Aerobic or resistance training improves autonomic control of circulation in oophorectomized rats with cardiometabolic dysfunctions: Impact on renal oxidative stress.

Cardiovascular autonomic dysfunction is associated with end organ damage and increased risk of mortality. Menopause and metabolic syndrome increase the risk for cardiorenal complications. In this study, we investigated the effects of aerobic or resistance exercise training on autonomic control of circulation and renal oxidative stress in a model of menopause and metabolic syndrome. Female Wistar rats and spontaneously hypertensive rats (SHR) were divided into 5 groups (n = 8): control (C), hypertensive (H), and sedentary (FHO), aerobic trained (FHOTa) and resistance trained (FHOTr) oophorectomized hypertensive treated with fructose (100 mg/mL drink water for 19 weeks). The FHO group presented increased vascular sympathetic modulation (LF-SBP), impaired baroreflex sensitivity (BRS) associated with increased blood pressure (BP) when compared to the H group. Aerobic exercise training enhanced tachycardic responses, while resistance training improved bradycardic responses to BP changes, thus ameliorating BRS. Moreover, despite unchanged BP, both exercise training protocols were effective in preventing increase in LF-SBP, reduction in systemic nitric oxide bioavailability (NOx), and increase in oxidative stress in the renal tissue, by decreasing lipid and protein oxidation in renal tissue. Positive correlation between LF-SBP and renal lipoperoxidation (r = 0.63, p < 0.05), as well as a negative correlation between NOx and renal lipoperoxidation (r = -0.66, p < 0.05) were observed. In conclusion, both aerobic and resistance exercise training were effective in improving autonomic control of circulation and reducing renal oxidative stress, thus attenuating the deleterious effects induced by arterial hypertension and fructose overload in female rats after ovarian hormone deprivation.

Correction: Impact of combined exercise training on the development of cardiometabolic and neuroimmune complications induced by fructose consumption in hypertensive rats.

[This corrects the article DOI: 10.1371/journal.pone.0233785.].

Impact of combined exercise training on the development of cardiometabolic and neuroimmune complications induced by fructose consumption in hypertensive rats.

This study evaluated the impact of combined exercise training on the development of cardiovascular and neuroimmune complications induced by fructose consumption (10% in the drinking water) in hypertensive rats (SHR). After weaning, SHR were divided into 3 groups: SHR (H), SHR+fructose (HF) and SHR+fructose+combined exercise training (treadmill+ladder, 40-60% of maximum capacity) (HFTC). Metabolic, hemodynamic, autonomic, inflammatory and oxidative stress parameters were evaluated in the subgroups (n = 6 group/time) at 7, 15, 30 and 60 days of protocol. Fructose consumption (H vs. HF groups) decreased spontaneous baroreflex sensitivity and total variance of pulse interval at day 7 (7 to 60); increased IL-6 and TNFα in the heart (at day 15, 30 and 60) and NADPH oxidase activity and cardiac lipoperoxidation (LPO) (day 60); increased white adipose tissue weight, reduced insulin sensitivity and increased triglycerides (day 60); induced an additional increase in mean arterial pressure (MAP) (days 30 and 60). Combined exercise training prevented such dysfunctions and sustained increased cardiac IL-10 (day 7) and glutathione redox balance (GSH/GSSG) for the entire protocol. In conclusion, combined exercise training performed simultaneously with exacerbated fructose consumption prevented early cardiovascular autonomic dysfunction, probably trigging positive changes in inflammation and oxidative stress, resulting in a better cardiometabolic profile in rats genetically predisposed to hypertension.

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.

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.

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.

Baroreflex Impairment Precedes Cardiometabolic Dysfunction in an Experimental Model of Metabolic Syndrome: Role of Inflammation and Oxidative Stress.

This study analyzes whether autonomic dysfunction precedes cardiometabolic alterations in spontaneously hypertensive rats (SHR) with fructose overload. Animals were randomly distributed into three groups: control, hypertensive and hypertensive with fructose overload. Fructose overload (100 g/L) was initiated at 30 days old, and the animals (n = 6/group/time) were evaluated after 7, 15, 30 and 60 days of fructose consumption. Fructose consumption reduced baroreflex sensitivity by day 7, and still induced a progressive reduction in baroreflex sensitivity over the time. Fructose consumption also increased TNFα and IL-6 levels in the adipose tissue and IL-1ß levels in the spleen at days 15 and 30. Fructose consumption also reduced plasmatic nitrites (day 15 and 30) and superoxide dismutase activity (day 15 and 60), but increased hydrogen peroxide (day 30 and 60), lipid peroxidation and protein oxidation (day 60). Fructose consumption increased arterial pressure at day 30 (8%) and 60 (11%). Fructose consumption also induced a late insulin resistance at day 60, but did not affect glucose levels. In conclusion, the results show that baroreflex sensitivity impairment precedes inflammatory and oxidative stress disorders, probably by inducing hemodynamic and metabolic dysfunctions observed in metabolic syndrome.