ABSTRACT
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.
ABSTRACT
O objetivo deste estudo foi verificar os efeitos da laserterapia de baixa potência no comprimento de onda ?=780nm entre diferentes períodos de tratamento 7, 14 e 21 dias e verificar a dose (10J/cm2 ou 50J/cm2) que promove melhor reparo muscular através das análises histopatológicas e imunohistoquímicas. Foram utilizados 54 ratos machos divididos em 3 grupos: GC: grupo controle (criolesão, sem tratamento); G10: criolesão do músculo tibial anterior (TA) e tratados com laser dose 10J/cm² e G50: criolesão do músculo TA e tratados com laser dose 50J/cm² que foram subdivididos em 3 subgrupos (n=6): 7, 14 e 21 dias de tratamento. Os achados histopatológicos revelaram maior organização das fibras musculares dos grupos tratados com laser 10J/cm² e 50J/cm² durante os períodos 7 e 14 dias em relação ao grupo controle; no período 21 dias os grupos apresentaram semelhanças na reparação tecidual. Em relação à área da lesão os grupos tratados com laser 10J/cm² e 50J/cm² durante 7 dias obtiveram diminuição significativa (p ? 0.05) da área da lesão em relação ao grupo controle, sendo que os grupos 14 e 21 dias não apresentaram diferenças significativas entre eles. Na contagem dos vasos o grupo tratado com laser 10J/cm² no 14° dia apresentou aumento dos vasos em relação ao grupo tratado com dose 50J/cm², mas não em relação ao grupo controle. Nos tempos de 7 e 21 dias os grupos não apresentaram diferença significativa entre si. Com relação às análises imunohistoquímicas da myoD no período de 7 dias os grupos tratados com laser 10J/cm² e 50J/cm² apresentaram maior imunomarcação comparada com o grupo controle, no período 14 e 21 dias a imunomarcação estava ausente.
The objective of this study was to assess the effects of 780nm low-level laser therapy at different periods of 7, 14 and 21 days after cryolesion, including the dose (10 or 50J/cm2) to promote a better muscle repair evidenced by histopathological and immumohistochemical analyses. Fifty-four male rats were divided into three groups: injured control group (CG) - injured animals without any treatment; injured 780nm laser treated group, at 10 J/cm² (G10) and injured 780nm laser treated group, at 50 J/cm² (G50). Each group was divided into 3 subgroups (n=6): 7, 14 and 21 days post-injury. Histopathological findings revealed better-organized muscle fibers in the G10 and G50 during the periods of 7 and 14 days compared to CG. The G10 and G50 during 7 days showed a significant reduction (p? 0.05) of lesion area compared to CG, without differences between groups treated for 14 and 21 days. The G10 showed an increase of the amount of vessels after 14 days compared to the G50, but not in relation to controls. With regard to the immumohistochemical analyses of the MyoD factor, The G10 and G50 during 7 days showed higher concentrations of immunomarkers than controls.