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.

Whole-body vibration promotes lipid mobilization in hypothalamic obesity rat.

OBJECTIVES: This study aimed to analyze the effect of whole-body vibration (WBV) on metabolic parameters using the monosodium l-glutamate (MSG) model of obesity. METHOD: MSG-obese rats that were exposed to WBV on a vibrating platform with 60 Hz frequency, 2 mm amplitude, three times/week, 10 min/day, during eight weeks (from postnatal day (PN) 80 to PN136). Blood glucose, creatine kinases (CK and CK-MB) and lipid profile through plasma and liver levels of lipids and lipoproteins were evaluated. Morphology and oxidative stress of adipose and hepatic tissues were further evaluated. RESULTS: When performing a WBV exercise, animals showed contrasting metabolic responses. Vibration Control group (CTL-WBV) presented a reduction in CK and liver triacylglycerol, an increase in glucose, lactate, total cholesterol, liver cholesterol, and LDL while MSG Vibration group (MSG-WBV) showed an increase in total triacylglycerol, VLDL, lactate, CK, liver cholesterol, additional liver lipid peroxidation and LDL, total cholesterol and CKMB reduction. CONCLUSION: Even although the MSG is a model of impacting injury, the metabolic demand of WBV exercise was able to induce mobilization of substrates, highlighting the lipid mobilization in obese animals, it should be used as a metabolic rehabilitation tool in patients with metabolic diseases, such as obesity and diabetes.

Histological Evaluation of Direct Pulp Capping with Silk Sericin: A Preliminary Animal Study.

Introduction: This histological study analyzed silk sericin as a potential direct pulp capping biomaterial in contact with pulp and comparing its response to calcium hydroxide. Methods and Materials: Twenty maxillary first molars from Wistar male rats were used, with 60 days of age, between 200 and 300 gr, which were divided in 4 groups (n=5): G1 and G3, controls, capped with calcium hydroxide in 7 and 30 days, respectively; G2 and G4, capped with silk sericin in 7 and 30 days, respectively. Circular cavities were prepared for pulp exposure, where capping materials were applied, being posteriorly restored with glass ionomer cement. After completion of each observation period, the animals were sacrificed and molars were histologically processed for analysis in light microscopy to evaluate presence of necrosis in pulp tissue, inflammatory cells infiltration and tertiary dentin formation. Data analysis was carried out using Kruskal-Wallis and Dunn's post hoc tests. Results: After 7 days, there was less necrosis and inflammatory cells infiltration in G1 when compared to G2 (P=0.007 and P=0.008, respectively). After 30 days, a sample of G3 induced tertiary dentin formation and G4 showed decrease in inflammation (P=0.041) compared to G2. Conclusion: Among the determined experiment conditions, it was concluded that contact between silk sericin and pulp tissue showed improved inflammatory response throughout treatment and new cells proliferation. However, silk sericin adhibition in pure form did not show capability for induction of tertiary dentin formation.

Características nociceptivas e histomorfométricasde nervos medianos de ratos com obesidade induzidapelo glutamato monossódico / Nociceptive and histomorphometric characteristics of median nerves of ratswith obesity induced by monosodium glutamate

Objetivos: Comparar a nocicepção e, histomorfometricamente, a secção transversa de nervos periféricos de ratos Wistar submetidos ao modelode obesidade induzida pelo glutamato monossódico com animais controle.Métodos: Foram utilizados ratos Wistar, divididos em grupo obeso e grupo controle. Desde o nascimento, durante os primeiros cinco dias devida, os ratos do grupo obeso receberam uma injeção diária subcutânea de glutamato monossódico (4g/kg de peso corporal/dia), enquanto osratos do grupo controle receberam solução salina hiperosmótica (1,25 g/kg de peso corporal/dia). Foi avaliada a nocicepção, pelo limiar deretirada do membro, com uso de analgesímetro digital tipo Von Frey, com o estímulo dado na região palmar da pata anterior direita. A primeiraavaliação foi realizada cerca de 20 dias antes da eutanásia, sendo a segunda avaliação realizada no dia anterior ao da eutanásia. Posteriormente,foi dissecado o nervo mediano, na região do cotovelo e processado com cortes transversais para análise histológica. As variáveis analisadasforam: número de axônios por campo; diâmetros dos axônios, das fibras e da bainha de mielina, e coeficiente G. Os resultados foram analisadospor meio do teste t de Student para amostras independentes e t pareado, com nível de significância de 5%.Resultados: Foram estudados 14 ratos, sendo sete no grupo obeso e sete no grupo controle. A avaliação da nocicepção mostrou que osanimais do grupo obeso apresentavam menor limiar de retirada. Para os dados histomorfométricos, os resultados não mostraram diferençassignificativas entre os dois grupos estudados.Conclusões: Os animais obesos apresentaram menor limiar nociceptivo, porém não houve diferenças morfométricas dos nervos medianosentre animais submetidos ao modelo de obesidade induzida pelo glutamato monossódico e os controles.

Aims: To compare nociception and, histomorphometrically, the transverse section of peripheral nerves (median) of Wistar rats submitted toobesity model induced by monosodium glutamate with control animals.Methods: Fourteen Wistar rats divided into control and obese groups were used. During the five first days since birth the rats from obese groupreceived a daily subcutaneous injection of monosodium glutamate (4 g/kg body weight/day), while the control group received hypertonic saline(1.25 g/kg body weight/day). Nociception was evaluated by the withdrawal threshold of the limb, using digital analgesymeter type Von Frey,with the stimulus given in the palmar region of the right hind paw. The first assessment was carried out about 20 days before euthanasia, andthe second assessment was performed on the day before euthanasia. Subsequently the median nerve was dissected in the elbow region andprocessed with cross sections for histological analysis. The analyzed variables were: number of axons per ; axons, fibers and myelin sheathdiameters, and G coefficient. The results were analyzed using the t test for independent samples and paired t test, with a significance level of 5%.Results: Fourteen rats were assessed, being seven of the obese group and seven of control group. The evaluation of nociception showed thatthe animals of the obese group had lower withdrawal threshold. For histomorphometric data, the results showed no significant differencesbetween the two groups.Conclusions: The obese animals showed lower nociceptive threshold, however, there were no morphometric differences of the median nervesbetween animals subjected to the model of obesity induced by monosodium glutamate and the control group.