RESUMO
Peripheral nerve injury (PNI) is associated with considerable functional impairment. Photobiomodulation (PBM) has demonstrated positive effects regarding neuromuscular repair after PNI when applied locally to the nerve or injured muscle. However, the effects of systemic PBM with transcutaneous application over an important artery, which is also denominated vascular PBM (VPBM), remain unclear. The aim of the study was to compare the effects of VPBM with low-level laser (LLL) and light-emitting diode (LED) on gait, sensitivity and muscle morphology following a PNI. PNI was induced on Wistar rats using the sciatic nerve crushing technique. VPBM was performed over the rat's artery tail region with LED (850 nm, 40 mW, 3.2 J) and LLL (780 nm, 40 mW, 3.2 J). Gait functionality, mechanical (nociceptive) sensitivity, and morphology of the tibialis anterior muscle were evaluated at 7, 14, and 21 days after injury. An improvement in functional gait was shown in the VPBM-LLL group in all periods. Motor sensitivity was found after 14 days in the VPBM-LLL group. The left/right (L/R) muscle mass ratio revealed a reduction in muscle atrophy in the VPBM-LLL group at 7 days. Muscle fiber diameter increased in the VPBM-LED group at 14 days and increases in the cross-section area were found in the VPBM-LED and VPBM-LLL groups at 7 days. VPBM with both light sources (LED and LLL) positively modulated functioning and neuromuscular recovery following sciatic nerve injury in rats, with more pronounced results when using LLL.
Assuntos
Terapia com Luz de Baixa Intensidade , Traumatismos dos Nervos Periféricos , Ratos , Animais , Ratos Wistar , Traumatismos dos Nervos Periféricos/radioterapia , Terapia com Luz de Baixa Intensidade/métodos , Nervo Isquiático , LasersRESUMO
Axonotmesis causes sensorimotor and neurofunctional deficits, and its regeneration can occur slowly or not occur if not treated appropriately. Low-level laser therapy (LLLT) promotes nerve regeneration with the proliferation of myelinating Schwann cells to recover the myelin sheath and the production of glycoproteins for endoneurium reconstruction. This study aimed to evaluate the effects of LLLT on sciatic nerve regeneration after compression injury by means of the sciatic functional index (SFI) and Raman spectroscopy (RS). For this, 64 Wistar rats were divided into two groups according to the length of treatment: 14 days (n = 32) and 21 days (n = 32). These two groups were subdivided into four sub-groups of eight animals each (control 1; control 2; laser 660 nm; laser 808 nm). All animals had surgical exposure to the sciatic nerve, and only control 1 did not suffer nerve damage. To cause the lesion in the sciatic nerve, compression was applied with a Kelly clamp for 6 s. The evaluation of sensory deficit was performed by the painful exteroceptive sensitivity (PES) and neuromotor tests by the SFI. Laser 660 nm and laser 808 nm sub-groups were irradiated daily (100 mW, 40 s, energy density of 133 J/cm2). The sciatic nerve segment was removed for RS analysis. The animals showed accentuated sensory and neurofunctional deficit after injury and their rehabilitation occurred more effectively in the sub-groups treated with 660 nm laser. Control 2 sub-group did not obtain functional recovery of gait. The RS identified sphingolipids (718, 1065, and 1440 cm-1) and collagen (700, 852, 1004, 1270, and 1660 cm-1) as biomolecular characteristics of sciatic nerves. Principal component analysis revealed important differences among sub-groups and a directly proportional correlation with SFI, mainly in the sub-group laser 660 nm treated for 21 days. In the axonotmesis-type lesion model presented herein, the 660 nm laser was more efficient in neurofunctional recovery, and the Raman spectra of lipid and protein properties were attributed to the basic biochemical composition of the sciatic nerve.
