Natalia Camargo Rodrigues

Low-level laser therapy (LLLT) (660 nm) alters gene expression during muscle healing in rats

INTRODUCTION The effects of LLLT were studied during muscle regeneration through gene expression. METHODS It was evaluated 10 and 50J/cm(2) doses during 7, 14 and 21days post cryoinjury, through histopathological analysis and mRNA MyoD, Myogenin, Vegf and Cox-2 expression. RESULTS Irradiated groups presented less inflammatory process than control group after 14 and 21days. Cox-2 levels were downregulated in all irradiated groups after 7, 14 and 21days. On day 7, both treated groups had a downregulation of Vegf levels, and an upregulation after 14 and 21days, mainly with 50J/cm(2). The MyoD levels were upregulated with high dose in all periods and with low dose after 21days. Myogenin expression was downregulated in both treated groups after 7days, and was upregulated with 10J/cm(2) after 21days. CONCLUSION These responses suggest that LLLT can improve the skeletal muscle regeneration through the gene expression stimulation.

Effects of low-level laser therapy on the expression of osteogenic genes related in the initial stages of bone defects in rats

Abstract. We evaluate the effects of low-level laser therapy (LLLT) on the histological modifications and temporal osteogenic genes expression during the initial phase of bone healing in a model of bone defect in rats. Sixty-four Wistar rats were divided into control and treated groups. Noncritical size bone defects were surgically created at the upper third of the tibia. Laser irradiation (Ga-Al-As laser 830 nm, 30 mW, 0.028  cm2, 1.071  W/cm2, 1 min and 34 s, 2.8 Joules, 100  J/cm2) was performed for 1, 2, 3, and 5 sessions. Histopathology revealed that treated animals presented higher inflammatory cells recruitment, especially 12 and 36 h postsurgery. Also, a better tissue organization at the site of the injury, with the presence of granulation tissue and new bone formation was observed on days three and five postsurgery in the treated animals. The quantitative real time polymerase chain reaction showed that LLLT produced a significantly increase in mRNA expression of Runx-2, 12 h and three days post-surgery, a significant upregulation of alkaline phosphatase mRNA expression after 36 h and three days post-surgery and a significant increase of osteocalcin mRNA expression after three and five days. We concluded that LLLT modulated the inflammatory process and accelerated bone repair, and this advanced repair pattern in the laser-treated groups may be related to the higher mRNA expression of genes presented by these animals.

