Aging Lengthens Taudd in C57BL/6J, DBA/2J, AND Outbred Swr Male Mice(Mus Musculus)

Abstract
The effect of aging on the free-running period (TauDD) of a circadian rhythm for wheel-running activity was observed in two inbred strains (DBA/2J and C57BL/6J) and one outbred strain (Tac: (SW)fBR) of laboratory mice (Mus musculus). TauDD in the DBA and C57 mice was monitored at approximately age 100 days and age 300 days. TauDD in the outbred strain was monitored at approximately age 100 days and age 600 days. TauDD increased with age in all three strains. Most studies of age effects in rodent species have shown a shortening of TauDD with age, with the exception of the C57BL inbred mice. These results show that the lengthening of TauDD with age in laboratory mice is not limited to the C57BL strain and may be a general characteristic of this species, in contrast to other rodent species examined.