Intermittent food restriction initiated late in life prolongs lifespan and retards the onset of age-related markers in the annual fish Nothobranchius guentheri.

Two of the most studied and widely accepted conjectures on possible aging mechanisms are the oxidative stress hypothesis and the insulin/insulin-like growth factor 1 (IGF-1) signaling (IIS) pathway. Intermittent fasting (IF) is known to modulate aging and to prolong lifespan in a variety of organisms, but the mechanisms are still under debate. In this study, we first demonstrated that late-onset two consecutive days a week fasting, a form of IF, termed intermittent food restriction (IFR), exhibited a time-dependent effect, and long-term late-onset IFR extended the mean lifespan and maximum lifespan by approximately 3.5 and 3 weeks, respectively, in the annual fish Nothobranchius guentheri. We also showed that IFR reduced the accumulation of lipofuscin in the gills and the protein oxidation and lipid peroxidation levels in the muscles. Moreover, IFR was able to enhance the activities of antioxidant enzymes catalase, glutathione peroxidase, and superoxide dismutase in the fish. Finally, IFR was also able to decelerate the decrease of SirT1 and Foxo3A, but accelerate the decrease of IGF-1. Collectively, our findings suggest that late-onset IFR can retard the onset of age-related markers, and prolong the lifespan of the aging fish, via a synergistic action of an anti-oxidant system and the IIS pathway. It also proposes that the combined assessment of anti-oxidant system and IIS pathway will contribute to providing a more comprehensive view of anti-aging process.