Effects of aerobic exercise training on cardiac renin-angiotensin system in an obese Zucker rat strain

Chronic exercise improves renal AT1 and ETB receptor functions via modulating GRK4 expression in obese Zucker rats

BACKGROUND

Physical activity has profound benefits on health, especially in patients with cardiovascular and metabolic disease. Exercise training can reduce oxidative stress, improve renal function, and thus lower blood pressure. However, the effect of exercise training on angiotensin II type 1 receptors (AT1R) and endothelin subtype B receptors (ETBR)-mediated diuresis and natriuresis in obese Zucker rats is unclear.

METHODS

Lean and obese Zucker rats were exercised or placed on a nonmoving treadmill for 8 weeks. Blood pressure was measured by tail-cuff plethysmography, and functions of AT1R and ETBR in the kidney were measured by natriuresis, respectively.

RESULTS

Our data showed that exercise training improved glucose and lipid metabolism, renal function and sodium excretion in obese Zucker rats, accompanied by decreased oxidative stress and GRK4 expression in obese Zucker rats. Moreover, exercise training reduced the Candesartan-induced an increase in diuresis and natriuresis and increased ETBR agonists (BQ3020)-mediated diuresis and natriuresis in obese Zucker rats, which were associated with decreased renal AT1R expression and ETBR phosphorylation levels.

CONCLUSIONS

The results demonstrate that exercise training lowers blood pressure via improving renal AT1R and ETBR function through modulating GRK4 expression in Obese Zucker Rats and provides potentially effective targets for obesity-related hypertension.

Potential role for vitamin D vs. intermittent fasting in controlling aquaporin-1 and aquaporin-3 expression in HFD-induced urinary bladder alterations in rats

Background: High-fat diet-induced obesity is linked to suppression of aquaporins (AQPs) expression in different tissues. Both vitamin D and intermittent fasting were identified to enhance AQPs expression. In the urinary bladder, AQP-1 and AQP-3 mRNA transcripts were identified. Vitamin D has an impact on a variety of genes that encode proteins that control cell proliferation, differentiation, and death. Aim: To assess potential benefits of vitamin D and intermittent fasting (IF) and to explore alterations to the urinary bladder triggered by high-fat diet (HFD) in a rat model of obesity. Methods: Each of the 4 groups contained six adult male albino rats; control: a standard rodent chew for 12 weeks, HFD: HFD and fructose were administered orally via gastric gavage for 12 weeks, and vitamin D: HFD and fructose were administered orally for 8 weeks, then 4 weeks of intraperitoneal injection of vitamin D (5 microns/Kg/2 days) and IF group: Received intraperitoneal injections of vitamin D (5 microns/Kg/2 days) for 4 weeks after consumption of HFD and fructose orally for 8 weeks. The serum lipid profile was conducted at end of the experiment. In the bladder homogenates, the levels of oxidative stress indicators were assessed. Quantitative real-time PCR was performed on recently collected bladder samples. AQP-1 and AQP-3 immunohistochemistry was done. Results: When compared to the HFD group, the vitamin D and IF groups both demonstrated a substantial improvement in histopathological, immunohistochemical, biochemical, and molecular markers. Conclusion: In all examined parameters, IF exceeded vitamin D as a preventive factor for the urinary bladder deterioration.

Protective effects of swimming exercises and metformin on cardiac and aortic damage caused by a high-fat diet in obese rats with type 2 diabetes, by regulating the Bcl2/Bax signaling pathway

Background/aim

Due to the increasing mortality and morbidity rates in diabetes mellitus (DM), which is one of the biggest health problems of our age, many treatment modalities are still being tried. The positive effects of metformin (MET) and physical exercise (EXE) on the pathophysiology of diabetes are well known. In this study, it was aimed to detail these positive effects of MET and EXE in combination on the basis of inflammation, apoptosis mechanisms, and endogen nesfatin-1 (NES-1) synthesis.

Materials and methods

Twenty-seven type 2 DM (DM-2) male Wistar Albino rats were divided into 4 groups, as the high-fat diet (HFD), MET, EXE, and MET+EXE groups. The total duration of the study was 3 months. At the end of the experiment, blood glucose and lipid profiles were measured. Histopathological evaluation was performed on the cardiac and aortic tissues and apoptotic markers were evaluated immunohistochemically. Inflammatory markers and NES-1 levels were analyzed by enzyme-linked immunosorbent assay.

Results

The plasma glucose, homeostatic model evaluation-insulin resistance (HOMA-IR), low-density lipoprotein (LDL) levels increased, and high-density lipoprotein (HDL) levels decreased significantly in the HFD group. In the treatment groups, the glucose, HOMA-IR, LDL, NES-1 levels in the plasma, as well as tumor necrosis factor alpha (TNF-α), interleukin-1 beta (IL-1β), IL-6, caspase-3 (Cas-3), Bcl-2-associated X protein (Bax), and histopathological findings of inflammation in tissues were decreased. Additionally, there was an increase in plasma insulin, HDL, and tissue B-cell lymphoma-2 and levels.

Conclusion

It was observed that the MET and EXE treatments in the DM-2 model reduced cellular damage mechanisms such as inflammation and apoptosis. The decrease in NES-1 levels was thought to be secondary to this antiinflammatory effect. In conclusion, the results demonstrated the effectiveness of EXE in reducing DM-2 and the NES-1 levels. Further studies are needed to evaluate the effect in different EXE models and treatment durations.

Protective Role of Short-term Aerobic Exercise Against Zinc Oxide Nanoparticles-Induced Cardiac Oxidative Stress Via Possible Changes of Apelin, Angiotensin II/Angiotensin II Type I Signalling Pathway

This study examined the protective role of short-term aerobic exercise on ZnO NPs-induced cardiac oxidative stress and possible changes of apelin, angiotensin II (AngII) and angiotensin II type I receptor (AT1R) signalling pathway. Thirty-five male Wistar rats were randomized into five groups of seven rats, including control, saline, ZnO NPs, exercise and exercise + ZnO NPs groups. The animal in ZnO NPs and exercise + ZnO NPs groups received 1 mg/kg of ZnO NPs. Rats underwent the treadmill exercise program. Treatments lasted four weeks, 5 days/week. After 4 weeks of treatment, superoxide dismutase (SOD) activity, malondialdehyde (MDA), apelin, Ang II and AT1R concentration were measured in heart tissue.Cardiac MDA, Ang II and AT1R levels significantly increased while SOD activity and apelin levels significantly decreased following ZnO NPs administration. The aerobic exercise induced a significant increase in the SOD activity and apelin levels and a significant decrease in the enhanced MDA, Ang II and AT1R levels in the heart of ZnO NPs-exposed rats. These results suggest that the exercise-induced attenuation of the Ang II-AT1R signalling pathway is mediated by reduced lipid peroxidation, augmented antioxidant defence and enhanced apelin synthesis that may be a protective mechanism to prevent and/or treatment ZnO NPs-induced cardiac oxidative stress.

Regular Exercise in Drosophila Prevents Age-Related Cardiac Dysfunction Caused by High Fat and Heart-Specific Knockdown of skd

Skuld (skd) is a subunit of the Mediator complex subunit complex. In the heart, skd controls systemic obesity, is involved in systemic energy metabolism, and is closely linked to cardiac function and aging. However, it is unclear whether the effect of cardiac skd on cardiac energy metabolism affects cardiac function. We found that cardiac-specific knockdown of skd showed impaired cardiac function, metabolic impairment, and premature aging. Drosophila was subjected to an exercise and high-fat diet (HFD) intervention to explore the effects of exercise on cardiac skd expression and cardiac function in HFD Drosophila. We found that Hand-Gal4>skd RNAi (KC) Drosophila had impaired cardiac function, metabolic impairment, and premature aging. Regular exercise significantly improved cardiac function and metabolism and delayed aging in HFD KC Drosophila. Thus, our study found that the effect of skd on cardiac energy metabolism in the heart affected cardiac function. Exercise may counteract age-related cardiac dysfunction and metabolic disturbances caused by HFD and heart-specific knockdown of skd. Skd may be a potential therapeutic target for heart disease.

