Metabolic, hemodynamic and structural adjustments to low intensity exercise training in a metabolic syndrome model.

BACKGROUND: The increase in fructose consumption is paralleled by a higher incidence of metabolic syndrome, and consequently, cardiovascular disease mortality. We examined the effects of 8 weeks of low intensity exercise training (LET) on metabolic, hemodynamic, ventricular and vascular morphological changes induced by fructose drinking in male rats. METHODS: Male Wistar rats were divided into (n = 8 each) control (C), sedentary fructose (F) and ET fructose (FT) groups. Fructose-drinking rats received D-fructose (100 g/l). FT rats were assigned to a treadmill training protocol at low intensity (30% of maximal running speed) during 1 h/day, 5 days/week for 8 weeks. Measurements of triglyceride concentrations, white adipose tissue (WAT) and glycemia were carried out together with insulin tolerance test to evaluate metabolic profile. Arterial pressure (AP) signals were directly recorded. Baroreflex sensitivity (BS) was evaluated by the tachycardic and bradycardic responses. Right atria, left ventricle (LV) and ascending aorta were prepared to morphoquantitative analysis. RESULTS: LET reduced WAT (-37.7%), triglyceride levels (-33%), systolic AP (-6%), heart weight/body weight (-20.5%), LV (-36%) and aortic (-76%) collagen fibers, aortic intima-media thickness and circumferential wall tension in FT when compared to F rats. Additionally, FT group presented improve of BS, numerical density of atrial natriuretic peptide granules (+42%) and LV capillaries (+25%), as well as the number of elastic lamellae in aorta compared with F group. CONCLUSIONS: Our data suggest that LET, a widely recommended practice, seems to be particularly effective for preventing metabolic, hemodynamic and morphological disorders triggered by MS.

Exercise training initiated at old stage of lifespan attenuates aging-and ovariectomy-induced cardiac and renal oxidative stress: Role of baroreflex.

BACKGROUND: The association of aging and menopause is a potent risk factor for cardiometabolic disease. We studied the impact of aerobic exercise training (ET) initiated in the old stage of lifespan in hemodynamics, metabolic, autonomic and oxidative stress. METHODS: Aged (18 months old) female Wistar rats were divided into: ovariectomized and untrained (AG-OVX), and ovariectomized and trained (AG-OVXt, ET for 8 weeks). Intact aged (AG) and young female rats (3 months old; Y) were also studied. Blood pressure and metabolic parameters were measured. Baroreflex sensitivity (BRS) was studied by bradycardic (BR) and tachycardic (TR) responses to vasoactive drugs. Cardiac and renal lipid peroxidation (LPO), catalase (CAT), superoxide dismutase (SOD) and gluthatione peroxidase (GPx), and gluthatione redox balance (GSH/GSSG) were analyzed. RESULTS: AG-OVXt group increased aerobic performance in 35%, decreased adipose tissue and triglycerides in 36% and 27%, respectively, and improved insulin tolerance in 50% in comparison to AG-OVX. AG-OVX presented hypertensive levels of blood pressure (systolic: 155 ±â€¯5, diastolic: 111 ±â€¯3 mmHg). In contrast, AG-OVXt presented blood pressure values similar to Y rats (systolic: 129 ±â€¯3, diastolic: 112 ±â€¯3 mmHg). TR and BR were reduced by 70% and 46%, respectively, in AG-OVX vs. Y. Once more, AG-OVXt presented similar results to Y. ET decreased LPO in the heart and kidney. In the latter, renal CAT and SOD were corrected by ET, while cardiac redox balance was partially recovered. Improved BRS was correlated with improved oxidative stress markers. CONCLUSIONS: Even when initiated after aging and ovariectomy deleterious effects, ET is able to normalize BRS and highly improve cardiac and renal oxidative stress.

Aerobic Training Is Better Than Resistance Training on Cardiac Function and Autonomic Modulation in Female ob/ob Mice.

