Circadian differences in neuronal activity of the suprachiasmatic nucleus in brain slices prepared from photo-responsive and photo-non-responsive Djungarian hamsters

Margraf, Russell R.; Zlomanczuk, Piotr; Liskin, Lauri A.; Lynch, G. Robert

doi:10.1016/0006-8993(91)90883-w

Cited by 39 publications

(18 citation statements)

References 25 publications

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“…Together with previous experiments investigating individual differences in circadian behaviour [50,51], this study demonstrates the use of top-down analyses of brain function. Individual differences in behavioural, physiological and cellular processes affect numerous aspects of biological function, and thus, understanding the bases of this variation remains important.…”

Section: Discussionsupporting

confidence: 65%

Neural correlates of individual differences in circadian behaviour

et al. 2015

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Daily rhythms in mammals are controlled by the circadian system, which is a collection of biological clocks regulated by a central pacemaker within the suprachiasmatic nucleus (SCN) of the anterior hypothalamus. Changes in SCN function have pronounced consequences for behaviour and physiology; however, few studies have examined whether individual differences in circadian behaviour reflect changes in SCN function. Here, PERIOD2::LUCIFERASE mice were exposed to a behavioural assay to characterize individual differences in baseline entrainment, rate of re-entrainment and free-running rhythms. SCN slices were then collected for ex vivo bioluminescence imaging to gain insight into how the properties of the SCN clock influence individual differences in behavioural rhythms. First, individual differences in the timing of locomotor activity rhythms were positively correlated with the timing of SCN rhythms. Second, slower adjustment during simulated jetlag was associated with a larger degree of phase heterogeneity among SCN neurons. Collectively, these findings highlight the role of the SCN network in determining individual differences in circadian behaviour. Furthermore, these results reveal novel ways that the network organization of the SCN influences plasticity at the behavioural level, and lend insight into potential interventions designed to modulate the rate of resynchronization during transmeridian travel and shift work.

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Section: Discussionsupporting

confidence: 65%

Neural correlates of individual differences in circadian behaviour

et al. 2015

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“…Supporting the concept that baboons are favorable models for human circadian system development, actograms generated from baboons A, B, and C were similar to the actograms of human newborns (44,(49)(50)(51).…”

Section: Discussionmentioning

confidence: 63%

Newborn primate infants are entrained by low intensity lighting

Rivkees

Hofman

Fortman

1997

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

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At the present time we do not know when the circadian timing system of human infants becomes responsive to light. Because of human study limitations, it is not currently possible to address this issue in clinical studies. Therefore, to provide insights into when the circadian system of humans becomes responsive to light, baboons were studied. We first assessed if the biological clock located in suprachiasmatic nuclei (SCN) is responsive to light at birth. When term newborn infants were exposed to bright light at night (5000 lux), SCN metabolic activity and c-fos mRNA expression increased, indicating the presence of photic responsiveness. When photic entrainment of developing rhythmicity was examined in infants, low intensity (200 lux) cycled lighting was sufficient to entrain circadian phase. However, low intensity lighting was not sufficient to induce changes in SCN metabolic activity or c-fos mRNA expression. Phase-response studies indicated that light exposure (200 lux) before the onset of activity most effectively shifted circadian phase. These data provide direct evidence that the SCN are responsive to visually mediated light information in a primate at birth. Further consideration of lighting conditions that infants are exposed to is therefore warranted.

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“…Until now, seasonal variations of vasopressin immunoreactivity have been the only reported changes in the SCN over the course of a year (29,30). While it appears likely that the pattern of spontaneous neuronal discharge of single SCN cells is also affected by photoperiod (31), there is no direct evidence on this point.…”

Section: Discussionmentioning

confidence: 99%

The rat suprachiasmatic nucleus is a clock for all seasons.

Sumová

Travnickova

Peters

et al. 1995

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

163

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Seasonal changes of daylength (photoperiod) affect the expression of hormonal and behavioral circadian rhythms in a variety of organisms. In mammals, such effects might reflect photoperiodic changes in the circadian pacemaking system [located in the suprachiasmatic nucleus (SCN) of the hypothalamus] that governs these rhythms, but to date no functionally relevant, intrinsic property of the SCN has been shown to be photoperiod dependent. We have analyzed the temporal regulation of light-induced c-fos gene expression in the SCN of rats maintained in long or short photoperiods. Both in situ hybridization and immunohistochemical assays show that the endogenous circadian rhythm of light responsiveness in the SCN is altered by photoperiod, with the duration of the photosensitive subjective night under the short photoperiod 5-6 h longer than under the long photoperiod. Our results provide evidence that a functional property of the SCN is altered by photoperiod and suggest that the nucleus is involved in photoperiodic time measurement. Over the course of the year, most mammals respond to seasonal changes of daylength (photoperiod) with altered physiology and behavior. Photoperiodic information from the environment is conveyed to the organism by a circadian rhythm of melatonin production in the pineal gland (1-4). In the rat, rhythmic melatonin production is driven by a circadian rhythm of the activity of pineal N-acetyltransferase (NAT), which synthesizes the melatonin precursor N-acetylserotonin (5, 6). The NAT rhythm is controlled by a light-entrainable circadian pacemaking system in the suprachiasmatic nucleus (SCN) of the hypothalamus; SCN lesions abolish this rhythm (7). Norepinephrine released at night from sympathetic nerve endings in the pineal gland stimulates adrenergic receptors and the cAMP pathway; the resulting induction and activation of pineal NAT activity leads to high nighttime melatonin levels (8). In the rat, the NAT rhythm is entrained to the 24-h light-dark (LD) cycle primarily by light onset at dawn (9). With longer daylengths, light at an earlier dawn advances the phase of the morning NAT decline, while light at a later dusk delays the phase of the evening NAT rise (3, 10). The resulting alteration in the duration of the nocturnal melatonin signal, compressed during long summer days and decompressed during short winter days, appears to serve as an endogenous photoperiodic message (2,3,11).When rats and hamsters are transferred from a long to a short photoperiod, the decompression of the melatonin signal occurs gradually (12-14). Since high NAT activity can be induced independent of the photoperiod by administration of a ,B-adrenergic agonist (15), it seems likely that the neural substrate for this gradual decompression lies upstream of the pineal gland, perhaps in the SCN. Importantly, another circadian rhythm governed by the SCN is photoperiodic. The duration of nocturnal locomotor activity (a) in hamsters is also compressed during long days and decompressed during short days (16, 17)...

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Circadian differences in neuronal activity of the suprachiasmatic nucleus in brain slices prepared from photo-responsive and photo-non-responsive Djungarian hamsters

Cited by 39 publications

References 25 publications

Neural correlates of individual differences in circadian behaviour

Neural correlates of individual differences in circadian behaviour

Newborn primate infants are entrained by low intensity lighting

The rat suprachiasmatic nucleus is a clock for all seasons.

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