Angiotensin Receptor Blocker is Associated with a Lower Fracture Risk: An Updated Systematic Review and Meta-Analysis

Background

Angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin receptor blockers (ARBs) are widely used in the treatment of hypertension. Hypertension is often accompanied by osteoporosis. However, the relationship between ACEI/ARB and fractures remains controversial. The purpose of this meta-analysis was to update the potential relationship between ACEI/ARB and fractures.

Methods

This meta-analysis was identified through PubMed, EMBASE, Cochrane Library, and Web of Science. Related studies about ACEI/ARB with the risk of fracture were published from inception to June 2022.

Results

Nine qualified prospective designed studies, involving 3,649,785 subjects, were included in this analysis. Overall, the RRs of ACEI compared with the nonusers were 0.98 (95% CI: 0.88, 1.10; P < 0.001) for composite fractures and 0.96 (95% CI: 0.87, 1.05; P=0.048) for hip fractures; the RRs of ARB compared to the nonusers were 0.82 (95% CI: 0.73, 0.91; P < 0.001) for composite fractures and 0.85 (95% CI: 0.74, 0.97; P=0.028) for hip fractures. Furthermore, in the subgroup analysis, male may benefit from ARB (RR = 0.65, 95% CI: 0.49, 0.89, P=0.028), and the European may also benefit from ARB (RR = 0.86, 95% CI: 0.80, 0.93, P=0.015).

Conclusions

ACEI usage will not decrease the risk of osteoporosis fracture. On the contrary, ARB usage can decrease the risk of total fracture and hip fracture, especially for males and Europeans. Compared with ACEI, for patients at higher risk of fracture in cardiovascular diseases such as hypertension, the protective effect of ARB should be considered.

Outcomes With Multidisciplinary Cardiac Rehabilitation in Post-acute Systolic Heart Failure Patients-A Retrospective Propensity Score-Matched Study

Background

Cardiac rehabilitation (CR) is recommended for patients with acute heart failure (HF). However, the results of outcome studies and meta-analyses on CR in post-acute care are varied. We aimed to assess the medium- to long-term impact of CR and ascertain the predictors of successful CR.

Methods

In this propensity score-matched retrospective cohort study, records of consecutive patients who survived acute HF (left ventricular ejection fraction <40) and participated in a multidisciplinary HF rehabilitation program post-discharge between May 2014 and July 2019 were reviewed. Patients in the CR group had at least one exercise session within 3 months of discharge; the others were in the non-CR group. After propensity score matching, the primary (all-cause mortality) and secondary (HF readmission and life quality assessment) outcomes were analyzed.

Results

Among 792 patients, 142 attended at least one session of phase II CR. After propensity score matching for covariates related to HF prognosis, 518 patients were included in the study (CR group, 137 patients). The all-cause mortality rate was 24.9% and the HF rehospitalization rate was 34.6% in the median 3.04-year follow-up. Cox proportional hazard analysis revealed that the CR group had a significant reduction in all-cause mortality compared to the non-CR group (hazard ratio [HR]: 0.490, 95% confidence interval [CI]: 0.308-0.778). A lower risk of the primary outcome with CR was observed in patients on renin-angiotensin-aldosterone system (RAAS) inhibitors, but was not seen in patients who were not prescribed this class of medications (interaction p = 0.014).

Conclusions

Cardiac rehabilitation participation was associated with reduced all-cause mortality after acute systolic heart failure hospital discharge. Our finding that the benefit of CR was decreased in patients not prescribed RAAS inhibitors warrants further evaluation.

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.

Morphological and Biochemical Investigation of the Healing Effects of Exercise on High Fat Diet Induced Kidney and Bladder Damage

Objective: The aim of this study was to assess the preventive effects of swimming exercise on kidney and bladder damage caused by a high-fat diet (HFD) using morphological and biochemical measures. Methods: Sprague Dawley rats were fed either standard chow (CONT, 6% fat) or HFD (45% fat) for 18 weeks, these rats were divided into two subgroups at the last 6 weeks of the experiment. The exercise groups (CONT+EXC, HFD+EXC) were trained daily swimming sessions (1 h per day for 5 days/week) during the last 6 weeks. Kidney and bladder samples were prepared for light and electron microscopic examination at the end of experiment. Malondialdehyde, glutathione, interleukin-6, and tumor necrosis factor-α were measured by biochemically.Results: Regular morphology of renal cortex and urinary bladder mucosa were observed in the CONT and CONT+EXC groups. Degenerated renal corpuscles and proximal tubules in kidney and degenerated urothelium with leaky tight junctions and increase of mast cells in bladder mucosa were observed in the HFD group. Ameliorated renal cortex and bladder mucosa were observed in the HFD+EXC group. Moreover, malondialdehyde, glutathione, interleukin-6 and tumor necrosis factor- α levels were compatible with histological findings. Conclusion: HFD induced kidney and bladder damage may have linked to increased oxidative damage. It was observed that histological damage and altered oxidative stress parameters were reversed with swimming exercise, and it is thought that moderate swimming exercise may have a role in the regulation of oxidative stress.

MicroRNAs in Obesity-Associated Disorders: The Role of Exercise Training

Obesity is a worldwide epidemic affecting over 13% of the adult population and is defined by an excess of body fat that predisposes comorbidities. It is considered a multifactorial disease in which environmental and genetic factors interact, and it is a risk marker for cardiovascular disease. Lifestyle modifications remain the mainstay of treatment for obesity based on adequate diet and physical exercise. In addition, obesity is related to cardiovascular and skeletal muscle disorders, such as cardiac hypertrophy, microvascular rarefaction, and skeletal muscle atrophy. The discovery of obesity-involved molecular pathways is an important step to improve both the prevention and management of this disease. MicroRNAs (miRNAs) are a class of gene regulators which bind most commonly, but not exclusively, to the 3'-untranslated regions of messenger RNAs of protein-coding genes and negatively regulate their expression. Considerable effort has been made to identify miRNAs and target genes that predispose to obesity. Besides their intracellular function, recent studies have demonstrated that miRNAs can be exported or released by cells and circulate within the blood in a remarkably stable form. The discovery of circulating miRNAs opens up intriguing possibilities for the use of circulating miRNA patterns as biomarkers for obesity and cardiovascular diseases. The aim of this review is to provide an overview of the recent discoveries of the role played by miRNAs in the obese phenotype and associated comorbidities. Furthermore, we will discuss the role of exercise training on regulating miRNAs, indicating the mechanisms related to these alterations.

Effects of endurance training on the expression of host proteins involved in SARS-CoV-2 cell entry in C57BL/6J mouse

The coronavirus disease 2019 (COVID-19) pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is threatening people's lives and impacting their health. It is still unclear whether people engaged in physical activity are at an increased risk of SARS-CoV-2 infection and severe forms of COVID-19. In order to provide data to help answer this question, we, therefore, investigated the effects of endurance training on the levels of host proteins involved in SARS-CoV-2 infection in mice. Eight-week-old C57BL/6J mice were subjected to treadmill running (17-25 m/min, 60-90 min, 5 sessions/week, 8 weeks). After the intervention, the levels of angiotensin-converting enzyme 2 (ACE2; host receptor for SARS-CoV-2), transmembrane protease serine 2 (TMPRSS2; host protease priming fusion of SARS-CoV-2 to host cell membranes), FURIN (host protease that promotes binding of SARS-CoV-2 to host receptors), and Neuropilin-1 (host coreceptor for SARS-CoV-2) were measured in 10 organs that SARS-CoV-2 can infect (larynx, trachea, lung, heart, jejunum, ileum, colon, liver, kidney, and testis). Six organs (heart, lung, jejunum, liver, trachea, and ileum) showed changes in the levels of at least one of the proteins. Endurance training increased ACE2 levels in heart (+66.4%), lung (+37.1%), jejunum (+24.7%) and liver (+27.4%), and FURIN in liver (+17.9%) tissue. In contrast, endurance training decreased Neuropilin-1 levels in liver (-39.7%), trachea (-41.2%), and ileum (-39.7%), and TMPRSS2 in lung (-11.3%). Taken together, endurance training altered the levels of host proteins involved in SARS-CoV-2 cell entry in an organ-dependent manner.

