Light-induced suppression of the rat circadian system

Deprés-Brummer, Petra; Lévi, Françis; Metzger, Gérard; Touitou, Yvan

doi:10.1152/ajpregu.1995.268.5.r1111

Cited by 83 publications

(73 citation statements)

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“…Within 2 d, these rats expressed an average free-running period of 24.6 Ϯ 0.1 hr (n ϭ 11) (Fig. 2), in agreement with previous reports (Depres-Brummer et al, 1995). Restored behavioral rhythmicity correlated with restored Per1-luc rhythmicity in the SCN (periods were 24.4 Ϯ 0.2 hr; n ϭ 3) and continued rhythmicity in the OB (21.6 Ϯ 0.5 hr; n ϭ 3).…”

Section: The Ob Oscillate Whereas the Scn Do Not In Arrhythmic Animalssupporting

confidence: 89%

“…Prolonged illumination has been shown to abolish circadian rhythms in a variety of organisms, including mammals (Winfree, 1974;Depres-Brummer et al, 1995;Power et al, 1995;Honma et al, 1996;Cambras et al, 1997;Ikeda et al, 2000). We chose the OB primarily because of its robust rhythmicity in vitro and indirect evidence implicating it in circadian timekeeping.…”

Section: Introductionmentioning

confidence: 99%

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The Suprachiasmatic Nucleus Entrains, But Does Not Sustain, Circadian Rhythmicity in the Olfactory Bulb

Granados‐Fuentes¹,

Prolo²,

Abraham³

et al. 2004

J. Neurosci.

139

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The suprachiasmatic nucleus (SCN) of the hypothalamus has been termed the master circadian pacemaker of mammals. Recent discoveries of damped circadian oscillators in other tissues have led to the hypothesis that the SCN synchronizes and sustains daily rhythms in these tissues. We studied the effects of constant lighting (LL) and of SCN lesions on behavioral rhythmicity and Period 1 (Per1) gene activity in the SCN and olfactory bulb (OB). We found that LL had similar effects on cyclic locomotor and feeding behaviors and Per1 expression in the SCN but had no effect on rhythmic Period 1 expression in the OB. LL lengthened the period of locomotor and SCN rhythms by ϳ1.6 hr. After 2 weeks in LL, nearly 35% of rats lost behavioral rhythmicity. Of these, 90% showed no rhythm in Per1-driven expression in their SCN. Returning the animals to constant darkness rapidly restored their daily cycles of running wheel activity and gene expression in the SCN. In contrast, the OB remained rhythmic with no significant change in period, even when cultured from animals that had been behaviorally arrhythmic for 1 month. Similarly, we found that lesions of the SCN abolished circadian rhythms in behavior but not in the OB. Together, these results suggest that LL causes the SCN to lose circadian rhythmicity and its ability to coordinate daily locomotor and feeding rhythms. The SCN, however, is not required to sustain all rhythms because the OB continues to oscillate in vivo when the SCN is arrhythmic or ablated.

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Section: The Ob Oscillate Whereas the Scn Do Not In Arrhythmic Animalssupporting

confidence: 89%

Section: Introductionmentioning

confidence: 99%

The Suprachiasmatic Nucleus Entrains, But Does Not Sustain, Circadian Rhythmicity in the Olfactory Bulb

Granados‐Fuentes¹,

Prolo²,

Abraham³

et al. 2004

J. Neurosci.

139

View full text Add to dashboard Cite

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“…Ablation of the SCN reliably eliminates rhythms, but also necessarily damages adjacent hypothalamic tissue and results in the nonspecific synthesis and release of stress and reproductive hormones (3)(4)(5). Chronic exposure to bright light, on the other hand, requires several weeks to eliminate rhythms but the effects are transient; daily oscillations resume within a few days after animals are returned to a light-dark (LD) cycle (6)(7)(8)(9). Moreover, constant bright light is also a major stressor to the animals.…”

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confidence: 99%

Hippocampal-dependent learning requires a functional circadian system

Ruby

Hwang²,

Wessells³

et al. 2008

Proc. Natl. Acad. Sci. U.S.A.

206

219

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Decades of studies have shown that eliminating circadian rhythms of mammals does not compromise their health or longevity in the laboratory in any obvious way. These observations have raised questions about the functional significance of the mammalian circadian system, but have been difficult to address for lack of an appropriate animal model. Surgical ablation of the suprachiasmatic nucleus (SCN) and clock gene knockouts eliminate rhythms, but also damage adjacent brain regions or cause developmental effects that may impair cognitive or other physiological functions. We developed a method that avoids these problems and eliminates rhythms by noninvasive means in Siberian hamsters (Phodopus sungorus). The present study evaluated cognitive function in arrhythmic animals by using a hippocampal-dependent learning task. Control hamsters exhibited normal circadian modulation of performance in a delayed novel-object recognition task. By contrast, arrhythmic animals could not discriminate a novel object from a familiar one only 20 or 60 min after training. Memory performance was not related to prior sleep history as sleep manipulations had no effect on performance. The GABA antagonist pentylenetetrazol restored learning without restoring circadian rhythms. We conclude that the circadian system is involved in memory function in a manner that is independent of sleep. Circadian influence on learning may be exerted via cyclic GABA output from the SCN to target sites involved in learning. Arrhythmic hamsters may have failed to perform this task because of chronic inhibitory signaling from the SCN that interfered with the plastic mechanisms that encode learning in the hippocampus.GABA ͉ hippocampus ͉ memory ͉ sleep ͉ suprachiasmatic nucleus

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“…In many organisms, including humans, the biological clock and its control of circadian organization can be disrupted by exposure to constant light (LL) environments (2)(3)(4)(5)(6). Although previous studies have focused on effects of LL on adult organisms, in humans, a particular concern is whether LL has acute or long-term disruptive effects on the developing biological clock of preterm infants, who may be exposed to LL conditions in neonatal intensive care units (NICUs).…”

mentioning

confidence: 99%

Constant Light Disrupts the Developing Mouse Biological Clock

2006

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ABSTRACT:The central biological clock of the brain, contained within the suprachiasmatic nuclei (SCN) of mammals, orchestrates an orderly "internal day" of physiology and behavior. The developing biological clock begins to respond to light at an early stage and a particular concern in humans is whether light exposure has disruptive effects on the developing biological clock of infants exposed to constant lighting conditions in neonatal intensive care units (NICUs). Worldwide, eighteen million, or 14%, of newborns estimated to be of low birth weight, are exposed to artificial lighting environments in hospital nurseries annually. Here, we have tested whether constant light (LL) exposure disrupts the developing biological clock of mice, using a circadian reporter transgenic mouse model in which the organization of the central biological clock can be assayed by real-time gene expression imaging. We now find that LL has both acute and long-term disruptive effects on developing biological clocks and that cyclic lighting conditions are critical for developing circadian clocks to coordinate their molecular circadian mechanisms. This suggests that, from the perspective of developing circadian organization in humans, cyclic light conditions in NICUs are likely to be most appropriate for infants. (Pediatr Res 60: 304-308, 2006)

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Light-induced suppression of the rat circadian system

Cited by 83 publications

References 0 publications

The Suprachiasmatic Nucleus Entrains, But Does Not Sustain, Circadian Rhythmicity in the Olfactory Bulb

The Suprachiasmatic Nucleus Entrains, But Does Not Sustain, Circadian Rhythmicity in the Olfactory Bulb

Hippocampal-dependent learning requires a functional circadian system

Constant Light Disrupts the Developing Mouse Biological Clock

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