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 Kas, M. J. H. Articles by Edgar, D. M. Search for Related Content PubMed PubMed Citation Articles by Kas, M. J. H. Articles by Edgar, D. M. Social Bookmarking                         What's this?

Scheduled Voluntary Wheel Running Activity Modulates Free-Running Circadian Body Temperature Rhythms in Octodon degus

Sleep & Circadian Neurobiology Laboratory, Sleep Research Center, Department of Psychiatry & Behavioral Sciences, Stanford University School of Medicine, Stanford, CA 94305, USA

Dale M. Edgar

Sleep & Circadian Neurobiology Laboratory, Sleep Research Center, Department of Psychiatry & Behavioral Sciences, Stanford University School of Medicine, Stanford, CA 94305, USA; Sleep Research Center, Stanford University School of Medicine, 701 Welch Rd., Suite #2226, Palo Alto, CA 94304, USA; dmedgar{at}stanford.edu.

Entrainment of the circadian pacemaker to nonphotic stimuli, such as scheduled wheel-running activity, is well characterized in nocturnal rodents, but little is known about activity-dependent entrainment in diurnal or crepuscular species. In the present study, effects of scheduled voluntary wheel-running activity on circadian timekeeping were investigated in Octodon degus,a hystricomorph rodent that exhibits robust crepuscular patterns of wakefulness. When housed in constant darkness, O. degus exhibited circadian rhythms in wheel-running activity and body temperature (Tb) with an average period length ([.tau]) of 23.39 ± 0.11 h. When wheel running was restricted to a fixed 2-h schedule every 24 h, [.tau] increased on average 0.39 ± 0.09 h but did not result in steady-state entrainment. Instead, relative coordination between the fixed running schedule and circadian timing was observed. [.tau] was greatest when scheduled wheel running occurred at CT 20.5 (0.4 h greater than DD baseline [.tau]). Scheduled running activity also influenced Tb waveform symmetry, reflecting concomitant changes in the circadian activity-rest ratio ([.alpha]:[.rho]). Aftereffects of the scheduled wheel-running paradigm were also observed. In 2 animals, [.tau] lengthened from 23.20 and 23.80 h to 24.14 and 24.15 h, respectively, and remained relatively stable for approximately 1 month during the wheel schedule. Although behavioral activity appears to be a weak zeitgeber in this species, these data suggest that nonphotic stimuli can phase delay the circadian pacemaker in O. degusat similar times of the day as in nocturnal hamsters and mice, and in humans.

Key Words: circadian rhythm • nonphotic • entrainment • crepuscular • aftereffects • supra-chiasmatic nucleus

Journal of Biological Rhythms, Vol. 16, No. 1, 66-75 (2001)
DOI: 10.1177/074873040101600108


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

This article has been cited by other articles:

				C. M. Novak and H. E. Albers Novel phase-shifting effects of GABAA receptor activation in the suprachiasmatic nucleus of a diurnal rodent Am J Physiol Regulatory Integrative Comp Physiol, May 1, 2004; 286(5): R820 - R825. [Abstract] [Full Text] [PDF]