Potential Physiological and Cellular Mechanisms of Exercise That Decrease the Risk of Severe Complications and Mortality Following SARS-CoV-2 Infection

The coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has unmasked mankind's vulnerability to biological threats. Although higher age is a major risk factor for disease severity in COVID-19, several predisposing risk factors for mortality are related to low cardiorespiratory and metabolic fitness, including obesity, cardiovascular disease, diabetes, and hypertension. Reaching physical activity (PA) guideline goals contribute to protect against numerous immune and inflammatory disorders, in addition to multi-morbidities and mortality. Elevated levels of cardiorespiratory fitness, being non-obese, and regular PA improves immunological function, mitigating sustained low-grade systemic inflammation and age-related deterioration of the immune system, or immunosenescence. Regular PA and being non-obese also improve the antibody response to vaccination. In this review, we highlight potential physiological, cellular, and molecular mechanisms that are affected by regular PA, increase the host antiviral defense, and may determine the course and outcome of COVID-19. Not only are the immune system and regular PA in relation to COVID-19 discussed, but also the cardiovascular, respiratory, renal, and hormonal systems, as well as skeletal muscle, epigenetics, and mitochondrial function.

Physical Activity and Inhibition of ACE Additively Modulate ACE/ACE-2 Balance in Heart Failure in Mice

Angiotensin-converting enzyme inhibition (ACE-I) and physical activity favorably modulate the ACE/ACE-2 balance. However, it is not clear whether physical activity and ACE-I could synergistically modulate ACE/ACE-2 balance in the course of heart failure (HF). Here, we studied the effects of combined spontaneous physical activity and ACE-I–based treatment on angiotensin (Ang) pattern and cardiac function in a mouse model of HF (Tgαq*44). Tgαq*44 mice with advanced HF (at the age of 12 months) were running spontaneously in a running wheel (exercise training group, ExT) and/or were treated with ACE inhibitor (ACE-I, perindopril, 10 mg/kg) for 2 months. Angiotensin profile was characterized by an LC-MS/MS-based method. The cardiac performance was assessed in vivo by MRI. Ang-(1–7)/Ang II ratio in both plasma and the aorta was significantly higher in the combined treatment group than the ACE-I group or ExT alone, suggesting the additive favorable effects on ACE-2/Ang-(1–7) and ACE/Ang II axes’ balance induced by a combination of ACE-I with ExT. The basal cardiac performance did not differ among the experimental groups of Tgαq*44 mice. We demonstrated additive changes in ACE/ACE-2 balance in both plasma and the aorta by spontaneous physical activity and ACE-I treatment in Tgαq*44 mice. However, these changes did not result in an improvement of failing heart function most likely because the disease was at the end-stage. Ang-(1–7)/Ang II balance represents a valuable biochemical end point for monitoring therapeutic intervention outcome in heart failure.

Physical activity effects on bladder dysfunction in an obese and insulin-resistant murine model

Objective

To investigate the role of physical activity in functional and molecular bladder alterations in an obese and insulin‐resistant murine model.

Methods

Wistar rats were randomized into 1. physical activity and standard diet; 2. physical activity and high‐fat diet; 3. no physical activity and standard diet; and 4. no physical activity and high‐fat diet. Groups 1 and 2 were subjected to a 10‐week swimming protocol. Urodynamic study (UDS) was performed, and the expression of genes in the bladder tissue related to the insulin pathway (IRS1/IRS2/PI3K/AKT/eNOS) was assessed using quantitative real‐time polymerase chain reaction.

Results

Groups 1 and 2 presented lower body weight gains than groups 3 (213.89 ± 13.77 vs 261.63 ± 34.20 grams (g), p = 0.04) and 4 (209.84 ± 27.40 vs 257.57 ± 32.95 g, p = 0.04), respectively. Group 4 had higher insulin level (6.05 ± 1.79 vs 4.14 ± 1.14 ng/ml, p = 0.038) and higher homeostasis model assessment of insulin resistance (HOMA‐IR) index (1.95 ± 0.73 vs 1.09 ± 0.37, p = 0.006) than group 1. On UDS, group 4 had greater number of micturition (13.6 ± 4.21 vs 6.0 ± 1.82, p = 0.04), higher postvoid pressure (8.06 ± 2.24 vs 5.08 ± 1.23, p = 0.04), lower capacity (0.29 ± 0.18 vs 0.91 ± 0.41 ml, p = 0.008), and lower bladder compliance (0.027 ± 0.014 vs 0.091 ± 0.034 ml/mmHg, p = 0.016) versus group 1. High‐fat diet was related to an underexpression throughout insulin signaling pathway, and physical activity was related to an overexpression of the pathway.

Conclusions

The insulin signaling pathway may be involved in the pathogenesis of bladder dysfunction related to a high‐fat diet. Physical activity may help to prevent bladder disfunction induced by a high‐fat diet through the insulin pathway.

Angiotensin-converting enzyme 2 and COVID-19: patients, comorbidities, and therapies

On March 11, 2020, the World Health Organization declared coronavirus disease 2019 (COVID-19) a pandemic, and the reality of the situation has finally caught up to the widespread reach of the disease. The presentation of the disease is highly variable, ranging from asymptomatic carriers to critical COVID-19. The availability of angiotensin-converting enzyme 2 (ACE2) receptors may reportedly increase the susceptibility and/or disease progression of COVID-19. Comorbidities and risk factors have also been noted to increase COVID-19 susceptibility. In this paper, we hereby review the evidence pertaining to ACE2's relationship to common comorbidities, risk factors, and therapies associated with the susceptibility and severity of COVID-19. We also highlight gaps of knowledge that require further investigation. The primary comorbidities of respiratory disease, cardiovascular disease, renal disease, diabetes, obesity, and hypertension had strong evidence. The secondary risk factors of age, sex, and race/genetics had limited-to-moderate evidence. The tertiary factors of ACE inhibitors and angiotensin II receptor blockers had limited-to-moderate evidence. Ibuprofen and thiazolidinediones had limited evidence.

Modulation of cardiac renin-angiotensin system, redox status and inflammatory profile by different volumes of aerobic exercise training in obese rats

Overactivation of the classical arm of the renin-angiotensin (Ang) system (RAS) occurs during inflammation, oxidative stress and obesity-induced cardiomyopathy. The activation of the protective arm of RAS may act to counterbalance the deleterious effects of the classical RAS. Although aerobic exercise training (AET) shifts the balance of the RAS towards the protective arm, little is known about the molecular adaptations to different volumes of AET. The aim of this study was to evaluate the impact of AET volume on the modulation of RAS, as well as on cardiac biomarkers of oxidative stress and inflammation, in a diet-induced obesity model. Male Wistar rats were fed either control (CON) or high fat (HF) diet for 32 weeks. At week 20, HF group was subdivided into sedentary, low (LEV, 150 min/week) or high (HEV, 300 min/week) exercise volume. After 12 weeks of exercise, body mass gain, systolic blood pressure and heart rate were evaluated, as well as RAS, oxidative stress and inflammation in the heart. Body mass gain, systolic blood pressure and heart rate were higher in HF group when compared with SC group. Both trained groups restored systolic blood pressure and heart rate, but only HEV reduced body mass gain. Regarding the cardiac RAS, the HF group exhibited favoring of the classical arm and both trained groups shifted the balance towards the counterregulatory protective arm. The HF group had higher B1R expression and lower B2R expression than the control group, and B2R expression was reverted in both trained groups. The HF group also presented oxidative stress. The LEV and HEV groups improved the cardiac redox status by reducing Nox 2 and nitrotyrosine expression, but only the LEV group was able to increase the antioxidant defense by increasing Nrf2 signaling. While the HF group presented higher TNF-α, IL-6 and NFκB expression, and lower IL-10 expression, than the SC group, both training protocols improved the inflammatory profile. Although both trained groups improved the deleterious changes related to obesity cardiomyopathy, it is clear that the molecular mechanisms differ between them. Our results suggest that different exercise volumes might reach different molecular targets, and this could be a relevant factor when using exercise to manage obesity.

