Dual origins of the intracellular circadian calcium rhythm in the suprachiasmatic nucleus

• Published in: Scientific reports 2017-02, Vol.7 (1), p.41733-41733, Article 41733
• Main Authors: Enoki, Ryosuke, Ono, Daisuke, Kuroda, Shigeru, Honma, Sato, Honma, Ken-ichi
• Format: Article
• Language: English
• Subjects: 631/1647/245/2225; 631/378/1385/1330; 631/443/376; Animals; Animals, Newborn; Biological clocks; Biomarkers; Calcium (intracellular); Calcium - metabolism; Calcium Signaling; Circadian Rhythm; Circadian rhythms; Cryptochromes; Cryptochromes - genetics; Cryptochromes - metabolism; Humanities and Social Sciences; Intracellular; Intracellular Space - metabolism; Mice; Mice, Knockout; Models, Biological; multidisciplinary; Period 2 protein; Period Circadian Proteins - genetics; Period Circadian Proteins - metabolism; Science; Science (multidisciplinary); Suprachiasmatic nucleus; Suprachiasmatic Nucleus - physiology; Synchronization
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/srep41733

In mammals, the master circadian clock is located in the suprachiasmatic nucleus (SCN), where most neurons show circadian rhythms of intracellular Ca 2+ levels. However, the origin of these Ca 2+ rhythms remains largely unknown. In this study, we successfully monitored the intracellular circadian Ca 2+ rhythms together with the circadian PER2 and firing rhythms in a single SCN slice ex vivo , which enabled us to explore the origins. The phase relation between the circadian PER2 and Ca 2+ rhythms, but not between the circadian PER2 and firing rhythms, was significantly altered in Cry1 / Cry2 double knockout mice, which display a loss of intercellular synchronization in the SCN. In addition, in Cry1 / Cry2 double knockout mice, circadian Ca 2+ rhythms were abolished in the dorsolateral SCN, but were maintained in the majority of the ventromedial SCN. These findings indicate that intracellular circadian Ca 2+ rhythms are composed of an exogenous and endogenous component involving PER2 expression.