Avaliação de expressão gênica em músculo lesionado de ratos Wistar expostos a laser infravermelho de baixa intensidade

Abstract

During the muscle repair process, reactive oxygen species activate important signaling pathways. However, if oxidative stress occurs it can lead to secondary damage of non-injured fibers. Damage from oxidative injury is repaired by the mechanism of base and nucleotide excision repair. Protection against non-oxidative DNA damage can occur through mechanisms called checkpoints. In addition, non-functional telomeres also function as DNA damage and activate pathways of DNA damage response. Low-power laser therapy is a safe and effective technique that has been widely used for the repair of muscle injuries. Recent studies have shown that the biostimulatory effects of laser influence the genomic stability. Thus, the aim of this study was to evaluate the influence of low level infrared laser on the expression of genes related to muscle injury repair, DNA repair and telomere maintenance in culture myoblast and muscle injury model using Wistar rats. For the in vitro study, C2C12 cells were used that were exposed to the laser and evaluated its effect on cell viability, generation of reactive oxygen species, apoptosis and necrosis, as well as the expression of genes related to muscle repair, genomic stability and the telomere maintenance. For the in vivo studies the cryoinjury model was used to cause muscle injury and the expression of genes related to muscle repair, genome stability, telomere maintenance and pro-inflammatory and anti-inflammatory cytokines were evaluated. The results of the in vitro study showed that low level laser exposure increases cell viability, reduces the percentage of apoptotic cells and increases necrosis depending on the fluence used. In addition, it modulates the expression of genes involved in repair of oxidative damage (APE1, OGG1, ERCC1, XPC), genomic stability (ATM and Tp53), muscle repair (MyoD and Pax7) and chromosome stability (TRF1 and TRF2). The in vivo study showed that power-dependent laser exposure modulates expression of genes related to genomic stability (TMJ and Tp53), telomere maintenance (TRF1 and TRF2), repair of muscle lesions (MyoD, Myf5, MyoG, MRF4 and Pax3), proinflammatory cytokines (IL-6 and IL-1β) and the anti-inflammatory cytokine IL-4. In conclusion, modulation of these genes in the in vitro studies and in the in vivo studies could be one of the beneficial effects of low level laser exposure.