Low intensity laser therapy accelerates muscle regeneration in aged rats

Abstract Background: Elderly people suffer from skeletal muscle disorders that undermine their daily activity and quality of life; some of these problems can be listed as but not limited to: sarcopenia, changes in central and peripheral nervous system, blood hypoperfusion, regenerative changes contributing to atrophy, and muscle weakness. Determination, proliferation and differentiation of satellite cells in the regenerative process are regulated by specific transcription factors, known as myogenic regulatory factors (MRFs). In the elderly, the activation of MRFs is inefficient which hampers the regenerative process. Recent studies found that low intensity laser therapy (LILT) has a stimulatory effect in the muscle regeneration process. However, the effects of this therapy when associated with aging are still unknown. Objective: This study aimed to evaluate the effects of LILT (λ=830 nm) on the tibialis anterior (TA) muscle of aged rats. Subjects and methods: The total of 56 male Wistar rats formed two population sets: old and young, with 28 animals in each set. Each of these sets were randomly divided into four groups of young rats (3 months of age) with n=7 per group and four groups of aged rats (10 months of age) with n=7 per group. These groups were submitted to cryoinjury + laser irradiation, cryoinjury only, laser irradiation only and the control group (no cryoinjury/no laser irradiation). The laser treatment was performed for 5 consecutive days. The first laser application was done 24 h after the injury (on day 2) and on the seventh day, the TA muscle was dissected and removed under anesthesia. After this the animals were euthanized. Histological analyses with toluidine blue as well as hematoxylin-eosin staining (for counting the blood capillaries) were performed for the lesion areas. In addition, MyoD and VEGF mRNA was assessed by quantitative polymerase chain reaction. Results: The results showed significant elevation (p<0.05) in MyoD and VEGF genes expression levels. Moreover, capillary blood count was more prominent in elderly rats in laser irradiated groups when compared to young animals. Conclusion: In conclusion, LILT increased the maturation of satellite cells into myoblasts and myotubes, enhancing the regenerative process of aged rats irradiated with laser. Zusammenfassung Hintergrund: Ältere Menschen leiden häufig unter Skeletterkrankungen, die ihre Tagesaktivitäten und Lebensqualität negativ beeinflussen. Häufig, aber nicht ausschließlich, lassen sich die Probleme auf Sarkopenie, Veränderungen des zentralen und peripheren Nervensystems, Durchblutungsstörungen oder regenerative Veränderungen (Muskelatrophie, Muskelschwäche) zurückführen. Determination, Ausbreitung und Differenzierung von Satellitenzellen im Regenerationsprozess werden durch spezifische Transkriptionsfaktoren, den sogenannten myogenen regulatorischen Faktoren (myogenic regulatory factors, MRFs) bestimmt. Im Alter ist die Aktivierung der MRFs ineffizient, was den Regenerationsprozess hemmt. Neuere Studien haben gezeigt, dass die Therapie mit Laserlicht niedriger Intensität (low intensity laser therapy, LILT) die Muskelregeneration stimuliert. Allerdings sind diese Effekte im Zusammenhang mit dem Altern noch wenig erforscht. Zielsetzung: Die vorliegende Studie evaluiert den Effekt der LILT (λ=830 nm) auf den Tibialis-anterior (TA)-Muskel von älteren Ratten. Material und Methoden: Es wurden an insgesamt 56 männlichen Wistar-Ratten, aufgeteilt in zwei Populations-klassen (jung, alt) mit jeweils 28 Versuchstieren, Untersuchungen durchgeführt. Jede dieser beiden Klassen wurde nach dem Zufallsprinzip in 4 Gruppen mit jeweils 7 jungen Ratten (3 Monate alt) bzw. 4 Gruppen mit jeweils 7 alten Ratten (10 Monate alt) aufgeteilt: Cryoschädigung des TA + Lasertherapie, nur Cryoschädigung, nur Lasertherapie oder weder Cryoschädigung noch Lasertherapie (Kontrollgruppe). Die Laserbehandlung erfolgte an 5 aufeinanderfolgenden Tagen. Die erste Behandlung wurde 24 Stunden nach Cryoschädigung durchgeführt (Tag 2). Am 7. Tag wurde der TA-Muskel unter Anästhesie präpariert und entnommen; anschließend wurden die Tiere eingeschläfert. Die entnommenen Gewebeproben wurden sowohl mit Toluidinblau als auch mit Hämatoxylin-Eosin eingefärbt und histologisch untersucht (Zählung der Blutgefäße). Zusätzlich wurde die Expression von MyoD and VEGF mRNA mittels quantitativer Polymerase-Kettenreaktion (quantitative polymerase chain reaction, qPCR) bestimmt. Ergebnisse: Im Ergebnis zeigte sich eine signifikante Erhöhung der MyoD- und VEGF-Expression (p<0.05). Außerdem stellten sich die kapillaren Blutgefäße bei den älteren lasertherapierten Ratten im Vergleich zu den jüngeren Ratten prominenter dar. Zusammenfassung: Die LILT verbesserte die Reifung der Satellitenzellen in Myoblasten und Myotuben, wodurch der Regenerationsprozess bei älteren, laserbehandelten Ratten verstärkt wurde.

Effect of Low-Level Laser Therapy (808 nm) in Skeletal Muscle After Resistance Exercise Training in Rats

OBJECTIVE The aim of this study was to evaluate the effects of 808 nm laser applied after a resistance training protocol, on biochemical markers and the morphology of skeletal muscle in rats. BACKGROUND DATA Strenuous physical activity results in fatigue and decreased muscle strength, impaired motor control, and muscle pain. Many biochemical and biophysical interventions have been studied in an attempt to accelerate the recovery process of muscle fatigue. Among these, low-level laser therapy (LLLT) has been demonstrated to be effective in increasing skeletal muscle performance in in vivo studies and in clinical trials. However, little is known about the effects of LLLT on muscle performance after resistance training. METHODS Thirty Wistar rats were randomly divided into three groups: control group (CG), trained group (TG), and trained and laser-irradiated group (TGL). The resistance training program was performed three times per week for 5 weeks, and consisted of a climbing exercise, with weights attached to the tail of the animal. Furthermore, laser irradiation was performed in the middle region of tibialis anterior (TA) muscle of both legs, after the exercise protocol. RESULTS Analysis demonstrated that TGL demonstrated significantly reduced resting lactate level and decreased muscle glycogen depletion than the animals that were exercised only, and significantly increased the cross-section area of TA muscle fibers compared with thoseo in the other groups. CONCLUSIONS These results suggest that LLLT could be an effective therapeutic approach in increasing muscle performance during a resistance exercise protocol.

