This Article Full Text (PDF) References Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to Saved Citations Download to citation manager Request Permissions Request Reprints Add to My Marked Citations Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Citing Articles via Scopus Google Scholar Articles by Koteja, P. Articles by Garland, T. Search for Related Content PubMed PubMed Citation Articles by Koteja, P., Jr. Articles by Garland, T. Social Bookmarking                         What's this?

Different Effects of Intensity and Duration of Locomotor Activity on Circadian Period

Institute of Environmental Sciences, Jagiellonian University, ul. Ingardena 6, 30-060 Kraków, Poland koteja{at}eko.uj.edu.pl

John G. Swallow

Department of Biology, University of South Dakota, 414 East Clark Street, Vermillion, SD 57069, USA,

Patrick A. Carter

School of Biological Sciences, Washington State University, Pullman, WA 99164-4236, USA

Theodore Garland, Jr.

Department of Biology, University of California, Riverside, CA 92521, USA

An outstanding unresolved issue in chronobiology is how the level of locomotor activity influences length of the free-running, endogenous circadian period (•). To address this issue, the authors studied a novel model, 4 replicate lines of laboratory house mice (Mus domesticus) that had been selectively bred for high wheel-running activity (S) and their 4 unselected control (C) lines. Previous work indicates that S mice run approximately twice as many revolutions/day and exhibit an altered dopaminergic function as compared with C mice. The authors report that S mice have a • shorter by about 0.5 h as compared with C mice. The difference in • was significant both under constant light (control lines: • = 25.5 h; selected: • = 24.9 h) and under constant dark (control lines: 23.7 h; selected: 23.4 h). Moreover, the difference remained statistically significant even when the effects of running speed and time spent running were controlled in ANCOVA. Thus, something more fundamental than just intensity or duration of wheel-running activity per se must underlie the difference in • between the S and C lines. However, despite significant difference in total wheel-running activity between females and males, • did not differ between the sexes. Similarly, among individuals within lines, • was not correlated with wheel-running activity measured as total revolutions per day. Instead, • tended to decrease with average running speed but increase with time spent running. Finally, within individuals, an increase in time spent running resulted in decreased • in the next few days, but changes in running speed had no statistically significant effect. The distinctions between effects of duration versus intensity of an activity, aswell as between the among- versus within-individual correlations, are critical to understanding the relation between locomotor activity and pace of the circadian clock.

Key Words: artificial selection • dopamine • hyperactivity • Lomb-Scargle periodogram • Mus domesticus • sleep disorder • tau • wheel running

Journal of Biological Rhythms, Vol. 18, No. 6, 491-501 (2003)
DOI: 10.1177/0748730403256998


CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    Twitter    What's this?

This article has been cited by other articles:

				K. M. Middleton, S. A. Kelly, and T. Garland Jr Selective breeding as a tool to probe skeletal response to high voluntary locomotor activity in mice Integr. Comp. Biol., September 1, 2008; 48(3): 394 - 410. [Abstract] [Full Text] [PDF]

				J. S. Rhodes, S. C. Gammie, and T. Garland Jr. Neurobiology of Mice Selected for High Voluntary Wheel-running Activity Integr. Comp. Biol., June 1, 2005; 45(3): 438 - 455. [Abstract] [Full Text] [PDF]