Beneficial effects of physical exercise on hypertension and cardiovascular adverse remodeling of diet-induced obese rats

Prevalence and associated factors of hypertension among adult patients attending the outpatient department at the primary hospitals of Wolkait tegedie zone, Northwest Ethiopia

Introduction

Hypertension, often known as increased blood pressure, is a worldwide public health concern. Globally, ~1 billion people have hypertension and 7.1 million die from this disease. It is disproportionately more prevalent in resource-poor nations, with inadequate health systems like Ethiopia. Moreover, information on the burden of disease from hypertension in the specific area, especially in the newly organized Wolkait Tegedie zone, is essential to develop effective prevention and control strategies. Therefore, this study aimed to assess the prevalence of hypertension and associated factors among adult patients evaluated at the outpatient department of the two district hospitals in the Wolkait Tegedie zone, Northwest Ethiopia.

Methods

An institution-based cross-sectional study was conducted from September to October 2021. A systematic random sampling technique was used to select a total of 449 participants. The data were collected and then entered using EPI-INFO version 7 and exported to STATA 14 for analysis. Bivariable and multivariable binary logistic regression analyses were performed. Adjusted odds ratio (AOR) with a 95% confidence interval (CI) was used as a measure of association. Variables having a p-value < 0.05 from the multivariable analysis were considered to have a significant association with the outcome.

Results

The prevalence of hypertension among adult patients in this study was 44.91% [95% CI: 40.26%, 49.65%], of which 63.92% were new diagnoses. Being >60 years [AOR = 1.81; 95% CI: 1.11, 3.20], having poor physical exercise [AOR = 1.74; 95% CI: 1.01, 3.15], consuming cruddy oil [AOR = 15.22; 95% CI: 3.86, 60.12], having a family history of hypertension [AOR = 13.02; 95% CI: 3.75, 45.16], and having a history of diabetes mellitus (DM) [AOR = 8.05; 95% CI: 1.24, 51.49] had a statistically significant association with having hypertension.

Conclusion

There is a relatively high prevalence of hypertension among adult patients in the outpatient department of the two primary hospitals, Northwest Ethiopia. Factors such as being of older age, having poor physical exercise behavior, cruddy oil consumption, and family history of DM and hypertension had a positive significant statistical association with being hypertensive. Community-based screening programs for hypertension should be designed and implemented to prevent this silent killer disease. Health education and promotion that focus on healthy nutrition and physical exercise should be delivered.

Leptin: Master Regulator of Biological Functions that Affects Breathing

Obesity is a global epidemic in developed countries accounting for many of the metabolic and cardiorespiratory morbidities that occur in adults. These morbidities include type 2 diabetes, sleep-disordered breathing (SDB), obstructive sleep apnea, chronic intermittent hypoxia, and hypertension. Leptin, produced by adipocytes, is a master regulator of metabolism and of many other biological functions including central and peripheral circuits that control breathing. By binding to receptors on cells and neurons in the brainstem, hypothalamus, and carotid body, leptin links energy and metabolism to breathing. In this comprehensive article, we review the central and peripheral locations of leptin's actions that affect cardiorespiratory responses during health and disease, with a particular focus on obesity, SDB, and its effects during early development. Obesity-induced hyperleptinemia is associated with centrally mediated hypoventilation with decrease CO₂ sensitivity. On the other hand, hyperleptinemia augments peripheral chemoreflexes to hypoxia and induces sympathoexcitation. Thus, "leptin resistance" in obesity is relative. We delineate the circuits responsible for these divergent effects, including signaling pathways. We review the unique effects of leptin during development on organogenesis, feeding behavior, and cardiorespiratory responses, and how undernutrition and overnutrition during critical periods of development can lead to cardiorespiratory comorbidities in adulthood. We conclude with suggestions for future directions to improve our understanding of leptin dysregulation and associated clinical diseases and possible therapeutic targets. Lastly, we briefly discuss the yin and the yang, specifically the contribution of relative adiponectin deficiency in adults with hyperleptinemia to the development of metabolic and cardiovascular disease. © 2020 American Physiological Society. Compr Physiol 10:1047-1083, 2020.

Moderate-intensity physical activity reduces systemic inflammation and maintains cardiorespiratory function following chronic particulate matter2.5 exposure in rats

Aims

The purpose of the current study is to 1) examine the beneficial effects of moderate levels of physical activity (PA) on functional and biochemical markers of the cardiorespiratory system, 2) establish the detrimental effects of a single, daily particulate matter (PM) exposure event on cardiorespiratory function and 3) determine if exercising during daily PM exposure increases the deleterious effects caused by PM exposure due to increased inhalation of particulates on cardiorespiratory function.

Methods

Four groups of 16 rats were used: control (CON), PA, PM_2.5 exposed and PA combined with PM_2.5 exposure (PA + PM). Animals were purchased at 4 weeks old. However, both PA and PM exposure was initiated when the animals reached 8 weeks of age, for 8 weeks.

Results

PA alone did not alter body weight or blood pressure (BP) compared to control animals. However, there was a significant decrease in epididymal fat pad mass in the PA group. The PM exposed rats were hypertensive, showed increased systemic inflammation and oxidative stress, and had decreased spleen mass without pathological changes in the cardiac action potential or impaired vascular function. PA was able to decrease systemic inflammation in PM exposed animals, including a reduction in IL-6 serum levels, however, this did not translate to an improvement in BP or vascular reactivity. Smooth muscle relaxation in the trachea from the combination PA + PM group was not significantly different to CON and PA groups but was significantly higher than the PM group.

