The role ofClock in the developmental expression of neuropeptides in the suprachiasmatic nucleus

Herzog, Erik D.; Grace, Michael S.; Harrer, Christine; Williamson, John; Shinohara, Kazuyuki; Block, Gene D.

doi:10.1002/1096-9861(20000814)424:1<86::aid-cne7>3.0.co;2-w

Cited by 36 publications

(34 citation statements)

References 81 publications

(119 reference statements)

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“…SCN-AVP expression increased from PD10 to PD24 in both mouse lines similarly to what has been observed in rat and hamster [13,14]. In contrast, mice derived from BALB/cJ Â C57BL/6JN revealed no further maturation of SCN-AVP expression after PD6, neither in cell number nor in cell size, although a trend in AVP OD increase was present from PD6 to PD30 [19].…”

Section: Discussionsupporting

confidence: 78%

Circadian dynamics of vasopressin in mouse selection lines: Translation and release in the SCN

et al. 2005

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Section: Discussionsupporting

confidence: 78%

Circadian dynamics of vasopressin in mouse selection lines: Translation and release in the SCN

et al. 2005

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“…In this study, there was no significant rhythmicity of the expression of the core clock genes Bmal1, per1, and per2 in liver or gastrocnemius muscle of Clock ⌬19 ϩ MEL mutant mice. The lack of rhythmic clock gene expression in these peripheral tissues confirms the outcomes of one previous study (14) that liver per2 and Bmal1 expression was arrhythmic in melatonin-deficient Clock ⌬19 mutant mice. In another study, Bmal1 expression in heart was not rhythmic, whereas per1 rhythmicity was apparently damped; yet the clock-controlled gene pai-1 was not rhythmic in Clock ⌬19 mutant mice (27).…”

Section: Discussionsupporting

confidence: 86%

Functional central rhythmicity and light entrainment, but not liver and muscle rhythmicity, are Clock independent

Kennaway

Owens²,

Voultsios³

et al. 2006

American Journal of Physiology-Regulatory, Integrative and Comp

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The circadian rhythmicity of hormone secretion, body temperature, and sleep/wakefulness results from an endogenous rhythm of neural activity generated by clock genes in the suprachiasmatic nucleus (SCN). One of these genes, Clock, has been considered essential for the generation of cellular rhythmicity centrally and in the periphery; however, melatonin-proficient Clock(Delta19) + MEL mutant mice retain melatonin rhythmicity, suggesting that their central rhythmicity is intact. Here we show that melatonin production in these mutants was rhythmic in constant darkness and could be entrained by brief single daily light pulses. Under normal light-dark conditions, per2 and prokineticin2 (PK2) mRNA expression was rhythmic in the SCN of Clock(Delta19) + MEL mice. Expression of Bmal1 and npas2 was not altered, whereas per1 expression was arrhythmic. In contrast to the SCN, per1 and per2 expression, as well as Bmal1 expression in liver and skeletal muscle, together with plasma corticosterone, was arrhythmic in Clock(Delta19) + MEL mutant mice in normal light-dark conditions. npas2 mRNA was also arrhythmic in liver but rhythmic in muscle. The Clock(Delta19) mutation does not abolish central rhythmicity and light entrainment, suggesting that a functional Clock homolog, possibly npas2, exists in the SCN. Nevertheless, the SCN of Clock(Delta19) + MEL mutant mice cannot maintain liver and muscle rhythmicity through rhythmic outputs, including melatonin secretion, in the absence of functional Clock expression in the tissues. Therefore, liver and muscle, but not SCN, have an absolute requirement for CLOCK, with as yet unknown Clock-independent factors able to generate the latter.

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“…In adults, VIP and its receptor VPAC2R play a critical role in synchronizing oscillators in the SCN (Harmar et al, 2002;Colwell et al, 2003;Aton et al, 2005;Maywood et al, 2006;Ciarleglio et al, 2009). Although the expression of VIP mRNAs has been detected at E18 in rat (Ban et al, 1997;Houdek and Sumová, 2014) and VIP protein expression has been studied during postnatal ages (Herzog et al, 2000), our results show that the protein is not detectable by immunochemistry before birth. Interestingly, embryonic SCN explants from mice lacking VIP maintain circadian oscillations at the tissue level (Wreschnig et al, 2014).…”

Section: Discussionmentioning

confidence: 54%

Ontogeny of Circadian Rhythms and Synchrony in the Suprachiasmatic Nucleus

et al. 2017

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In mammals, the suprachiasmatic nucleus (SCN) of the hypothalamus coordinates daily rhythms including sleep-wake, hormone release and gene expression. The cells of the SCN must synchronize to each other to drive these circadian rhythms in the rest of the body. The ontogeny of circadian cycling and intercellular coupling in the SCN remains poorly understood. Recent in vitro studies have recorded circadian rhythms from the whole embryonic SCN. Here, we tracked the onset and precision of rhythms in PERIOD2 (PER2), a clock protein, within the SCN isolated from embryonic and postnatal mice of undetermined sex. We found that a few SCN cells developed circadian periodicity in PER2 by 14.5 days after mating (E14.5) with no evidence for daily cycling on E13.5. On E15.5, the fraction of competent oscillators increased dramatically corresponding with stabilization of their circadian periods. The cells of the SCN harvested at E15.5 expressed sustained, synchronous daily rhythms. By postnatal day 2 (P2), SCN oscillators displayed the daily, dorsal-ventral phase wave in clock gene expression typical of the adult SCN.Strikingly, vasoactive intestinal polypeptide (VIP), a neuropeptide critical for synchrony in the adult SCN, and its receptor, VPAC2R, reached detectable levels after birth and after the onset of circadian synchrony. Antagonists of GABA or VIP signaling or action potentials did not disrupt circadian synchrony in the E15.5 SCN. We conclude that endogenous daily rhythms in the fetal SCN begin with few noisy oscillators on E14.5, followed by widespread oscillations that rapidly synchronize on E15.5 by an unknown mechanism. 2 Significance StatementWe recorded the onset of PER2 circadian oscillations during embryonic development in the mouse SCN. When isolated at E13.5, the anlagen of the SCN expresses high, arrhythmic PER2. In contrast, a few cells show noisy circadian rhythms in the isolated E14.5 SCN and most show reliable, self-sustained, synchronized rhythms in the E15.5 SCN. Strikingly, this synchrony at E15.5 appears prior to expression of VIP or its receptor and persists in the presence of blockers of VIP, GABA or neuronal firing. Finally, the dorsal-ventral phase wave of PER2 typical of the adult SCN appears around P2, indicating that multiple signals may mediate circadian synchrony during the ontogeny of the SCN.

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The role ofClock in the developmental expression of neuropeptides in the suprachiasmatic nucleus

Cited by 36 publications

References 81 publications

Circadian dynamics of vasopressin in mouse selection lines: Translation and release in the SCN

Circadian dynamics of vasopressin in mouse selection lines: Translation and release in the SCN

Functional central rhythmicity and light entrainment, but not liver and muscle rhythmicity, are Clock independent

Ontogeny of Circadian Rhythms and Synchrony in the Suprachiasmatic Nucleus

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