| Cones are required for normal temporal responses to light of phase shifts and clock gene expression. | |
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MedLine Citation:
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PMID: 20560710 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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In mammals, non-visual responses to light involve intrinsically photosensitive melanopsin-expressing retinal ganglion cells (ipRGCs) that receive synaptic inputs from rod and cone photoreceptors. Several studies have shown that cones also play a role in light entrainment, photic responses of the suprachiasmatic nucleus (SCN), pupil constriction, and sleep induction. These studies suggest that cones are mainly involved in the initial response to light, whereas melanopsin provides a sustained input for non-visual responses during continued light exposure. Based on this idea, we explored the effects of the absence of middle-wavelength (MW)-cones on the temporal responses of circadian behavior and clock gene expression in light. In mice lacking MW-cones, our results show a reduction in behavioral phase shifts in response to light stimulations of short duration at 480 and 530 nm, but no alteration for short-wavelength (360-nm) light exposures. Similarly, induction of the period gene mPer1 and mPer2 mRNAs in the SCN are attenuated in response to light exposures of mid to long wavelengths. Modeling of the photoresponses shows that mice lacking MW-cones have an overall reduction in sensitivity that increases with longer wavelengths. The differences in photic responsiveness are consistent with the idea that cones provide a strong initial phasic input to the circadian system at light-onset and may confer a priming effect on ipRGC responses to sub-threshold light exposures. In summary, the contribution of MW-cones is essential for the normal expression of phase shifts and clock gene induction by light in mammals. |
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Authors:
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Anna Dollet; Urs Albrecht; Howard M Cooper; Ouria Dkhissi-Benyahya |
Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't |
Journal Detail:
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Title: Chronobiology international Volume: 27 ISSN: 1525-6073 ISO Abbreviation: Chronobiol. Int. Publication Date: 2010 Jun |
Date Detail:
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Created Date: 2010-06-21 Completed Date: 2010-10-04 Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 8501362 Medline TA: Chronobiol Int Country: England |
Other Details:
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Languages: eng Pagination: 768-81 Citation Subset: IM |
Affiliation:
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INSERM, U846, Stem Cell and Brain Research Institute, Department of Chronobiology, Bron, France. |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Animals Biological Clocks / physiology* Circadian Rhythm / physiology* Gene Expression* Light* Male Mice Mice, Knockout Period Circadian Proteins* / genetics, metabolism Photic Stimulation Retinal Cone Photoreceptor Cells / physiology* Suprachiasmatic Nucleus / physiology Time Factors |
| Chemical | |
Reg. No./Substance:
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0/Per1 protein, mouse; 0/Per2 protein, mouse; 0/Period Circadian Proteins |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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