Angiotensin II type 2 receptor mediates high fat diet-induced cardiomyocyte hypertrophy and hypercholesterolemia

Obesity is the major risk factor for several cardiovascular and metabolic disorders. Previous studies reported that deletion of Angiotensin II type 2 receptor (AT2R) protects against metabolic dysfunctions induced by high fat (HF) diet. However, the role of AT2R in obesity-induced cardiac hypertrophy remains unclear. Male AT2R knockout (AT2RKO) and wild type (AT2RWT) mice were fed with control or HF diet for 10 weeks. HF diet increased cardiac expression of AT2R in obese mice. Deletion of AT2R did not affect body weight gain, glucose intolerance and fat mass gain induced by HF feeding. However, loss of AT2R prevented HF diet-induced hypercholesterolemia and cardiac remodeling. Mechanistically, we found that pharmacological inhibition or knockdown of AT2R prevented leptin-induced cardiomyocyte hypertrophy in vitro. Collectively, our results suggest that AT2R is involved in obesity-induced cardiac hypertrophy.

High-intensity aerobic training lowers blood pressure and modulates the renal renin-angiotensin system in spontaneously hypertensive rats

Background: This study aimed to verify the effects of high-intensity aerobic training (HIAT) on BP control and renin-angiotensin system (RAS) components in renal tissue of SHR. Ten SHRs received HIAT or control for 8-weeks. At the end of the training, the SBP showed a reduction of ~ 30mmHg (p < .01) in HIAT and increased by ~ 15 mmHg in the  control group. HIAT resulted in a higher release of nitrite, IL-6, ACE2 and ATR2. These results indicated an association between BP, NO and renal RAS.Abbreviations: JAA: writing, carried out all experimental procedures, performed statistical analysis, original draft and revised manuscript DMS: data interpretation, formal analysis, writing, editing and revised manuscript BAP: carried all experimental procedures, revised manuscritpt CPCG: carried all experimental procedures, revised manuscritpt MEN: experimental procedures, revised manuscript and data interpretation RWP: drafted and revised manuscript RCA: writing, experimental procedures, revised manuscript JP: writing, data interpretation and revised manuscript OLF: writing, original draft and revised manuscript.

Exercise training prevents obesity-associated disorders: Role of miRNA-208a and MED13

Exercise training (ET) has been established as an important treatment for obesity, since it counteracts aberrant cardiac metabolism and weight gain; however, underlying mechanisms remain to be further determined. MicroRNAs (miRNAs) inhibit protein expression by base-pairing with the 3' UTRs of mRNA targets. MiRNA-208a is a cardiac-specific miRNA that regulates β-MHC content and systemic energy homeostasis via MED13. We investigated whether ET regulates the cardiac miRNA-208a and its target MED13, reducing the weight gain and β-MHC expression in obese Zucker rats (OZR). OZR (n = 11) and Lean (L, n = 10) male rats were assigned into 4 groups: OZR, trained OZR (OZRT), L and trained L (LT). Swimming ET consisted of 60 min of duration, 1x/day, 5x/week/10 weeks. MiRNA and gene expression were analyzed by real-time PCR and protein levels by western blot. Resting bradycardia was observed in trained groups. ET reduced weight gain, retroperitoneal fat weight and adipocyte cell size in OZRT compared with OZR group. Cardiac miRNA-208a levels increased 57% in OZR paralleled with a decrease of 39% in MED13 protein levels compared with L group. In contrast, ET corrected the cardiac miRNA-208a and MED13 levels in OZRT compared with L group. Furthermore, ET reduced the increased cardiac mass and normalized β-MHC protein levels caused by obesity. These results suggest that ET can prevent weight gain and pathological cardiac hypertrophy via increased of cardiac MED13 by the regulation of miRNA-208a. Therefore, miRNA-208a can be used as potential therapeutic target for metabolic and cardiac disorders.

Mild exercise along with limb blood-flow restriction modulates the electrocardiogram, angiotensin, and apelin receptors of the heart in aging rats

OBJECTIVES

Considering the lack of information, the effects of mild endurance exercise plus blood flow restriction (BFR) on electrocardiographic parameters, hypertrophy index, and expression of angiotensin II receptors type 1 (AT1R) and type 2 (AT2R) and apelin receptor (APJ) were assessed in hearts of old male rats.

MATERIALS AND METHODS

Animal were grouped as control (CTL), Sham (Sh), lower extremities blood flow restriction (BFR), exercise (Ex), Sham + exercise (Sh + Ex), and blood flow restriction + exercise (BFR + Ex).

RESULTS

Exercise plus BFR significantly decreased the corrected QT (QTc) interval (P<0.01 vs CTL and Sh groups) and increased the heart hypertrophy index (P<0.05 vs CTL and BFR groups). Exercise alone increased expression of the APJ (P<0.01, vs CTL, Sh, and BFR groups) and AT2 receptors (P<0.001, vs Sh, CTL, BFR, and BFR + exercise groups), whereas it reduced expression of AT1R (P<0.01 in comparison with CTL, Sh, and BFR groups). Exercise plus BFR caused a significant increase in APJ (P<0.05 vs Ex, Sh+Ex and P<0.001 vs CTL, Sh, and BFR groups) and also expression of AT1R (P<0.001 vs Ex, Sh + Ex, CTL, Sh, and P<0.01 vs BFR groups). Accompaniment of exercise with BFR destroyed the effect of exercise on the expression of AT2R.

CONCLUSION

Mild endurance exercise plus BFR can alter the expression of angiotensin II and apelin receptors that leads to cardiac hypertrophy and improves the ventricular conductivity of aging rats.

Exercise Training Restores the Cardiac Microrna-16 Levels Preventing Microvascular Rarefaction in Obese Zucker Rats

OBJECTIVE

To evaluate the effects of aerobic exercise training (AET) on cardiac miRNA-16 levels and its target gene VEGF related to microvascular rarefaction in obese Zucker rats (OZR).

METHODS

OZR (n = 11) and lean (L; n = 10) male rats were assigned into 4 groups: OZR, trained OZR (OZRT), L and trained L (LT). Swimming exercise training lasted 60 min, 1×/day/10 weeks, with 4% body weight workload. Cardiac angiogenesis was assessed by histological analysis (periodic acid-Schiff) by calculating the capillary/fiber ratio. The protein expressions of VEGF, VEGFR2, and CD31 were evaluated by western blot. The expression of miRNA-16 was evaluated by real-time PCR.

RESULTS

Heart rate decreased in the trained groups compared to sedentary groups. The cardiac capillary/fiber ratio was reduced in OZR compared to L, LT and OZRT groups, indicating that aerobic exercise training (AET) was capable of reversing the microvascular rarefaction in the obese animals. miRNA-16 expression was increased in OZR compared to L, LT and OZRT. In contrast, its target, VEGF protein expression was 24% lower in OZR compared to L group, which has been normalized in OZRT group. VEGFR2 protein expression was increased in trained groups compared to their controls. CD31, a endothelial cells marker, showed increased expression in OZRT compared to OZR, indicating greater vascularization in OZRT group.

CONCLUSION

AET induced cardiac angiogenesis in obese animals. This revascularization is associated with a decrease in miRNA-16 expression permissive for increased VEGF protein expression, suggesting a mechanism for potential therapeutic application in vascular diseases.

