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Infrared (810 nm) Low-level Laser Therapy in Rat Achilles Tendinitis: A Consistent Alternative to Drugs

Authors

  • Rodrigo Labat Marcos,

    1. Laboratory of Pharmacology and Experimental Therapeutics, Department of Pharmacology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP-Brazil
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  • Ernesto Cesar Pinto Leal Junior,

    1. Post Graduate Program in Rehabilitation Sciences, Nove de Julho University (UNINOVE), São Paulo, SP-Brazil
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  • Felipe de Moura Messias,

    1. Post Graduate Program in Rehabilitation Sciences, Nove de Julho University (UNINOVE), São Paulo, SP-Brazil
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  • Maria Helena Catelli de Carvalho,

    1. Laboratory of Hypertension, Department of Pharmacology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP-Brazil
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  • Rodney Capp Pallotta,

    1. Laboratory of Pharmacology and Experimental Therapeutics, Department of Pharmacology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP-Brazil
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  • Lúcio Frigo,

    1. Biological Sciences and Health Center, Cruzeiro do Sul University, São Paulo, SP-Brazil
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  • Rosângela Aparecida dos Santos,

    1. Laboratory of Hypertension, Department of Pharmacology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP-Brazil
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  • Luciano Ramos,

    1. Laboratory of Pharmacology and Experimental Therapeutics, Department of Pharmacology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP-Brazil
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  • Simone Teixeira,

    1. Laboratory of Pharmacology and Experimental Therapeutics, Department of Pharmacology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP-Brazil
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  • Jan Magnus Bjordal,

    1. Section of Evidence Based Practice, Bergen University College, Bergen, Norway
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  • Rodrigo Álvaro Brandão Lopes-Martins

    Corresponding author
    1. Laboratory of Pharmacology and Experimental Therapeutics, Department of Pharmacology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP-Brazil
    2. Post Graduate Program in Rehabilitation Sciences, Nove de Julho University (UNINOVE), São Paulo, SP-Brazil
      Corresponding author email: rmartins@icb.usp.br (Rodrigo Álvaro Brandão Lopes-Martins)
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Corresponding author email: rmartins@icb.usp.br (Rodrigo Álvaro Brandão Lopes-Martins)

Abstract

Nonsteroidal anti-inflammatory drugs (NSAIDs) are widely used and can reduce musculoskeletal pain in spite of the cost of adverse reactions like gastrointestinal ulcers or cardiovascular events. The current study investigates if a safer treatment such as low-level laser therapy (LLLT) could reduce tendinitis inflammation, and whether a possible pathway could be through inhibition of either of the two-cyclooxygenase (COX) isoforms in inflammation. Wistar rats (six animals per group) were injected with saline (control) or collagenase in their Achilles tendons. Then, we treated them with three different doses of IR LLLT (810 nm; 100 mW; 10 s, 30 s and 60 s; 3.57 W cm−2; 1 J, 3 J, 6 J) at the sites of the injections, or intramuscular diclofenac, a nonselective COX inhibitor/NSAID. We found that LLLT dose of 3 J significantly reduced inflammation through less COX-2-derived gene expression and PGE2 production, and less edema formation compared to nonirradiated controls. Diclofenac controls exhibited significantly lower PGE2 cytokine levels at 6 h than collagenase control, but COX isoform 1-derived gene expression and cytokine PGE2 levels were not affected by treatments. As LLLT seems to act on inflammation through a selective inhibition of the COX-2 isoform in collagenase-induced tendinitis, LLLT may have potential to become a new and safer nondrug alternative to coxibs.

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