Gene expression in the geniculate induced by a nonphotic circadian phase shifting stimulus

Janik, Daniel S.; Mrosovsky, N.

doi:10.1097/00001756-199207000-00007

Cited by 86 publications

(37 citation statements)

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“…The non-photic cue failed to induce phosphoryla tion of CREB. This result is comparable to that obtained for the expression of the immediate-early genes c-fos and egr-1 insofar as the transcription of both is induced by light pulses [14][15][16], but neither is responsive to nonphotic cues which shift the circadian clock [6,17,18;Hastings and Mead,unpubl. data].…”

Section: Discussionsupporting

confidence: 82%

Non-Photic Circadian Entrainment in the Syrian Hamster Is Not Associated with Phosphorylation of the Transcriptional Regulator CREB within the Suprachiasmatic Nucleus, but Is Associated with Adrenocortical Activation

Sumová¹,

Ebling²,

Maywood³

et al. 1994

Neuroendocrinology

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The mechanisms which mediate non-photic entrainment of the circadian clock are not known. The free-running circadian rhythm of the wheel-running activity of Syrian hamsters was phase advanced by subcutaneous injection of saline and the associated handling at circadian time (CT) 10 (2 h before activity onset, CT 12). Over several experiments, approximately 80% of the animals were sensitive to this non-photic cue and were, therefore, designated as ‘shifters’. Injection at CT 6 had no phase-shifting effect in any animals. A series of six injections presented to shifters at CT 10 over 14 circadian cycles produced a cumulative phase advance to the activity rhythm which free ran from the phase established by the final injection, demonstrating that the non-photic stimulus caused true entrainment of the circadian clock, rather than simply masking its expression. Entrainment by light is associated with the rapid phosphorylation of the transcription regulatory factor, cyclic adenosine monophosphate response element binding protein (CREB), in the suprachiasmatic nuclei (SCN), the principal circadian clock. The induction of immunoreactivity to the phosphorylated form of CREB (P-CREB-ir) was used to determine whether phosphorylation is also activated by a non-photic phase-shifting cue. No significant P-CREB-ir was found in shifters maintained under constant dim red light and sampled at either CT 10.05 or 14.05, i.e., times when animals are sensitive to non-photic stimuli and light pulses, respectively. Exposure of animals to light for 5 min at CT 14 caused a dramatic increase in P-CREB-ir within the SCN at CT 14.05. However, despite being sensitive to the phase-shifting effects of handling and injection at CT 10, none of the shifters sampled 5 min after injection of saline at CT 10 exhibited P-CREB-ir within the SCN. These data demonstrate that non-photic cues do not activate a cellular pathway (phosphorylation of CREB) known to be activated within the SCN by light. To assess the importance of arousal in non-photic entrainment, the effect of injection of saline upon activation of the adrenocortical axis, a peripheral index of arousal, was investigated. As anticipated, there was a marked circadian variation in serum cortisol concentrations. In animals identified as shifters, the levels were low during mid-subjective day (CT 6) and rose in advance of activity onset (CT 10). Injection and handling at CT 6 did not have a significant effect upon serum cortisol levels. In contrast, injection of shifters at CT 10 was associated with a pronounced rise in serum cortisol levels. In non-shifters, which did not shift in response to the non-photic cue, the serum levels of cortisol did not rise following handling and injection. These results show that non-photic shifting of the circadian clock is associated with adrenocortical activation and support the hypothesis that arousal is an important non-photic zeitgeber in the Syrian hamster.

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Section: Discussionsupporting

confidence: 82%

Non-Photic Circadian Entrainment in the Syrian Hamster Is Not Associated with Phosphorylation of the Transcriptional Regulator CREB within the Suprachiasmatic Nucleus, but Is Associated with Adrenocortical Activation

Sumová¹,

Ebling²,

Maywood³

et al. 1994

Neuroendocrinology

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“…The complex and sometimes variable responses to illumination suggest that these neurons may receive both direct retinal projections and indirect input from other regions, such as the contralateral IGL or local interneurons (Card and Moore, 1989;Zhang and Rusak, 1989;Vrang et al, 2003). Because NPYimmunoreactive cells respond to nonphotic stimuli with increased c-Fos expression (Janik and Mrosovsky, 1992), and be- Figure 5A. The cell showed a moderate firing rate in darkness, a sharp increase in firing at illumination onset (upward deflections of the line above the histogram), and sustained high firing during each 60 s light exposure.…”

