Is the PRC for Dark Pulses in LL a Mirror Image of the PRC for Light Pulses in DD in Mice?

Barbacka-Surowiak, G

doi:10.1076/brhm.31.5.531.5659

Cited by 13 publications

(6 citation statements)

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“…Consistent with studies in Syrian hamster and Swiss mouse, we found that a 6 h dark pulse robustly phase-advances C57BL/6J wheel-running rhythms when initiated during the mid- to late subjective day [ 24 - 30 ]. Further, our observation that the magnitude of dark pulse-evoked wheel-running activity does not necessarily correlate with the magnitude of the phase shift is also in broad agreement with other studies [ 31 - 33 ].…”

Section: Discussionsupporting

confidence: 88%

“…Further, our observation that the magnitude of dark pulse-evoked wheel-running activity does not necessarily correlate with the magnitude of the phase shift is also in broad agreement with other studies [ 31 - 33 ]. Previously, dark pulses given during the late subjective night/early subjective day were found to elicit phase-delays in Syrian hamster and Swiss mouse wheel-running rhythms [ 24 - 26 ]. Although we did observe that some C57BL/6J mice phase-delayed to dark pulses given at this time of the circadian cycle (see Figures 2 and 3 ), delays were not consistently evoked.…”

Section: Discussionmentioning

confidence: 99%

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Circadian and dark-pulse activation of orexin/hypocretin neurons

et al. 2008

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Temporal control of brain and behavioral states emerges as a consequence of the interaction between circadian and homeostatic neural circuits. This interaction permits the daily rhythm of sleep and wake, regulated in parallel by circadian cues originating from the suprachiasmatic nuclei (SCN) and arousal-promoting signals arising from the orexin-containing neurons in the tuberal hypothalamus (TH). Intriguingly, the SCN circadian clock can be reset by arousal-promoting stimuli while activation of orexin/hypocretin neurons is believed to be under circadian control, suggesting the existence of a reciprocal relationship. Unfortunately, since orexin neurons are themselves activated by locomotor promoting cues, it is unclear how these two systems interact to regulate behavioral rhythms. Here mice were placed in conditions of constant light, which suppressed locomotor activity, but also revealed a highly pronounced circadian pattern in orexin neuronal activation. Significantly, activation of orexin neurons in the medial and lateral TH occurred prior to the onset of sustained wheel-running activity. Moreover, exposure to a 6 h dark pulse during the subjective day, a stimulus that promotes arousal and phase advances behavioral rhythms, activated neurons in the medial and lateral TH including those containing orexin. Concurrently, this stimulus suppressed SCN activity while activating cells in the median raphe. In contrast, dark pulse exposure during the subjective night did not reset SCN-controlled behavioral rhythms and caused a transient suppression of neuronal activation in the TH. Collectively these results demonstrate, for the first time, pronounced circadian control of orexin neuron activation and implicate recruitment of orexin cells in dark pulse resetting of the SCN circadian clock.

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Section: Discussionsupporting

confidence: 88%

Section: Discussionmentioning

confidence: 99%

Circadian and dark-pulse activation of orexin/hypocretin neurons

et al. 2008

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“…Interestingly, our PRC is very similar to the PRC for dark pulses in mice under LL described by Barbacka-Surowiak (2000). PRCs for nonphotic stimuli are characterized by maximal phase advances during mid-subjective day, and generally smaller phase delays during subjective night.…”

Section: Discussionsupporting

confidence: 69%

“…The phase response curve (PRC) graphically shows quantitative and qualitative variations of the sensitivity of the SCN to environmental cues like light, dark pulses, behavioral arousal, social entrainment, and pharmacological agents (Subbaraj and Chandrashekaran 1978;Mrosovsky 1988Mrosovsky , 1995Mrosovsky , 1996Barbacka-Surowiak 2000).…”

Section: Introductionmentioning

confidence: 99%

The phase shift of locomotor activity rhythm after application of 8-OH-DPAT under constant light in mice