Objective: This study evaluated the effects of aerobic, resistance, and combined exercise training on cardiac function and autonomic modulation in female ob/ob mice. Methods: Four-week-old female wild type and obese (ob/ob) mice were divided into five groups (n = 8): control (WT), obese (OB) obese + aerobic training (OBA), obese + resistance training (OBR), and obese + combined training (OBC). The exercise training was performed on treadmill and/or ladder at 40-60% maximum test during 8 weeks. Cardiac function was measured using echo machine. Heart rate variability (HRV) was evaluated in the time and frequency domain. Results: OB group presented higher body weight gain (~600%), glycemia (~44%) and glucose intolerance (~150%), reduction of cardiac vagal modulation, evidenced by a lower RMMSD (~56%), total power and high frequency band, and a higher isovolumic relaxation time (IVRT) (~24%) in relation to the WT group. Aerobic and combined training led to a lower IVRT (OBA: ~14%; OBC: ~14%) and myocardial global index (OBA: ~37%; OBC: ~44%). The OBA group presented an increased in vagal indexes of HRV than the other ob/ob groups. A negative correlation was observed between the delta of aerobic exercise capacity and MPI (r = 0.45; p = 0.002) and exercise capacity and body weight gain (r = 0.39; p = 0.002). Conclusion: Only the obese females underwent to aerobic exercise training showed improvement in cardiac function and HRV. Moreover, the aerobic exercise capacity as well as a greater responsivity to aerobic exercise training is intimately associated with these improvements, reinforcing the importance of aerobic exercise training to this population.

Measurement of Mouse Heart Rate Variability using Echocardiographic System.

AIM: We employed an echocardiographic (ECHO) system as the backbone for the collection of electrocardiogram (ECG) and heart rate variability (HRV) data. The system was tested using an exercise model in which C57 male mice were exposed to sham or forced wheel running. METHODS: Peak/peak (RR) interval was recorded over a 3 min period using the ECG platform of the ECHO system. Isoflurane-anesthetized male mice were divided into two groups (n = 8/group): sedentary (S) and forced wheel trained (T). HRV was analyzed in time and frequency domains (Fast Fourier Transform). Exercise training (T) was performed on a motorized wheel at low intensity 1 h/day, 5 days/week, 8 weeks duration. Cardiac morphometry and function were analyzed using ECHO while ECG was the basis to measure HRV. The sampling rate was 8000 Hz. Results show that the trained mice presented a reduction in heart rate as compared to the sedentary group. This was associated with lower cardiac sympathetic and higher parasympathetic modulation leading to an improved sympathetic/parasympathetic ratio (low-frequency band/high-frequency band). The trained group showed a reduction in isovolumetric relaxation time, reduced myocardial performance index, increased relative wall thickness, and left ventricle mass when compared to the sedentary group. CONCLUSION: Results document the utility of combining the ECHO and the ECG platform, allowing for the dual measurement of autonomic and cardiac function in mice.

Impact of aging on cardiac function in a female rat model of menopause: role of autonomic control, inflammation, and oxidative stress.

OBJECTIVE: The aim of this study was to evaluate the effects of aging on metabolic, cardiovascular, autonomic, inflammatory, and oxidative stress parameters after ovarian hormone deprivation (OVX). METHODS: Female Wistar rats (3 or 22 months old) were divided into: young controls, young ovariectomized, old controls, and old ovariectomized (bilateral ovaries removal). After a 9-week follow-up, physical capacity, metabolic parameters, and morphometric and cardiac functions were assessed. Subsequently, arterial pressure was recorded and cardiac autonomic control was evaluated. Oxidative stress was measured on the cardiac tissue, while inflammatory profile was assessed in the plasma. RESULTS: Aging or OVX caused an increase in body and fat weight and triglyceride concentration and a decrease in both insulin sensitivity and aerobic exercise capacity. Left ventricular diastolic dysfunction and increased cardiac overload (myocardial performance index) were reported in old groups when compared with young groups. Aging and OVX led to an increased sympathetic tonus, and vagal tonus was lower only for the old groups. Tumor necrosis factor-α and interleukin-6 were increased in old groups when compared with young groups. Glutathione redox balance (GSH/GSSG) was reduced in young ovariectomized, old controls, and old ovariectomized groups when compared with young controls, indicating an increased oxidative stress. A negative correlation was found between GSH/GSSG and tumor necrosis factor-α (r=-0.6, P<0.003). Correlations were found between interleukin-6 with adipose tissue (r=0.5, P<0.009) and vagal tonus (r=-0.7, P<0.0002); and among myocardial performance index with interleukin-6 (r=0.65, P<0.0002), sympathetic tonus (r=0.55, P<0.006), and physical capacity (r=-0.55, P<0.003). The findings in this trial showed that ovariectomy aggravated the impairment of cardiac and functional effects of aging in female rats, probably associated with exacerbated autonomic dysfunction, inflammation, and oxidative stress.

