Abstract
Abstract AIMS We evaluated whether exercise training ameliorates cardiovascular autonomic dysfunction in obesity-induced by high-fat diet (HFD) in rats. METHODS Wistar male rats were assigned in normal diet, sedentary (ND-S) and trained (ND-T) and HFD, sedentary (HFD-S) and trained (HFD-T). Blood pressure (BP), heart rate (HR), HR variability (HRV), BP variability (BPV), cardiac baroreflex and cardiac autonomic tonus were assessed. RESULTS HFD-S showed higher bodyweight increase (19.4%) compared to all other groups (HFD-T: 13.2%, ND-S: 14% and ND-T: 12.4%). Relative epididymal, retroperitoneal and visceral fat was also greater in HFD-S compared to all other groups. Resting bradycardia in ND-T (339.5±10.6 bpm) and HFD-T (341.0 ± 9.4 bpm) was more pronounced than ND-S (438.4 ± 6.3 bpm; p<0.05) and HFD-S (448.5 ± 18.7 bpm; p<0.05). The HFD-T group showed lower systolic (125.3 ( 1.9 mmHg), diastolic (88.5 ( 2.0 mmHg) and mean BP (100.3 ± 2.5 mmHg) in comparison with HFD-S (153.8 ( 3.7; 103.5 ( 2.6 and 120.5 ± 3.7 mmHg; p<0.05, respectively). Lower variance of HRV and higher variance of diastolic BPV was observed in HFD-S compared to other groups while sympathetic modulation of HRV and BPV was higher in HFD-S, as well as the LF/HF ratio. HFD-T showed a decrease in sympathetic tonus compared to HFD-S. ND-T and HFD-T showed higher cardiac vagal tonus than respective sedentary groups. Analysis showed an association between visceral fat, sympathetic activity and BP. CONCLUSIONS HFD induces hypertension and is associated with autonomic imbalance in rats, while exercise training may reverse these harmful changes.
Highlights
Contemporary lifestyle is often characterized by sedentary behavior and an excess intake of a high-fat diet (HFD), increasing the chances of developing of obesity[1] and several chronic diseases, including arterial hypertension[2] and autonomic alterations[3]
Under baseline conditions, resting bradycardia in both ND-T (339.5 ± 10.6 bpm) and HFD-T (341.0 ± 9.4 bpm) male rats has been more closely pronounced when compared with their respective sedentary groups (438.4 ± 6.3 bpm in ND-S and 448.5 ± 18.7 bpm in HFD-S, p
Similar results were observed for diastolic blood pressure (BP) in HFD-S (103.5 ± 2.6 mmHg) versus HFD-T (88.5 ± 2.0 mmHg; p
Summary
Contemporary lifestyle is often characterized by sedentary behavior and an excess intake of a high-fat diet (HFD), increasing the chances of developing of obesity[1] and several chronic diseases, including arterial hypertension[2] and autonomic alterations[3]. Conflicting results have emerged over the nature of autonomic activity in obesity[4]. These investigators showed that obese subjects presented lower sympathetic activity but no change in parasympathetic modulation. An increase in body weight (BW) is associated with sympathetic overactivity and attenuation in parasympathetic activity[5]. Obese subjects have shown an imbalance in autonomic nervous system (ANS) activity, which is characterized by an increase in parasympathetic nervous system (PNS) tonus and/or a decrease in the sympathetic nervous system (SNS) tonus[6]. Body mass index (BMI), waist circumference and sum of skinfolds are associated with a reduced cardiac vagal tonus and indicators of central obesity as compared to total indicators of obesity[10]. Increase of BW is associated with a decline in PNS, accompanied by a rise in heart rate (HR), and HR declines during weight reduction This is a point important because increment in HR has been shown as a marker associated with increased mortality[11]
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