Conclusions

The current study showed that while there is an increased cardiovascular disease (CVD) risk associated with PM exposure, engaging in PA during exposure events imposes no increased risk with exercise providing a protective mechanism against some of the biochemical signaling changes caused by inhaled PM.

Improvement of microvascular endothelial dysfunction induced by exercise and diet is associated with microRNA-126 in obese adolescents

OBJECTIVE

Microvascular endothelial dysfunction, which is at the early stage of atherosclerosis, precedes macrovascular endothelial dysfunction. The study is aimed to investigate the mechanism underlying the improvement of microvascular endothelial dysfunction by exercise and diet in obese adolescents.

METHODS

A quasi-randomized study was carried out with 2 cohorts: the experimental group (57 obese male adolescents; age: 15.38 ± 2.82 years, BMI: 33.21 ± 4.23 kg/m²) completed a 6-week exercise program with dietary intervention, and control group (10 normal weight adolescents; age: 15.38 ± 2.82 years, BMI: 23.21 ± 4.23 kg/m²) maintained sedentary. Clinical characteristics, circulating NO, ET-1 and microRNA-126 (miR-126) levels were measured before and after 6 weeks. The Reactive Hyperemia Index (RHI) was measured using EndoPAT-2000 system.

RESULTS

After 6-weeks intervention, obese adolescents' body circumferences and glucolipid metabolism are significantly improved. RHI (p < 0.01) and serum levels of NO/ET-1 (p < 0.01) are significantly increased, while microRNA-126 significantly decreased (p < 0.01). ΔMiR-126 were positive correlated with ΔBMI (r = 0.60, p < 0.01), ΔRHI (r = 0.69, p < 0.05), and ΔNO/ET-1 (r = -0.68, p < 0.05).

CONCLUSIONS

Combination of exercise and diet control can effectively improve glycolipid metabolism of obese adolescents, and thus their microvascular endothelial function, which might be related to changes in serum miRNA-126.

Therapeutic and preventive effects of exercise on cardiometabolic parameters in aging and obese rats

BACKGROUND AND AIMS

Aging, obesity and sedentarism are among the most important predictors of cardiometabolic diseases. Aiming to reduce the impact of the combination of these three factors, we tested the therapeutic and preventive effects of exercise in aging and obese rats on the following cardiometabolic disease risk parameters: body fat, blood pressure, blood lipids, and glycemic homeostasis.

METHODS

Eighteen male Wistar rats (initial age = 4 months, and final age = 14 months) were randomly distributed into three aging and obese groups: sedentary, therapeutic exercise and preventive exercise. Food and caloric intake, body adiposity, muscle mass, cardiovascular parameters, biochemical markers, glycemic homeostasis, and gene expression of insulin-dependent, insulin-independent and insulin resistance pathways in skeletal muscle were evaluated.

RESULTS

Therapeutic and preventive exercises were associated with higher food and caloric intake, and expression of TBC1D1 in the soleus muscle, as well as lower total cholesterol/HDL and LDL/HDL ratios, glucose levels at the end (90 min) of the glucose tolerance test and IKBKB expression in the gastrocnemius and soleus muscles. Only the preventive exercise improved the cardiovascular and body composition parameters, glucose tolerance, insulin resistance and insulin sensitivity, besides reducing total cholesterol, triglycerides, triglycerides/HDL ratio, plasmatic insulin and MAPK8 expression in soleus. The preventive exercise group also presented greater expression of INRS, IRS1, IRS2, PIK3CA, AKT1, and SLC2A4 in gastrocnemius and soleus, TBC1D1 in gastrocnemius, and AKT2 and PRKAA1 in soleus.

CONCLUSIONS

Therapeutic exercise promoted some improvements on cardiometabolic parameters in aging and obese rats, however, the best benefits were achieved through the preventive exercise.

α-Linolenic acid and exercise training independently, and additively, decrease blood pressure and prevent diastolic dysfunction in obese Zucker rats

KEY POINTS

α-linolenic acid (ALA) and exercise training both attenuate hyperlipidaemia-related cardiovascular derangements, however, there is a paucity of information pertaining to their mechanisms of action when combined. We investigated both the independent and combined effects of exercise training and ALA consumption in obese Zucker rats, aiming to determine the potential for additive improvements in cardiovascular function. ALA and exercise training independently improved cardiac output, end-diastolic volume, left ventricular fibrosis and mean blood pressure following a 4 week intervention. Combining ALA and endurance exercise yielded greater improvements in these parameters, independent of changes in markers of oxidative stress or endogenous anti-oxidants. We postulate that divergent mechanisms of action may explain these changes: ALA increases peripheral vasodilation, and exercise training stimulates angiogenesis.

ABSTRACT

Although α-linolenic acid (ALA) and endurance exercise training independently attenuate hyperlipidaemia-related cardiovascular derangements, there is a paucity of information pertaining to their mechanisms of action and efficacy when combined as a preventative therapeutic approach. Therefore, we used obese Zucker rats to investigate the independent and combined effects of these interventions on cardiovascular disease. Specifically, animals were randomly assigned to one of the following groups: control diet-sedentary, ALA supplemented-sedentary, control diet-exercise trained or ALA supplemented-exercise trained. Following a 4 week intervention, although the independent and combined effects of ALA and exercise reduced (P < 0.05) the serum free/esterified cholesterol ratio, only the ALA supplemented-exercise trained animals displayed a reduction in the content of both serum free and esterified cholesterol. Moreover, although ALA and endurance training individually increased cardiac output, stroke volume and end-diastolic volume, as well as reduced left ventricle fibrosis, mean blood pressure and total peripheral resistance, these responses were all greater following the combined intervention (ALA supplemented-exercise trained). These effects occurred independent of changes in oxidative phosphorylation proteins, markers of oxidative stress or endogenous anti-oxidant capacity. We propose that the beneficial effects of a combined intervention occur as a result of divergent mechanisms of action elicited by ALA and endurance exercise because only exercise training increased the capillary content in the left ventricle and skeletal muscle, and tended to decrease protein carbonylation in the left ventricle (P = 0.06). Taken together, our data indicate that combining ALA and endurance exercise provides additional improvements in cardiovascular disease risk reduction compared to singular interventions in the obese Zucker rat.

