Short-term calorie restriction protects against renal senescence of aged rats by increasing autophagic activity and reducing oxidative damage.

To explore the effect of short-term calorie restriction (CR) on renal aging, 8-week CR with 60% of the food intake of the ad libitum group was administered in 25-month-old male Sprague-Dawley rats. Aged rats subjected to short-term CR had lower body weight, level of triglycerides and ratio of urine protein to urine creatinine, respectively. Short-term CR blunted the increased glomerular volume, the degree of fibrosis, p16 and the positive rate of senescence-associated β-galactosidase staining of the kidneys in old ad libitum group. Light chain 3/Atg8 as an autophagy marker exhibited a marked decline in aged kidneys, which was increased by short-term CR. The levels of p62/SQSTM1 and polyubiquitin aggregates, which were increased in older kidneys, were blunted by short-term CR. Short-term CR retarded the level of 8-hydroxydeoxyguanosine, a marker of mitochondrial DNA oxidative damage. Moreover, we found an increased level of SIRT1 and AMPK, and a decreased level of mTOR in aged kidneys after short-term CR. These results suggested that short-term CR could be considered as a potential intervention for retardation of renal senescence by increasing autophagy and subsequently reducing oxidative damage. Three master regulators of energy metabolism, SIRT1, AMPK and mTOR are associated with these effects.