Swimming training reduces glucose‐amplifying pathway and cholinergic responses in islets from lean‐ and MSG‐obese rats

Exercise and inactivity as modifiers of β cell function and type 2 diabetes risk

Exercise and regular physical activity are beneficial for the prevention and management of metabolic diseases such as obesity and type 2 diabetes, whereas exercise cessation, defined as deconditioning from regular exercise or physical activity that has lasted for a period of months to years, can lead to metabolic derangements that drive disease. Adaptations to the insulin-secreting pancreatic β-cells are an important benefit of exercise, whereas less is known about how exercise cessation affects these cells. Our aim is to review the impact that exercise and exercise cessation have on β-cell function, with a focus on the evidence from studies examining glucose-stimulated insulin secretion (GSIS) using gold-standard techniques. Potential mechanisms by which the β-cell adapts to exercise, including exerkine and incretin signaling, autonomic nervous system signaling, and changes in insulin clearance, will also be explored. We will highlight areas for future research.

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.

Vitamin D supplementation combined with aerobic physical exercise restores the cell density in hypothalamic nuclei of rats exposed to monosodium glutamate

BACKGROUND & AIMS

In view of the increase in the prevalence of obesity and metabolic syndrome in childhood and adolescence, this study proposed the early and combined use of treatments to restore brain areas related to satiety. The vitamin D supplementation, aerobic exercise and the combination of these interventions on the structure of arcuate (ARC) and ventromedial (VMH) nuclei of hypothalamus were investigated in monosodium glutamate (MSG)-treated rats.

METHODS

Wistar rats were separated into five groups: Control group (CT); Obese group injected with MSG (OB); Obese group supplemented with vitamin D (OBvd); Obese group submitted to forced swimming training (OBexe) and Obese group treated with vitamin D supplementation and forced swimming training (OBvd + exe).

RESULTS

In the OB group, the visceral fat weight was significantly higher, there was a reduction in the number of glial cells in the ARC nucleus and also in the number of neurons in the ARC and VMH nuclei. Aerobic exercise was able to reduce the visceral fat weight in the OBexe group. The combination of treatments used in the OBvd + exe group reversed the loss of neurons and glial cells produced by MSG in the ARC nucleus. All treated groups exhibited a higher number of neurons in VMH nucleus, but an increase in the glial cells were observed only in the OBexe and OBvd + exe groups.

CONCLUSIONS

The effectiveness of obesity treatment can be favored through the early and combined use of vitamin D supplementation and aerobic exercise, since these therapies are able to restore brain nuclei involved in the control of food intake.

Whole-Body Vibration Promotes Skeletal Muscle Restructuring and Reduced Obesogenic Effect of MSG in Wistar Rats

The negative changes of obesity to the locomotor system are a major concern in the current scenario, where obesity and metabolic syndrome are recurrent in Western societies. A physical exercise is an important tool as a way to rehabilitate obesity, highlighting whole-body vibration, as it is an easy-access modality with few restrictions. In this sense, we sought to evaluate the effect of whole-body vibration on the extensor digitorum longus muscle on a monosodium glutamate-induced obesity model. The main findings of the present study are related to the ability of the treatment with vibration to reduce the obesogenic characteristics and slow down the dyslipidemic condition of the animals. Likewise, the vibration promoted by the vibrating platform was essential in the recovery of the muscle structure, as well as the recovery of the muscle's oxidative capacity, initially compromised by obesity.

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.