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<< BACK TO ARTICLESThe Effects of a 785-nm AlGaInP Laser on the Regeneration of Rat Anterior Tibialis Muscle after Surgically-Induced Injury
Cressoni, M.D.C., Giusti, H.H.K.D., Casarotto, R.A., Anaruma, C.A.
Photomedicine and Laser Surgery 2008
26(5): 461-466
Photomedicine and Laser Surgery 2008
26(5): 461-466
Objective: This study aims to investigate the effects of low-level laser therapy (LLLT) on muscle regeneration. For this purpose, the anterior tibialis muscle of 48 male Wistar rats received AlGaInP laser treatment (785nm) after surgically-induced injury.
Background Data: Few studies have been conducted on the effects of LLLT on muscle regeneration at difference irradiation doses.
Materials and Methods: The animals were randomized into four groups: uninjured rats (UN); uninjured and laser-irradiated rats (ULI); injured rats (IN); and injured and laser-irradiated rats (ILI). The direct contact laser treatment was started 24h after surgery. An AlGaInP diode laser emitting 75mW of continuous power at 785nm was used for irradiation. The laser probe was placed at three treatment points to deliver 0.9J per point, for a total dose of 2.7J per treatment session. The animals were euthanized after treatment sessions 1, 2, and 4. Mounted sections were stained with hematoxylin and eosin and used for quantitative morphological analysis, in which the number of leukocytes and fibroblasts were counted over an area of 4480 µm². The data were statistically analyzed by analysis of variance (ANOVA) and the Bonferroni t-test.
Results: Quantitative data showed that the number of both polymorphonuclear and mononuclear leukocytes in the inflammatory infiltrate at the injury site was smaller in the ILI1, ILI2, and ILI4 subgroups compared with their respective control subgroups (IN1, IN2, and IN4) for sessions 1, 2, and 4, respectively (p < 0.05). On the other hand, the number of fibroblasts increased after the fourth treatment session (p < 0.05). With regard to the regeneration of muscle fibers following injury, only after the fourth treatment session was it possible to find muscle precursor cells such as myoblasts and some myotubes in the ILI4 subgroup.
Conclusion: During the acute inflammatory phase, the AlGaInP laser treatment was found to have anti-inflammatory effects, reducing the number of leukocytes at the injury site and accelerating the regeneration of connective tissue.
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