An Early and Sustained Inflammatory State Induces Muscle Changes and Establishes Obesogenic Characteristics in Wistar Rats Exposed to the MSG-Induced Obesity Model.

The model of obesity induced by monosodium glutamate cytotoxicity on the hypothalamic nuclei is widely used in the literature. However, MSG promotes persistent muscle changes and there is a significant lack of studies that seek to elucidate the mechanisms by which damage refractory to reversal is established. This study aimed to investigate the early and chronic effects of MSG induction of obesity upon systemic and muscular parameters of Wistar rats. The animals were exposed to MSG subcutaneously (4 mg·g-1 b.w.) or saline (1.25 mg·g-1 b.w.) daily from PND01 to PND05 (n = 24). Afterwards, in PND15, 12 animals were euthanized to determine the plasma and inflammatory profile and to assess muscle damage. In PND142, the remaining animals were euthanized, and samples for histological and biochemical analyses were obtained. Our results suggest that early exposure to MSG reduced growth, increased adiposity, and inducted hyperinsulinemia and a pro-inflammatory scenario. In adulthood, the following were observed: peripheral insulin resistance, increased fibrosis, oxidative distress, and a reduction in muscle mass, oxidative capacity, and neuromuscular junctions, increased fibrosis, and oxidative distress. Thus, we can conclude that the condition found in adult life and the difficulty restoring in the muscle profile is related to the metabolic damage established early on.

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.

Alterations in neuromuscular junctions and oxidative stress of the soleus muscle of obese Wistar rats caused by vibratory platform training.

OBJECTIVES: evaluate the effects that whole-body vibration (WBV) causes on the neuromuscular junctions and oxidative stress of the soleus muscle of obese Wistar rats. METHODS: 32 male Wistar rats were used, 16 of which were obesity induced by monosodium glutamate, randomized into four groups: control (GC), control with WBV (GCP), obese (GO) and obese with WBV (GOP). At the 70 days old, the training on WBV was started, performed 3 times a week, during 8 consecutive weeks. At the 130 days old, the animals were euthanized and the soleus muscles were collected. RESULTS: Regarding the analysis of the neuromuscular junctions, the obese groups had lower mean size when compared to the control groups. On the other hand, the WBV presented higher averages when compared to the groups that did not perform the training. Regarding the oxidative stress, for the lipid peroxidation there was a significant difference between obese and non-obese animals, however, there was no difference between the animals WBV and those who did not. CONCLUSION: WBV promotes beneficial changes such as increased measurements of the structures of the neuromuscular junctions, but is not able to promote changes in the concentration of the cholinesterase enzyme in the synaptic cleft.

Avaliação comportamental de ratos treinados em natação forçada / Behavioral assessment of rats through the forced-swimming test

Objetivos: O exercício físico regular tem diversos efeitos benéficos, contudo, há relatos de aumento na concentração de corticosteroides endógenos, os quais podem inibir a neurogênese e piorar as funções cognitivas, sendo este um aspecto dúbio do exercício físico. O objetivo deste estudo foi avaliar, por meio de testes comportamentais, o efeito do exercício crônico por natação forçada com e sem sobrecarga, sobre parâmetros de ansiedade em ratos Wistar.Métodos: Foram utilizados 24 ratos Wistar, separados em três grupos: Grupo Controle - submetido apenas a avaliações e contato com a água; Grupo Natação - composto por animais submetidos à natação com tempo progressivo; Grupo Natação com Sobrecarga - composto por animais submetidos à natação com sobrecarga de 10% do peso corporal. O exercício ocorreu três vezes por semana, no período vespertino, com aumento no tempo a cada duas semanas (20, 30 e 40 minutos), totalizando seis semanas. Foi realizado em um tanque de água circular de 200 litros, com profundidade de 50 cm e temperatura da água mantida entre 30 e 32º C. A ansiedade dos animais foi avaliada pelos testes Labirinto em Cruz Elevado e Campo Aberto.Resultados: Não houve diferenças significativas em qualquer dos testes comportamentais, comparando os três grupos.Conclusões: Não houve alteração no padrão comportamental de ratos Wistar submetidos a diferentes protocolos de exercício (natação forçada com e sem sobrecarga) quando comparados ao grupo controle não submetido a exercícios.

Aims: Regular exercise has several beneficial effects. However, reports show increasing concentrations of endogenous corticosteroids, which may inhibit neurogenesis and deteriorate cognitive functions, thus raising doubts as to the benefits of physical exercise. The objective of this study was to evaluate, through behavioral tests, the effect of chronic forced swimming with and without overload on anxiety parameters in Wistar rats. Methods: Twenty-four Wistar rats, divided into three groups, were assessed: Control Group - subjected only to evaluations and contact with water; Swimming Group - consisting of animals submitted to progressive swimming time; Weight-loaded Swimming Group - consisting of animals submitted to swimming with loads in excess of 10% of their body weight. The exercise was performed three times a week in the afternoon, with swimming time increases every two weeks (20, 30, and 40 minutes), during six weeks, A 200-liter circular water tank, filled to a depth of 50 cm, was used, and the water temperature was kept between 30º and 32º C. The animals' anxiety was assessed by the Elevated Plus Maze and Open Field tests. Results: No significant differences between the three groups were detected by any of the behavioral tests.Conclusions: No changes were observed in the behavioral pattern of Wistar rats submitted to different exercise protocols (forced swimming with and without overload) compared to the control group.