Low-Level Laser Therapy in Different Wavelengths on the Tibialis Anterior Muscle of Wistar Rats After Nerve Compression Injury.

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, lesion + 660-nm laser, and lesion + 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.

Morphometric Effects of Whole-Body Vibration on the Bone in a Rat Model of Postmenopausal Osteoporosis.

OBJECTIVE: The purpose of this study was to analyze the morphometric effects of mechanical vibration with a duration of 4 or 8 weeks on the femur of oophorectomized Wistar rats. METHODS: Sixty-four female rats were submitted to oophorectomy or a sham operation, and each of those 2 groups were randomized into 4 groups: untreated and euthanized at week 12, untreated and euthanized at week 16, treated for 4 weeks and euthanized at week 12, and treated for 8 weeks and euthanized at week 16. The vibration treatment was performed for 10 min/d, with a frequency of 60 Hz, 3 d/wk. The rats were then euthanized and the right femur dissected. Subsequently, histomorphometric analysis was performed on the proximal epiphysis and diaphysis of the spongy and cortical bone, respectively. RESULTS: As expected, the oophorectomy groups presented reduction of spongy and cortical bone tissue. Further, the vibration therapy of 4 and 8 weeks' duration in the oophorectomized groups led to increased bone mass, observed as an increased percentage of spongy tissue, and increased thickness and percentage of cortical tissue. However, the variables of femoral neck diameter, mean area of the shaft, and number of osteocytes were not altered by oophorectomy and vibration. CONCLUSION: The mechanical vibration was effective in increasing the bone mass of the femur of oophorectomized Wistar rats, observed by increasing the percentage of spongy bone and increasing the percentage and thickness of cortical bone.

Redução da nocicepção articular induzida pela formalina em ratos tratados com laser de baixa potência 670 ou 830 nm / Reduction of joint nociception induced by formalin in rats treated ith low level laser therapy 670 or 830 nm

Modelo do estudo: estudo experimental, de caráter transversal. Objetivo: avaliar os efeitos do laser de baixa potência (LBP), com comprimento de onda de 670nm e 820nm, na nocicepção de ratos Wistar submetidos à hipernocicepção articular no joelho direito. Metodologia: foram utilizados 18 ratos Wistar, separados em 3 grupos: G1 – não tratados; G2 – tratados com LBP 670 nm; G3 – tratados com LBP 830nm. Para a indução da hipernocicepção foi injetado no espaço articular tíbio-femoral 100 µL de formalina 5%. Para avaliar a nocicepção foi utilizado o filamento de von Frey digital, tanto com pressão sobre o joelho, quanto na região plantar; esta avaliação aconteceu: pré-lesão (AV1), após 15 (AV2), 30 (AV3) e 60(AV4) minutos da indução da hipernocicepção. Para o tratamento com LBP foi usada fluência de 8 J/cm, logo após AV2. Resultados: o limiar de retirada, quando a pressão foi realizada no joelho, mostrou que 670 nm produziu elevação do limiar em AV3 e AV4, retornando para valores semelhantes aos de AV1.Para a região plantar, apenas 830 nm mostrou restauração dos valores em AV4, e foi maior em AV3 ao comparar com o grupo controle. Conclusão: ambos os comprimentos de onda produziram elevação do limiar de retirada da pata, em ratos com hipernocicepção em joelho.

Study design: experimental study of cross-cutting nature. Objective: To evaluate the low level laser therapy (LLLT) effects, with a wavelength of 670 and 820nm, in nociception of Wistar rats submitted to hypernociception in his right knee. Methods: 18 Wistar rats, separated into 3 groups: G1 – untreated; G2– treated with LBP 670 nm; G3 – treated with LBP 830 nm. For the hypernociception induction was injected into the tibiofemoral articular space 100 µL of 5% formalin. To evaluate nociception was used digital von Frey filament, both with pressure on the knee, as in the plantar region. The evaluations occurred: pre-injury (EV1), 15 (EV2), 30 (EV3) and 60 (EV4) minutes after hypernociception induction. For the treatment with LBP was used to 8 J/cm2, after EV2. Results: the with drawal threshold, when the pressure was held at the knee, showed that 670 nm produced threshold elevation in EV3 and EV4, returning to values similar to those of EV1. For the plantar region, only 830 nm showed restoration of values inEV4, and was higher in EV3 when comparing with G1. Conclusion: Both wavelengths produced raising the paw with drawal threshold in rats with knee hypernociception.