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 Watanabe, K. Articles by Meijer, J. H. Search for Related Content PubMed PubMed Citation Articles by Watanabe, K. Articles by Meijer, J. H. Social Bookmarking                         What's this?

Light-Induced Resetting of the Circadian Pacemaker: Quantitative Analysis of Transient versus Steady-State Phase Shifts

Department of Physiology, Dokkyo University School of Medicine, 321-02 Mibu, Japan

Tom Deboer

Department of Physiology, Leiden University Medical Center, Leiden, the Netherlands

Johanna H. Meijer

Department of Physiology, Leiden University Medical Center, Leiden, the Netherlands; Department of Physiology, LUMC, P.O. Box 9604, 2300 RC Leiden, the Netherlands

The suprachiasmatic nuclei of the hypothalamus contain the major circadian pacemaker in mammals, driving circadian rhythms in behavioral and physiological functions. This circadian pacemaker's responsiveness to light allows synchronization to the light-dark cycle. Phase shifting by light often involves several transient cycles in which the behavioral activity rhythm gradually shifts to its steady-state position. In this article, the authors investigate in Syrian hamsters whether a phase-advancing light pulse results in immediate shifts of the PRC at the next circadian cycle. In a first series of experiments, the authors aimed a light pulse at CT 19 to induce a phase advance. It appeared that the steady-state phase advances were highly correlated with activity onset in the first and second transient cycle. This enabled them to make a reliable estimate of the steady-state phase shift induced by a phase-advancing light pulse on the basis of activity onset in the first transient cycle. In the next series of experiments, they presented a light pulse at CT 19, which was followed by a second light pulse aimed at the delay zone of the PRC on the next circadian cycle. The immediate and steady-state phase delays induced by the second light pulse were compared with data from a third experiment in which animals received a phase-delaying light pulse only. The authors observed that the waveform of the phase-delay part of the PRC (CT 12-16) obtained in Experiment 2 was virtually identical to the phase-delay part of the PRC for a single light pulse (obtained in Experiment 3). This finding allowed for a quantitative assessment of the data. The analysis indicates that the delay part of the PRC—between CT 12 and CT 16—is rapidly reset following a light pulse at CT 19. These findings complement earlier findings in the hamster showing that after a light pulse at CT 19, the phase-advancing part of the PRC is immediately shifted. Together, the data indicate that the basis for phase advancing involves rapid resetting of both advance and delay components of the PRC.

Key Words: circadian rhythms • suprachiasmatic nucleus • entrainment • phase shift • transients • phase response curve • evening/morning oscillators

Journal of Biological Rhythms, Vol. 16, No. 6, 564-573 (2001)
DOI: 10.1177/074873001129002259


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

This article has been cited by other articles:

				T. L. Sletten, V. L. Revell, B. Middleton, K. A. Lederle, and D. J. Skene Age-Related Changes in Acute and Phase-Advancing Responses to Monochromatic Light J Biol Rhythms, February 1, 2009; 24(1): 73 - 84. [Abstract] [PDF]

				N. Bagheri, S. R Taylor, K. Meeker, L. R Petzold, and F. J Doyle III Synchrony and entrainment properties of robust circadian oscillators J R Soc Interface, August 6, 2008; 5(Suppl_1): S17 - S28. [Abstract] [Full Text] [PDF]

				I. N. Karatsoreos, L. Yan, J. LeSauter, and R. Silver Phenotype Matters: Identification of Light-Responsive Cells in the Mouse Suprachiasmatic Nucleus J. Neurosci., January 7, 2004; 24(1): 68 - 75. [Abstract] [Full Text] [PDF]

				M. J. Vansteensel, T. Deboer, A. Dahan, and J. H. Meijer Differential Responses of Circadian Activity Onset and Offset Following GABA-ergic and Opioid Receptor Activation J Biol Rhythms, August 1, 2003; 18(4): 297 - 306. [Abstract] [PDF]

				J. H. Meijer and W. J. Schwartz In Search of the Pathways for Light-Induced Pacemaker Resetting in the Suprachiasmatic Nucleus J Biol Rhythms, June 1, 2003; 18(3): 235 - 249. [Abstract] [PDF]