Behavioral arousal blocks light-induced phase advances in locomotor rhythmicity but not light-induced Per1 and Fos expression in the hamster suprachiasmatic nucleus.
Neuroscience
; 118(1): 253-61, 2003.
Article
em En
| MEDLINE
| ID: mdl-12676155
ABSTRACT
Both photic and nonphotic stimuli entrain circadian rhythms. Although the adaptive significance of nonphotic clock resetting is unknown, one possibility is that nonphotic cues modulate circadian responses to light. Results of studies on the interaction between photic and nonphotic stimuli support this idea. During the day, light blocks the effects of nonphotic stimuli on the phase of locomotor rhythms and on expression of clock genes in suprachiasmatic nucleus (SCN) neurons. At night, novelty-induced activity prior to and during exposure to light attenuates the phase-shifting response to that light, but the effects of this manipulation on clock gene expression are unknown. The present experiments explore the interaction between behavioral state and response to light at the molecular level. We show that confining hamsters to novel wheels immediately after a light pulse during the late subjective night attenuates light-induced phase advances of wheel-running rhythms and the transient effects on circadian period. In contrast to the striking effect of novelty-induced activity on behavioral responses to light, Fos protein and Per1 mRNA were robustly expressed in the SCN of all light-pulsed animals, regardless of behavioral treatment. Our results are inconsistent with the idea that light and nonphotic stimuli block each other's effects on phase shifts by inducing or attenuating transcription of Per1. Photic regulation of clock genes and spontaneous rhythmic expression of clock genes are probably mediated by different mechanisms.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Estimulação Luminosa
/
Nível de Alerta
/
Núcleo Supraquiasmático
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Proteínas Nucleares
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Ritmo Circadiano
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Atividade Motora
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Neurônios
Limite:
Animals
Idioma:
En
Revista:
Neuroscience
Ano de publicação:
2003
Tipo de documento:
Article
País de afiliação:
Canadá