatin and GAPDH, regard to the constitutive gene. The data will be subjected to statistical analysis.