Impact of a switch diet after high-fat diet induced obesity combined with aging on cardiac function.

Aging and obesity both contribute to the onset of metabolic disorders and cardiovascular disease. Whether aging worsens high-fat diet (HFD)-induced obesity cardiac alterations in a murine model is not yet demonstrated. Furthermore, the beneficial effect of a weight loss induced by switch diet (SD), from HFD to control diet (CD) has been demonstrated on cardiac remodelling and function in young mice but not in aged mice. Our aim was first to assess the impact of HFD in old mice and to evaluate the reversibility of HFD-induced cardiac alterations by SD in young and aged mice. We performed a study in young (5-month-old) and old (12-month-old) mice, fed with HFD (60% fat + 5% sucrose) for 20 weeks or switched to CD for 8 weeks (SD group) after 12 weeks of HFD. We performed metabolic tests (GTT, ITT) and echocardiography [cardiac function assessed by left ventricular ejection fraction (LVEF) and systolic strain rate (SR)]. The comparison between young and old mice in CD groups shows that aging increases the body weight, adiposity index and cardiac hypertrophy and impairs myocardial function (SR but not LVEF). HFD regimen increases similarly body weight and adiposity index in both young and old mice, whilst cardiac function is impaired with a similar decrease of systolic SR in young and old mice. SD induces a similar weight loss and decrease of the adiposity index in young and old mice. However, SD improves systolic function assessed by SR in young but not aged mice. Interestingly, this improvement in SR was associated with an amelioration of glucose tolerance in young mice. Our data demonstrate that HFD-induced obesity and SD-induced weight loss modulate cardiac function differently with aging. Thus, the improvement of cardiac function by SD in young mice is not found in old mice. [ABSTRACT FROM AUTHOR]