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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)
In the present study, we show that melatonin induces the expression of gamma-glutamylcysteine synthetase (gamma-GCS), the rate-limiting enzyme of glutathione (GSH) synthesis, in ECV304 human vascular endothelial cells. One micromolar melatonin induced the expression of gamma-GCS mRNA followed by an increase in the concentration of GSH with a peak at 24 h.(More)
A superfamily gene which encodes a bHLH (basic helix-loop-helix)/PAS transcription factor, BMAL1, was cloned and sequenced from rat cDNA. A robust circadian rhythm of rat BMAL1 expression was detected by in situ hybridization in the suprachiasmatic nucleus (SCN), the site of the circadian clock, with the highest level at the subjective night. Less prominent(More)
Chronic treatment of methamphetamine (MAP) in rats desynchronized the locomotor activity rhythm from the light-dark cycle. When the activity rhythm was completely phase-reversed with respect to a light dark-cycle, 24 h profiles were examined for the clock gene (rPer1, rPer2, rBMAL1, rClock) expressions in several brain structures by in situ hybridization,(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)
In the rat suprachiasmatic nucleus slice culture, circadian rhythms in the release of arginine vasopressin and vasoactive intestinal polypeptide were measured simultaneously and longitudinally. The phase relationship between the two peptide rhythms was relatively constant in the culture without a treatment of antimitotic drugs but became diverse by an(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)
Temporal profiles of the amount of vasoactive intestinal polypeptide (VIP) were examined in the medium of organotypic suprachiasmatic nucleus (SCN) slice cultures over a 2-day period. Arginine-vasopressin (AVP) level was also measured in the same medium. The slices of the SCN were obtained from 7-8-day-old rats and cultured individually in tubes on a roller(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)