Effects of low-intensity pulsed ultrasound on injured skeletal muscle

BACKGROUND Low-intensity pulsed ultrasound (LIPUS) has been shown to stimulate tissue metabolism and accelerate muscle healing. However, the optimal parameters in the use of LIPUS are still not clear. OBJECTIVE The aim of this study was to analyze the effects of LIPUS on muscle healing in rats subjected to a cryolesion. METHOD Twenty rats were divided into the following groups: an injured control group (CG) and an injured treated group (TG). Both groups were divided into 2 sub-groups (n=5 each) that were sacrificed 7 and 13 days post-surgery. Treatments were started 24 hours after the surgical procedure and consisted of 3 or 6 sessions. After euthanasia, the muscles were submitted to standard histological procedures. RESULTS Qualitative analyses were based on morphological assessments of the muscle. The histopathological analysis on day 7 revealed that the muscles in the CG and the TG presented an intense inflammatory infiltrate, a large necrotic area and a disorganized tissue structure. After 13 days, both the CG and the TG had granulation tissue and newly formed fibers. The TG presented a more organized tissue structure. The quantitative analysis of collagen indicated similar findings among the groups, although the qualitative analysis revealed a better organization of collagen fibers in the TG at 13 days. The immunohistochemical analysis indicated that, at both time points, the expression of cyclooxygenase-2 was upregulated in the TG compared to the CG. CONCLUSIONS LIPUS used as a treatment for muscle injury induced a more organized tissue structure at the site of the injury and stimulated the expression of COX-2 and the formation of new muscle fibers.

Morphological aspects and Cox-2 expression after exposure to 780-nm laser therapy in injured skeletal muscle: an in vivo study

Background: The effectiveness of low-level laser therapy in muscle regeneration is still not well known. Objective: To investigate the effects of laser irradiation during muscle healing. Method: For this purpose, 63 rats were distributed to 3 groups: non-irradiated control group (CG); group irradiated at 10 J/cm² (G10); and group irradiated at 50 J/cm² (G50). Each group was divided into 3 different subgroups (n=7), and on days 7, 14 and 21 post-injury the rats were sacrificed. Results: Seven days post-surgery, the CG showed destroyed zones and extensive myofibrillar degeneration. For both treated groups, the necrosis area was smaller compared to the CG. On day 14 post-injury, treated groups demonstrated better tissue organization, with newly formed muscle fibers compared to the CG. On the 21st day, the irradiated groups showed similar patterns of tissue repair, with improved muscle structure at the site of the injury, resembling uninjured muscle tissue organization. Regarding collagen deposition, the G10 showed an increase in collagen synthesis. In the last period evaluated, both treated groups showed statistically higher values in comparison with the CG. Furthermore, laser irradiation at 10 J/cm2 produced a down-regulation of cyclooxygenase 2 (Cox-2) immunoexpression on day 7 post-injury. Moreover, Cox-2 immunoexpression was decreased in both treated groups on day 14. Conclusions: Laser therapy at both fluencies stimulated muscle repair through the formation of new muscle fiber, increase in collagen synthesis, and down-regulation of Cox-2 expression.

Influência de diferentes comprimentos de onda da laserterapia de baixa intensidade na regeneração tendínea do rato após tenotomia