Assuntos
Lesões por Esmagamento , Terapia com Luz de Baixa Intensidade , Traumatismos dos Nervos Periféricos , Neuropatia Ciática , Animais , Lesões por Esmagamento/radioterapia , Terapia com Luz de Baixa Intensidade/métodos , Compressão Nervosa , Regeneração Nervosa/fisiologia , Traumatismos dos Nervos Periféricos/radioterapia , Ratos , Ratos Wistar , Nervo Isquiático/lesões , Neuropatia Ciática/patologia , Análise Espectral RamanRESUMO
OBJECTIVE: Traumatic injuries are common and may promote disruption of neuromuscular communication, triggering phenomena that lead to nerve degeneration and affect muscle function. A laser accelerates tissue recovery; however, the parameters used are varied, making it difficult to compare studies. The purpose of this study was to evaluate the effect of low-level laser therapy, at 660- and 830-nm wavelengths, on the tibialis anterior muscle of Wistar rats after sciatic nerve compression. METHODS: Twenty animals were separated into 4 groups: control, sciatic nerve injury, lesionâ¯+â¯660-nm laser, and lesionâ¯+â¯830-nm laser. In the lesion groups, the right sciatic nerve was surgically exposed and compressed with hemostatic forceps for 30 seconds. After the third postoperative day, the groups with laser therapy were submitted to treatment for 2 weeks totaling 10 applications, performed directly on the surgical scar of the nerve injury. Grip strength was analyzed before and after the nerve injury and during the treatment period. The tibialis anterior muscle was processed for light microscopy, area measurement, smaller diameter, number of fibers, nuclei, and connective tissue. RESULTS: The animals submitted to the injury experienced muscular atrophy and morphological changes in the number of muscle fibers and nuclei. In the connective tissue morphometry, there was a decrease in the treated groups compared with the untreated groups. CONCLUSION: The laser treatment at different wavelengths showed no improvement in the tibialis anterior muscle of Wistar rats within the morphological and functional aspects evaluated.
Assuntos
Terapia com Luz de Baixa Intensidade/métodos , Músculo Esquelético/efeitos da radiação , Traumatismos dos Nervos Periféricos/radioterapia , Neuropatia Ciática/radioterapia , Animais , Tecido Conjuntivo/patologia , Ratos , Ratos Wistar , Nervo Isquiático/efeitos da radiação , Neuropatia Ciática/fisiopatologiaRESUMO
Phototherapy has demonstrated positive effects in the treatment of peripheral nerve injury, but there is a need to investigate the dosimetric parameters. Thus, the aim of the present study was to conduct a literature review on the effects of photobiomodulation with the use of low-level laser therapy (LLLT) on the treatment of peripheral nerve injury in experimental models. The databases of PubMed/MEDLINE, SCOPUS, and SPIE Digital Library were searched for articles on the use of LLLT in experimental models of peripheral nerve injury published in English between January 2007 and March 2016. The laser parameter variability was wavelength (632.8 to 980 nm), power (10 to 190 mW), and total energy (0.15 to 90 J) in pulsed or continuous wave and single or multiple points. Eighteen original articles demonstrating the effects of LLLT on the acceleration of functional recovery, morphological aspects as well as the modulation of the expression inflammatory cytokines, and growth factors were selected. LLLT is a viable phototherapeutic modality for the treatment of peripheral nerve injury, demonstrating positive effects on the neuromuscular repair process using either red or infrared light. The majority of studies used a power of up to 50 mW and total energy of up to 15 J administered to multiple points. The determination of these parameters is important to the standardization of a LLLT protocol to enhance the regeneration process following a peripheral nerve injury.
