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The suprachiasmatic nucleus (SCN) is the neuroanatomical locus of the mammalian circadian pacemaker. Here we demonstrate that an abrupt shift in the light/dark (LD) cycle disrupts the synchronous oscillation of circadian components in the rat SCN. The phases of the RNA cycles of the period genes Per1 and Per2 and the cryptochrome gene Cry1 shifted rapidly(More)
Mammalian circadian clocks consist of complex integrated feedback loops that cannot be elucidated without comprehensive measurement of system dynamics and determination of network structures. To dissect such a complicated system, we took a systems-biological approach based on genomic, molecular and cell biological techniques. We profiled suprachiasmatic(More)
Photic resetting of a biological clock is one of the fundamental characteristics of circadian systems and allows living organisms to adjust to a particular environment. Nocturnal light induces the Per1 and Per2 genes, which leads to a resetting of the circadian clock in the suprachiasmatic nucleus (SCN), the mammalian circadian center. In our present study,(More)
Kisspeptin/metastin has been implicated as a critical regulator in luteinizing hormone (LH) secretion and the reproductive system mediating the effect of estrogen on GnRH neurons. In the present study we examined the sex differences in the effects of estrogen on Kiss1/kisspeptin expression in the forebrain by using gonadectomized rats to assess the(More)
Melatonin is an important hormone regulating circadian clocks in birds, but the specific cellular sites of action are not completely known. The present study was designed to determine whether astrocytes derived from chick brain contained functional melatonin receptors. Primary cell cultures of diencephalon astrocytes that express glial fibrillary acidic(More)
The expression of Kiss1 in the anteroventral periventricular nucleus (AVPV) and its product, metastin/kisspeptin, show a circadian pattern with a peak in the evening, which shows a strong phase relationship with the time of the gonadotropin-releasing hormone (GnRH)/luteinizing hormone (LH) surge in rodents. Here we report that a circadian transcriptional(More)
The mammalian circadian oscillator is composed of interacting positive and negative transcription events. The clock proteins PER1 and PER2 play essential roles in a negative limb of the feedback loop that generates the circadian rhythm in mammals. In addition, the proteins CLOCK and BMAL1 (also known as ARNTL) form a heterodimer that drives the Per genes(More)
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