Objective: The aim of this study was to compare the effect of the low level laser therapy in the organization of the collagen fibers with 3 J/cm² of dose in two wavelengths (670nm and 904nm) and in the combination of both on the tissue repair of the calcaneus tendon. Methods: We used 37 female Wistar rats divided in 5 groups which had been submitted to the total tenotomy. Group GA (n= 8) was submitted to the laser irradiation in λ= 904nm, GaAS, pulsated emission, peak power 15W and dose of 3J/ cm², group GB (n= 8) was submitted to laser irradiation λ= 670nm AlGaInP diode, continuous emission, power 30 mW and dose 3J/cm², group GAB (n= 8) was submitted to association of both of lasers and group GCL (n= 7) which the calcaneum tendon was submitted to placebo treatment. The group GP (n= 6) was a standard group without lesion and treatment. The animals received 12 sessions of lasertherapy and submitted to euthanasia on 14 th day after surgery. The tendons were submitted to histological procedure and were analyzed to evaluate the optic retardation (in nm) for the birefringence measurement. Results: The statistic analysis showed that the irradiated groups have higher values of optic retardation statistically significant than placebo group (p= 0,00001). It indicates that all the treated groups show better organization of collagen fibers in the longitudinal axis of the tendon, evidencing better quality in the tissue repair. The group GAB was that shown best results (p= 0,00001) when compared to another groups.Influence of different low-intensity laser therapy wavelengths for rat tendon regeneration following tenotomy Objective: The aim of this study was to compare the effect of the low level laser therapy in the organization of the collagen fibers with 3 J/cm² of dose in two wavelengths (670nm and 904nm) and in the combination of both on the tissue repair of the calcaneus tendon. Methods: We used 37 female Wistar rats divided in 5 groups which had been submitted to the total tenotomy. Group GA (n= 8) was submitted to the laser irradiation in λ= 904nm, GaAS diode, pulsated emission, peak power 15W and dose of 3J/cm², group GB (n= 8) was submitted to laser irradiation λ= 670nm AlGaInP diode, continuous emission, power 30 mW and dose 3J/cm², group GAB (n= 8) was submitted to association of both of lasers and group GCL (n= 7) which the calcaneum tendon was submitted to placebo treatment. The group GP (n= 6) was a standard group without lesion and treatment. The animals received 12 sessions of lasertherapy and submitted to euthanasia on 14 th day after surgery. The tendons were submitted to histological procedure and were analyzed to evaluate the optic retardation (in nm) for the birefringence measurement. Results: The statistic analysis showed that the irradiated groups have higher values of optic retardation statistically significant than placebo group (p= 0,00001). It indicates that all the treated groups show better organization of collagen fibers in the longitudinal axis of the tendon, evidencing better quality in the tissue repair. The group GAB was that shown best results (p= 0,00001) when compared to another groups.

Effects of 660 nm low-level laser therapy on muscle healing process after cryolesion.

The aim of this study was to evaluate the effects of 660 nm low-level laser therapy (LLLT) on muscle regeneration after cryolesion in rat tibialis anterior muscle. Sixty-three Wistar rats were divided into a control group, 10 J/cm(2) laser-treated group, and 50 J/cm(2) laser-treated group. Each group formed three subgroups (n = 7 per group), and the animals were sacrificed 7, 14, or 21 d after lesion. Histopathological findings revealed a lower inflammatory process in the laser-treated groups after 7 d. After 14 d, irradiated animals at both fluences showed higher granulation tissue, new muscle fibers, and organized muscle structure. After 21 d, full tissue repair was observed in all groups. Moreover, irradiated animals at both fluences showed smaller necrosis area in the first experimental period evaluated. MyoD immunoexpression was observed in both treated groups 7 d postinjury. Myogenin immunoexpression was detected after 7 and 14 d. The higher fluence increased the number of blood vessels after 14 and 21 d. These results suggest that LLLT, at both fluences, positively affects injured skeletal muscle in rats, accelerating the muscle-regeneration process.

Influences of different low level laser therapy wavelengths in rat tendon regeneration after tenotomy