Physical Activity and Sedentary Behavior Associated with Components of Metabolic Syndrome among People in Rural China

Background

Metabolic syndrome is prevalent worldwide and its prevalence is related to physical activity, race, and lifestyle. Little data is available for people living in rural areas of China. In this study we examined associations of physical activity and sedentary behaviors with metabolic syndrome components among people in rural China.

Methods

The Nantong Metabolic Syndrome Study recruited 13,505 female and 6,997 male participants between 2007 and 2008. Data of socio-demographic characteristics and lifestyle were collected. The associations of physical activity and sedentary behaviors with metabolic syndrome components were analyzed.

Results

Prevalence of metabolic syndrome was 21.6%. It was significantly lower in men than in women. Low risks of metabolic syndrome were observed in those who did less sitting and engaged in more vigorous physical activity. The highest tertile of vigorous physical activity was associated with 15–40% decreased odds of metabolic syndrome and all of its components, except for low high-density lipoprotein cholesterol in men. Women with the highest tertile of moderate physical activity had 15–30% lower odds of central obesity, high glucose, and high triglycerides compared with those in the lowest tertile. Sitting time >42 hours per week had a 4%-12% attributable risk of metabolic syndrome, central obesity, and high triglycerides in both genders, and abnormal glucose and diastolic blood pressure in women. Sleeping for more than 8 hours per day was associated with risk of high serum glucose and lipids.

Conclusions

Our data suggested that physical activity has a preventive effect against metabolic syndrome and all its abnormal components, and that longer sitting time and sleep duration are associated with an increased risk of metabolic syndrome components, including central obesity and high triglycerides, glucose, and diastolic blood pressure. This study could provide information for future investigation into these associations. Also, recommendations are developed to reduce prevalence of metabolic syndrome and its components in rural Chinese populations.

Resistance training prevents the cardiovascular changes caused by high-fat diet

AIMS

Aerobic exercise is indicated for prevention and treatment of obesity-induced cardiovascular disorders. Although the resistance training (RT) may also produce effects similar to aerobic exercise, this is not completely clear yet. In the present study, we tested if RT in moderate intensity might prevent alterations in blood pressure (BP), sympathetic modulation of systolic blood pressure (SBP), baroreflex function and the changes in renin-angiotensin system (RAS) and cytokines mRNA expression within the nucleus of the tract solitary (NTS) in rats fed with high-fat diet (HFD).

MAIN METHODS

Male Holtzman rats (300-320 g) were divided into 4 groups: sedentary with standard chow diet (SED-SD); sedentary with high-fat diet (SED-HFD); RT with standard chow diet (RT-SD); and RT with high-fat diet (RT-HFD). The trained groups performed a total of 10 weeks of moderate intensity RT in a vertical ladder. In the first 3 weeks all experimental groups were fed with SD. In the next 7 weeks, the SED-HFD and RT-HFD groups were fed with HFD.

KEY FINDINGS

In SED-HFD, BP and sympathetic modulation of SBP increased, whereas baroreflex bradycardic responses were attenuated. RT prevented the cardiovascular and inflammatory responses (increases in tumoral necrosis factor-α and interleukin-1β) produced by HFD in SED rats. The anti-inflammatory interleukin-10, angiotensin type 2 receptor, Mas receptor and angiotensin converting enzyme 2 mRNA expressions in the NTS increased in the RT-HFD compared to SED-HFD.

SIGNIFICANCE

The data demonstrated that moderate intensity RT prevented obesity-induced cardiovascular disorders simultaneously with reduced inflammatory responses and modifications of RAS in the NTS.

Resistance training attenuates the effects of aging in the aorta of Wistar rats

Abstract The objective of the present study was to follow the structural modifications of the aortic wall in middle-aged rats submitted to a resistance training protocol for a period of four months. Three groups of 8 animals per group were considered: middle-aged group (MA), old control group (OC) and old trained group (OT). Training consisted in to climb a 1.1-m vertical (80° incline) ladder with weights tied to their tail. Aortic wall structural modifications were studied through light and electron microscopy and morphometry. The mean arterial blood pressure at rest was similar in the three experimental groups (p = .07). At the beginning of the experiment, the OC and OT groups had similar repetition maximums, ranging from 1.6-fold to 1.9-fold the body weight. At the end of the experiment, the repetition maximum of the OT group was 5-fold greater than the body weight (p = .03). The LV weight was 15% larger in the OT group than in the MA group and 12% larger than in the OC group (p = .02). The LV wall thickness of the OT group was significantly larger than that of both, the MA group and the OC group (p = .03). The LV internal diameter in the OT group was significantly smaller than that observed in the MA and OC groups (p = .02). Resistance training diminished the alterations associated with aging improving aortic wall structure by reducing the thickness, normalising the elastic material, the collagen and the smooth muscle cells. Resistance training seems to be a potential treatment for reducing the deleterious effects of aging on the aortic wall.

