Effects of exercise and low-level laser therapy on quadriceps muscle in rats with osteoarthritis induced by transection of the anterior cruciate ligament

Abstract

The knee osteoarthritis (OA) is one of the most common causes of functional limitation and the prevalence has increased in recent decades. This disease has an inflammatory and degenerative character of the articular cartilage of the knee, initiates a process of atrophy and weakness of the quadriceps muscle, causing significant functional limitation. Thus, the development of therapeutic strategies aiming to soften the muscle changes resulting from knee OA becomes important for rehabilitation. The effects of physical exercise in a moderate intensity and Low-Level Laser Therapy (LLLT) in the clinical treatment of OA knee are being investigated, and its demonstrated benefits, but the mechanisms activated by these resources about the periarticular musculature remain uncertain. The objective of this study is to evaluate the effects of moderate aerobic exercise, LLLT and the association of both on the quadriceps muscle of rats submitted to an experimental model of OA induced by anterior cruciate ligament (ACLT). It will used 50 Wistar, male rats, divided into 5 groups (n=10): control (GC); osteoarthritic (OA); osteoarthritic and exercise (GOE); osteoarthritic and irradiated with LLLT (GOL); osteoarthritic and exercise and irradiated with LLLT (GOEL). The treatments will begin three weeks after surgery. The aerobic exercise protocol will be on a treadmill (speed of 16 m/min, 50 min, 3 times per week) during 8 weeks. Will use a GaAlAs laser (continue; »=808 nm; P=50 mW, beam area = 0,000785 cm²; t = 28 s; D= 178J/cm²; E=1,4 J; irradiance= 6,3 mW/cm²) 3 times per week and / or after training sessions in 2 spots in each left hind leg (medial and lateral joint line). To evaluate and compare the effects of treatments will be performed to analyze the cross-sectional area of muscle fibers (AST) of the vastus medialis and the immunohistochemical expression of MURF-1 and atrogin-1. It is expected that the results of this project will bring significant contribution to the elucidation of mechanisms of action by exercise, LLLT and the association of both in atrophy and muscle weakness present in knee OA, thus optimizing the use of resources safe and effective in the rehabilitation of degenerative disorders. (AU)