title: Food-reward signalling in the suprachiasmatic clock.
abstract: Under special restricted feeding conditions the mammalian circadian clock, contained in the hypothalamic suprachiasmatic nucleus (SCN), can be entrained by food. During food restriction, hungry animals are very motivated to obtain food. This motivational state could be a key component in altering the SCN timing by feeding. In order to comprehend how hedonic signals of food affect the SCN clock, we evaluated the effects of a daily palatable snack on the behavioural rhythm of mice fed ad libitum with regular food, and housed under constant darkness conditions. As light synchronization of the SCN is modulated by feeding/metabolic cues, the effects of a palatable meal coupled to a light pulse were tested on behavioural and molecular rhythms. A daily palatable snack entrained behavioural rhythms of mice in constant darkness conditions. Furthermore, palatable meal access at the activity onset reduced light-induced behavioural phase-delays and Period genes expression in the SCN. In addition, an increase in the dopamine content and Period genes expression in the forebrain of mice was observed, concomitant with a c-FOS activation in dopaminergic and orexinergic neurons, suggesting that the effects of a palatable snack on the SCN clock are mediated by the reward/arousal central systems. In conclusion, this study establishes an underlying sensitivity of the master circadian clock to changes in motivational states related to palatable food intake.
authors.affiliation: Département de Neurobiologie des Rythmes UPR 3212, CNRS, Associéà l'Université de Strasbourg, Institut de Neurosciences Cellulaires et Intégratives, France. jmendoza@inci-cnrs.unistra.fr
authors.forename: Jorge
authors.initials: J
authors.lastname: Mendoza
authors.forename: Daniel
authors.initials: D
authors.lastname: Clesse
authors.forename: Paul
authors.initials: P
authors.lastname: Pévet
authors.forename: Etienne
authors.initials: E
authors.lastname: Challet
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001835:Body Weight / Q000502:physiology; D002452:Cell Count / Q000379:methods; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D002940:Circadian Rhythm / Q000502:physiology*; D004435:Eating / Q000502:physiology; D004563:Electrochemistry / Q000379:methods; D005247:Feeding Behavior / Q000502:physiology; D005502:Food; D005508:Food Deprivation; D005518:Food Preferences / Q000502:physiology; D005786:Gene Expression Regulation / Q000502:physiology; D008124:Locomotion / Q000502:physiology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018377:Neurotransmitter Agents / Q000378:metabolism; D016761:Oncogene Proteins v-fos / Q000378:metabolism; D056950:Period Circadian Proteins / Q000235:genetics / Q000378:metabolism; D012055:Reinforcement Schedule; D012201:Reward; D013493:Suprachiasmatic Nucleus / Q000166:cytology / Q000502:physiology*; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism
chemical_list: D018377:Neurotransmitter Agents; D016761:Oncogene Proteins v-fos; D056950:Period Circadian Proteins; D014446:Tyrosine 3-Monooxygenase