Assuntos
Terapia com Luz de Baixa Intensidade/métodos , Traumatismos dos Nervos Periféricos/radioterapia , Animais , Modelos Animais de Doenças , Regeneração Nervosa/efeitos da radiação , Recuperação de Função FisiológicaRESUMO
BACKGROUND AND OBJECTIVES: Peripheral nerve function can be debilitated by different kinds of injury. Low-level laser therapy (LLLT) has been used successfully during rehabilitation to stimulate recovery. The aim of this study was to evaluate the effects of LLLT (660 nm, 60 J/cm(2) , 40 mW/cm(2) ) on acute sciatic nerve injury. MATERIALS AND METHODS: Thirty Wistar male rats were divided into three groups: (1) Normal, intact nerves; (2) I3d, crushed nerves evaluated on Day-3 post-injury; (3) I + L3d, crushed nerves submitted to two sessions of LLLT and investigated at 3 days post-injury. Sciatic nerves were removed and processed for gene expression analysis (real-time PCR) of the pro-inflammatory factors TWEAK, Fn14 and TNF-α and extracellular matrix remodeling and axonal growth markers, such as TIMP-1, MMP-2, and MMP-9. Zymography was used to determine levels of MMP-2 and MMP-9 activity and Western blotting was used to evaluate TNF-α protein content. Shapiro-Wilk and Levene's tests were applied to evaluate data normality and homogeneity, respectively. One-way ANOVA followed by Tukey test was used for statistical analysis with a significance level set at 5%. RESULTS: An increase in TNF-α protein level was found in I + L3 compared to Normal and I3d (P < 0.05). Zymography showed an increase in proMMP-9 activity, in both I3d and I + L3d groups (P < 0.05). The increase was more evident in I + L3d (P = 0.02 compared to I3d). Active-MMP-9 isoform activity was increased in I + L3d compared to Normal and I3d groups (P < 0.05). Furthermore, the activity of active-MMP-2 isoform was increased in I3d and I + L3 (P < 0.05). An increase in TIMP-1 expression was observed in both I3d and I + L3d groups (P < 0.05). CONCLUSIONS: The current study showed that LLLT increased MMPs activity, mainly MMP-9, and TNF-α protein level during the acute phase of nerve injury, modulating inflammation. Based on these results, it is recommended that LLLT should be started as soon as possible after peripheral nerve injury.
Assuntos
Lasers Semicondutores/uso terapêutico , Terapia com Luz de Baixa Intensidade , Traumatismos dos Nervos Periféricos/radioterapia , Nervo Isquiático/lesões , Animais , Biomarcadores/metabolismo , Western Blotting , Regulação da Expressão Gênica/efeitos da radiação , Inflamação/etiologia , Inflamação/genética , Inflamação/metabolismo , Masculino , Traumatismos dos Nervos Periféricos/complicações , Traumatismos dos Nervos Periféricos/genética , Traumatismos dos Nervos Periféricos/metabolismo , Distribuição Aleatória , Ratos , Ratos Wistar , Reação em Cadeia da Polimerase em Tempo Real , Recuperação de Função Fisiológica/efeitos da radiação , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Nervo Isquiático/metabolismo , Resultado do TratamentoRESUMO
BACKGROUND: Peripheral nerve injury (PNI) rehabilitation remains a challenge for physical therapists because PNI effects are very disabling. Low-level laser therapy (LLLT) has been described as a physical resource that is able to influence enzymes called metallopeptidases (MMPs) associated with extracellular matrix (ECM) turnover, thus accelerating neuromuscular recovery after nerve crush injuries. However, the effects of LLLT in the treatment of severe nerve injuries and denervated slow-twitch muscles are still inconclusive. OBJECTIVES: The aim of this study was to evaluate the effects of different wavelengths and energy densities of LLLT irradiation, applied to a severe nerve injury after reconstruction, on denervated slow-twitch skeletal muscle adaptation. METHOD: Rats were submitted to a neurotmesis of the sciatic nerve followed by end-to-end neurorrhaphy. They received transcutaneous LLLT irradiation at the lesion site. The LLLT parameters were: wavelengths - 660 or 780 nm; energy densities - 10, 60 or 120 J/cm²; power - 40 mW; spot - 4 mm². Sciatic functional index (SFI), histological, morphometric, and zymographic analyses were performed. One-way ANOVA followed by Tukey's test was used (p<0.05). RESULTS: An atrophic pattern of muscle fibers was observed in all injured groups. The MMP activity in the soleus muscle reached normal levels. On the other hand, SFI remained below normality after PNI, indicating incapacity. No difference was found among PNI groups submitted or not to LLLT in any variable. CONCLUSIONS: LLLT applied to the nerve post-reconstruction was ineffective in delaying degenerative changes to the slow-twitch denervated muscles and in functional recovery in rats. New studies on recovery of denervated slow-twitch muscle are necessary to support clinical practice.