Association between renin-angiotensin-aldosterone system blockade and future osteoporotic fracture risk in hypertensive population: A population-based cohort study in Taiwan

Tissue renin-angiotensin-aldosterone system (RAAS) activation in sites of osteoporosis had been demonstrated in animal studies; however, the possibility of RAAS blockade to prevent future osteoporotic fracture had rarely been verified in clinical studies. We Used the Taiwan Longitudinal Health insurance database 2000 to 2008, the cohort study comprised patients age over 40 with a recorded new diagnosis of hypertension between January 1, 2000 to December 31, 2008, in addition, patients who had diagnosis of osteoporosis before the date of cohort enter were excluded. After the definite diagnosis of hypertension, each patient was followed until osteoporotic fracture happened or the end of 2008. The occurrence of osteoporotic fracture was evaluated in patients who either were or without taking RAAS blockade agents. Cox proportional hazard regressions were used to evaluate the osteoporotic fracture incidence after adjusting for known confounding factors. In total, 57,132 hypertensive patients comprised the study cohort. Our study results showed that the incidence of osteoporosis fracture in the whole cohort was significantly higher in the RAAS blockade non-user group than the user group. This phenomenon was observed in both sex and all age categories. Sensitivity analysis further showed the concordant lower osteoporosis fracture risk in patients with various RAAS blockers usage durations; the risk of osteoporosis fracture was the lowest in those drug use >365 days when compared with the non-user cohort. In conclusion, our study result demonstrated the lower future osteoporotic fracture risk in hypertensive subjects who received long term RAAS blocker treatment.

Exercise Training Restores Cardiac MicroRNA-1 and MicroRNA-29c to Nonpathological Levels in Obese Rats

We previously reported that aerobic exercise training (AET) consisted of 10 weeks of 60-min swimming sessions, and 5 days/week AET counteracts CH in obesity. Here, we evaluated the role of microRNAs and their target genes that are involved in heart collagen deposition and calcium signaling, as well as the cardiac remodeling induced by AET in obese Zucker rats. Among the four experimental Zucker groups: control lean rats (LZR), control obese rats (OZR), trained lean rats (LZR + TR), and trained obese rats (OZR + TR), heart weight was greater in the OZR than in the LZR group due to increased cardiac intramuscular fat and collagen. AET seems to exert a protective role in normalizing the heart weight in the OZR + TR group. Cardiac microRNA-29c expression was decreased in OZR compared with the LZR group, paralleled by an increase in the collagen volumetric fraction (CVF). MicroRNA-1 expression was upregulated while the expression of its target gene NCX1 was decreased in OZR compared with the LZR group. Interestingly, AET restored cardiac microRNA-1 to nonpathological levels in the OZR-TR group. Our findings suggest that AET could be used as a nonpharmacological therapy for the reversal of pathological cardiac remodeling and cardiac dysfunction in obesity.

Obesity Downregulates MicroRNA-126 Inducing Capillary Rarefaction in Skeletal Muscle: Effects of Aerobic Exercise Training

Background. We investigated the effects of exercise training (ET) on miR-126 levels and skeletal muscle angiogenesis in obese Zucker rats. Results. Zucker rats were randomly assigned to sedentary and swimming-trained groups: lean sedentary (LS) and trained (LTR); obese sedentary (OB) and trained (OBTR). The OB group displayed capillary rarefaction compared with the LS group. In contrast, ET increased the capillary/fiber ratio by 38% in the LTR group and normalized capillary rarefaction in the OBTR group. VEGF, PI3K, and eNOS levels were reduced in the skeletal muscle of the OB group. ET normalized VEGF, PI3K, and eNOS levels in OBTR, contributing to vascular network homeostasis. PI3KR2 inhibits PI3K, a key mediator of the VEGF signaling pathway. Obesity decreased miR-126 and increased PI3KR2 levels compared with the LS group. However, ET normalized miR-126 levels in the OBTR group versus the LS group and decreased expression of PI3KR2. Conclusion. Our findings show that obesity leads to skeletal muscle capillary rarefaction, which is regulated by decreased miR-126 levels and increased PI3KR2. Inversely, ET normalizes miR-126 levels and VEGF signaling and should be considered an important therapeutic strategy for vascular disorders.

Ameliorative Effects of Endurance Exercise with Two Different Intensities on Nandrolone Decanoate-Induced Neurodegeneration in Rats: Involving Redox and Apoptotic Systems

Despite the importance of this issue, less has been paid to the influence of exercise on the neural side effects of anabolic androgenic steroids and mechanisms. We investigated the effects of two levels of endurance exercise on neurodegeneration side effects of nandrolone. The study period was 8 weeks. Wistar rats were divided into nine groups including the control (CTL) group, mild exercise (mEx) group, and vehicle (Arach) group which received arachis oil intramuscularly, nandrolone (Nan) group which received nandrolone decanoate 5 mg/kg two times weekly, mEx+Arach group which treated with arachis oil along with mild exercise, mEx+Nan group which treated with nandrolone along with mild exercise, severe exercise (sEx) group, sEx+Arach, and sEx+Nan groups. Finally, brain samples were taken for histopathological, biochemical, and western blot analysis. Nandrolone significantly decreased the intact cells of the hippocampus, total antioxidant capacity (TAC) (P < 0.05 versus CTL and Arach groups), TAC to malondialdehyde ratio (TAC/MDA), and Bcl-2. Nandrolone increased the Bax/Bcl-2 ratio of the brain tissue (P < 0.01 versus CTL and Arach groups). Combination of mild exercise and nandrolone rescued the intact cells to some extent, and this effect was associated with the improvement of Bcl-2 level and Bax/Bcl-2 ratio of brain tissue. Combination of severe exercise and nandrolone rescued the intact cells and improved the TAC, TAC/MDA, and Bax/Bcl-2 ratios. The findings suggest that low- and high-intensity endurance exercise decreased the risk of neurodegeneration effect of nandrolone in the hippocampus of rats. This effect can be explained by the regulation of the redox system and cell homeostasis.

Differential effects of Mas receptor deficiency on cardiac function and blood pressure in obese male and female mice

Angiotensin-(1-7) [ANG-(1-7)] acts at Mas receptors (MasR) to oppose effects of angiotensin II (ANG II). Previous studies demonstrated that protection of female mice from obesity-induced hypertension was associated with increased systemic ANG-(1-7), whereas male obese hypertensive mice exhibited increased systemic ANG II. We hypothesized that MasR deficiency (MasR^-/- ) augments obesity-induced hypertension in males and abolishes protection of females. Male and female wild-type (MasR^+/+ ) and MasR^-/- mice were fed a low-fat (LF) or high-fat (HF) diet for 16 wk. MasR deficiency had no effect on obesity. At baseline, male and female MasR^-/- mice had reduced ejection fraction (EF) and fractional shortening than MasR^+/+ mice. Male, but not female, HF-fed MasR^+/+ mice had increased systolic and diastolic (DBP) blood pressures compared with LF-fed controls. In HF-fed females, MasR deficiency increased DBP compared with LF-fed controls. In contrast, male HF-fed MasR^-/- mice had lower DBP than MasR^+/+ mice. We quantified cardiac function after 1 mo of HF feeding in males of each genotype. HF-fed MasR^-/- mice had higher left ventricular (LV) wall thickness than MasR^+/+ mice. Moreover, MasR^+/+ , but not MasR^-/- , mice displayed reductions in EF from HF feeding that were reversed by ANG-(1-7) infusion. LV fibrosis was reduced in HF-fed MasR^+/+ but not MasR^-/- ANG-(1-7)-infused mice. These results demonstrate that MasR deficiency promotes obesity-induced hypertension in females. In males, HF feeding reduced cardiac function, which was restored by ANG-(1-7) in MasR^+/+ but not MasR^-/- mice. MasR agonists may be effective therapies for obesity-associated cardiovascular conditions.NEW & NOTEWORTHY MasR deficiency abolishes protection of female mice from obesity-induced hypertension. Male MasR-deficient obese mice have reduced blood pressure and declines in cardiac function. ANG-(1-7) infusion restores obesity-induced cardiac dysfunction of wild-type, but not MasR-deficient, male mice. MasR agonists may be cardioprotective in obese males and females.

