Long-lived mice exhibit 24 h locomotor circadian rhythms at young and old age.

αMUPA transgenic mice exhibit spontaneously reduced eating and increased life span compared with their wild type (WT) control FVB/N mice. αMUPA mice also show high-amplitude circadian rhythms in food intake, body temperature, and hepatic clock gene expression. Here we examined young and aged WT and αMUPA mice for the period of locomotor activity (tau) under total darkness (DD). We show that tau changed in WT mice from a period <24 h at 8 months to a period >24 h at 18 months. However, the period of αMUPA mice was ~24 h at both 8 and 18 months. As deviation of tau from 24 h has been found to be inversely related to life span in a large number of rodents, our results suggest that the sustainable endogenous period of ~24 h in αMUPA mice may contribute to their prolonged life span.