Effect of photobiomodulation on connective tissue remodeling and regeneration of skeletal muscle in elderly rats
The purpose of this study was to evaluate the effects of low-level laser therapy (LLLT) on morphological aspects, IL-6 and IL-1β expressions, as well as the distribution and organization of collagen in the tibialis anterior (TA) muscle of elderly rats submitted to cryoinjury. Histological photomicrographs were taken of TA muscles stained with HE and picrosirius red. Immunohistochemistry was used for the evaluation of IL-6 and IL-1β. Male Wistar rats, aged 20 months, were distributed into three groups: (1) control animals not injured or treated with LLLT (n = 5), (2) cryoinjury without LLLT treatment (n = 15), and (3) cryoinjury treated with infrared LLLT (n = 15). LLLT was applied to the TA 2 h after of the injury induction and consisted of daily applications until the sacrifice (1, 3, and 7 days). The following parameters were used: λ = 780 nm, power density 1 W/cm2, output power 40 mW, 10 s per point, 8 points, and 3.2 J of total energy. In the histomorphological analysis, the treated group exhibited a significant decrease in inflammatory infiltrate (p < 0.001) as well as an increase immature fibers and new blood vessels at 7 days compared to the untreated group (p < 0.05). Furthermore, treatment induced a better collagen distribution and organization at 7 days in comparison to the untreated group (p < 0.05). In conclusion, LLLT demonstrated a modulatory effect on the muscle repair process in elderly animals with regard to the collagen remodeling and morphological aspects of muscle tissue.
KeywordsAging Regeneration Low-level laser therapy LLLT Collagen Skeletal muscle
Compliance with ethical standards
This study was developed at the research laboratory of the Postgraduate Program in Biophotonics Applied to Health Sciences using a methodology in accordance with international ethical standards for animal experimentation (National Research Council, 1996).
Conflict of interest
The authors declare that they have no conflict of interest.
Ethical approval and informed consent
The protocol of this study plan was approved by the Ethics Committee for Animal Research of University Nove de Julho (no. An0002/2014). This study does not include human participants.
- 2.Ceafalan LC, Popescu BO, Hinescu ME (2014) Cellular players in skeletal muscle regeneration. Biomed Res Int 957014Google Scholar
- 11.Visser M, Pahor M, Taaffe DR, Goodpaster BH, Simonsick EM, Newman AB, Nevitt M, Harris TB (2002) Relationship of interleukin-6 and tumor necrosis factor-alpha with muscle mass and muscle strength in elderly men and women: the Health ABC Study. J Gerontol A Biol Sci Med Sci 57(5):M326–M332CrossRefPubMedGoogle Scholar
- 12.Schaap LA, Pluijm SM, Deeg DJ, Harris TB, Kritchevsky SB, Newman AB, Colbert LH, Pahor M, Rubin SM, Tylavsky FA, Visser M, Health ABC Study (2009) Higher inflammatory marker levels in older persons: associations with 5-year change in muscle mass and muscle strength. J Gerontol A BiolSci Med Sci 64(11):1183–1189CrossRefGoogle Scholar
- 31.Pires D, Xavier M, Araújo T, Silva JA Jr, Aimbire F, Albertini R (2011) Low-level laser therapy (LLLT; 780 nm) acts differently on mRNA expression of anti- and pro-inflammatory mediators in an experimental model of collagenase-induced tendinitis in rat. Lasers Med Sci 26:85–94CrossRefPubMedGoogle Scholar
- 45.Pinheiro AL, Soares LG, Aciole GT, Correia NA, Barbosa AF, Ramalho LM et al (2011) Light microscopic description of the effects of laser phototherapy on bone defects grafted with mineral trioxide aggregate, bone morphogenetic proteins, and guided bone regeneration in a rodent model. J Biomed Mater Res A 98(2):212–221CrossRefPubMedGoogle Scholar
- 46.Melo Rambo CS, Silva JA Jr, Serra AJ, Ligeiro AP, de Paula Vieira R, Albertini R, Leal-Junior EC, de Tarso Camillo de Carvalho P (2014) Comparative analysis of low-level laser therapy (660 nm) on inflammatory biomarker expression during the skin wound-repair process in young and aged rats. Lasers Med Sci 29(5):1723–1733CrossRefPubMedGoogle Scholar