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Development of the mammalian circadian clock
Author(s) -
Honma Sato
Publication year - 2020
Publication title -
european journal of neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.346
H-Index - 206
eISSN - 1460-9568
pISSN - 0953-816X
DOI - 10.1111/ejn.14318
Subject(s) - circadian rhythm , suprachiasmatic nucleus , light effects on circadian rhythm , biology , bacterial circadian rhythms , circadian clock , clock , entrainment (biomusicology) , neuroscience , oscillating gene , period (music) , master clock , vasoactive intestinal peptide , cryptochrome , endocrinology , medicine , microbiology and biotechnology , rhythm , neuropeptide , genetics , receptor , clock signal , physics , electrical engineering , acoustics , electronic circuit , engineering
Abstract The mammalian circadian system is composed of a central clock situated in the hypothalamic suprachiasmatic nucleus (SCN) and peripheral clocks of each tissue and organ in the body. While much has been learned about the pre‐ and postnatal development of the circadian system, there are still many unanswered questions about how and when cellular clocks start to tick and form the circadian system. Most SCN neurons contain a cell‐autonomous circadian clock with individual specific periodicity. Therefore, the network of cellular oscillators is critical for the coherent rhythm expression and orchestration of the peripheral clocks by the SCN. The SCN is the only circadian clock entrained by an environmental light–dark cycle. Photic entrainment starts postnatally, and the SCN starts to function gradually as a central clock that controls physiological and behavioral rhythms during postnatal development. The SCN exhibits circadian rhythms in clock gene expression from the embryonic stage throughout postnatal life and the rhythm phenotypes remain basically unchanged. However, the disappearance of coherent circadian rhythms in cryptochrome ‐deficient SCN revealed changes in the SCN networks that occur in postnatal weeks 2–3. The SCN network consists of multiple clusters of cellular circadian rhythms that are differentially integrated by the vasoactive intestinal polypeptide and arginine vasopressin signaling depending on the period of postnatal development.