Resistance exercise training increase activation of AKT-eNOS and Ref-1 expression by FOXO-1 activation in aorta of F344 rats

PURPOSE

This study investigated the effects of resistance exercise on the Akt-eNOS, the activation of antioxidant protein and FOXO1 in the aorta of F344 rats.

METHODS

Male 7 week-old F344 rats were randomly divided into 2 groups: a climbing group (n = 6) and a sedentary group (n = 6). H&E staining and western blotting were used to analyze the rat aortas and target proteins.

RESULTS

Resistance exercise training did not significantly affect aortic structure. Phosphorylation of AKT and eNOS and expression of MnSOD and Ref-1 were significantly increased while FOXO1 phosphorylation was significantly decreased in the resistance exercise group compared with the sedentary group.

CONCLUSION

We demonstrate that resistance exercise activates the Akt-eNOS and Ref-1 protein without changes to aortic thickness via FOXO-1 activation in the aorta of F344 rats.

Moderate intensity physical activity prevents increased blood glucose concentrations, fat pad deposition and cardiac action potential prolongation following diet-induced obesity in a juvenile-adolescent rat model

Background

Both obesity and a lack of physical activity have been associated with an elevated risk of cardiovascular disease (CVD). The incidence of obesity is increasing, especially in juvenile-adolescents. While there is limited research examining the chronic effects of obesity in adolescent humans and animal models of this condition, little is also known concerning how moderate physical activity might prevent or attenuate secondary cardiovascular complications induced by obesity during adolescence. We investigated the effects of diet-induced obesity (consisting of a high-fat, high-carbohydrate diet (HFHC)) on biometric indices, vascular and airway function, cardiovascular function, systemic oxidative stress and markers of inflammation in a juvenile-adolescent rodent model. Four groups were used: control (CON), physical activity (PA) treated, HFHC and HFHC + PA (n = 16 per group). HFHC feeding started at 4 weeks of age for a period of 12 weeks. Physical activity treatment was initiated (PA and HFHC + PA groups) when the animals were 8 weeks of age, for 8 weeks.

Results

Physical activity in juvenile-adolescent healthy rats showed no change in comparison to the CON group in all experimental parameters except for increases in lipid peroxidation, decreases in inflammatory cytokines, improvements in vascular reactivity and decreased atrial responses to positive chronotropic agents. The HFHC animals were mildly hyperglycemic, hypertensive, displayed renal hypertrophy and showed increased retroperitoneal fat pad deposition compared to the CON group. HFHC + PA rats were also hypertensive, however showed improvements in cardiac electrophysiology, body weight, fat pad deposition and inflammatory signaling, in comparison to the HFHC fed rats and CON animals.

Conclusion

In conclusion, in a juvenile-adolescent animal model of diet-induced obesity engagement in physical activity is beneficial in reducing the inflammatory effects of obesity.

Chronic aerobic exercise associated to dietary modification improve endothelial function and eNOS expression in high fat fed hamsters

Obesity is epidemic in the western world and central adipose tissue deposition points to increased cardiovascular morbidity and mortality, independently of any association between obesity and other cardiovascular risk factors. Physical exercise has been used as non-pharmacological treatment to significantly reverse/attenuate obesity comorbidities. In this study we have investigated effects of exercise and/or dietary modification on microcirculatory function, body composition, serum glucose, iNOS and eNOS expression on 120 male hamsters treated for 12 weeks with high fat chow (HF, n = 30) starting on the 21st day of birth. From week 12 to 20, animals were randomly separated in HF (no treatment change), return to standard chow (HFSC, n = 30), high fat chow associated to an aerobic exercise training program (AET) (HFEX, n = 30) and return to standard chow+AET (HFSCEX, n = 30). Microvascular reactivity in response to acetylcholine and sodium nitroprusside and macromolecular permeability increase induced by 30 minutes ischemia followed by reperfusion were assessed on the cheek pouch preparation. Total body fat and aorta eNOS and iNOS expression by immunoblotting assay were evaluated on the experimental day. Compared to HFSC and HFSCEX groups, HF and HFEX ones presented increased visceral fat [(mean±SEM) (HF)4.9±1.5 g and (HFEX)4.7±0.9 g vs. (HFSC)*3.0±0.7 g and (HFSCEX)*1.9±0.4 g/100 g BW]; impaired endothelial-dependent vasodilatation [Ach 10(-8) M (HF)87.9±2.7%; (HFSC)*116.7±5.9%; (HFEX)*109.1±4.6%; (HFSCEX)*105±2.8%; Ach10(-6) M (HF)95.3±3.1%; (HFSC)*126±6.2%; (HFEX)*122.5±2.8%; (HFSCEX)*118.1±4.3% and Ach10(-4) M (HF)109.5±4.8%; (HFSC)*149.6±6.6%; (HFEX)*143.5±5.4% and (HFSCEX)*139.4±5.2%], macromolecular permeability increase after ischemia/reperfusion [(HF)40.5±4.2; (HFSC)*19.0±1.6; (HFEX)*18.6±2.1 and (HFSCEX)* 21.5±3.7 leaks/cm2), decreased eNOS expression, increased leptin and glycaemic levels. Endothelial-independent microvascular reactivity was similar between groups, suggesting that only endothelial damage had occurred. Our results indicate that an aerobic routine and/or dietary modification may cause significant improvements to high fat fed animals, diminishing visceral depots, increasing eNOS expression and reducing microcirculatory dysfunction.

