Bright light during lactation alters the functioning  of the circadian system of adult rats

Canal-Corretger, M. M.; Cambras, Trinitat; Vilaplana, Jordi; Dı́ez-Noguera, Antoni

doi:10.1152/ajpregu.2000.278.1.r201

Cited by 20 publications

(18 citation statements)

References 33 publications

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“…To establish effects of early light experience on the behaviour of C57BL ⁄ 6J mice kept in LD after weaning, we monitored their locomotor activity rhythms throughout the experiment. We found that, similar to the results obtained for Wistar rats and Swiss mice (11,12), the expression of the locomotor activity rhythm of our mice was affected by postnatal light experience. No differences in the phase of entrainment were observed between the groups, which suggests that the entraining mechanisms of the clock are not affected by early light experience.…”

Section: Discussionsupporting

confidence: 90%

“…In the present study, LL‐reared mice showed low levels of VIP staining compared to LD‐ and DD‐reared mice. Because light responses are altered in LL‐reared animals (11, 12, 14, 16), we believe that these low levels may reflect a difference in how the light input is processed in the retinorecipient area of the SCN. However, no differences in the period or the phase of entrainment were found amongst groups, and the amplitude and stability of the circadian rhythm of locomotor activity were even increased in LL‐reared mice compared to LD‐ and DD‐reared mice, suggesting that the decrease in VIP expression observed in the SCN of LL‐reared mice: (i) is not sufficient to cause a major disruption of clock functioning and (ii) may activate compensatory mechanisms within the clock (e.g.…”

Section: Discussionmentioning

confidence: 99%

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Expression of Circadian Neuropeptides in the Hypothalamus of Adult Mice is Affected by Postnatal Light Experience

Smith

Canal

2009

J Neuroendocrinology

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The suprachiasmatic nuclei (SCN) of the hypothalamus are the principal pacemaker in mammals, controlling daily, circadian rhythms in physiology and behaviour. Environmental light during development has long-term effects on circadian behaviour, but it is still unclear what the relevant adaptations within the brain are. In the present study, we examined the manifestation of the circadian rhythm of locomotor activity, and the expression of arginine-vasopressin (AVP) and vasointestinal polypeptide (VIP) in the SCN of adult mice reared under different light environments during the suckling period, and synchronised to light/dark cycles after weaning. We found that animals reared under constant light had higher amplitude and more stable activity rhythms, together with lower levels of VIP- and AVP-immunostaining in the SCN, compared to mice reared under light/dark cycles or constant darkness. Differences in AVP expression were also found in the paraventricular nucleus and the supraoptic nucleus, two brain areas which receive SCN projections. These results indicate that the postnatal light experience may affect clock function and clock output, and suggest implications for the control of hormonal homeostasis and circadian behaviour.

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Section: Discussionsupporting

confidence: 90%

Section: Discussionmentioning

confidence: 99%

Expression of Circadian Neuropeptides in the Hypothalamus of Adult Mice is Affected by Postnatal Light Experience

Smith

Canal

2009

J Neuroendocrinology

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“…SCN cultures from these animals express circadian oscillations of Per1-luc expression indefinitely, while oscillations in cultured peripheral tissues damp after several cycles (Yamazaki et al, 2000). The phases of central and peripheral circadian oscillators are held in specific relationships under light-dark (LD) cycles (Yamazaki et al, 2000;Abe et al, 1 To whom correspondence should be addressed: Michael Menaker Department of Biology, University of Virginia, Charlottesville, VA 22903; Tel: 434-982-5767; Fax: 434-982-5626; e-mail: mm7e@virginia Like SCN lesion, prolonged constant light (LL) exposure disrupts behavioral circadian rhythms in rodents, resulting first in an increase in circadian period and then in arrhythmicity (Honma et al, 1996, Benstaali et al, 2001Canal-Corretger et al, 2000). It has been suggested that this effect of LL might be the result of disrupting the coupling among SCN cells (Mason 1991; Zlomanazuck et al, 1991;Ohta et al, 2005).…”

Section: Introductionmentioning

confidence: 99%

Effects of Preparation Time on Phase of Cultured Tissues Reveal Complexity of Circadian Organization

