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.
Skip Nav Destination
Close
Article navigation
June 2011
Issue Editors
- Cover Image
- PDF Icon PDF LinkFront Matter
Review Article|
June 30 2011
Entrainment of circadian clocks in mammals by arousal and food
Ralph E Mistlberger
;
Ralph E Mistlberger
1
*Department of Psychology, Simon Fraser University, 8888 University Drive, Burnaby, BC, Canada, V5A 1S6,
1To whom correspondence should be addressed (mistlber@sfu.ca).
Search for other works by this author on:
Michael C Antle
Michael C Antle
†;Department of Psychology, University of Calgary, 2500 University Drive NW, Calgary, AB, Canada, T2N 1N4
‡Hotchkiss Brain Institute and Department of Physiology and Pharmacology, University of Calgary, 3330 Hospital Drive NW, Calgary, AB, Canada, T2N 4N1
Search for other works by this author on:
Essays Biochem (2011) 49: 119–136.
Citation
Hugh D. Piggins, Clare Guilding, Ralph E Mistlberger, Michael C Antle; Entrainment of circadian clocks in mammals by arousal and food. Essays Biochem 30 June 2011; 49 119–136. doi: https://doi.org/10.1042/bse0490119
Download citation file:
Close
Sign in
Don't already have an account? Register
Sign in to your personal account
You could not be signed in. Please check your email address / username and password and try again.
Biochemical Society Member Sign in
Sign InSign in via your Institution
Sign in via your InstitutionGet Access To This Article
Cited By
Get Email Alerts
Related Articles
Insect circadian clock outputs
Essays Biochem (June,2011)
Synchronizing the Neurospora crassa circadian clock with the rhythmic environment
Biochem Soc Trans (October,2005)
Zebrafish circadian clocks: cells that see light
Biochem Soc Trans (October,2005)
The sweet tooth of the circadian clock
Biochem Soc Trans (July,2017)