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MED64 JOURNALS

Circadian dynamics of cytosolic and nuclear ca 2+ in single suprachiasmatic nucleus neurons.

Ikeda M, Sugiyama T, Wallace CS, Gompf HS, Yoshioka T, Miyawaki A, Allen CN.
Neuron 2003 Apr 24;38(2):253-63

Department of Molecular Behavioral Biology, Osaka Bioscience Institute, 6-2-4 Furuedai, Suita, 565-0874, Osaka, Japan

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.