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The circadian rhythms in mammals are regulated by a pacemaker located in the suprachiasmatic nucleus of the hypothalamus. Four clock-gene families have been found to be involved in a transcription-translation feedback loop that generates the circadian rhythm at the intracellular level. The proteins Clock and Bmal1 form a heterodimer which activates the(More)
The pattern of circadian behavioral rhythms is photoperiod-dependent, highlighted by the conservation of a phase relation between the behavioral rhythm and photoperiod. A model of two separate, but mutually coupled, circadian oscillators has been proposed to explain photoperiodic responses of behavioral rhythm in nocturnal rodents: an evening oscillator,(More)
Cholesterol 7alpha-hydroxylase (CYP7A) and sterol 12alpha-hydroxylase (CYP8B) in bile acid biosynthesis and 3-hydroxyl-3-methylglutaryl CoA reductase (HMGCR) in cholesterol biosynthesis are the key enzymes in hepatic metabolic pathways, and their transcripts exhibit circadian expression profiles in rodent liver. The authors determined transcript levels of(More)
The ability of nursing mothers to entrain the circadian pacemaker of rat pups was examined by measuring the rat Per1 (rPer1) and rPer2 expression levels in the suprachiasmatic nuclei (SCN). Newborn rats from mothers under a light-dark cycle (LD) were blinded immediately after birth and reared by foster mothers under either LD (LD blind pups) or reversed(More)
A convenient way to estimate internal body time (BT) is essential for chronotherapy and time-restricted feeding, both of which use body-time information to maximize potency and minimize toxicity during drug administration and feeding, respectively. Previously, we proposed a molecular timetable based on circadian-oscillating substances in multiple mouse(More)
The circadian periods of single cultured neurons of the hypothalamic suprachiasmatic nucleus (SCN) in rats were assessed by means of multi-electrode array dish. Although the mean circadian period was not different between the dispersed cell culture and organotypic slice culture, the periods distributed in a wide range from 20.0 to 30.9 h in the former(More)
The circadian pacemaker in the hypothalamic suprachiasmatic nucleus (SCN) is a hierarchical multioscillator system in which neuronal networks play crucial roles in expressing coherent rhythms in physiology and behavior. However, our understanding of the neuronal network is still incomplete. Intracellular calcium mediates the input signals, such as(More)
Effects of absence of nursing mothers on the circadian pacemaker of their offspring were examined by measuring clock genes, the rat Per1 (rPer1) and rPer2 expression rhythms in the pup suprachiasmatic nuclei (SCN). Neonate rats born to mothers kept under a 12-h light : 12-h dark cycle (LD) were blinded immediately after birth and exposed to periodic(More)
A macroglycolipid containing galactose and N-acetylglucosamine as predominant sugar constituents was prepared together with glycophorin from rabbit erythrocyte membranes by extraction with lithium diiodosalicylate and partition in aqueous phenol. The macroglycolipid was effectively separated from the glycophorin fraction by ion-exchange chromatography in(More)
The basic helix-loop-helix transcription factor DEC1 is expressed in a circadian manner in the suprachiasmatic nucleus where it seems to play a role in regulating the mammalian circadian rhythm by suppressing the CLOCK/BMAL1-activated promoter. The interaction of DEC1 with BMAL1 has been suggested as one of the molecular mechanisms of the suppression(More)