The main purpose of the present study was to investigate the effects of low-level laser therapy (LLLT) used in two different fluencies on injured skeletal muscle after cryolesion by means of histopathological analysis and immunohistochemistry for COX-2. A total of sixty male Wistar rats were randomly distributed into three groups: injured animals without any treatment; 808 nm laser treated group, at 10 J/cm² and 808 nm laser treated group, at 50 J/cm². Each group was divided into two different subgroups (n=10) on days 6 and 13 post-injury. The results showed that the animals irradiated with laser at 10 J/cm² or 50 J/cm² presented the areas with cell infiltrate and pointed out to minor and mild areas with destroyed zones compared with the control group. Also, a COX-2 downregulation was noticed in the groups exposed to laser at two fluences evaluated in this study. Significant statistically differences (p<0.05) were noticed to collagen deposition in the laser treated animals, with the fluence of 50 J/cm² when compared to the other groups on day 13 post-surgery. Taken together, these results suggested that laser therapy could have positive effects on muscle repair in the rats after cryolesion.
low level laser therapy; rat; muscle repair; COX-2
