Obesity-induced skeletal muscle remodeling: A comparative analysis of exercise training and ACE-inhibitory drug in male mice

Obesity over-activates the classical arm of the renin-angiotensin system (RAS), impairing skeletal muscle remodeling. We aimed to compare the effect of exercise training and enalapril, an angiotensin-converting enzyme inhibitor, on RAS modulation in the skeletal muscle of obese animals. Thus, we divided C57BL/6 mice into two groups: standard chow (SC) and high-fat (HF) diet for 16 weeks. At the eighth week, the HF-fed animals were divided into four subgroups-sedentary (HF), treated with enalapril (HF-E), exercise training protocol (HF-T), and combined interventions (HF-ET). After 8 weeks of treatment, we evaluated body mass and index (BMI), body composition, exercise capacity, muscle morphology, and skeletal muscle molecular markers. All interventions resulted in lower BMI and attenuation of overactivation in the classical arm, while favoring the B2R in the bradykinin receptors profile. This was associated with reduced apoptosis markers in obese skeletal muscles. The HF-T group showed an increase in muscle mass and expression of biosynthesis markers and a reduction in expression of degradation markers and muscle fiber atrophy due to obesity. These findings suggest that the combination intervention did not have a synergistic effect against obesity-induced muscle remodeling. Additionally, the use of enalapril impaired muscle's physiological adaptations to exercise training.

Renin-angiotensin system modulation through enalapril and/or exercise training improves visceral adiposity in obese mice

INTRODUCTION

Obesity-related metabolic diseases occur as a result of disruptions in white adipose tissue (WAT) plasticity, especially through visceral fat accumulation and adipocyte hypertrophy. This study aimed to evaluate the impact of renin-angiotensin system (RAS) and bradykinin receptors modulation by enalapril treatment and/or exercise training on WAT morphology and related deleterious outcomes.

METHODS

Male C57BL/6 mice were fed either a standard chow or a high-fat (HF) diet for 16 weeks. At the 8th week, HF-fed animals were divided into sedentary (HF), enalapril treatment (HF-E), exercise training (HF-T), and enalapril treatment plus exercise training (HF-ET) groups. Following the experimental protocol, body mass gain, adiposity index, insulin resistance, visceral WAT morphometry, renin-angiotensin system, and bradykinin receptors were evaluated.

RESULTS

The HF group displayed increased adiposity, larger visceral fat mass, and adipocyte hypertrophy, which was accompanied by insulin resistance, overactivation of Ang II/AT1R arm, and favoring of B1R in bradykinin receptors profile. All interventions ameliorated visceral adiposity and related outcomes by favoring the Ang 1-7/MasR arm and the B2R expression in B1R/B2R ratio. However, combined therapy additively reduced Ang II/Ang 1-7 ratio.

CONCLUSION

Our results suggest that Ang 1-7/MasR arm and B2R activation might be relevant targets in the treatment of visceral obesity.

High, but not low, exercise volume shifts the balance of renin-angiotensin system toward ACE2/Mas receptor axis in skeletal muscle in obese rats

Metabolic syndrome is a cluster of metabolic risk factors that is linked to central obesity, elevated blood pressure, insulin resistance (IR), and dyslipidemia, where the renin-angiotensin system (RAS) may provide a link among them. This study aimed to evaluate volume exercise effects comparing low vs. high volume of chronic aerobic exercise on RAS axes in skeletal muscle in a diet-induced obesity (DIO) rat model. For this, male Wistar-Kyoto rats were fed a standard chow (SC) diet or a high-fat (HF) diet for 32 wk. Animals receiving the HF diet were randomly divided into low exercise volume (LEV, 150 min/wk) and high exercise volume (HEV, 300 min/wk) at the 20th week. After 12 wk of aerobic treadmill training, the body mass and composition, blood pressure, glucose and lipid metabolism, RAS axes, insulin signaling, and inflammatory pathway were performed. HEV slowed the body mass gain, reduced intra-abdominal fat pad and leptin levels, improved total and peripheral body composition and inflammatory cytokine, reduced angiotensin II type 1 receptor expression, and increased Mas receptor protein expression compared with the HF animals. Sedentary groups (SC and HF) presented lower time to exhaustion and maximal velocity compared with the LEV and HEV groups. Both exercise training groups showed reduced resting systolic blood pressure and heart rate, improved glucose tolerance, IR, insulin signaling, and lipid profile. We conclude that the HEV, but not LEV, shifted the balance of RAS toward the ACE2/Mas receptor axis in skeletal muscle, presenting protective effects against the DIO model.