CONTEXTUALIZAÇÃO: A reabilitaçao das lesões nervosas periféricas (LNP) ainda é um desafio para a fisioterapia. A terapia com o laser de baixa potência (LBP) é descrita como um recurso físico capaz de interagir com enzimas relacionadas à alteração da matrix extracelular. Denominadas metalopeptidases (MMPs), essas enzimas atuam durante a recuperação neuromuscular após LNP. No entanto, os efeitos da LBP no tratamento de músculos desnervados de contração lenta após LNP graves ainda são inconclusivos. OBJETIVO: Avaliar os efeitos de diferentes comprimentos de onda e densidades de energia de irradiação de LBP, aplicado sobre o local do nervo após LNP grave e reconstrução. MÉTODO: Ratos foram submetidos a neurotmese do nervo isquiático e neurorrafia término-terminal. Os parâmetros do laser são: comprimento de onda: 660 ou 780 nm; densidades de energia: 10, 60 ou 120 J/cm²; potência: 40 mw; spot: 4 mm². O índice funcional isquiático (IFC) e análises histológicas, morfométricas e zimografia foram realizados. ANOVA one-way e teste de Tukey (p<0,05) foram utilizados. RESULTADOS: Um padrão atrófico das fibras musculares foi observado em todos os grupos com LNP. A atividade das MMPs no músculo sóleo alcançaram níveis normais. Entretanto, o IFC permaneceu inferior à normalidade após a LNP, indicando incapacidade. Não houve diferença entre os grupos de LNP submetidos ou não à LBP em qualquer variável. CONCLUSÃO: O LBP é incapaz de retardar alterações degenerativas em músculos sóleos desnervados e é ineficaz na recuperação funcional de ratos. Novos estudos sobre a recuperação do músculo de contração lenta desnervados são necessários para apoiar a prática clínica.
Assuntos
Animais , Masculino , Ratos , Terapia com Luz de Baixa Intensidade , Traumatismos dos Nervos Periféricos/radioterapia , Traumatismos dos Nervos Periféricos/cirurgia , Adaptação Fisiológica , Denervação Muscular , Músculo Esquelético/inervação , Ratos Wistar , Recuperação de Função FisiológicaRESUMO
BACKGROUND: Peripheral nerve injury (PNI) rehabilitation remains a challenge for physical therapists because PNI effects are very disabling. Low-level laser therapy (LLLT) has been described as a physical resource that is able to influence enzymes called metallopeptidases (MMPs) associated with extracellular matrix (ECM) turnover, thus accelerating neuromuscular recovery after nerve crush injuries. However, the effects of LLLT in the treatment of severe nerve injuries and denervated slow-twitch muscles are still inconclusive. OBJECTIVES: The aim of this study was to evaluate the effects of different wavelengths and energy densities of LLLT irradiation, applied to a severe nerve injury after reconstruction, on denervated slow-twitch skeletal muscle adaptation. METHOD: Rats were submitted to a neurotmesis of the sciatic nerve followed by end-to-end neurorrhaphy. They received transcutaneous LLLT irradiation at the lesion site. The LLLT parameters were: wavelengths--660 or 780 nm; energy densities--10, 60 or 120 J/cm²; power--40 mW; spot--4 mm². Sciatic functional index (SFI), histological, morphometric, and zymographic analyses were performed. One-way ANOVA followed by Tukey's test was used (p≤0.05). RESULTS: An atrophic pattern of muscle fibers was observed in all injured groups. The MMP activity in the soleus muscle reached normal levels. On the other hand, SFI remained below normality after PNI, indicating incapacity. No difference was found among PNI groups submitted or not to LLLT in any variable. CONCLUSIONS: LLLT applied to the nerve post-reconstruction was ineffective in delaying degenerative changes to the slow-twitch denervated muscles and in functional recovery in rats. New studies on recovery of denervated slow-twitch muscle are necessary to support clinical practice.