Document Detail

Dim light at night disrupts molecular circadian rhythms and increases body weight.
MedLine Citation:
PMID:  23929553     Owner:  NLM     Status:  MEDLINE    
With the exception of high latitudes, life has evolved under bright days and dark nights. Most organisms have developed endogenously driven circadian rhythms that are synchronized to this daily light/dark cycle. In recent years, humans have shifted away from the naturally occurring solar light cycle in favor of artificial and sometimes irregular light schedules produced by electric lighting. Exposure to unnatural light cycles is increasingly associated with obesity and metabolic syndrome; however, the means by which environmental lighting alters metabolism are poorly understood. Thus, we exposed mice to dim light at night and investigated changes in the circadian system and metabolism. Here we report that exposure to ecologically relevant levels of dim (5 lux) light at night altered core circadian clock rhythms in the hypothalamus at both the gene and protein level. Circadian rhythms in clock expression persisted during light at night; however, the amplitude of Per1 and Per2 rhythms was attenuated in the hypothalamus. Circadian oscillations were also altered in peripheral tissues critical for metabolic regulation. Exposure to dimly illuminated, as compared to dark, nights decreased the rhythmic expression in all but one of the core circadian clock genes assessed in the liver. Additionally, mice exposed to dim light at night attenuated Rev-Erb expression in the liver and adipose tissue. Changes in the circadian clock were associated with temporal alterations in feeding behavior and increased weight gain. These results are significant because they provide evidence that mild changes in environmental lighting can alter circadian and metabolic function. Detailed analysis of temporal changes induced by nighttime light exposure may provide insight into the onset and progression of obesity and metabolic syndrome, as well as other disorders involving sleep and circadian rhythm disruption.
Laura K Fonken; Taryn G Aubrecht; O Hecmarie Meléndez-Fernández; Zachary M Weil; Randy J Nelson
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.    
Journal Detail:
Title:  Journal of biological rhythms     Volume:  28     ISSN:  1552-4531     ISO Abbreviation:  J. Biol. Rhythms     Publication Date:  2013 Aug 
Date Detail:
Created Date:  2013-08-09     Completed Date:  2013-10-17     Revised Date:  2014-05-27    
Medline Journal Info:
Nlm Unique ID:  8700115     Medline TA:  J Biol Rhythms     Country:  United States    
Other Details:
Languages:  eng     Pagination:  262-71     Citation Subset:  IM    
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MeSH Terms
Blood Glucose / metabolism
Body Weight / physiology*
CLOCK Proteins / biosynthesis,  genetics
Circadian Rhythm / physiology*
Corticosterone / metabolism
Feeding Behavior / physiology
Motor Activity
Polymerase Chain Reaction
Suprachiasmatic Nucleus / metabolism,  physiology
Grant Support
Reg. No./Substance:
0/Blood Glucose; EC Proteins; W980KJ009P/Corticosterone

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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