Longitudinal development of activity rhythms in Long Evans rats.
A longitudinal examination of activity rhythm development in Long Evans rats aging from 27 to 647 days was conducted. Wheel-running activity was sampled during five test periods: postweanling, periadolescence, young adulthood, presenescence, and senescence. On each test day, data were collected during both light and dark phases of the 12:12 hr light/dark photocycle. Analyses of variance (ANOVAs) on the activity data confirmed a recent cross-sectional study in two respects: First, gradual intensification of mean daily activity to adulthood was followed by a decline in senescence to a level below that found in early youth. Second, in comparison with early adulthood, a decline in activity during the dark phase was combined with an increase during the light phase as aging to senescence occurred.
Dawson
K A
KA
Psychology Department, University of Waterloo, Ontario, Canada.
Crowne
D P
DP
D000375:Aging / Q000502:physiology*; D000818:Animals; D002940:Circadian Rhythm; D009043:Motor Activity / Q000502:physiology*; D051381:Rats; D011919:Rats, Inbred Strains / Q000502:physiology*