Exercise training prevents diastolic dysfunction induced by metabolic syndrome in rats.

OBJECTIVE: High fructose consumption contributes to the incidence of metabolic syndrome and, consequently, to cardiovascular outcomes. We investigated whether exercise training prevents high fructose diet-induced metabolic and cardiac morphofunctional alterations. METHODS: Wistar rats receiving fructose overload (F) in drinking water (100 g/l) were concomitantly trained on a treadmill (FT) for 10 weeks or kept sedentary. These rats were compared with a control group (C). Obesity was evaluated by the Lee index, and glycemia and insulin tolerance tests constituted the metabolic evaluation. Blood pressure was measured directly (Windaq, 2 kHz), and echocardiography was performed to determine left ventricular morphology and function. Statistical significance was determined by one-way ANOVA, with significance set at p<0.05. RESULTS: Fructose overload induced a metabolic syndrome state, as confirmed by insulin resistance (F: 3.6 ± 0.2 vs. C: 4.5 ± 0.2 mg/dl/min), hypertension (mean blood pressure, F: 118 ± 3 vs. C: 104 ± 4 mmHg) and obesity (F: 0.31 ± 0.001 vs. C: 0.29 ± 0.001 g/mm). Interestingly, fructose overload rats also exhibited diastolic dysfunction. Exercise training performed during the period of high fructose intake eliminated all of these derangements. The improvements in metabolic parameters were correlated with the maintenance of diastolic function. CONCLUSION: The role of exercise training in the prevention of metabolic and hemodynamic parameter alterations is of great importance in decreasing the cardiac morbidity and mortality related to metabolic syndrome.

Exercise training prevents diastolic dysfunction induced by metabolic syndrome in rats

OBJECTIVE: High fructose consumption contributes to the incidence of metabolic syndrome and, consequently, to cardiovascular outcomes. We investigated whether exercise training prevents high fructose diet-induced metabolic and cardiac morphofunctional alterations. METHODS: Wistar rats receiving fructose overload (F) in drinking water (100 g/l) were concomitantly trained on a treadmill (FT) for 10 weeks or kept sedentary. These rats were compared with a control group (C). Obesity was evaluated by the Lee index, and glycemia and insulin tolerance tests constituted the metabolic evaluation. Blood pressure was measured directly (Windaq, 2 kHz), and echocardiography was performed to determine left ventricular morphology and function. Statistical significance was determined by one-way ANOVA, with significance set at p<0.05. RESULTS: Fructose overload induced a metabolic syndrome state, as confirmed by insulin resistance (F: 3.6 ± 0.2 vs. C: 4.5 ± 0.2 mg/dl/min), hypertension (mean blood pressure, F: 118 ± 3 vs. C: 104 ± 4 mmHg) and obesity (F: 0.31±0.001 vs. C: 0.29 ± 0.001 g/mm). Interestingly, fructose overload rats also exhibited diastolic dysfunction. Exercise training performed during the period of high fructose intake eliminated all of these derangements. The improvements in metabolic parameters were correlated with the maintenance of diastolic function. CONCLUSION: The role of exercise training in the prevention of metabolic and hemodynamic parameter alterations is of great importance in decreasing the cardiac morbidity and mortality related to metabolic syndrome.

