title: Circadian feeding entrains anticipatory metabolic activity in piriform cortex and olfactory tubercle, but not in suprachiasmatic nucleus.
abstract: Animals maintained under conditions of food-availability restricted to a specific period of the day show molecular and physiological circadian rhythms and increase their locomotor activity 2-3h prior to the next scheduled feeding, called food anticipatory activity (FAA). Although the anatomical substrates and underlying mechanisms of the food-entrainable oscillator are not well understood, experimental evidence indicates that it involves multiple structures and systems. Using rabbit pups entrained to circadian nursing as a natural model of food restriction, we hypothesized that the anterior piriform cortex (APCx) and the olfactory tubercle (OTu) are activated during nursing-associated FAA. Two groups of litters were entrained to one of two different nursing times. At postnatal day 7, when litters showed clear FAA, pups from each litter were euthanized at nursing time, or 1, 2, 4, 8, 12, 16 or 20h later. Neural metabolic activities of the APCx, OTu, olfactory bulb (OB) and suprachiasmatic nucleus (SCN) were assessed by cytochrome oxidase histochemistry. Additionally, two fasted groups were nurse-deprived for two cycles before being euthanized at postnatal day 9. In nursed pups, metabolic activity of APCx, OTu and OB increased during FAA and after feeding, independently of the geographical time. Metabolic activity in SCN was not affected by nursing schedule. Given that APCx and OTu are in a key network position to integrate temporal odor signals with body energetic state, brain arousal and reward mechanisms, we suggest that these structures could be an important part of the conditioned oscillatory mechanism that leads to food entrainment.
authors.affiliation: Programa de Doctorado en Ciencias Biomédicas, Universidad Veracruzana, Xalapa, Ver., Mexico. Electronic address: dolivo@uv.mx.
authors.forename: Diana
authors.initials: D
authors.lastname: Olivo
authors.affiliation: Centro de Investigaciones Biomédicas, Universidad Veracruzana, Xalapa, Ver., Mexico. Electronic address: mcaba@uv.mx.
authors.forename: Mario
authors.initials: M
authors.lastname: Caba
authors.affiliation: Department of Psychology and Institute for Neuroscience, The University of Texas at Austin, Austin, TX 78712, USA. Electronic address: gonzalezlima@utexas.edu.
authors.forename: F
authors.initials: F
authors.lastname: Gonzalez-Lima
authors.affiliation: Programa de Doctorado en Ciencias Biomédicas, Universidad Veracruzana, Xalapa, Ver., Mexico. Electronic address: zs10019626@estudiantes.uv.mx.
authors.forename: Araceli
authors.initials: A
authors.lastname: Vázquez
authors.affiliation: Laboratorio de Investigación Genómica y Fisiológica, Facultad de Nutrición, Médicos y odontólogos s/n, Col. Unidad del Bosque, Universidad Veracruzana, 91010 Xalapa, Ver., Mexico. Electronic address: alecorona@uv.mx.
authors.forename: Aleph
authors.initials: A
authors.lastname: Corona-Morales
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D059031:Anticipation, Psychological / Q000502:physiology; D002940:Circadian Rhythm / Q000502:physiology*; D003576:Electron Transport Complex IV / Q000378:metabolism; D005247:Feeding Behavior / Q000502:physiology*; D005508:Food Deprivation / Q000502:physiology; D007774:Lactation; D009043:Motor Activity / Q000502:physiology; D009830:Olfactory Bulb / Q000502:physiology; D066208:Olfactory Tubercle / Q000502:physiology*; D066195:Piriform Cortex / Q000502:physiology*; D011817:Rabbits; D011897:Random Allocation; D013493:Suprachiasmatic Nucleus / Q000502:physiology*
chemical_list: D003576:Electron Transport Complex IV
keywords: Anticipatory activity; Circadian rhythms; Cytochrome oxidase histochemistry; Food entrainment; Olfactory bulb; Olfactory cortex