Chymase-dependent production of angiotensin II: an old enzyme in old hearts

Age-dependent alteration of the renin-angiotensin system (RAS) and generation of angiotensin II (Ang II) are well documented. By contrast, RAS-independent generation of Ang II in aging and its responses to exercise have not been explored. To this end, we examined the effects of chymase, a secretory serine protease, on the angiotensin-converting enzyme (ACE)-independent conversion of Ang I to Ang II. We hypothesized that age-dependent alteration of cardiac Ang II formation is chymase dependent in nature and is prevented by exercise training. Experiments were conducted on hearts isolated from young (3 mo), aged sedentary (24 mo), and aged rats chronically exercised on a treadmill. In the presence of low Ang I levels and downregulation of ACE expression/activity, cardiac Ang II levels were significantly higher in aged than young rats, suggesting an ACE-independent response. Aged hearts also displayed significantly increased chymase expression and activity, as well as upregulation of tryptase, a biological marker of mast cells, confirming a mast cell-sourced increase in chymase. Coincidently, cardiac superoxide produced from NADPH oxidase (Nox) was significantly enhanced in aged rats and was normalized by exercise. Conversely, a significant reduction in cardiac expression of ACE2 followed by lower Ang 1-7 levels and downregulation of the Mas receptor (binding protein of Ang 1-7) in aged rats were completely reversed by exercise. In conclusion, local formation of Ang II is increased in aged hearts, and chymase is primarily responsible for this increase. Chronic exercise is able to normalize the age-dependent alterations via compromising chymase/Ang II/angiotensin type 1 receptor/Nox actions while promoting ACE2/Ang 1-7/MasR signaling.

NEW & NOTEWORTHY

Aging increases angiotensin-converting enzyme (ACE)-independent production of cardiac angiotensin II (Ang II), a response that is driven by chymase in an exercise-reversible manner. These findings highlight chymase, in addition to ACE, as an important therapeutic target in the treatment and prevention of Ang II-induced deterioration of cardiac function in the elderly.

The Effects of Nandrolone Decanoate Along with Prolonged Low-Intensity Exercise on Susceptibility to Ventricular Arrhythmias

We examined the influence of chronic administration of nandrolone decanoate with low-intensity endurance swimming exercise on susceptibility to lethal ventricular arrhythmias in rat. The animal groups included the control group, exercise group (EX), nandrolone group (Nan), vehicle group (Arach), trained vehicle group (Arach + Ex) and trained nandrolone group (Nan + Ex) that treated for 8 weeks. Then, arrhythmia induction was performed by intravenous infusion of aconitine and electrocardiogram recorded. Then, malondialdehyde (MDA), hydroxyproline (HYP) and glutathione peroxidase of heart tissue were measured. Chronic administration of nandrolone with low-intensity endurance swimming exercise had no significant effect on blood pressure, heart rate and basal ECG parameters except RR interval that showed increase (P < 0.05). Low-intensity exercise could prevent the incremental effect of nandrolone on MDA and HYP significantly. It also increased the heart hypertrophy index (P < 0.05) and reduced the abating effect of nandrolone on animal weighting. Nandrolone along with exercise significantly increased the duration of VF (P < 0.05) and reduced the VF latency (P < 0.05). The findings suggest that chronic co-administration of nandrolone with low-intensity endurance swimming exercise to some extent facilitates the occurrence of ventricular fibrillation in rat. Complementary studies are needed to elucidate the involved mechanisms of this abnormality.

Severe Obesity Shifts Metabolic Thresholds but Does Not Attenuate Aerobic Training Adaptations in Zucker Rats

Severe obesity affects metabolism with potential to influence the lactate and glycemic response to different exercise intensities in untrained and trained rats. Here we evaluated metabolic thresholds and maximal aerobic capacity in rats with severe obesity and lean counterparts at pre- and post-training. Zucker rats (obese: n = 10, lean: n = 10) were submitted to constant treadmill bouts, to determine the maximal lactate steady state, and an incremental treadmill test, to determine the lactate threshold, glycemic threshold and maximal velocity at pre and post 8 weeks of treadmill training. Velocities of the lactate threshold and glycemic threshold agreed with the maximal lactate steady state velocity on most comparisons. The maximal lactate steady state velocity occurred at higher percentage of the maximal velocity in Zucker rats at pre-training than the percentage commonly reported and used for training prescription for other rat strains (i.e., 60%) (obese = 78 ± 9% and lean = 68 ± 5%, P < 0.05 vs. 60%). The maximal lactate steady state velocity and maximal velocity were lower in the obese group at pre-training (P < 0.05 vs. lean), increased in both groups at post-training (P < 0.05 vs. pre), but were still lower in the obese group at post-training (P < 0.05 vs. lean). Training-induced increase in maximal lactate steady state, lactate threshold and glycemic threshold velocities was similar between groups (P > 0.05), whereas increase in maximal velocity was greater in the obese group (P < 0.05 vs. lean). In conclusion, lactate threshold, glycemic threshold and maximal lactate steady state occurred at similar exercise intensity in Zucker rats at pre- and post-training. Severe obesity shifted metabolic thresholds to higher exercise intensity at pre-training, but did not attenuate submaximal and maximal aerobic training adaptations.

The risk of life-threatening ventricular arrhythmias in presence of high-intensity endurance exercise along with chronic administration of nandrolone decanoate

Anabolic steroids used to improve muscular strength and performance in athletics. Its long-term consumption may induce cardiovascular adverse effects. We assessed the risk of ventricular arrhythmias in rats which subjected to chronic nandrolone plus high-intensity endurance exercise. Animals were grouped as; control (CTL), exercise (Ex): 8 weeks under exercise, vehicle group (Arach): received arachis oil, and Nan group: received nandrolone decanoate 5 mg/kg twice a week for 8 weeks, Arach+Ex group, and Nan+Ex. Finally, under anesthesia, arrhythmia was induced by infusion of 1.5 μg/0.1 mL/min of aconitine IV and ventricular arrhythmias were recorded for 15 min. Then, animals' hearts were excised and tissue samples were taken. Nandrolone plus exercise had no significant effect on blood pressure but decreased the heart rate (P<0.01) and increased the RR (P<0.01) and JT intervals (P<0.05) of electrocardiogram. Nandrolone+exercise significantly increased the ventricular fibrillation (VF) frequency and also decreased the VF latency (P<0.05 versus CTL group). Combination of exercise and nandrolone could not recover the decreasing effects of nandrolone on animals weight gain but, it enhanced the heart hypertrophy index (P<0.05). In addition, nandrolone increased the level of hydroxyproline (HYP) and malondialdehyde (MDA) but had not significant effect on glutathione peroxidase of heart. Exercise only prevented the effect of nandrolone on HYP. Nandrolone plus severe exercise increases the risk of VF that cannot be explained only by the changes in redox system. The intensification of cardiac hypertrophy and prolongation of JT interval may be a part of involved mechanisms.