Effects of aerobic training, resistance training, or combined resistance-aerobic training on the left ventricular myocardium in a rat model

This study follows the left ventricular (LV) hypertrophy in rats undergoing aerobic training alone (A), resistance training alone (R), or combined resistance and aerobic training (RA) (usually referred as concurrent training) program. A sedentary control group (C) was included. LV remodeling was evaluated using electron and light microscopy. The LV weight to body weight (LVW: BW) increased 11.4% in A group, 35% in the R group, and 18% in the RA group compared to the C group. The LV thickness increased 6% in the A group, 17% in the R group, and 10% in the RA group. The LV internal diameter increased 19% in the A group, 3% in the R group, and 8% in the RA group compared with the C group. The cross-sectional area of cardiomyocyte increased by 1% with the A group, 27% with R group, and 12% with RA training. The capillary density increased by 5.4% with A training, 11.0% with R training, and 7.7% with RA training compared with the C group. The volume fraction of interstitial collagen increased by 0.4% with training A, increased by 2.8% with R training, and 0.9% with RA training. In conclusion, except for the LV internal diameter, which increased more in the A group, the cardiac parameters increased more in the R group than in the other groups and in RA group than in A group. Collagen density increased from 5.4 ± 0.8% in the C group to 5.8 ± 0.6% in the A group (n. s.) (P > 0.05), to 8.2 ± 0.7% in the R group (P < 0.05), and to 6.3 ± 0.4% in the RA group (P < 0.05). These results demonstrate a significant increase for collagen content in the LV with R and RA exercise, but the increase was higher with R training alone than with RA training.

Exercise prevents leptin-induced increase in blood pressure in Sprague-Dawley rats

Although leptin has been shown to increase blood pressure (BP), it is however unclear if this increase can be prevented by exercise. This study therefore investigated the effect of leptin treatment with concurrent exercise on blood pressure (BP), sodium output, and endothelin-1 (ET-1) levels in normotensive rats. Male Sprague-Dawley rats weighing 250-270 g were divided into four groups consisting of a control group (n = 6), leptin-treated (n = 8), non-leptin-treated exercise group (n = 8), and a leptin-treated exercise group (n = 8). Leptin was given subcutaneously daily for 14 days (60 μg/kg/day). Animals were exercised on a treadmill for 30 min at a speed of 0.5 m/s and at 5° incline four times per week. Measurement of systolic blood pressure (SBP) and collection of urine samples for estimation of sodium and creatinine was done once a week. Serum samples were collected at the end of the experiment for determination of sodium, creatinine and ET-1. At day 14, mean SBP and serum ET-1 level in the leptin-treated group was significantly higher than that in the control group whereas mean SBP and serum ET-1 level was significantly lower in the leptin-treated exercise group than those in leptin-treated and control groups. Creatinine clearance, urinary sodium excretion, and urine output were not different between the four groups. Regular treadmill exercise prevents leptin-induced increases in SBP in rats, which might in part result from increased urinary sodium excretion and preventing the leptin-induced increases in serum ET-1 concentration.

Exercise training starting at weaning age preserves cardiac pacemaker function in adulthood of diet-induced obese rats

Peripheral sympathetic overdrive in young obese subjects contributes to further aggravation of insulin resistance, diabetes, and hypertension, thus inducing worsening clinical conditions in adulthood. Exercise training has been considered a strategy to repair obesity autonomic dysfunction, thereby reducing the cardiometabolic risk. Therefore, the aim of this study was to assess the effect of early exercise training, starting immediately after weaning, on cardiac autonomic control in diet-induced obese rats. Male Wistar rats (weaning) were divided into four groups: (i) a control group (n = 6); (ii) an exercise-trained control group (n = 6); (iii) a diet-induced obesity group (n = 6); and (iv) an exercise-trained diet-induced obesity group (n = 6). The development of obesity was induced by 9 weeks of palatable diet intake, and the training program was implemented in a motor-driven treadmill (5 times per week) during the same period. After this period, animals were submitted to vein and artery catheter implantation to assess cardiac autonomic balance by methylatropine (3 mg/kg) and propranolol (4 mg/kg) administration. Exercise training increased running performance in both groups (p < 0.05). Exercise training also prevented the increased resting heart rate in obese rats, which seemed to be related to cardiac pacemaker activity preservation (p < 0.05). Additionally, the training program preserved the pressure and bradycardia responses to autonomic blockade in obese rats (p < 0.05). An exercise program beginning at weaning age prevents cardiovascular dysfunction in obese rats, indicating that exercise training may be used as a nonpharmacological therapeutic strategy for the treatment of cardiometabolic diseases.

Resistance training may concomitantly benefit body composition, blood pressure and muscle MMP-2 activity on the left ventricle of high-fat fed diet rats

OBJECTIVE

The purpose of this study was to evaluate the effect of resistance training (RT) on body composition, systolic and diastolic blood pressures (BP), and activity of muscle MMP-2 in the left ventricle of high-fat fed rats.

MATERIALS/METHODS

We have evaluated 32 male Wistar rats divided into four experimental groups (n=8/each) according to diet and exercise status: sedentary (SED; standard diet), sedentary obese (SED-OB; diet: 30% of fat), RT (RT; standard diet) and RT obese (RT-OB; diet: 30% of fat). After weaning (day 21), animals were subjected to the experimental diet according to their groups during 24 weeks. A 12-week strength-training period was used, during which the rats climbed a 1.1-m vertical ladder with weights attached to their tails. Sessions were performed three times/week (Mondays, Wednesdays and Fridays), with 4-9 climbs/session and 8-12 dynamic movements/climb.

