Abstract
ObjectiveObesity and renin angiotensin system (RAS) hyperactivity are profoundly involved in cardiovascular diseases, however aerobic exercise training (EXT) can prevent obesity and cardiac RAS activation. The study hypothesis was to investigate whether obesity and its association with EXT alter the systemic and cardiac RAS components in an obese Zucker rat strain.MethodsThe rats were divided into the following groups: Lean Zucker rats (LZR); lean Zucker rats plus EXT (LZR+EXT); obese Zucker rats (OZR) and obese Zucker rats plus EXT (OZR+EXT). EXT consisted of 10 weeks of 60-min swimming sessions, 5 days/week. At the end of the training protocol heart rate (HR), systolic blood pressure (SBP), cardiac hypertrophy (CH) and function, local and systemic components of RAS were evaluated. Also, systemic glucose, triglycerides, total cholesterol and its LDL and HDL fractions were measured.ResultsThe resting HR decreased (∼12%) for both LZR+EXT and OZR+EXT. However, only the LZR+EXT reached significance (p<0.05), while a tendency was found for OZR versus OZR+EXT (p = 0.07). In addition, exercise reduced (57%) triglycerides and (61%) LDL in the OZR+EXT. The systemic angiotensin I-converting enzyme (ACE) activity did not differ regardless of obesity and EXT, however, the OZR and OZR+EXT showed (66%) and (42%), respectively, less angiotensin II (Ang II) plasma concentration when compared with LZR. Furthermore, the results showed that EXT in the OZR prevented increase in CH, cardiac ACE activity, Ang II and AT2 receptor caused by obesity. In addition, exercise augmented cardiac ACE2 in both training groups.ConclusionDespite the unchanged ACE and lower systemic Ang II levels in obesity, the cardiac RAS was increased in OZR and EXT in obese Zucker rats reduced some of the cardiac RAS components and prevented obesity-related CH. These results show that EXT prevented the heart RAS hyperactivity and cardiac maladaptive morphological alterations in obese Zucker rats.
Highlights
According to the World Health Organization, over 1.7 billion people worldwide are overweight or obese [1]
Experimental animals Twenty male Zucker rats at 20 weeks of age were assigned to four groups (n = 5 each): Lean Zucker rat (LZR), lean Zucker rat plus exercise training (LZR+EXT), obese Zucker rat (OZR), obese Zucker rat plus exercise training (OZR+EXT)
Both obese groups (OZR, obese Zucker rats (OZR)+EXT) showed higher Body Weight (BW) before and after the training protocol when compared with the Lean groups (LZR, Lean Zucker rats (LZR)+EXT) (p,0.0001), while no significant EXT effect was observed
Summary
According to the World Health Organization, over 1.7 billion people worldwide are overweight or obese [1]. The RAS is one of the most important neurohumoral contributors to the progression of pathological CH [5]. There is still controversy about the modulation of cardiac RAS in obesity, since some studies have observed an increase in some of the components of cardiac RAS, whereas others found no difference [9,10,11]. These results were demonstrated in independent studies, so the literature lacks studies demonstrating the association between each of the RAS components with obesity
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