Abstract:
:In isolated slices of hypothalamus, suprachiasmatic nucleus (SCN) neurons were recorded intracellularly. Blockade of Ca++ channels increased spike duration, eliminating an early component of the afterhyperpolarization (AHP) that followed evoked spikes. The duration and reversal potential of AHPs were, however, unaffected, suggesting that only an early, fast component of the AHP was Ca(++)-dependent. Unlike other central neurons that exhibit pacemaker activity, therefore, SCN neurons do not display a pronounced, long-lasting Ca(++)-dependent AHP. Extracellular Ba++ and intracellular Cs+ both revealed slow depolarizing potentials evoked either by depolarizing current injection, or by repolarization following large hyperpolarizations. They had different effects on the shape of spikes and the AHPs that followed them, however. Cs+, which blocks almost all K+ channels, dramatically reduced resting potential, greatly increased spike duration (to tens of milliseconds), and blocked AHPs completely. In contrast, Ba++ had little effect on resting potential and produced only a small increase in spike duration, depressing an early Ca(++)-dependent component and a later Ca(++)-independent component of the AHP. The relatively weak pacemaker activity of SCN neurons appears to involve voltage-dependent activation of at least one slowly inactivating inward current, which brings the cells to firing threshold and maintains tonic firing; both Ca(++)-dependent and Ca(++)-independent K+ channels, which repolarize cells after spikes and maintain interspike intervals; and Ca++ channels, which contribute to activation of Ca(++)-activated K+ currents and may also contribute to slow depolarizing potentials. In the absence of powerful synaptic inputs, SCN neurons express a pacemaker activity that is sufficient to maintain an impressively regular firing pattern. Slow, repetitive activation of optic input, however, increases local circuit activity to such an extent that the normal pacemaker potentials are overridden and firing patterns are altered. Since SCN neurons are very small and have large input resistances, they are particularly susceptible to synaptic input.
journal_name
J Biol Rhythmsjournal_title
Journal of biological rhythmsauthors
Thomson AM,West DCdoi
10.1177/074873049000500106subject
Has Abstractpub_date
1990-04-01 00:00:00pages
59-75issue
1eissn
0748-7304issn
1552-4531journal_volume
5pub_type
杂志文章abstract::Seasonal changes in numerous aspects of mammalian immune function arise as a result of the annual variation in environmental day length (photoperiod), but it is not known if absolute photoperiod or relative change in photoperiod drives these changes. This experiment tested the hypothesis that an individual's history o...
journal_title:Journal of biological rhythms
pub_type: 杂志文章
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更新日期:2009-12-01 00:00:00
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journal_title:Journal of biological rhythms
pub_type: 杂志文章
doi:10.1177/0748730406287996
更新日期:2006-06-01 00:00:00
abstract::The classical power spectrum, computed in the frequency domain, outranks traditionally used periodograms derived in the time domain (such as the chi2 periodogram) regarding the search for biological rhythms. Unfortunately, classical power spectral analysis is not possible with unequally spaced data (e.g., time series ...
journal_title:Journal of biological rhythms
pub_type: 杂志文章
doi:10.1177/074873099129000984
更新日期:1999-12-01 00:00:00
abstract::Melatonin is secreted systemically from the pineal gland maximally at night but is also produced locally in many tissues. Its chronobiological function is mainly exerted by pineal melatonin. It is a feedback regulator of the main circadian pacemaker in the hypothalamic suprachiasmatic nuclei and of many peripheral osc...
journal_title:Journal of biological rhythms
pub_type: 杂志文章
doi:10.1177/0748730415616678
更新日期:2016-02-01 00:00:00
abstract::A 24-h treatment with the cytokine tumor necrosis factor-alpha (TNF-alpha) suppresses transcription of E-box-driven clock genes (D-site albumin promoter binding protein, Dbp; Tyrotroph embryonic factor, Tef ; Hepatic leukemia factor, Hlf; Period homolog to Drosophila 1/2/3, Per1, Per2, and Per3) by yet unknown molecul...