Section: Discussionmentioning

confidence: 99%

“…These effects can be quite potent and can counteract some effects of light on circadian rhythms (Biello and Mrosovsky, 1995;Schaap and Meijer, 2001). Several lines of evidence demonstrate that the IGL and its NPY projection to the SCN are involved in mediating at least some nonphotic effects on rhythms (Janik and Mrosovsky, 1992;Huhman and Albers, 1994;Edelstein and Amir, 1995;Janik et al, 1995;Biello and Mrosovsky, 1996;Marchant et al, 1997;Weber and Rea, 1997;Lall and Biello, 2003).…”

Section: Introductionmentioning

confidence: 99%

Juxtacellular Recording/Labeling Analysis of Physiological and Anatomical Characteristics of Rat Intergeniculate Leaflet Neurons

Thankachan¹,

Rusak²

2005

J. Neurosci.

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The thalamic intergeniculate leaflet (IGL) is involved in mediating effects of both photic and nonphotic stimuli on mammalian circadian rhythms. IGL neurons containing neuropeptide Y (NPY) have been implicated in mediating nonphotic effects, but little is known about those involved in photic entrainment. We used juxtacellular recording/labeling in rats to characterize both photic responses and neurochemical phenotypes of neurons in the lateral geniculate area, focusing on the IGL and ventral lateral geniculate (VLG). Single neurons were recorded to characterize photic responsiveness and were labeled with Neurobiotin (Nb); tissue was stained for Nb, NPY, and in some cases for orexin A. Three classes of neurons were identified in the IGL/VLG. Type I neurons lacked NPY and showed sustained activations during retinal illumination and moderate firing rates in darkness. Type II neurons contained large amounts of NPY throughout the soma and showed varied responses to illumination: suppression, complex responses, or no response. Type III neurons had patches of NPY both on the external soma surface and within the soma, apparently representing internalization of NPY. Type III neurons resembled type I cells in their sustained activation by illumination but were virtually silent during the intervening dark period. These neurons appear to receive NPY input, presumably from other IGL cells, which may suppress their activity during darkness. These results demonstrate the presence of several classes of neurons in the IGL defined by their functional and anatomical features and reinforce the role of the IGL/VLG complex in integrating photic and nonphotic inputs to the circadian system.

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“…It is possible that the circadian phase-related actions of intra-DRN GABA involve the same GABA A -benzodiazepine receptor population responsible for mediating the phase-resetting effects of triazolam (Turek and Losee-Olson, 1986;Turek and Van Reeth, 1988;Van Reeth and Turek, 1989;Marchant and Morin, 1999). However, it is unlikely that the DRN is a target for the phase-shifting action of triazolam (Meyer-Bernstein and Morin, 1998;Marchant and Morin, 1999), and triazolam and behavioral stimuli do not act via the same phase-resetting mechanism (Meyer-Bernstein and Morin, 1998;Janik and Mrosovsky, 1992;Marchant and Morin, 1999).…”

Section: Intra-raphe Gabaergic Mechanisms Regulate Scn 5-ht Releasementioning

confidence: 99%

Midbrain Raphe Modulation of Nonphotic Circadian Clock Resetting and 5-HT Release in the Mammalian Suprachiasmatic Nucleus

et al. 2003

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Gene expression in the geniculate induced by a nonphotic circadian phase shifting stimulus

Cited by 86 publications

References 0 publications

Non-Photic Circadian Entrainment in the Syrian Hamster Is Not Associated with Phosphorylation of the Transcriptional Regulator CREB within the Suprachiasmatic Nucleus, but Is Associated with Adrenocortical Activation

Non-Photic Circadian Entrainment in the Syrian Hamster Is Not Associated with Phosphorylation of the Transcriptional Regulator CREB within the Suprachiasmatic Nucleus, but Is Associated with Adrenocortical Activation

Juxtacellular Recording/Labeling Analysis of Physiological and Anatomical Characteristics of Rat Intergeniculate Leaflet Neurons

Midbrain Raphe Modulation of Nonphotic Circadian Clock Resetting and 5-HT Release in the Mammalian Suprachiasmatic Nucleus

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