Opposing tissue-specific roles of angiotensin in the pathogenesis of obesity, and implications for obesity-related hypertension

Metabolic disease, specifically obesity, has now become the greatest challenge to improving cardiovascular health. The renin-angiotensin system (RAS) exists as both a circulating hormone system and as a local paracrine signaling mechanism within various tissues including the brain, kidney, and adipose, and this system is strongly implicated in cardiovascular health and disease. Growing evidence also implicates the RAS in the control of energy balance, supporting the concept that the RAS may be mechanistically involved in the pathogenesis of obesity and obesity hypertension. Here, we review the involvement of the RAS in the entire spectrum of whole organism energy balance mechanisms, including behaviors (food ingestion and spontaneous physical activity) and biological processes (digestive efficiency and both aerobic and nonaerobic resting metabolic rates). We hypothesize that opposing, tissue-specific effects of the RAS to modulate these various components of energy balance can explain the apparently paradoxical results reported by energy-balance studies that involve stimulating, versus disrupting, the RAS. We propose a model in which such opposing and tissue-specific effects of the RAS can explain the failure of simple, global RAS blockade to result in weight loss in humans, and hypothesize that obesity-mediated uncoupling of endogenous metabolic rate control mechanisms can explain the phenomenon of obesity-related hypertension.

Nandrolone Plus Moderate Exercise Increases the Susceptibility to Lethal Arrhythmias

Background:

Until now, no experimental study has directly assessed the arrhythmogenesis of chronic consumption of anabolic androgenic steroids along with moderate-intensity endurance exercise.

Objectives:

We evaluated the influence of integration of anabolic androgenic steroids along with moderate-intensity endurance exercise on susceptibility to lethal ventricular arrhythmias in rat.

Materials and Methods:

The animal groups were as follows: control group (CTL); exercise group (EX) which were under 6 weeks of treadmill exercise; nandrolone group (Nan) which received 5 mg/kg of nandrolone decanoate twice a week; vehicle group (Arach) which received Arachis oil (solvent of nandrolone); trained vehicle group (Arach + Ex); and trained nandrolone group (Nan + Ex). One day after ending of the intervention period, arrhythmia was inducted by intravenous infusion of aconitine and ventricular arrhythmias were recorded. Then malondialdehyde (MDA) and glutathione peroxidase (GPX) of heart tissue were measured.

Results:

Nandrolone, exercise, and their combination were associated with heart hypertrophy. Exercise could prevent the incremental effect of nandrolone on MDA/GPX ratio. Chronic administration of nandrolone with moderate-intensity endurance exercise had no significant effect on blood pressure, heart rate, and basal electrocardiographic parameters. Combination of nandrolone and exercise significantly increased the incidence of ventricular fibrillation (VF) and reduced the VF latency (P < 0.05).

Conclusions:

The findings suggest that chronic coadministration of nandrolone with moderate-intensity endurance exercise facilitates the VF occurrence in rat. Complementary studies are needed to elucidate the involved mechanisms of this abnormality.

Modulation of angiotensin II signaling following exercise training in heart failure

Sympathetic activation is a consistent finding in the chronic heart failure (CHF) state. Current therapy for CHF targets the renin-angiotensin II (ANG II) and adrenergic systems. Angiotensin converting enzyme (ACE) inhibitors and ANG II receptor blockers are standard treatments along with β-adrenergic blockade. However, the mortality and morbidity of this disease is still extremely high, even with good medical management. Exercise training (ExT) is currently being used in many centers as an adjunctive therapy for CHF. Clinical studies have shown that ExT is a safe, effective, and inexpensive way to improve quality of life, work capacity, and longevity in patients with CHF. This review discusses the potential neural interactions between ANG II and sympatho-excitation in CHF and the modulation of this interaction by ExT. We briefly review the current understanding of the modulation of the angiotensin type 1 receptor in sympatho-excitatory areas of the brain and in the periphery (i.e., in the carotid body and skeletal muscle). We discuss possible cellular mechanisms by which ExT may impact the sympatho-excitatory process by reducing oxidative stress, increasing nitric oxide. and reducing ANG II. We also discuss the potential role of ACE2 and Ang 1-7 in the sympathetic response to ExT. Fruitful areas of further investigation are the role and mechanisms by which pre-sympathetic neuronal metabolic activity in response to individual bouts of exercise regulate redox mechanisms and discharge at rest in CHF and other sympatho-excitatory states.

Angiotensin 1-7: a peptide for preventing and treating metabolic syndrome

Angiotensin-(1-7) is one of the most important active peptides of the renin-angiotensin system (RAS) with recognized cardiovascular relevance; however several studies have shown the potential therapeutic role of Ang-(1-7) on treating and preventing metabolic disorders as well. This peptide achieves a special importance considering that in the last few decades obesity and metabolic syndrome (MS) have become a growing worldwide health problem. Angiotensin (Ang) II is the most studied component of RAS and is increased during obesity, diabetes and dyslipidemia (MS); some experimental evidence has shown that Ang II modulates appetite and metabolism as well as mechanisms that induce adipose tissue growth and metabolism in peripheral organs. Recent articles demonstrated that Ang-(1-7)/Mas axis modulates lipid and glucose metabolism and counterregulates the effects of Ang II. Based on these data, angiotensin-converting enzyme 2 (ACE2)/Ang-(1-7)/Mas pathway activation have been advocated as a new tool for treating metabolic diseases. This review summarizes the new evidence from animal and human experiments indicating the use of Ang-(1-7) in prevention and treatment of obesity and metabolic disorders.

Duodenal nutrient exclusion improves metabolic syndrome and stimulates villus hyperplasia

OBJECTIVE

Surgical interventions that prevent nutrient exposure to the duodenum are among the most successful treatments for obesity and diabetes. However, these interventions are highly invasive, irreversible and often carry significant risk. The duodenal-endoluminal sleeve (DES) is a flexible tube that acts as a barrier to nutrient-tissue interaction along the duodenum. We implanted this device in Zucker Diabetic Fatty (ZDF) rats to gain greater understanding of duodenal nutrient exclusion on glucose homeostasis.

DESIGN

ZDF rats were randomised to four groups: Naive, sham ad libitum, sham pair-fed, and DES implanted. Food intake, body weight (BW) and body composition were measured for 28 days postoperatively. Glucose, lipid and bile acid metabolism were evaluated, as well as histological assessment of the upper intestine.

RESULTS

DES implantation induced a sustained decrease in BW throughout the study that was matched by pair-fed sham animals. Decreased BW resulted from loss of fat, but not lean mass. DES rats were also found to be more glucose tolerant than either ad libitum-fed or pair-fed sham controls, suggesting fat mass independent metabolic benefits. DES also reduced circulating triglyceride and glycerol levels while increasing circulating bile acids. Interestingly, DES stimulated a considerable increase in villus length throughout the upper intestine, which may contribute to metabolic improvements.

CONCLUSIONS

Our preclinical results validate DES as a promising therapeutic approach to diabetes and obesity, which offers reversibility, low risk, low invasiveness and triple benefits including fat mass loss, glucose and lipid metabolism improvement which mechanistically may involve increased villus growth in the upper gut.

Contribution of renin-angiotensin system to exercise-induced attenuation of aortic remodeling and improvement of endothelial function in spontaneously hypertensive rats

INTRODUCTION

It is well known that exercise alleviates aortic remodeling and preserves endothelial function in spontaneously hypertensive rats (SHRs). However, the underlying molecular mechanism remains unclear. This study aimed to investigate the role of renin-angiotensin system (RAS) components in exercise-induced attenuation of aortic remodeling and improvement of endothelial function in an animal model of human essential hypertension.

METHODS

The 10-week-old male SHR and age-matched normotensive Wistar-Kyoto rats were given moderate-intensity exercise for 12weeks (four groups, n=80-86 in each group).

RESULTS

In this work, exercise training reduced blood pressure and effectively attenuated aortic remodeling, marked by a reduction in aortic weight/length, wall thickness, and aortic levels of elastin and hydroxyproline, and improved endothelium-mediated vascular relaxations of aortas in response to acetylcholine. Exercise training in SHR reduced angiotensin II (AngII) levels and enhanced Ang-(1-7) levels in aortas. Exercise training in SHR suppressed aortic angiotensin-converting enzyme (ACE) and AngII type 1 receptor (AT1R) messenger RNA (mRNA) levels and protein expression and up-regulated ACE2, AngII type 2 receptor, and Mas mRNA levels and protein expression. In addition, exercise training in SHR increased levels of microRNA-27a (targeting ACE) and microRNA-155 (targeting AT1R) and decreased levels of microRNA-143 (targeting ACE2) in the aortas.

