Moderate calorie restriction attenuates age‑associated alterations and improves cardiac function by increasing SIRT1 and SIRT3 expression

Calorie restriction (CR) extends the lifespan of mammals and improves cardiac function by attenuation of age‑associated alterations. Sirtuins (SIRT) are involved in these mechanisms, however, the extent to which CR affects cardiac function and sirtuin expression remains unknown. Therefore, the present study aimed to determine to what extent CR affects cardiac function and sirtuin expression. A total of 60 female Sprague‑Dawley rats were randomly divided into four groups, including normal control (NC), 25% calorie restriction (25% CR), 45% calorie restriction (45% CR) and high‑fat diet (HF). The groups were maintained on these specific regimens for 2 months. CR rats were observed to have significantly lower body weight, heart weight, and left ventricle mass index compared with NC and HF rats. Visceral fat, triglyceride, and low density lipoprotein levels were significantly decreased in CR rats. Compared with the 25% CR group, the 45% CR group heart function decreased. The heart rate, left ventricular systolic pressure, +dp/dt and ‑dp/dt of the 45% CR rats decreased, whereas the left ventricular end‑diastolic pressure increased. To explore the molecular mechanism of CR on cardiac function, immunoblotting was used to detect the protein expression of SIRT1 and SIRT3. The 25% CR diet increased the expression of SIRT1 and SIRT3 in myocardium, whereas the 45% CR and HF diets resulted in a decrease in SIRT1 and SIRT3 expression. Moderate calorie restriction (25% CR) improves cardiac function by attenuation of age‑associated alterations in rats. SIRT1 and SIRT3 are associated with these effects.