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更新日期:2009-08-01 00:00:00
abstract::Transplantation of the fetal suprachiasmatic nucleus (SCN) in arrhythmic SCN-lesioned rats can reinstate circadian drinking rhythms in 40% to 50% of the cases. In the current article, it was investigated whether the failure in the other rats could be due to the absence of a circadian rhythm in the grafted SCN, using a...
journal_title:Journal of biological rhythms
pub_type: 杂志文章
doi:10.1177/074873099129000416
更新日期:1999-02-01 00:00:00
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journal_title:Journal of biological rhythms
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更新日期:1993-10-01 00:00:00
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journal_title:Journal of biological rhythms
pub_type: 杂志文章
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更新日期:2007-10-01 00:00:00
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journal_title:Journal of biological rhythms
pub_type: 杂志文章
doi:10.1177/074873002129002348
更新日期:2002-02-01 00:00:00
abstract::In mammals, the suprachiasmatic nucleus (SCN) is the central pacemaker organizing circadian rhythms of behavior and physiology. At the cellular level, the mammalian clock consists of autoregulatory feedback loops involving a set of "clock genes," including the Cryptochrome (Cry) genes, Cry1 and Cry2. Experimental evid...
journal_title:Journal of biological rhythms
pub_type: 杂志文章
doi:10.1177/0748730412461246
更新日期:2012-12-01 00:00:00
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journal_title:Journal of biological rhythms
pub_type: 杂志文章
doi:10.1177/0748730402238239
更新日期:2002-12-01 00:00:00
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journal_title:Journal of biological rhythms
pub_type: 杂志文章
doi:10.1177/0748730420932073
更新日期:2020-10-01 00:00:00
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journal_title:Journal of biological rhythms
pub_type: 杂志文章
doi:10.1177/074873049000500301
更新日期:1990-10-01 00:00:00
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journal_title:Journal of biological rhythms
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更新日期:2017-02-01 00:00:00
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journal_title:Journal of biological rhythms
pub_type: 杂志文章
doi:10.1177/0748730413476827
更新日期:2013-04-01 00:00:00
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journal_title:Journal of biological rhythms
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更新日期:2008-08-01 00:00:00
abstract::Social jetlag represents the discrepancy between circadian and social clocks, which is measured as the difference in hours in midpoint of sleep between work days and free days. Previous studies have shown social jetlag to be associated with body mass index (BMI), glycated hemoglobin levels, heart rate, depressive symp...
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doi:10.1177/0748730414550199
更新日期:2014-10-01 00:00:00
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journal_title:Journal of biological rhythms
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更新日期:2010-12-01 00:00:00
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journal_title:Journal of biological rhythms
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更新日期:2014-12-01 00:00:00
abstract::The circadian timing system has three principal elements: the retina, the intergeniculate leaflet (IGL) of the thalamus, and the suprachiasmatic nucleus (SCN). Since the human circadian timing system cannot be studied experimentally, we have used another primate, the macaque monkey, to help provide insight into the or...
journal_title:Journal of biological rhythms
pub_type: 杂志文章,评审
doi:
更新日期:1993-01-01 00:00:00
abstract::Little is known about the differences in the neural substrates of circadian rhythms that are responsible for the maintenance of differences between diurnal and nocturnal patterns of activity in mammals. In both groups of animals, the suprachiasmatic nucleus (SCN) functions as the principal circadian pacemaker, and sur...
journal_title:Journal of biological rhythms
pub_type: 杂志文章
doi:10.1177/074873099129000713
更新日期:1999-08-01 00:00:00
abstract::On the southern Iberian Peninsula, the seasonal life history of the large white butterfly, Pieris brassicae, comprises 2 different photoperiodically induced developmental arrests: a hibernation diapause at photophases < 11 h and an estivation diapause at photophases > 14 h. At intermediate photophases (12 h to 13 h), ...
journal_title:Journal of biological rhythms
pub_type: 杂志文章
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更新日期:2004-12-01 00:00:00
abstract::DEC1 and DEC2-basic helix-loop-helix transcription factors-exhibit a circadian expression in the suprachiasmatic nucleus and other peripheral tissues and seem to play roles in regulating the mammalian circadian rhythm by suppressing the CLOCK/BMAL1-activated promoters of Per1, Dec1, and Dec2. The authors present data ...
journal_title:Journal of biological rhythms
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更新日期:2005-10-01 00:00:00
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journal_title:Journal of biological rhythms
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更新日期:2009-02-01 00:00:00
abstract::Surgical isolation of the suprachiasmatic nuclei (SCN) within a hypothalamic island is reported to produce loss of circadian rhythmicity. The results have been interpreted to indicate that SCN efferents are necessary for the expression of circadian rhythms. It is not clear, however, whether the loss of circadian rhyth...
journal_title:Journal of biological rhythms
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更新日期:1991-07-01 00:00:00
abstract::Intertidal species have both circadian and circatidal clocks. Although the behavioral evidence for these oscillators is more than 5 decades old, virtually nothing is known about their molecular clockwork. Pigment-dispersing hormones (PDHs) were originally described in crustaceans. Their insect homologs, pigment-disper...
journal_title:Journal of biological rhythms
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更新日期:2011-12-01 00:00:00