Yoshikawa¹,

Yamazaki

Menaker

2005

J Biol Rhythms

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The phases of central (SCN) and peripheral circadian oscillators are held in specific relationships under LD cycles, but in the absence of external rhythmic input may damp or drift out of phase with each other. Rats exposed to prolonged constant light become behaviorally arrhythmic, perhaps as a consequence of dissociation of phases among SCN cells. We asked whether individual central and peripheral circadian oscillators were rhythmic in LL treated arrhythmic rats and, if rhythmic, what were the phase relationships among them. We prepared SCN, pineal gland, pituitary and cornea cultures from transgenic Per1-luc rats whose body temperature and locomotor activity were arrhythmic, and from several groups of rhythmic rats held in LD, DD, and short-term LL. We measured mPer1 gene expression by recording light output with sensitive photomultipliers. Most of the cultures from all groups displayed circadian rhythms. This could reflect persistent rhythmicity in vivo prior to culture, or, alternatively, rhythmicity that may have been initiated by the culture procedure. To test this we cultured tissues at two different times 12 h apart and asked whether phase of the rhythm was related to culture time. The pineal, pituitary and SCN cultures showed partial or complete dependence of phase on culture time, while peak phases of the cornea cultures were independent of culture time in rhythmic rats, and were randomly distributed regardless of culture time in arrhythmic animals. These results suggest that in behaviorally arrhythmic rats oscillators in the pineal, pituitary and SCN had been arrhythmic or severely damped in vivo while the cornea oscillator was free-running. The peak phases of the SCN cultures were particularly sensitive to some aspect of the culture procedure since rhythmicity of SCN cultures from robustly rhythmic LDentrained rats was strongly influenced when the procedure was carried out at any time except the second half of the day. Keywords circadian organization; Period1; constant light; suprachiasmatic nucleus; pineal; pituitary; cornea; culture While the molecular mechanisms that generate circadian oscillations within cells have been extensively studied (Reppert and Weaver 2002;Lowrey and Takahashi, 2004), understanding of the mechanisms that connect the molecular framework to physiological function and behavior is still limited (Buijs et al., 2003). We have approached these questions using a transgenic rat model carrying a luciferase gene under the control of the mouse Period1 (Per1) promoter. SCN cultures from these animals express circadian oscillations of Per1-luc expression indefinitely, while oscillations in cultured peripheral tissues damp after several cycles (Yamazaki et al., 2000). The phases of central and peripheral circadian oscillators are held in specific relationships under light-dark (LD) cycles (Yamazaki et al., 2000;Abe et al., 1 To whom correspondence should be addressed: Michael Menaker Department of Biology, University of Virginia, Charlottesville, VA 22903; Tel: 434-982-5767; F...

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“…We found that rats reared under LL develop a stable circadian rhythm under LL and that this rhythm is maintained throughout the lifespan of the animal (4). Specifically, we observed that the development of the adult's circadian rhythm under LL depended on the length of the exposure to LL during lactation (5) and that at least 12 days under LL during lactation were needed for it to develop.…”

Section: Discussionmentioning

confidence: 99%

Functioning of the rat circadian system is modified by light applied in critical postnatal days

Canal-Corretger

Vilaplana

Cambras

et al. 2001

American Journal of Physiology-Regulatory, Integrative and Comp

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Lighting conditions influence biological clocks. The present experiment was designed to test the presence of a critical window of days during the lactation stage of the rat in which light has a decisive role on the development of the circadian system. Rats were exposed to 4, 8, or 12 days of constant light (LL) during the first days of life. Their circadian rhythm was later studied under LL and constant darkness. The response to a light pulse was also examined. Results show that the greater the number of LL days during lactation, the stronger the rhythm under LL and the smaller the phase shift due to the light pulse. These responses are enhanced when rats are exposed to LL days around postnatal day 12. A mathematical model was built to explain the responses of the circadian system with respect to the timing of LL during lactation, and we deduced that between postnatal days 10 to 20 there is a critical period of sensitivity to light; consequently, exposure to LL during this time modifies the circadian organization of the motor activity.

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Bright light during lactation alters the functioning of the circadian system of adult rats

Cited by 20 publications

References 33 publications

Expression of Circadian Neuropeptides in the Hypothalamus of Adult Mice is Affected by Postnatal Light Experience

Expression of Circadian Neuropeptides in the Hypothalamus of Adult Mice is Affected by Postnatal Light Experience

Effects of Preparation Time on Phase of Cultured Tissues Reveal Complexity of Circadian Organization

Functioning of the rat circadian system is modified by light applied in critical postnatal days

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