Interactions between light, mealtime and calorie restriction to control daily timing in mammals.
Daily variations in behaviour and physiology are controlled by a circadian timing system consisting of a network of oscillatory structures. In mammals, a master clock, located in the suprachiasmatic nuclei (SCN) of the hypothalamus, adjusts timing of other self-sustained oscillators in the brain and peripheral organs. Synchronisation to external cues is mainly achieved by ambient light, which resets the SCN clock. Other environmental factors, in particular food availability and time of feeding, also influence internal timing. Timed feeding can reset the phase of the peripheral oscillators whilst having almost no effect in shifting the phase of the SCN clockwork when animals are exposed (synchronised) to a light-dark cycle. Food deprivation and calorie restriction lead not only to loss of body mass (>15%) and increased motor activity, but also affect the timing of daily activity, nocturnal animals becoming partially diurnal (i.e. they are active during their usual sleep period). This change in behavioural timing is due in part to the fact that metabolic cues associated with calorie restriction affect the SCN clock and its synchronisation to light.
Challet
Etienne
E
Department of Neurobiology of Rhythms, National Center for Scientific Research, Neurosciences Federation of Strasbourg IFR37, Institute for Cellular and Integrative Neurosciences (UPR3212) , 5 rue Blaise Pascal, 67084 Strasbourg, France. challet@inci-cnrs.unistra.fr
D000344:Afferent Pathways / Q000502:physiology; D000818:Animals; D001522:Behavior, Animal / Q000502:physiology*; D001683:Biological Clocks / Q000502:physiology; D001833:Body Temperature Regulation / Q000502:physiology; D031204:Caloric Restriction; D002940:Circadian Rhythm / Q000502:physiology*; D005247:Feeding Behavior / Q000502:physiology; D005508:Food Deprivation / Q000502:physiology; D008027:Light; D008136:Longevity; D008322:Mammals / Q000378:metabolism*; D009043:Motor Activity / Q000502:physiology; D010775:Photic Stimulation; D017299:Rod Opsins / Q000502:physiology; D013493:Suprachiasmatic Nucleus / Q000502:physiology*; D013787:Thalamic Nuclei; D000099210:Melanopsin
D017299:Rod Opsins; D000099210:Melanopsin