Isolated obesity resistance condition or associated with aerobic exercise training does not promote cardiac impairment.

J.P Cordeiro,D.H Campos,A.C Cicogna,A.P Lima-Leopoldo,V.L Da Silva,A.S Leopoldo

doi:10.1590/1414-431x2020e10669

Abstract

Mechanisms involved in cardiac function and calcium (Ca2+) handling in obese-resistant (OR) rats are still poorly determined. We tested the hypothesis that unsaturated high-fat diet (HFD) promotes myocardial dysfunction in OR rats, which it is related to Ca2+ handling. In addition, we questioned whether exercise training (ET) becomes a therapeutic strategy. Male Wistar rats (n=80) were randomized to standard or HFD diets for 20 weeks. The rats were redistributed for the absence or presence of ET and OR: control (C; n=12), control + ET (CET; n=14), obese-resistant (OR; n=9), and obese-resistant + ET (ORET; n=10). Trained rats were subjected to aerobic training protocol with progressive intensity (55-70% of the maximum running speed) and duration (15 to 60 min/day) for 12 weeks. Nutritional, metabolic, and cardiovascular parameters were determined. Cardiac function and Ca2+ handling tests were performed in isolated left ventricle (LV) papillary muscle. OR rats showed cardiac atrophy with reduced collagen levels, but there was myocardial dysfunction. ET was efficient in improving most parameters of body composition. However, the mechanical properties and Ca2+ handling from isolated papillary muscle were similar among groups. Aerobic ET does not promote morphological and cardiac functional adaptation under the condition of OR.

Highlights

Obesity is characterized by excess adipose tissue sufficient to cause health damage
Scientists investigating animals fed on a high-fat diet identified a third category that does not become obese, presenting similar or lower weight gain than animals fed on a low-fat diet [7]
At the 20th week, after applying the cutoff point, the redefinition of the groups indicated that within the group exposed to the high-fat diet (HFD), 19 animals were characterized as OR and 21 as OP

Summary

Introduction

Obesity is characterized by excess adipose tissue sufficient to cause health damage This condition is a complex multifactorial disease that is influenced by genetic and environmental factors [1], and it is directly linked to the development of risk factors associated with metabolic and inflammatory changes as well as with impairment of cardiac function and morphology [2,3,4]. Scientists investigating animals fed on a high-fat diet identified a third category that does not become obese, presenting similar or lower weight gain than animals fed on a low-fat diet [7]. This characteristic gives these rats the capacity to resist the morphological condition of obesity, being classified as obese-resistant (OR). Resistance to obesity seems to reflect the ability of these animals to present higher energy expenditure as an adaptive response to high-calorie intake, which compensates weight gain [8]

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