RESULTS

RT induced higher muscle MMP-2 activity in the left ventricle in RT and RT-OB groups. Moreover, this study demonstrated that RT promoted lower body and fat masses, fat percentage, systolic and diastolic BPs and higher fat free mass in both trained groups.

CONCLUSION

RT increased muscle MMP-2 activity in the left ventricle, induced positive changes on body composition and lowered BPs in high-fat diet fed rats, suggesting that it may be a useful tool to prevent alterations induced by high-fat diet consumption.

Effects of exercise training on cardiac apoptosis in obese rats

BACKGROUND AND AIM

The purpose of this study was to evaluate the effects of exercise training on cardiac apoptotic pathways in obesity.

METHODS AND RESULTS

Sixteen lean Zucker rats (LZR) and sixteen obese Zucker rats (OZR) of 5-6 months of age as well as the other sixteen obese rats were subjected to treadmill running exercise for 1 h everyday for 3 months (OZR-EX). After exercise training or sedentary status of the rats, the excised hearts from the three groups were measured by heart weight index, H&E staining, TUNEL assays and Western blotting. Cardiac TUNEL-positive apoptotic cells, the protein levels of TNF alpha, Fas ligand, Fas receptors, Fas-associated death domain (FADD), Bad, Bax, activated caspase 8, activated caspase 9, and activated caspase 3 were higher in OZR than those in LZR. The protein levels of TNF alpha, Fas ligand, Fas receptors, FADD, activated caspase 8, and activated caspase 3 (Fas pathway) and the protein levels of Bad, Bax, Bax-to-Bcl2 ratio, activated caspase 9, and activated caspase 3 (mitochondria pathway) were lower in OZR-EX than those in OZR.

CONCLUSION

Cardiac Fas-dependent and mitochondria-dependent apoptotic pathways become more activated in obesity. Exercise training can prevent obesity-activated cardiac Fas-dependent and mitochondria-dependent apoptotic pathways. Our findings demonstrate a new therapeutic effect of exercise training to prevent delirious cardiac Fas-mediated and mitochondria-mediated apoptosis in obesity.

Extensive impact of saturated fatty acids on metabolic and cardiovascular profile in rats with diet-induced obesity: a canonical analysis

Background

Although hypercaloric interventions are associated with nutritional, endocrine, metabolic, and cardiovascular disorders in obesity experiments, a rational distinction between the effects of excess adiposity and the individual roles of dietary macronutrients in relation to these disturbances has not previously been studied. This investigation analyzed the correlation between ingested macronutrients (including sucrose and saturated and unsaturated fatty acids) plus body adiposity and metabolic, hormonal, and cardiovascular effects in rats with diet-induced obesity.

Methods

Normotensive Wistar-Kyoto rats were submitted to Control (CD; 3.2 Kcal/g) and Hypercaloric (HD; 4.6 Kcal/g) diets for 20 weeks followed by nutritional evaluation involving body weight and adiposity measurement. Metabolic and hormonal parameters included glycemia, insulin, insulin resistance, and leptin. Cardiovascular analysis included systolic blood pressure profile, echocardiography, morphometric study of myocardial morphology, and myosin heavy chain (MHC) protein expression. Canonical correlation analysis was used to evaluate the relationships between dietary macronutrients plus adiposity and metabolic, hormonal, and cardiovascular parameters.

Results

Although final group body weights did not differ, HD presented higher adiposity than CD. Diet induced hyperglycemia while insulin and leptin levels remained unchanged. In a cardiovascular context, systolic blood pressure increased with time only in HD. Additionally, in vivo echocardiography revealed cardiac hypertrophy and improved systolic performance in HD compared to CD; and while cardiomyocyte size was unchanged by diet, nuclear volume and collagen interstitial fraction both increased in HD. Also HD exhibited higher relative β-MHC content and β/α-MHC ratio than their Control counterparts. Importantly, body adiposity was weakly associated with cardiovascular effects, as saturated fatty acid intake was directly associated with most cardiac remodeling measurements while unsaturated lipid consumption was inversely correlated with these effects.

Conclusion

Hypercaloric diet was associated with glycemic metabolism and systolic blood pressure disorders and cardiac remodeling. These effects directly and inversely correlated with saturated and unsaturated lipid consumption, respectively.

Endurance exercise in a rat model of metabolic syndrome

We have measured the responses to endurance exercise training on body composition and glucose regulation, as well as cardiovascular and liver structure and function in rats fed a high carbohydrate and high fat (HCHF) diet as a model of human metabolic syndrome. Male Wistar rats (9-10 weeks old) were randomly allocated into corn starch (CS) or HCHF diet groups for 16 weeks; half of each group were exercised on a treadmill for 20, 25, and then 30 min/day, 5 days/week, during the last 8 weeks of the protocol. Metabolic, cardiovascular, and liver parameters were monitored. The HCHF diet induced symptoms of metabolic syndrome, including obesity, dyslipidemia, impaired glucose tolerance, and increased systolic blood pressure associated with the development of cardiovascular remodeling and nonalcoholic steatohepatitis. Exercise in HCHF rats decreased body mass, abdominal fat pads and circumference, blood glucose concentrations, plasma lipid profiles, systolic blood pressure, left ventricular diastolic stiffness, collagen deposition and inflammatory cell infiltration in the left ventricle, improved aortic contractile and relaxation responses, and decreased liver mass and hepatic fat accumulation. This study demonstrates that endurance exercise is effective in this rat model of diet-induced metabolic syndrome in improving body composition and glucose regulation, as well as cardiovascular and liver structure and function.