Objective: The aim of this study was to compare the effect of the low level laser therapy in the organization of the collagen fibers with 3 J/cm² of dose in two wavelengths (670nm and 904nm) and in the combination of both on the tissue repair of the calcaneus tendon. Methods: We used 37 female Wistar rats divided in 5 groups which had been submitted to the total tenotomy. Group GA (n= 8) was submitted to the laser irradiation in λ= 904nm, GaAS, pulsated emission, peak power 15W and dose of 3J/ cm², group GB (n= 8) was submitted to laser irradiation λ= 670nm AlGaInP diode, continuous emission, power 30 mW and dose 3J/cm², group GAB (n= 8) was submitted to association of both of lasers and group GCL (n= 7) which the calcaneum tendon was submitted to placebo treatment. The group GP (n= 6) was a standard group without lesion and treatment. The animals received 12 sessions of lasertherapy and submitted to euthanasia on 14 th day after surgery. The tendons were submitted to histological procedure and were analyzed to evaluate the optic retardation (in nm) for the birefringence measurement. Results: The statistic analysis showed that the irradiated groups have higher values of optic retardation statistically significant than placebo group (p= 0,00001). It indicates that all the treated groups show better organization of collagen fibers in the longitudinal axis of the tendon, evidencing better quality in the tissue repair. The group GAB was that shown best results (p= 0,00001) when compared to another groups.Influence of different low-intensity laser therapy wavelengths for rat tendon regeneration following tenotomy Objective: The aim of this study was to compare the effect of the low level laser therapy in the organization of the collagen fibers with 3 J/cm² of dose in two wavelengths (670nm and 904nm) and in the combination of both on the tissue repair of the calcaneus tendon. Methods: We used 37 female Wistar rats divided in 5 groups which had been submitted to the total tenotomy. Group GA (n= 8) was submitted to the laser irradiation in λ= 904nm, GaAS diode, pulsated emission, peak power 15W and dose of 3J/cm², group GB (n= 8) was submitted to laser irradiation λ= 670nm AlGaInP diode, continuous emission, power 30 mW and dose 3J/cm², group GAB (n= 8) was submitted to association of both of lasers and group GCL (n= 7) which the calcaneum tendon was submitted to placebo treatment. The group GP (n= 6) was a standard group without lesion and treatment. The animals received 12 sessions of lasertherapy and submitted to euthanasia on 14 th day after surgery. The tendons were submitted to histological procedure and were analyzed to evaluate the optic retardation (in nm) for the birefringence measurement. Results: The statistic analysis showed that the irradiated groups have higher values of optic retardation statistically significant than placebo group (p= 0,00001). It indicates that all the treated groups show better organization of collagen fibers in the longitudinal axis of the tendon, evidencing better quality in the tissue repair. The group GAB was that shown best results (p= 0,00001) when compared to another groups.

Influence of different low-intensity laser therapy wavelengths for rat tendon regeneration following tenotomy

Objective: The aim of this study was to compare the effect of the low level laser therapy in the organization of the collagen fibers with 3 J/cm² of dose in two wavelengths (670nm and 904nm) and in the combination of both on the tissue repair of the calcaneus tendon. Methods: We used 37 female Wistar rats divided in 5 groups which had been submitted to the total tenotomy. Group GA (n= 8) was submitted to the laser irradiation in λ= 904nm, GaAS, pulsated emission, peak power 15W and dose of 3J/ cm², group GB (n= 8) was submitted to laser irradiation λ= 670nm AlGaInP diode, continuous emission, power 30 mW and dose 3J/cm², group GAB (n= 8) was submitted to association of both of lasers and group GCL (n= 7) which the calcaneum tendon was submitted to placebo treatment. The group GP (n= 6) was a standard group without lesion and treatment. The animals received 12 sessions of lasertherapy and submitted to euthanasia on 14 th day after surgery. The tendons were submitted to histological procedure and were analyzed to evaluate the optic retardation (in nm) for the birefringence measurement. Results: The statistic analysis showed that the irradiated groups have higher values of optic retardation statistically significant than placebo group (p= 0,00001). It indicates that all the treated groups show better organization of collagen fibers in the longitudinal axis of the tendon, evidencing better quality in the tissue repair. The group GAB was that shown best results (p= 0,00001) when compared to another groups.Influence of different low-intensity laser therapy wavelengths for rat tendon regeneration following tenotomy Objective: The aim of this study was to compare the effect of the low level laser therapy in the organization of the collagen fibers with 3 J/cm² of dose in two wavelengths (670nm and 904nm) and in the combination of both on the tissue repair of the calcaneus tendon. Methods: We used 37 female Wistar rats divided in 5 groups which had been submitted to the total tenotomy. Group GA (n= 8) was submitted to the laser irradiation in λ= 904nm, GaAS diode, pulsated emission, peak power 15W and dose of 3J/cm², group GB (n= 8) was submitted to laser irradiation λ= 670nm AlGaInP diode, continuous emission, power 30 mW and dose 3J/cm², group GAB (n= 8) was submitted to association of both of lasers and group GCL (n= 7) which the calcaneum tendon was submitted to placebo treatment. The group GP (n= 6) was a standard group without lesion and treatment. The animals received 12 sessions of lasertherapy and submitted to euthanasia on 14 th day after surgery. The tendons were submitted to histological procedure and were analyzed to evaluate the optic retardation (in nm) for the birefringence measurement. Results: The statistic analysis showed that the irradiated groups have higher values of optic retardation statistically significant than placebo group (p= 0,00001). It indicates that all the treated groups show better organization of collagen fibers in the longitudinal axis of the tendon, evidencing better quality in the tissue repair. The group GAB was that shown best results (p= 0,00001) when compared to another groups.