title: Circadian waves of cytosolic calcium concentration and long-range network connections in rat suprachiasmatic nucleus.
abstract: The suprachiasmatic nucleus (SCN) is the master clock in mammals governing the daily physiological and behavioral rhythms. It is composed of thousands of clock cells with their own intrinsic periods varying over a wide range (20-28 h). Despite this heterogeneity, an intact SCN maintains a coherent 24 h periodic rhythm through some cell-to-cell coupling mechanisms. This study examined how the clock cells are connected to each other and how their phases are organized in space by monitoring the cytosolic free calcium ion concentration ([Ca(2+)](c)) of clock cells using the calcium-binding fluorescent protein, cameleon. Extensive analysis of 18 different organotypic slice cultures of the SCN showed that the SCN calcium dynamics is coordinated by phase-synchronizing networks of long-range neurites as well as by diffusively propagating phase waves. The networks appear quite extensive and far-reaching, and the clock cells connected by them exhibit heterogeneous responses in their amplitudes and periods of oscillation to tetrodotoxin treatments. Taken together, our study suggests that the network of long-range cellular connectivity has an important role for the SCN in achieving its phase and period coherence.
authors.affiliation: Center for Cell Dynamics and Department of Physics, Korea University, Anam-Dong 5-1, Sungbuk-Gu, Seoul 136-713, Korea.
authors.forename: Jin Hee
authors.initials: JH
authors.lastname: Hong
authors.forename: Byeongha
authors.initials: B
authors.lastname: Jeong
authors.forename: Cheol Hong
authors.initials: CH
authors.lastname: Min
authors.forename: Kyoung J
authors.initials: KJ
authors.lastname: Lee
mesh_terms: D000200:Action Potentials / Q000187:drug effects / Q000502:physiology; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002135:Calcium-Binding Proteins / Q000235:genetics / Q000378:metabolism; D002940:Circadian Rhythm / Q000502:physiology*; D003600:Cytosol / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D007091:Image Processing, Computer-Assisted; D009682:Magnetic Resonance Spectroscopy; D009434:Neural Pathways / Q000187:drug effects / Q000502:physiology; D009924:Organ Culture Techniques; D051381:Rats; D017207:Rats, Sprague-Dawley; D026941:Sodium Channel Blockers / Q000494:pharmacology; D013493:Suprachiasmatic Nucleus / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D013779:Tetrodotoxin / Q000494:pharmacology; D013997:Time Factors; D014162:Transfection
chemical_list: D002135:Calcium-Binding Proteins; D026941:Sodium Channel Blockers; C495639:yellow cameleon; D013779:Tetrodotoxin; D002118:Calcium