title: Suprachiasmatic nucleus: cellular clocks and networks.
abstract: The suprachiasmatic nucleus (SCN), the master circadian clock of mammals, is composed of multiple circadian oscillator neurons. Most of them exhibit significant circadian rhythms in their clock gene expression and spontaneous firing when cultured in dispersed cells, as well as in an organotypic slice. The distribution of periods depends on the SCN tissue organization, suggesting that cell-to-cell interaction is important for synchronization of the constituent oscillator cells. This cell-to-cell interaction involves both synaptic interactions and humoral mediators. Cellular oscillators form at least three separate but mutually coupled regional pacemakers, and two of them are involved in the photoperiodic regulation of behavioral rhythms in mice. Coupling of cellular oscillators in the SCN tissue compensates for the dysfunction due to clock gene mutations, on the one hand, and desynchronization within and between the regional pacemakers that suppresses the coherent rhythm expression from the SCN, on the other hand. The multioscillator pacemaker structure of the SCN is advantageous for responding to a wide range of environmental challenges without losing coherent rhythm outputs.
authors.affiliation: Department of Physiology, Hokkaido University Graduate School of Medicine, Sapporo, Japan; Department of Chronomedicine, Hokkaido University Graduate School of Medicine, Sapporo, Japan. Electronic address: sathonma@med.hokudai.ac.jp.
authors.forename: Sato
authors.initials: S
authors.lastname: Honma
authors.affiliation: Department of Physiology, Hokkaido University Graduate School of Medicine, Sapporo, Japan; Advanced Photonic Bioimaging Section, Research Center for Cooperative Projects, Hokkaido University Graduate School of Medicine, Sapporo, Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Ono
authors.affiliation: Advanced Photonic Bioimaging Section, Research Center for Cooperative Projects, Hokkaido University Graduate School of Medicine, Sapporo, Japan.
authors.forename: Yohko
authors.initials: Y
authors.lastname: Suzuki
authors.affiliation: Department of Physiology, Hokkaido University Graduate School of Medicine, Sapporo, Japan.
authors.forename: Natsuko
authors.initials: N
authors.lastname: Inagaki
authors.affiliation: Advanced Photonic Bioimaging Section, Research Center for Cooperative Projects, Hokkaido University Graduate School of Medicine, Sapporo, Japan.
authors.forename: Tomoko
authors.initials: T
authors.lastname: Yoshikawa
authors.affiliation: Department of Physiology, Hokkaido University Graduate School of Medicine, Sapporo, Japan; Department of Chronodentistry, Osaka University Graduate School of Dentistry, Suita, Osaka, Japan.
authors.forename: Wataru
authors.initials: W
authors.lastname: Nakamura
authors.affiliation: Department of Chronomedicine, Hokkaido University Graduate School of Medicine, Sapporo, Japan.
authors.forename: Ken-Ichi
authors.initials: KI
authors.lastname: Honma
mesh_terms: D000818:Animals; D002450:Cell Communication; D002940:Circadian Rhythm / Q000502:physiology*; D056925:Circadian Rhythm Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D051379:Mice; D009415:Nerve Net / Q000502:physiology*; D013493:Suprachiasmatic Nucleus / Q000166:cytology* / Q000378:metabolism*
chemical_list: D056925:Circadian Rhythm Signaling Peptides and Proteins