Effects of high-fat chow on heart tissue in acute and chronic experimental murine schistosomiasis mansoni

This study aimed to investigate myocardial injuries in mice infected with Schistosoma mansoni and fed a high-fat chow. Sections of myocardial tissue from S. mansoni-infected mice, and controls that had been killed 9 and 17 weeks post-infection, were stained with H&E and Picrosirius red. Histopathological examination, stereological design-based method (optical disector) and morphometry (vessels, cardiomyocytes and an amount of collagen) were used. Data were analysed using two-way ANOVA. Regardless of time of infection, myocardial tissue from the infected mice fed high-fat chow showed myocarditis characterized by a higher number of inflammatory foci, several areas displaying coagulation of cardiac fibres, a greater loss of cardiomyocytes and fibroblast proliferation than in the standard chow control. Comparing infected mice from acute and chronic infections, a higher cardiomyocyte hyperplasia (P < 0·0001) and higher amounts of collagen (P < 0·05) were observed than in standard chow control. In addition, all animals fed high-fat chow showed lower numerical density and total number of cardiomyocytes (P < 0·05), thicker vessel walls and narrowed luminal intramyocardial vessels (P > 0·05) than in the standard chow control. Altogether the data supported the view that a double burden has a synergistic deleterious effect on the myocardial tissue.

Exercise as a potential treatment for drug abuse: evidence from preclinical studies

Epidemiological studies reveal that individuals who engage in regular aerobic exercise are less likely to use and abuse illicit drugs. Until recently, very few studies had examined the causal influences that mediate this relationship, and it was not clear whether exercise was effective at reducing substance use and abuse. In the past few years, several preclinical studies have revealed that exercise reduces drug self-administration in laboratory animals. These studies have revealed that exercise produces protective effects in procedures designed to model different transitional phases that occur during the development of, and recover from, a substance use disorder (e.g., acquisition, maintenance, escalation, and relapse/reinstatement of drug use). Moreover, recent studies have revealed several behavioral and neurobiological consequences of exercise that may be responsible for its protective effects in these assays. Collectively, these studies have provided convincing evidence to support the development of exercise-based interventions to reduce compulsive patterns of drug intake in clinical and at-risk populations.

High fat diet induces central obesity, insulin resistance and microvascular dysfunction in hamsters

Microvascular dysfunction is an early finding in obesity possibly related to co-morbidities like diabetes and hypertension. Therefore we have investigated changes on microvascular function, body composition, glucose and insulin tolerance tests (GTT and ITT) on male hamsters fed either with high fat (HFD, n=20) or standard (Control, n=21) diet during 16 weeks. Total body fat and protein content were determined by carcass analysis, aorta eNOS and iNOS expression by immunoblotting assay and mean blood pressure (MAP) and heart rate (HR) by an arterial catheter. Microvascular reactivity in response to acetylcholine and sodium nitroprusside, functional capillary density (FCD), capillary recruitment induced by a hyperinsulinemic status and macromolecular permeability after 30 min ischemia was assessed on either cheek pouch or cremaster muscle preparations. Compared to Control, HFD animals have shown increased visceral fat (6.0 ± 0.8 vs. 13.8 ± 0.6g/100g BW), impaired endothelial dependent vasodilatation, decreased FCD (11.3 ± 1.3 vs. 6.8 ± 1.2/field) and capillary recruitment during hyperinsulinemia and increased macromolecular permeability after ischemia/reperfusion (86.4 ± 5.2 vs.105.2 ± 5.1 leaks/cm(2)), iNOS expression and insulin resistance. MAP, HR, endothelial independent vasodilatation and eNOS expression were not different between groups. Our results have shown that HFD elicits an increase on visceral fat deposition, microvascular dysfunction and insulin resistance in hamsters.

Exercise training enhances elastin, fibrillin and nitric oxide in the aorta wall of spontaneously hypertensive rats

This work aimed to analyze the effect of low-intensity exercise training on ultrastructural and molecular aortic remodeling. Male Wistar-Kyoto rats (WKY) and spontaneously hypertensive rats (SHR) were allocated into four groups: sedentary WKY (SED-WKY), exercised WKY (EX-WKY, 1 h/day, 5 days/week treadmill exercise training), sedentary SHR (SED-SHR), and exercised SHR (EX-SHR). EX-SHR showed blood pressure reduction of 26% in comparison to SED-SHR after 1 month of exercise (P<0.05). At the 20th week, BP level was not different between EX-SHRs and WKYs. Circumferential wall tension (CWT) was higher by 77% in SED-SHRs than in SED-WKYs (P<0.001). Exercise training reduced CWT by 30% in EX- vs. SED-SHR (P<0.001). In SED-SHRs, endothelial cells showed large and numerous cytoplasmatic vacuoles, fragmented inner elastic lamina and scarce elastin and fibrillin, while exercise training ameliorated it in EX-SHR group. The highest eNOS immunodensity was observed in EX-SHR, which was 50% higher than EX-WKY (P<0.01) and 120% higher than SED-SHR (P<0.0001). In conclusion, present findings indicate beneficial effects of exercise training in hypertensive rats since it increased elastin, fibrillin and eNOS content in the aortic wall.

Postconditioning hormesis put in perspective: an overview of experimental and clinical studies

A beneficial effect of applying mild stress to cells or organisms, that were initially exposed to a high dose of stress, has been referred to as 'postconditioning hormesis'. The initial high dose of stress activates intrinsic self-recovery mechanisms. Modulation of these endogenous adaptation strategies by administration of a subsequent low dose of stress can confer effects that are beneficial to the biological system. Owing to its potentially therapeutic applications, postconditioning hormesis is subject to research in various scientific disciplines. This paper presents an overview of the dynamics of postconditioning hormesis and illustrates this phenomenon with a number of examples in experimental and clinical research.