Bartoszewicz

Barbacka-Surowiak

2010

Biological Rhythm Research

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The evidence from a variety of studies suggests the involvement of 5-HT in both the response of SCN neurons to light and the phase-resetting properties of nonphotic stimuli. Although it is well known that 8-OH-DPAT serotonin agonist causes a phase shift of the activity rhythm, there are few reports of experiments on the influence of serotonin upon the locomotor activity rhythm of nocturnal rodents kept under constant light (LL) conditions. Here we examine the effect of 8-OH-DPAT (5 mg/kg) on the phase of the locomotor activity rhythm in mice under constant light. The phase response curve (PRC) for 8-OH-DPAT (8-hydroxy-2-[di-n-propyloamino]-tetralin) under LL in mice closely resembled the PRC for dark pulses. PRCs for nonphotic stimuli are characterized by maximal phase advances during mid-subjective day, and generally smaller phase delays during subjective night. Only dark pulses produce phase advances throughout the first half of subjective night. We observed the same effect after administration of 8-OH-DPAT.

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“…For example, exposure of bats, mice, and hamsters kept in constant light (LL) to pulses of darkness for 2-6 h phase-dependently phase resets their behavioral activity rhythms in a characteristic pattern of temporal sensitivity that differs markedly from photic PRCs (4,5,10,16,34). In hamsters, dark pulses evoke phase advances during the middle to late subjective day and phase delays when given at late subjective night and early subjective day (5,16).…”

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confidence: 99%

Resetting of the hamster circadian system by dark pulses

Canal

Piggins

2006

American Journal of Physiology-Regulatory, Integrative and Comp

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-Circadian rhythms of animals are reset by exposure to light as well as dark; however, although the parameters of photic entrainment are well characterized, the phaseshifting actions of dark pulses are poorly understood. Here, we determined the tonic and phasic effects of short (0.25 h), moderate (3 h), and long (6 -9 h) duration dark pulses on the wheel-running rhythms of hamsters in constant light. Moderate-and long-duration dark pulses phase dependently reset behavioral rhythms, and the magnitude of these phase shifts increased as a function of the duration of the dark pulse. In contrast, the 0.25-h dark pulses failed to evoke consistent effects at any circadian phase tested. Interestingly, moderate-and long-dark pulses elevated locomotor activity (wheel-running) on the day of treatment. This induced wheel-running was highly correlated with phase shift magnitude when the pulse was given during the subjective day. This, together with the finding that animals pulsed during the subjective day are behaviorally active throughout the pulse, suggests that both locomotor activity and behavioral activation play an important role in the phase-resetting actions of dark pulses. We also found that the robustness of the wheel-running rhythm was weakened, and the amount of wheel-running decreased on the days after exposure to dark pulses; these effects were dependent on pulse duration. In summary, similarly to light, the resetting actions of dark pulses are dependent on both circadian phase and stimulus duration. However, dark pulses appear more complex stimuli, with both photic and nonphotic resetting properties. phase shift; nonphotic; wheel-running; entrainment ALL LIVING ORGANISMS SHOW temporal organization in their physiology and behavior. Endogenous oscillations with a periodicity of ϳ24 h are called circadian rhythms, and in mammals the main circadian pacemaker or clock is contained in the suprachiasmatic nuclei (SCN) of the hypothalamus (24,25). This SCN clock is synchronized (entrained) by recurring external time cues or zeitgebers. Daily variation in environmental light is a potent zeitgeber, and such photic information is relayed directly to the SCN via the monosynaptic retinohypothalamic tract (14

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Is the PRC for Dark Pulses in LL a Mirror Image of the PRC for Light Pulses in DD in Mice?

Cited by 13 publications

References 0 publications

Circadian and dark-pulse activation of orexin/hypocretin neurons

Circadian and dark-pulse activation of orexin/hypocretin neurons

The phase shift of locomotor activity rhythm after application of 8-OH-DPAT under constant light in mice

Resetting of the hamster circadian system by dark pulses

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