Document Detail

Orexinergic signaling mediates light-induced neuronal activation in the dorsal raphe nucleus.
MedLine Citation:
PMID:  22710065     Owner:  NLM     Status:  MEDLINE    
Seasonal affective disorder (SAD), a major depressive disorder recurring in the fall and winter, is caused by the reduction of light in the environment, and its depressive symptoms can be alleviated by bright light therapy. Both circadian and monoaminergic systems have been implicated in the etiology of SAD. However, the underlying neural pathways through which light regulates mood are not well understood. The present study utilized a diurnal rodent model, Arvicanthis niloticus, to explore the neural pathways mediating the effects of light on brain regions involved in mood regulation. Animals kept in constant darkness received light exposure in early subjective day, the time when light therapy is usually applied. The time course of neural activity following light exposure was assessed using Fos protein as a marker in the following brain regions/cells: the suprachiasmatic nucleus (SCN), orexin neurons in the perifornical-lateral hypothalamic area (PF-LHA) and the dorsal raphe nucleus (DRN). A light-induced increase in Fos expression was observed in orexin neurons and the DRN, but not in the SCN. As the DRN is densely innervated by orexinergic inputs, the involvement of orexinergic signaling in mediating the effects of light on the DRN was tested in the second experiment. The animals were injected with the selective orexin receptor type 1 (OXR1) antagonist SB-334867 prior to the light exposure. The treatment of SB-334867 significantly inhibited the Fos induction in the DRN. The results collectively point to the role of orexin neurons in mediating the effects of light on the mood-regulating monoaminergic areas, suggesting an orexinergic pathway that underlies light-dependent mood fluctuation and the beneficial effects of light therapy.
W Adidharma; G Leach; L Yan
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, U.S. Gov't, Non-P.H.S.     Date:  2012-06-16
Journal Detail:
Title:  Neuroscience     Volume:  220     ISSN:  1873-7544     ISO Abbreviation:  Neuroscience     Publication Date:  2012 Sep 
Date Detail:
Created Date:  2012-08-06     Completed Date:  2012-12-14     Revised Date:  2013-09-20    
Medline Journal Info:
Nlm Unique ID:  7605074     Medline TA:  Neuroscience     Country:  United States    
Other Details:
Languages:  eng     Pagination:  201-7     Citation Subset:  IM    
Copyright Information:
Copyright © 2012 IBRO. Published by Elsevier Ltd. All rights reserved.
Department of Psychology, Michigan State University, East Lansing, MI 48824, USA.
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MeSH Terms
Circadian Rhythm / physiology
Intracellular Signaling Peptides and Proteins / metabolism*
Neural Pathways / physiology*
Neurons / metabolism
Neuropeptides / metabolism*
Proto-Oncogene Proteins c-fos / analysis,  biosynthesis
Raphe Nuclei / physiology*
Seasonal Affective Disorder / metabolism,  physiopathology
Signal Transduction / physiology*
Grant Support
Reg. No./Substance:
0/Intracellular Signaling Peptides and Proteins; 0/Neuropeptides; 0/Proto-Oncogene Proteins c-fos; 0/orexins

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