Abstract-The aim of the present study was to determine the modeling of muscle fibers in rats submitted to different exercise protocols. Fifty-five Wistar rats were submitted divided into four different groups: Control group (CG; N=16); endurance training group (ETG; N=13), strength training group (STG; N=13) and concurrent training group (CTG; N=13). The intensity of endurance training was determined by the critical workload. Statistical analysis involved the Kruskal-Wallis test for multiple comparisons, followed by Dunn's post test (p<0.05). All animals submitted to training exhibited an increase in the cross-sectional area of the muscle fibers. The largest increase (p>0.05) occurred in the STG and CTG at both four (mean:2952,95 ± 878,39 mean:2988,84 ± 822,58) and eight weeks respectively (mean:3020,26 ± 800.91; mean:3104,91 ± 817,87). The findings demonstrate similar results obtained with strength training and concurrent training, with a greater increase in muscle fiber area in both groups in comparison to the control group and group submitted to endurance training.Keywords: skeletal muscle, soleus muscle, concurrent training, aerobic exercise, anaerobic exercise Resumo-"Efeito do treinamento concorrente nas fibras musculares de ratos Wistar." O objetivo deste estudo foi observar a modelação das fibras musculares de ratos submetidos a diferentes protocolos de treinamento físico. Foram utilizados 55 animais da raça Wistar, dos quais foram submetidos a quatro diferentes tratamentos, sendo estes: o grupo controle (CTLE), treinamento aeróbio (TAE), treinamento de força (TAN) e treinamento concorrente (TCc). A intensidade do treinamento aeróbio foi determinada pela carga crítica de trabalho. Utilizouse o teste de Kruscal-Wallis para comparações múltiplas, com pós-teste de Dunn, adotou-se o valor de significância de 5% (p=0,05). Observou-se que os grupos de animais treinados mostraram aumento na área de secção transversa (AST) das fibras musculares. Não foi verificada diferença significante (p>0,05) entre os grupos TAN e TCc, tanto em quatro (média:2952,95 ± 878,39 média:2988,84 ± 822,58) como após oito semanas (média:3020,26 ± 800,91; média:3104,91 ± 817,87). Os protocolos de TAN e TCc não se diferenciaram entre si e demonstraram aumento da AST quando comparados aos demais grupos de animais.Palavras-chaves: músculo esquelético, músculo sóleo, treinamento concorrente, exercício anaeróbico Resumen-"Efecto del entrenamiento concurrente en fibras musculares de las ratas Wistar." Nota el modelado de las fibras musculares en ratas sometidas a diferentes protocolos del entrenamiento físico. Se utilizaron 55 ratas Wistar, que fueron sometidas a cuatro tratamientos diferentes: grupo de control (CTLE), entrenamiento aeróbico (TAE), entrenamiento de fuerza (TF) y la entrenamiento concurrente (TC). La intensidad de entrenamiento aeróbico se determinó por el carga crítica del trabajo. Se utilizó la prueba Kruscal-Wallis para comparaciones múltiples con Dunn del postest, se adoptó el nivel del significancia en 5% (p=0,05). Se ob...

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BackgroundRight-sided heart failure has high morbidity and mortality, and may be caused by pulmonary arterial hypertension. Fractal dimension is a differentiated and innovative method used in histological evaluations that allows the characterization of irregular and complex structures and the quantification of structural tissue changes.ObjectiveTo assess the use of fractal dimension in cardiomyocytes of rats with monocrotaline-induced pulmonary arterial hypertension, in addition to providing histological and functional analysis.MethodsMale Wistar rats were divided into 2 groups: control (C; n = 8) and monocrotaline-induced pulmonary arterial hypertension (M; n = 8). Five weeks after pulmonary arterial hypertension induction with monocrotaline, echocardiography was performed and the animals were euthanized. The heart was dissected, the ventricles weighed to assess anatomical parameters, and histological slides were prepared and stained with hematoxylin/eosin for fractal dimension analysis, performed using box-counting method. Data normality was tested (Shapiro-Wilk test), and the groups were compared with non-paired Student t test or Mann Whitney test (p < 0.05).ResultsHigher fractal dimension values were observed in group M as compared to group C (1.39 ± 0.05 vs. 1.37 ± 0.04; p < 0.05). Echocardiography showed lower pulmonary artery flow velocity, pulmonary acceleration time and ejection time values in group M, suggesting function worsening in those animals.ConclusionThe changes observed confirm pulmonary-arterial-hypertension-induced cardiac dysfunction, and point to fractal dimension as an effective method to evaluate cardiac morphological changes induced by ventricular dysfunction.

