Circadian dynamics of cytosolic and nuclear Ca2+ in single suprachiasmatic nucleus neurons.
Intracellular free Ca(2+) regulates diverse cellular processes, including membrane potential, neurotransmitter release, and gene expression. To examine the cellular mechanisms underlying the generation of circadian rhythms, nucleus-targeted and untargeted cDNAs encoding a Ca(2+)-sensitive fluorescent protein (cameleon) were transfected into organotypic cultures of mouse suprachiasmatic nucleus (SCN), the primary circadian pacemaker. Circadian rhythms in cytosolic but not nuclear Ca(2+) concentration were observed in SCN neurons. The cytosolic Ca(2+) rhythm period matched the circadian multiple-unit-activity (MUA)-rhythm period monitored using a multiple-electrode array, with a mean advance in phase of 4 hr. Tetrodotoxin blocked MUA, but not Ca(2+) rhythms, while ryanodine damped both Ca(2+) and MUA rhythms. These results demonstrate cytosolic Ca(2+) rhythms regulated by the release of Ca(2+) from ryanodine-sensitive stores in SCN neurons.
Ikeda
Masayuki
M
Department of Molecular Behavioral Biology, Osaka Bioscience Institute, 6-2-4 Furuedai, Suita, 565-0874, Osaka, Japan. msikeda@obi.or.jp
Sugiyama
Takashi
T
Wallace
Christopher S
CS
Gompf
Heinrich S
HS
Yoshioka
Tohru
T
Miyawaki
Atsushi
A
Allen
Charles N
CN
D000200:Action Potentials / Q000187:drug effects / Q000502:physiology; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling / Q000187:drug effects; D002135:Calcium-Binding Proteins / Q000235:genetics / Q000378:metabolism; D002467:Cell Nucleus / Q000378:metabolism*; D002940:Circadian Rhythm / Q000187:drug effects / Q000502:physiology*; D046508:Culture Techniques / Q000295:instrumentation / Q000379:methods; D003600:Cytosol / Q000378:metabolism*; D007150:Immunohistochemistry; D051379:Mice; D008810:Mice, Inbred C57BL; D008839:Microelectrodes; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D010507:Periodicity; D012433:Ryanodine / Q000494:pharmacology; D013493:Suprachiasmatic Nucleus / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D013779:Tetrodotoxin / Q000494:pharmacology; D014162:Transfection
D002135:Calcium-Binding Proteins; D012433:Ryanodine; D013779:Tetrodotoxin; D002118:Calcium