Influência do Treinamento Físico em parâmetros cardíacos, vasculares, inflamatórios e de estresse oxidativo em um modelo de menopausa e síndrome metabólica no envelhecimento / Training influence in cardiac, vascular, inflammatory and oxidative stress parameters in a model of menopause and metabolic syndrome in aging

Em 2013, a população idosa mundial era de 841 milhões e espera-se que aumente mais de três vezes até 2050. Neste sentido, a expectativa de vida das mulheres tem sido maior do que a dos homens. Apesar das doenças cardiovasculares (DCV) se desenvolverem mais tarde nas mulheres do que nos homens ela ainda é a principal causa de morte em mulheres. Adicionalmente, o aumento do consumo calórico, especialmente carboidratos refinados e frutose, tem sido correlacionado com o aumento de síndrome metabólica (SM). Estes dados confirmam que a idade, maus hábitos alimentares e o gênero têm uma importância significativa na incidência de risco cardiovascular. Evidências consistentes sobre os benefícios do treinamento físico nas alterações cardiovasculares, metabólicas e autonômicas associadas a DCV, têm levado muitos pesquisadores a sugerirem o treinamento físico regular como um procedimento não farmacológico importante na prevenção e tratamento de diferentes patologias. Neste sentido, o objetivo deste estudo foi investigar o papel do treinamento físico sobre os efeitos do envelhecimento e da ingestão de frutose em parâmetros metabólicos, cardiovasculares, inflamatórios e de estresse oxidativo em ratas submetidas à privação dos hormônios ovarianos. Métodos: Os experimentos foram realizados ratos Wistar fêmeas (n=56), jovens (3 meses) e idosas (22 meses) divididas nos seguintes grupos: jovem controle sedentária (JCS), jovem ooforectomizada sedentária (JOS), idosa controle sedentátia (ICS), idosa ooforectomizada sedentária (IOS), idosa ooforectomizada frutose (IOF), idosa ooforectomizada treinada (IOT) e idosa ooforectomizada frutose treinada (IOTF). A ovariectomia foi realizada por remoção dos ovários de forma bilateral. Os grupos frutose foram tratados com D-frutose (100g / L) na água de beber durante 10 semanas. O treinamento físico foi realizado em esteira durante 8 semanas. A morfometria e a função cardíaca foram avaliadas por ecocardiografia. A pressão arterial (PA)...

In 2013 the world elderly population was 841 million and it is expected to increase more than three times in 2050. In this sense, women's life expectancy has been higher than men. In addition CVD develops later in women than in men and is still the major cause of death in women. Additionally increased caloric consumption, especially refined carbohydrates and fructose, has been correlated with the metabolic syndrome (MS) increase. These data, confirm that the age, habits and gender have a significant importance in the incidence of cardiovascular risk. Constant evidences of cardiovascular, metabolic and autonomic benefits of chronic exercise training have led many researchers to suggest a regular physical training as an important non-pharmacological procedure in the prevention and treatment in pathologies conditions. In this sense, the objective of this study was to investigate the effects of aging and fructose on metabolic, cardiovascular, inflammatory and oxidative stress parameters in female rats submitted to ovarian hormone deprivation (OVX), as well as the role of exercise training in this condition. Methods: experiments were performed on 56 female rats. Sixteen young rats with 3 months of age and forty old rats with 22 month of age (n = 8 in each group) were divided into: adult control (JCS), ovariectomized sedentary (IOS), aged sedentary control (ICS), aged ovariectomized sedentary (IOS), aged ovariectomized fructose (IOF), aged ovariectomized trained (IOT) and aged ovariectomized trained fructose (IOTF). Ovariectomy was performed by bilateral ovaries removal. Fructose-fed rats received D-fructose (100g/L) in drinking water for 10 weeks. The exercise training was performed on a treadmill for 8 weeks. Cardiac morphometric and function were evaluated by echocardiography. Blood pressure (BP) and heart rate (HR) were evaluated by recording direct through a PA system for data acquisition. The baroreflex sensitivity (SBR) was evaluated by tachycardic (RT) and...