Exercise training modulates the hepatic renin-angiotensin system in fructose-fed rats

NEW FINDINGS

What is the central question of this study? What are the effects of exercise training on the hepatic renin-angiotensin system and their contribution to damage resulting from fructose overload in rats? What is the main finding and its importance? Exercise training attenuated the deleterious actions of the angiotensin-converting enzyme/angiotensin II/angiotensin II type 1 receptor axis and increased expression of the counter-regulatory (angiotensin-converting enzyme 2/angiotensin (1-7)/Mas receptor) axis in the liver. Therefore, our study provides evidence that exercise training modulates the hepatic renin-angiotensin system, which contributes to reducing the progression of metabolic dysfunction and non-alcoholic fatty liver disease in fructose-fed rats. The renin-angiotensin system (RAS) has been implicated in the development of metabolic syndrome. We investigated whether the hepatic RAS is modulated by exercise training and whether this modulation improves the deleterious effects of fructose overload in rats. Male Wistar rats were divided into (n = 8 each) control (CT), exercise control (CT-Ex), high-fructose (HFr) and exercise high-fructose (HFr-Ex) groups. Fructose-drinking rats received d-fructose (100 g l^-1 ). After 2 weeks, CT-Ex and HFr-Ex rats were assigned to a treadmill training protocol at moderate intensity for 8 weeks (60 min day^-1 , 4 days per week). We assessed body mass, glucose and lipid metabolism, hepatic histopathology, angiotensin-converting enzyme (ACE) and angiotensin-converting enzyme 2 (ACE2) activity, the angiotensin concentration and the expression profile of proteins affecting the hepatic RAS, gluconeogenesis and inflammation. Neither fructose overload nor exercise training influenced body mass gain and serum ACE and ACE2 activity. The HFr group showed hyperinsulinaemia, but exercise training normalized this parameter. Exercise training was effective in preventing hepatic steatosis and in preventing triacylglycerol and glycogen accumulation. Furthermore, exercise improved the response to the deleterious effects of HFr overload by normalizing the gluconeogenesis pathway and the protein levels of interleukin-6 and tumour necrosis factor-α. The HFr rats displayed increased hepatic ACE activity and protein expression and angiotensin II concentration, which were attenuated by exercise training. Exercise training restored the ACE2/angiotensin-(1-7)/Mas receptor axis. Exercise training may favour the counter-regulatory ACE2/angiotensin-(1-7)/Mas receptor axis over the classical RAS (ACE/angiotensin II/angiotensin II type 1 receptor axis), which could be responsible for the reduction of metabolic dysfunction and the prevention of non-alcoholic fatty liver disease.

Association of GRIN2B gene polymorphism and Obsessive Compulsive disorder and symptom dimensions: A pilot study

The etiology of OCD is largely unknown, but neuroimaging and pharmacological studies suggest that glutamatergic system plays a significant role on OCD development. We genotyped one polymorphism at GRIN2B (rs1019385) by real time Polymerase Chain Reaction in a sample of Brazilian Obsessive-Compulsive patients and healthy controls, and evaluated its influence on OCD. We found the T-allele and TT genotype to be significantly associated with OCD and ordering dimension. The T-allele was also significantly associated with checking. These preliminary results demonstrated that the GRIN2B gene may confer to some extent the susceptibility to OCD and its symptoms.