Document Detail

Entrainment of circadian clocks in mammals by arousal and food.
MedLine Citation:
PMID:  21819388     Owner:  NLM     Status:  In-Data-Review    
Circadian rhythms in mammals are regulated by a system of endogenous circadian oscillators (clock cells) in the brain and in most peripheral organs and tissues. One group of clock cells in the hypothalamic SCN (suprachiasmatic nuclei) functions as a pacemaker for co-ordinating the timing of oscillators elsewhere in the brain and body. This master clock can be reset and entrained by daily LD (light-dark) cycles and thereby also serves to interface internal with external time, ensuring an appropriate alignment of behavioural and physiological rhythms with the solar day. Two features of the mammalian circadian system provide flexibility in circadian programming to exploit temporal regularities of social stimuli or food availability. One feature is the sensitivity of the SCN pacemaker to behavioural arousal stimulated during the usual sleep period, which can reset its phase and modulate its response to LD stimuli. Neural pathways from the brainstem and thalamus mediate these effects by releasing neurochemicals that inhibit retinal inputs to the SCN clock or that alter clock-gene expression in SCN clock cells. A second feature is the sensitivity of circadian oscillators outside of the SCN to stimuli associated with food intake, which enables animals to uncouple rhythms of behaviour and physiology from LD cycles and align these with predictable daily mealtimes. The location of oscillators necessary for food-entrained behavioural rhythms is not yet certain. Persistence of these rhythms in mice with clock-gene mutations that disable the SCN pacemaker suggests diversity in the molecular basis of light- and food-entrainable clocks.
Ralph E Mistlberger; Michael C Antle
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Essays in biochemistry     Volume:  49     ISSN:  1744-1358     ISO Abbreviation:  Essays Biochem.     Publication Date:  2011 Jun 
Date Detail:
Created Date:  2011-08-08     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0043306     Medline TA:  Essays Biochem     Country:  England    
Other Details:
Languages:  eng     Pagination:  119-36     Citation Subset:  IM    
*Department of Psychology, Simon Fraser University, 8888 University Drive, Burnaby, BC, Canada, V5A 1S6.
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