Prolonged bedrest and microgravity induce alterations to bone, leading to bone fragility and compromising the quality of life. In this study, we characterized the physicochemical changes, microstructure, and biomechanics of the femurs of female adult rats in response to hindlimb unloading for 21 days. Twenty 6-month-old Wistar female rats were distributed into control (CON) and hindlimb unloading (HLU) groups. Analysis the in vivo bone mineral density (BMD) by dual energy x-ray absorptiometry (DXA) from the femurs was performed at the beginning and end of the experiment; plasma levels of calcium, phosphorus, and alkaline phosphatase, tartrate-resistant acid phosphatase activity, assessed by spectrophotometry, and estradiol, measured by enzyme-linked immunosorbent assay, was performed after the experiment. We evaluated changes in the trabecular and cortical structure of the femur, after disuse, by micro-computed tomography with high resolution, for analysis of cortical porosity, Raman spectroscopy to measure the amount of physicochemical properties, and the biomechanical test to estimate the changes in biomechanical properties. Our results demonstrated that, after 21 days, HLU animals had decreased femoral BMD, deteriorated bone microarchitecture, particularly in the cortical compartment, with changes in the physicochemical properties and porosity, and reduced deformation capacity of the bone and resistance to the bone stresses. Nevertheless, this study showed the critical role of mechanical stimulation in maintaining the structure of the skeleton in female adults and that disuse, even for a few days, leads to microscopic changes in the structure of the bone matrix, which increases the risk of fracture.

SUMMARY:The aim of this study was to analyze changes in the skeletal muscle tissue of rats after muscle stretch injury using fractal analysis. Nineteen rats were divided into three groups, Control (n= 5) (C), Lesion two days (n= 7) (L2), and Lesion seven days (n= 7) (L7). Histological slides of the gastrocnemius muscle of the animals were prepared and stained with Hematoxylin and eosin for analysis of the inflammatory process, and picrosirius for the demonstration of collagen. The stained slides were subsequently analyzed using Fractal Dimension (FD). The results showed high FD values of the inflammatory process in the experimental groups L2 and L7 in relation to C (p= 0.000). The analysis of collagen in the picrosirius stained slides showed high FD in the L2 group compared to the L7 (p= 0.0001), with no statistically significant difference among other groups. In summary, the present study demonstrated that fractal analysis was able to identify changes in the inflammatory process in injured skeletal muscle tissue.

Objectives: To evaluate alterations from different therapies in muscular injury using the Fractal Dimension (FD) method. Methods: 35 animals were allocated in Control Group (C), Injury Control Group (IC), Injury Low Level Laser Therapy Group (ILT), Injury Platelet Rich Plasma Group (IP), and Injury LLLT and PRP Group (ILP). The animals suffered a stretch injury in gastrocnemius muscle and after that IP and ILP groups received PRP application. The ILT and ILP groups received daily LLLT applications for seven days. After seven days the animals were euthanized and the gastrocnemius muscle removed and frozen. The muscles were stained with Hematoxylin and Eosin (HE) and Picrosirius Red, for observation of the morphology of the injury and semi-quantitative and quantitative analysis through the Fractal Dimension (FD) method. Results: In the qualitative and semi-quantitative analysis, in relation to IC group, the ILT presented a reduction in rounded fibers and the IP in angular fibers. The ILP group demonstrated a reduction in both polymorphic fibers and inflammatory infiltrate. The FD of the muscles stained with HE was higher in the groups that suffered the injury when compared to the C group (p < 0.05); the FD of the collagen demonstrated no statistical difference between the groups. Conclusion: Both treatments were able to accelerate injury repair, and the association of both presented better results than the isolated applications. However, the FD method showed no sensitivity to differentiate the treatments, either in the histological aspects or the injury in collagen.

Treatment of muscle injuries usually results in the interruption of sports practice; thus, studies aimed at accelerating the return to activity, with proper tissue repair, are important. Therefore, this study aimed to evaluate the effects of photobiomodulation (PBM), associated or not with platelet-rich plasma (PRP), on the treatment of muscle injury. Thirty-five animals were used and divided into five groups (n = 7): control (C), control lesion (CL), lesion treated with low-level laser therapy (LLLT) (LLt), lesion treated with PRP (LP), and lesion treated with both techniques, LLLT and PRP (LLtP). Muscle injury was induced by stretching the gastrocnemius muscle, and the animals in the LLtP and LP groups received the application of PRP immediately following the injury. The LLLT was applied daily for 7 days. The animals were euthanized 7 days after the injury. Analysis of the NADH/NAD ratio and collagen was performed by Raman spectroscopy; in addition to which, histological analysis of the gastrocnemius muscle was performed. The LLtP group demonstrated a reduction in the area of injury, regenerating cells and a healthy appearance of muscle fibers. The Raman analyses showed a reduction in the NADH/NAD ratio in the CL group, demonstrating oxidative stress, and the collagen presented a reduction in the CL and LLt groups, when compared with the C group. It is concluded that either PBM or PRP, and the association of both, was able to reduce the oxidative stress promoted by injury and modulate collagen production at the site of the injury. Furthermore, although both treatments individually were effective for repairing the damage caused by muscle injury, the association of both demonstrated a better histological aspect.

HighlightsLLLT and PRP can be used to enhance muscle regeneration.The association of LLLT with PRP produces better treatment than their use in isolation.LLLT could modulate the production of collagen during muscle injury.