Development of a histopathological index for skeletal muscle analysis in Rattus norvegicus (Rodentia: Muridae).

Skeletal muscle histopathological changes induced or caused by pathologies in animal models, can impair functionality, being the main focus of therapeutic studies. This study aimed to propose a histopathological index to assess, in a quantitative manner, skeletal muscle changes induced by experimental protocols for Rodentia's models. For the development, evaluation of fit and parsimony, replicability, and sensitivity index, Wistar rats from experiments with the same experimental design, but with different variation factors, were used to achieve different levels of damage. The anterior tibial muscle of these animals was collected, processed histologically, and stained with hematoxylin and eosin. The adjustment and parsimony of the index were availed through Confirmatory Factor Analysis, reproducibility for evaluation of three people trained through the Intra-Class Correlation, and the discrimination capacity through a one-way ANOVA Test. We pointed out the adjustment for the proposed index while the ICC showed high reproducibility (n = 56; k = 3; ICC = 0.9790) and differences in the extent of damage between groups, following the hierarchical association promoted by experimental model stresses. The results show that the proposed index has a good fit and parsimony (χ2 = 426.34; p < 0.0001), in addition to being easily replicable by other researchers who know the morphology of muscle tissue and its morphological changes. It is worth mentioning that the development of tools that facilitate histopathological analysis, and that can quantitatively express the findings, are of great importance for the studies of regenerative science, reinforcing the relevance of this study.

Morphometric aspects of the articular cartilage of rats treated with low-level laser therapy and exercise in a rheumatoid arthritis model

INTRODUCTION: Rheumatoid arthritis (RA) is classified as an autoimmune, chronic disease affecting diarthrodial joints and periarticular structures. OBJECTIVE: To evaluate whether low-intensity laser treatment (LLLT) and/or exercise reduce the deleterious effects of tissue in a rheumatoid arthritis model. METHODS: 128 rats were divided into two inflammatory periods: acute (7 days) and chronic (28 days) and subdivided into control, injury and treatment. The protocol with Freund's Complete Adjuvant was used in two inoculations, one intradermal and one intraarticular in the tibiofemoral joint, the control animals received saline solution. For treatment, LLLT 660 nm, 5 J/cm² was used in the sensitized joint and climbing exercise in stairways with an overload of 100 grams. After the experimental period, the animals were euthanized and the joints were prepared for morphometric analysis of the total thickness, superficial, deep, and cellular density of the articular cartilage. Generalized Linear Models with Sidak post-test were chosen. RESULTS: The control group was found to be different from the lesion group with greater joint cartilage thickness, andthe animals treated with exercise alone increased the joint cartilage compared to thecontrol group. CONCLUSION: The animals treated with laser association and exercise showed improvement in the morphometric aspects of the articular cartilage.

Analysis of Wistar Rats Submitted to a Gout Model, Treated with Double Cryotherapy Protocol.

Gout arthritis commonly affects joint regions by deposition of crystals, promoting functional damage mainly during periods of exacerbation. Cryotherapy is a commonly used resource to contain inflammatory processes, however, its use during a gout crisis is not yet well understood. Therefore, the objective was to evaluate the parameters of Wistar rats submitted to an experimental gout model and treated with dual cryotherapy protocol. Twenty-one male Wistar rats were used, separated into three groups: control group (CG), lesion group (LG), and lesion + cryotherapy group (LCG). Gout model induction was through intra-articular injection, with urate crystal solution, in the right knee and cryoimmersion treatment was performed for 20 minutes at a temperature of 5° ± 2°C. Seven evaluations and two treatment moments were performed, and the following parameters were analyzed: joint edema, grip strength, joint disability, motor function, and leukocyte migration through synovial lavage. In the statistical analysis we used SPSS 20.0 with Generalized Linear Models, with least significant difference posttest, always with 5% significance level. The treatment reduced edema, promoted strength recovery, and was effective in reducing total leukocytes in the synovial fluid. No difference was observed between the injured groups for joint disability and motor function. Cryotherapy promoted edema reduction and increased pelvic limb grip strength in Wistar rats during the acute period.

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.

Physical exercise and low-level laser therapy on the nociception and leukocyte migration of Wistar rats submitted to a model of rheumatoid arthritis.

Rheumatoid arthritis denotes hyperplasia and intense inflammatory process. Treatment involves exercise protocols and use of resources such as low-level laser therapy (LLLT) to modulate the inflammatory process and maintain physical capacity. The objective was to investigate whether treatment with LLLT and exercise modulates the inflammatory process and peripheral functionality. Sample is composed of 128 male rats, separated into three groups, control, treated and untreated, in the acute and chronic period of the disease with 64 animals in each group, divided into 8 subgroups with n = 8. The animals were immunized with injection at the base of the tail and 7 days after intra-articular injection with complete Freund adjuvant (CFA) for lesion groups, and saline solution for the controls. Joint disability was evaluated by PET (paw elevation time) and joint edema and treated with LLLT and/or resisted stair climbing exercise. Normality Shapiro-Wilk test, ANOVA mixed for the functional analyses, and ANOVA one-way for the variables of cellular differentiation, with Bonferroni post hoc, p = 5% were used. For the evaluations of joint disability and nociception, there was a significant difference between the evaluations, the groups, and the interaction groups-evaluations. The treated groups showed recovery of functionality; it is still verified that laser therapy increased the nociceptive threshold of the chronic inflammatory period, and the exercise reflected in significant functional improvement and modulation of the inflammatory process both in the acute and chronic periods. LLLT, resistance exercise, or a combination of treatments had a positive effect on the modulation of the inflammatory process, reducing the migration of leukocytes, in addition to helping the return of peripheral functionality by reducing joint disability in a model of rheumatoid arthritis induced by CFA in rats.