Exercise counters diet-induced obesity, proteinuria, and structural kidney alterations in rat

We studied the effects of exercise training in treating renal impairment due to hypertension and obesity in rats. Diet-induced obese and non-obese Wistar rats were assigned to four groups: Sed-Ob, Ex-Ob, Sed-C, and Ex-C (motor treadmill for 13 weeks; Ex=exercise-trained, C=control, Ob=obese, Sed=sedentary). Creatinine, proteinuria, and kidney structure were evaluated. Sed-C rats had normal and stable blood pressure (BP), while Sed-Ob rats developed hypertension. After 4 weeks of exercise, BP decreased in exercise-trained groups (less than 25% at the end of the experiment in obese rats, and less than 10% in non-obese rats). Both the body mass and retroperitoneal fat mass were lower in the exercise-trained groups than in the sedentary ones. Serum creatinine was not different among the groups, but the urinary protein excretion was significantly higher in the Sed-Ob group than in the matched non-obese group. Compared to the non-obese animals the mean glomerular volume increased by 45% in Sed-Ob rats and by 30% in Ex-Ob rats. Obese animals also showed increased mesangial volume density compared to non-obese animals. The present findings allow us to conclude that the exercise training could be an auxiliary practice to attenuate renal alterations seen in diet-induced obesity.

Left ventricular hypertrophy induced by overnutrition early in life

BACKGROUND AND AIMS

Human overnutrition has caused a rise in the prevalence of obesity in recent years. In addition to the deleterious effects of obesity during childhood, the long-term effects in adulthood have also been described. For instance, cardiovascular diseases, particularly left ventricular hypertrophy, and type 2 diabetes are among the diseases associated with a history of obesity. However, it remains uncertain during which period of life this association is established. Several authors have suggested that the early period of life is critical for the emergence of cardiac disorders.

METHODS AND RESULTS

In this study, we examined the impact of overnutrition on the heart morphology and stereology of obese animals using an experimental model to induce an overweight phenotype. In these animals, overfeeding during lactation was able to induce a significant increase in body weight and visceral fat starting at the 10th day of life, and this increased weight persisted until 21 days of age. Impairments in triglyceride levels and cholesterol were also observed in these animals. Moreover, an increased heart weight/tibia length ratio was observed, indicating an enlarged heart. The overfed animals also had left ventricular hypertrophy with an increased area of cardiomyocytes and a decreased vessel density.

CONCLUSIONS

Our findings showed that overnutrition during early life induced obesity and cardiac hypertrophy in the pups, perhaps due to a decrease in the intramyocardial vessel.

Determination of the lactate threshold and maximal blood lactate steady state intensity in aged rats

The reliability of the lactate threshold (LT) determined in aged rats and its validity to identify an exercise intensity corresponding to the maximal blood lactate steady state (MLSS) were analyzed. Eighteen male aged Wistar rats (approximately 365 days) were submitted to two incremental swimming tests until exhaustion, consisting of an initial load corresponding to 1% of body mass (BM) and increments of 1% BM at each 3-min with blood lactate ([lac]) measurements. The LT was determined by visual inspection (LT(V)) as well by applying a polynomial function on the [lac]/workload ratio (LT(P)) by considering the vertices of the curve. For the MLSS, twelve animals were submitted, on different days, to 3-4 exercise sessions of 30-min with workload corresponding to 4, 5 or 6% BM. The MLSS was considered the highest exercise intensity at which the [lac] variation was not higher than 0.07 mM.min(-1) during the last 20-min. No differences were observed for the test-retest results (4.9 +/- 0.7 and 5.0 +/- 0.8 %BM for LTv; and 6.0 +/- 0.6 and 5.8 +/- 0.6 %BM for LTp) that did not differ from the MLSS (5.4 +/- 0.5 %BM). The LT identified for aged rats in swimming, both by visual inspection and polynomial function, was reliable and did not differ from the MLSS.

Short term effects of physical exercise and low calorie diet on left ventricular function in obese subjects: a tissue Doppler study

BACKGROUND AND AIM

The effects of combined physical exercise and a hypocaloric diet on left ventricular function in obese subjects without heart disease are not well defined and have never been studied with the tissue Doppler technique. The purpose of our study was to describe the modification of left ventricular systolic and diastolic functions after a short period of physical exercise and a hypocaloric diet in obese patients.

METHODS AND RESULTS

Fifteen patients (10 females and 5 males) aged 29.7+/-6.1 years with uncomplicated obesity (mean body mass index=41.4+/-5.5 kg/m(2)) were subjected to a low calorie diet and physical exercise. Systolic and diastolic functions were evaluated by Doppler and tissue Doppler echocardiography. After 3 weeks echocardiographic and conventional Doppler measurements were unchanged, while Sa increased (0.109+/-0.019 vs 0.118+/-0.016 m/s) and Ea decreased (0.162+/-0.029 vs 0.147+/-0.022 m/s, P=0.044) resulting in a decrease in Ea/Aa (1.66+/-0.53 vs 1.40+/-0.28, P=0.033) and an increase in E/Ea (5.65+/-1.00 vs 6.35+/-1.21, P=0.038).

CONCLUSION

Physical exercise and a hypocaloric diet in obese healthy subjects result in an improvement of a TDI index of systolic function and a slight reduction in early diastolic velocity of mitral annulus.