The aims of this study were to investigate the impact of caloric restriction (CR) on cardiac senescence in an animal model of diabetes and examine the signal transduction mechanisms for changes in cell survival as well as cardiac function. Male 8-week-old Otsuka Long-Evans Tokushima fatty (OLETF) diabetic rats were divided into 2 groups: a group fed ad libitum (AL), and a group fed with CR (30% energy reduction). Long-Evans Tokushima Otsuka (LETO) non-diabetic rats were used as controls. LETO rats were divided into 3 groups: a high fat diet (HFD) group with a 22% increase in caloric intake, a CR group, and a group fed AL. At 40 weeks of age, the telomere length was significantly shorter in the heart tissue of HFD rats but was not altered by CR in experimental rats with or without CR, however, telomerase activity in both strains of CR rats was significantly elevated. Protein expression of IGF-1, Sirt 1 and phospho-FoxO1 was increased in both CR groups. Echocardiography showed that CR preserved LV diastolic function with a significantly shorter E-wave deceleration time and a greater E/A ratio compared with the AL groups. These findings suggest that CR protocol increased telomerase activity without changing of telomere length, enhanced autophagy and improved LV diastolic function in animal model of diabetes rats. It is finally suggested that those impacts may be important for the maintenance of normal cardiac function and for delayed cardiac aging.

中文翻译：

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卡路里限制可延迟心脏衰老并改善肥胖糖尿病大鼠的心脏功能。

本研究的目的是在糖尿病动物模型中研究热量限制 (CR) 对心脏衰老的影响，并检查细胞存活和心脏功能变化的信号转导机制。雄性 8 周大 Otsuka Long-Evans Tokushima 脂肪 (OLETF) 糖尿病大鼠分为 2 组：一组随意喂养 (AL)，一组喂养 CR（能量减少 30%）。Long-Evans Tokushima Otsuka (LETO) 非糖尿病大鼠用作对照。LETO 大鼠分为 3 组：热量摄入增加 22% 的高脂肪饮食 (HFD) 组、CR 组和喂食 AL 的组。在 40 周龄时，HFD 大鼠心脏组织中的端粒长度显着缩短，但在有或没有 CR 的实验大鼠中，端粒长度没有被 CR 改变，然而，两种 CR 大鼠品系的端粒酶活性均显着升高。两个 CR 组中 IGF-1、Sirt 1 和磷酸化 FoxO1 的蛋白质表达均增加。超声心动图显示，与 AL 组相比，CR 保留了 LV 舒张功能，具有明显更短的 E 波减速时间和更大的 E/A 比。这些发现表明，CR 方案在不改变端粒长度的情况下增加了端粒酶活性，增强了自噬并改善了糖尿病大鼠动物模型中的 LV 舒张功能。最后提出，这些影响对于维持正常心脏功能和延缓心脏衰老可能很重要。超声心动图显示，与 AL 组相比，CR 保留了 LV 舒张功能，具有明显更短的 E 波减速时间和更大的 E/A 比。这些发现表明，CR 方案在不改变端粒长度的情况下增加了端粒酶活性，增强了自噬并改善了糖尿病大鼠动物模型中的 LV 舒张功能。最后提出，这些影响对于维持正常心脏功能和延缓心脏衰老可能很重要。超声心动图显示，与 AL 组相比，CR 保留了 LV 舒张功能，具有明显更短的 E 波减速时间和更大的 E/A 比。这些发现表明，CR 方案在不改变端粒长度的情况下增加了端粒酶活性，增强了自噬并改善了糖尿病大鼠动物模型中的 LV 舒张功能。最后提出，这些影响对于维持正常心脏功能和延缓心脏衰老可能很重要。