Efeito do laser de baixa intensidade na apoptose muscular induzida pelo exercício resistido em ratos

Abstract

Resistance exercise (RE) is conceptualized as a type of exercise that arouses muscle tension against opposite force. Acute adaptation to high-load RE is marked by patent alteration of muscle homeostasis, with fatigue and increased pro- inflammatory proteins. Subsequent muscle injury derives mainly from cell necrosis, but there are also studies that attach relevance to apoptosis. In apoptosis, cell death is programmed, organized and demands energy, and the participating biochemical, molecular and morphological events are regulated by specific proteins. In recente studies from our research group, it was shown that photobiomodulation (PBM), represented by the low level laser intensity (LLLT) attenuated muscle necrosis, inflammation and oxidative stress ir rats submitted to a maximum load session. In this proposal, the objective was to analyze the impact of LLLT on the expression of diferente factors that modulate muscle apoptosis in rats submitted to a RE session. For this, 40 Wistar rats female were divided into five groups with 8 animals per group: Sham (n=8) non-exercised submitted to placebo-PBM; RE, exercised submitted to placebo-PBM. 2J – rats submitted to the RE and previously irradiated with 2 J of energy; 4J rats submitted to the RE and previously irradiated with 4 J of energy; 8J– rats submitted to the RE and previously irradiated with 8 J of energy. An 830-nm DMC Lase Photon III® (São Carlos, Brazil) was applied on three points in gastrocnemius muscles with the radiant energy of 2,4 or 8J. RE session comprised four climbs bearing the maximum load with a 2 min time interval between each climb. Immediately after the end of the exercise, the animals were euthanized and the gastrocnemius muscle was collected for Western blot protein expression analysis. Statistical analyzes were performed using GraphPad software, version 6,01. Data were presented as mean ± as mean and standard deviation (SD) of the mean. Normally distributed data were analyzed with on-way ANOVA (Newman-Keuls post-test). Kruskal-Wallis (Dunns) post-test was applied to nonparametric data. Significance level of p≤0.05. The results showed a significant increase in a Bcl-2 protein expression in the RE and photobiomodulated groups in relation to the expression of cleaved Caspase 3 was attenuated in the 4J group when compared to the RE group and other irradiated groups. There were no significant changes in protein expression of Bax, Bad, total and phosphorylated Akt