title: Regional circadian period difference in the suprachiasmatic nucleus of the mammalian circadian center.
abstract: The suprachiasmatic nucleus (SCN) is the mammalian circadian rhythm center. Individual oscillating neurons have different endogenous circadian periods, but they are usually synchronized by an intercellular coupling mechanism. The differences in the period of each oscillating neuron have been extensively studied; however, the clustering of oscillators with similar periods has not been reported. In the present study, we artificially disrupted the intercellular coupling among oscillating neurons in the SCN and observed regional differences in the periods of the oscillating small-latticed regions of the SCN using a transgenic rat carrying a luciferase reporter gene driven by regulatory elements from a per2 clock gene (Per2::dluc rat). The analysis divided the SCN into two regions--aregion with periods shorter than 24 h (short-period region, SPR) and another with periods longer than 24 h (long-period region, LPR). The SPR was located in the smaller medial region of the dorsal SCN, whereas the LPR occupied the remaining larger region. We also found that slices containing the medial region of the SCN generated shorter circadian periods than slices that contained the lateral region of the SCN. Interestingly, the SPR corresponded well with the region where the SCN phase wave is generated. We numerically simulated the relationship between the SPR and a large LPR. A mathematical model of the SCN based on our findings faithfully reproduced the kinetics of the oscillators in the SCN in synchronized conditions, assuming the existence of clustered short-period oscillators.
authors.affiliation: Department of Anatomy and Neurobiology, Faculty of Medicine, Kinki University, 377-2 Ohno-Higashi, Osaka-Sayama, Osaka, 589-8511, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Koinuma
authors.forename: Takeshi
authors.initials: T
authors.lastname: Asakawa
authors.forename: Mamoru
authors.initials: M
authors.lastname: Nagano
authors.forename: Keiichi
authors.initials: K
authors.lastname: Furukawa
authors.forename: Mitsugu
authors.initials: M
authors.lastname: Sujino
authors.forename: Koh-Hei
authors.initials: KH
authors.lastname: Masumoto
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Nakajima
authors.forename: Seiichi
authors.initials: S
authors.lastname: Hashimoto
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Yagita
authors.forename: Yasufumi
authors.initials: Y
authors.lastname: Shigeyoshi
mesh_terms: D000818:Animals; D057906:Circadian Clocks / Q000187:drug effects; D005576:Colforsin / Q000494:pharmacology; D008297:Male; D009474:Neurons / Q000378:metabolism*; D056950:Period Circadian Proteins / Q000235:genetics / Q000378:metabolism*; D051381:Rats; D055647:Rats, Transgenic; D017208:Rats, Wistar; D013493:Suprachiasmatic Nucleus / Q000187:drug effects / Q000502:physiology*
chemical_list: C539024:Per1 protein, rat; C513311:Per2 protein, rat; D056950:Period Circadian Proteins; D005576:Colforsin
keywords: Per2; circadian rhythms; forskolin; luciferase; synchronization