Effect of prior application with and without post-injury treatment with low-level laser on the modulation of key proteins in the muscle repair process

Abstract

The aim of the present study was to evaluate the effects of LLLT prior to muscle injury with and without post-injury irradiation on the expression of isoforms of myosin heavy chain (MyHC), calcineurin (CaN), and myostatin during the repair process. Wistar rats were divided into five groups: control (n = 7); injury (n = 21); LLLT + injury (n = 21); injury + LLLT (n = 21), and LLLT + injury + LLLT (n = 21). Cryoinjury was performed on the tibialis anterior (TA) muscle. The injured groups were euthanized at 3, 7, and 14 days after injury. LLLT was performed using an infrared laser (780 nm) with the following parameters: 10 J/cm, 40 mW, 10 s per point, 8 points, and 3.2 J of total energy. At the end of each period, the TA muscle was removed for the analysis of MyHC, CaN, and myostatin gene expression using real-time PCR. The data were tested statistically by Kruskal-Wallis with Dunn's post hoc test (p < 0.05). The results demonstrated that prior irradiation reduced the mRNA expression of all proteins at 3 days. Post irradiation reduced the mRNA expression of MyHC-1, MyHC-2a, MyHC-2b, and CaN at 7 days. Prior irradiation combined with post-injury irradiation reduced the mRNA expression of MyHC-2x and CaN at 14 days and increased the mRNA expression of myostatin in the same period. In conclusion, different protocols of photobiomodulation can modulate the expression of the different isoforms of MyHC, CaN, and myostatin during the repair process. It is noteworthy that the combination of the prior and post-injury irradiation was the protocol that most promoted changes in the final phase of the repair process.

Histological and biochemical effects of preventive and therapeutic vascular photobiomodulation on rat muscle injury

“…Experimental studies are fundamental to the assessment of the safety, effectiveness, and applicability of different therapeutic modalities. For the analysis of the muscle repair process in in vivo studies, the cryoinjury method is well established and has viable reproducibility [12,16,[22][23][24]27]. Moreover, this model mimics the response of a muscle regarding damage compatible with a contusion [14,43].…”

“…Ribeiro et al [15] evaluated irradiation performed previous to the induction of injury alone and in combination with PMB performed after the induction of injury using the red and infrared spectra (660 and 780 nm, 10 J/ cm 2 per point, 40 mW, 3.2 J, total of 8 points), reporting that the wavelength of 780 nm led to a positive modulation of the activity of antioxidant enzymes and a reduction in markers of oxidative stress in the microenvironment 3 and 7 days after the muscle injury. Using the same total energy in the infrared spectrum (780 nm, 10 J/cm 2 per point, 40 mW, 3.2 J, total of 8 points), Rodrigues et al [16] found that PBM administered previously at the site of the injury promoted the modulation of myostatin, calcineurin, and myostatin heavy chains after 3 days. The parameters described in these studies involving PBM administered locally to the tibialis anterior muscle were the same as those employed in the present investigation (780 nm, total of 80 J/cm 2 , 40 mW, 3.2 J) and demonstrated similar positive effects in muscle repair, despite the different form of application (directly over the injury vs transcutaneously over the vascular bed).…”

“…The dosimetric parameters are listed in Table 1. The dosimetric parameters were based on previous studies using the same experimental model but with PBM (780 nm; 40 mW; total energy 3.2 J) applied to the injury site [14, 16, 20, 21].…”

“…Therefore, here is a constant quest for therapeutic tools that can decrease the time for the muscle repair and increase the quality of the newly formed tissue. Photobiomodulation (PBM) therapy administered with distinct light sources locally, over the injury site, is one such tool that has demonstrated positive effects in skeletal muscle repair in both clinical and experimental studies [9–16]. PBM acts enhancing the number of newly formed muscle fiber [12, 14, 17–19], decreasing the size of the injury [20–22], and restoring the muscle function when administrated either preventively (before the occurrence of an injury) [14–16, 19, 23–25] or after the injury [12, 13, 22, 26, 27].…”

Immunology Guides Skeletal Muscle Regeneration

“…Autocrine and paracrine muscle-growth inhibition has previously been attributed to myostatin, which is a TGFβ family member that is most dominantly expressed in skeletal muscle [ 102 ]. TGFβ1 and myostatin are released by muscle cells to provide signaling cues for muscle regeneration [ 103 ].…”