Lasertherapy effects on muscle repair process in rats with chronic alcohol ingestion

Abstract

High-level alcohol consumption in patients with traumatic injuries is associated with longer hospital stays and admission to the intensive care unit after injury, higher injury severity scores, and an increased mortality rate. These findings have a multifactorial basis, but they have been attributed in large part to alcohol-associated modulation of host-defense systems and the immune response. While acute consumption is inhibitory for inflammation, chronic consumption seems to increase pro-inflammatory cellular response. The inflammation associated with muscular injury is necessary to remove the injured tissue and can promote regeneration by the interaction with myoblasts which promote myogenic differentiation. Low-level laser therapy effectively decreases the post-injury inflammatory process, stimulates new blood vessel formation, and accelerates soft tissue healing. This therapeutic modality has been demonstrated to improve muscle repair by inducing rapid vascularization on injury area, muscle fiber regeneration, the parallel orientation of regenerated myofibers and increase tissue repair by accelerating the membrane reactions begin, increasing macrophage, fibroblasts, and lymphocytes activity. The aim of this study includes analyzing the effects of low-level laser therapy on the muscle repair process in rats with chronic alcohol ingestion. Forty-eight Wistar male rats, age average 60 days, will be divided into three groups: injury (n=16), injury+alcohol (n=16), injury+alcohol+laser (n=16). Each group will be subdivided into two groups of eight animals for analyzes 3 days post-injury (n=24) and 7 days post-injury (n=24). Alcohol administration will be with a two-bottle choice drinking paradigm, with access to one bottle of water and another with alcohol solution 20%, 3 days per week for 45 days. Muscle injury will be induced by a cryo lesion on the right tibial anterior muscle and laser treatment will be started immediately post-injury. Transversal histological sections will be stained for qualitative analysis of the inflammatory process, granulation tissue, necrosis area, and tissue structure. The immunohistochemical analysis will be performed with the objective of verify myoD expression, myogenin, COX-2, and VEGF. Comparison between quantitative results of treatment and control group will be performed by analysis of variance (ANOVA), and the Bonferroni post-test. (AU)