CONCLUSION

Chronic aerobic exercise training improved RAS balance in the aortas, which may in part explain the protective effect of exercise on aortic function and structure.

SUMMARY

Chronic aerobic exercise training improved RAS balance in the aortas, which may explain the protective effect of exercise on aortic function and structure, at least in part.

The efficacy and tolerability of azilsartan in obese insulin-resistant mice with left ventricular pressure overload

Angiotensin II receptor blockers (ARBs) are used widely for the treatment of heart failure. However, their use in obese and insulin-resistant patients remains controversial. To clarify their potential efficacy in these conditions, we administered azilsartan medoxomil (azilsartan), a prodrug of an angiotensin II receptor blocker to mice fed a high-fat diet (HFD) with left ventricular (LV) pressure overload (aortic banding). LV fibrosis (hydroxyproline), cardiac plasminogen activator inhibitor-1 (PAI-1; a marker of profibrosis), and creatine kinase (a marker of myocardial viability and energetics) were assessed. LV wall thickness and cardiac function were assessed echocardiographically. Mice given a HFD were obese and insulin resistant. Their LV hypertrophy was accompanied by greater LV PAI-1 and reduced LV creatine kinase compared with normal diet controls. Drug treatment reduced LV wall thickness, hypertrophy, and PAI-1 and increased cardiac output after aortic banding compared with results in HFD vehicle controls. Thus, azilsartan exerted favorable biological effects on the hearts of obese insulin-resistant mice subjected to LV pressure overload consistent with its potential utility in patients with analogous conditions.

ACE2: angiotensin II/angiotensin-(1-7) balance in cardiac and renal injury

Our current recognition of the renin-angiotensin system is more convoluted than originally thought due to the discovery of multiple novel enzymes, peptides, and receptors inherent in this interactive biochemical cascade. Over the last decade, angiotensin-converting enzyme 2 (ACE2) has emerged as a key player in the pathophysiology of hypertension and cardiovascular and renal disease due to its pivotal role in metabolizing vasoconstrictive/hypertrophic/proliferative angiotensin II into favorable angiotensin-(1-7). This review addresses the considerable advancement in research on the role of tissue ACE2 in the development and progression of hypertension and cardiac and renal injury. We summarize the results from recent clinical and experimental studies suggesting that serum or urine soluble ACE2 may serve as a novel biomarker or independent risk factor relevant for diagnosis and prognosis of cardiorenal disease. We also review recent proceedings on novel therapeutic approaches to enhance ACE2/angiotensin-(1-7) axis.

Swimming exercise changes hemodynamic responses evoked by blockade of excitatory amino receptors in the rostral ventrolateral medulla in spontaneously hypertensive rats

Exercise training reduces sympathetic activity in hypertensive humans and rats. We hypothesized that the swimming exercise would change the neurotransmission in the rostral ventrolateral medulla (RVLM), a key region involved in sympathetic outflow, and hemodynamic control in spontaneously hypertensive rats (SHR) and Wistar-Kyoto (WKY) rats. Bilateral injections of kynurenic acid (KYN) were carried out in the RVLM in sedentary- (S-) or exercised- (E-) SHR and WKY rats submitted to swimming for 6 weeks. Rats were α-chloralose anesthetized and artificially ventilated, with Doppler flow probes around the lower abdominal aorta and superior mesenteric artery. Injections into the RVLM were made before and after i.v. L-NAME (nitric oxide synthase, NOS, inhibitor). Injections of KYN into the RVLM elicited a major vasodilation in the hindlimb more than in the mesenteric artery in E-SHR compared to S-SHR, but similar decrease in arterial pressure was observed in both groups. Injections of KYN into the RVLM after i.v. L-NAME attenuated the hindlimb vasodilation evoked by KYN and increased the mesenteric vasodilation in E-SHR. Swimming exercise can enhance the hindlimb vasodilation mediated by peripheral NO release, reducing the activation of neurons with EAA receptors in the RVLM in SHR.

Tissue Renin-Angiotensin systems: a unifying hypothesis of metabolic disease

The actions of angiotensin peptides are diverse and locally acting tissue renin-angiotensin systems (RAS) are present in almost all tissues of the body. An activated RAS strongly correlates to metabolic disease (e.g., diabetes) and its complications and blockers of RAS have been demonstrated to prevent diabetes in humans. Hyperglycemia, obesity, hypertension, and cortisol are well-known risk factors of metabolic disease and all stimulate tissue RAS whereas glucagon-like peptide-1, vitamin D, and aerobic exercise are inhibitors of tissue RAS and to some extent can prevent metabolic disease. Furthermore, an activated tissue RAS deteriorates the same risk factors creating a system with several positive feedback pathways. The primary effector hormone of the RAS, angiotensin II, stimulates reactive oxygen species, induces tissue damage, and can be associated to most diabetic complications. Based on these observations, we hypothesize that an activated tissue RAS is the principle cause of metabolic syndrome and type 2 diabetes, and additionally is mediating the majority of the metabolic complications. The involvement of positive feedback pathways may create a self-reinforcing state and explain why metabolic disease initiate and progress. The hypothesis plausibly unifies the major predictors of metabolic disease and places tissue RAS regulation in the center of metabolic control.

Late-onset exercise in female rat offspring ameliorates the detrimental metabolic impact of maternal obesity

Rising rates of maternal obesity/overweight bring the need for effective interventions in offspring. We observed beneficial effects of postweaning exercise, but the question of whether late-onset exercise might benefit offspring exposed to maternal obesity is unanswered. Thus we examined effects of voluntary exercise implemented in adulthood on adiposity, hormone profiles, and genes involved in regulating appetite and metabolism in female offspring. Female Sprague Dawley rats were fed either normal chow or high-fat diet (HFD) ad libitum for 5 weeks before mating and throughout gestation/lactation. At weaning, female littermates received either chow or HFD and, after 7 weeks, half were exercised (running wheels) for 5 weeks. Tissues were collected at 15 weeks. Maternal obesity was associated with increased hypothalamic inflammatory markers, including suppressor of cytokine signaling 3, TNF-α, IL-1β, and IL-6 expression in the arcuate nucleus. In the paraventricular nucleus (PVN), Y1 receptor, melanocortin 4 receptor, and TNF-α mRNA were elevated. In the hippocampus, maternal obesity was associated with up-regulated fat mass and obesity-associated gene and TNF-α mRNA. We observed significant hypophagia across all exercise groups. In female offspring of lean dams, the reduction in food intake by exercise could be related to altered signaling at the PVN melanocortin 4 receptor whereas in offspring of obese dams, this may be related to up-regulated TNF-α. Late-onset exercise ameliorated the effects of maternal obesity and postweaning HFD in reducing body weight, adiposity, plasma leptin, insulin, triglycerides, and glucose intolerance, with greater beneficial effects in offspring of obese dams. Overall, hypothalamic inflammation was increased by maternal obesity or current HFD, and the effect of exercise was dependent on maternal diet. In conclusion, even after a significant sedentary period, many of the negative impacts of maternal obesity could be improved by voluntary exercise and healthy diet.

Exercise perspective on common cardiac medications

Medicinal tablets have been used for a long time to treat cardiovascular disease. However, mortality rate is steadily increasing partly because of the patients’ sedentary lifestyle and unhealthy diet. By contrast, exercise has been systematically shown to have multiple benefits. Regular exercise training can prevent various diseases in healthy individuals. Combined exercise and cardiac medications may lead to the improvement of heart disease. Numerous exercise training pathways still need further investigations. How exercise can prevent, treat, or attenuate diseases remains somewhat elusive. Thus, this review will discuss cardiac medications in parallel with the mechanism of action of exercise.