Behavioural Brain Research 316 (2017) 261–270 Contents lists available at ScienceDirect Behavioural Brain Research jou rn al hom epage: www.elsevier.com/locate/bbr Research report Metabolic activation of amygdala, lateral septum and accumbens circuits during food anticipatory behavior Diana Olivo a , Mario Caba b , Francisco Gonzalez-Lima c , Juan F. Rodríguez-Landa d , Aleph A. Corona-Morales e,∗ a Programa de Doctorado en Ciencias Biomédicas, Universidad Veracruzana, Xalapa, Veracruz 91190, Mexico b Centro de Investigaciones Biomédicas, Universidad Veracruzana, Xalapa, Veracruz 91190, Mexico c Department of Psychology and Institute for Neuroscience, The University of Texas at Austin, Austin, TX 78712, USA d Laboratorio de Neurofarmacología, Instituto de Neuroetología, Universidad Veracruzana, Xalapa, Veracruz 91190, Mexico e Laboratorio de Investigación Genómica y Fisiológica, Facultad de Nutrición, Médicos y odontólogos s/n, Col. Unidad del Bosque, 91010, Universidad Veracruzana, Xalapa, Veracruz, Mexico h i g h l i g h t s • We used cytochrome oxidase histochemistry to study brain metabolic circadian rhythms. • Neural rhythms were studied in rabbit pups entrained to circadian feeding. • Extended amygdala, lateral septum and accumbens core peaked during food anticipation. • Accumbens shell, caudate, putamen and cortical amygdala peaked after feeding. • Temporal conditioning circuits may contribute to food anticipatory activity. a r t i c l e i n f o Article history: Received 9 May 2016 Received in revised form 25 August 2016 Accepted 6 September 2016 Available online 9 September 2016 Keywords: Circadian rhythm ontogeny Cytochrome oxidase histochemistry Food anticipatory activity Conditioned emotional behavior Reward expectation a b s t r a c t When food is restricted to a brief fixed period every day, animals show an increase in temperature, corticosterone concentration and locomotor activity for 2–3 h before feeding time, termed food anticipa- tory activity. Mechanisms and neuroanatomical circuits responsible for food anticipatory activity remain unclear, and may involve both oscillators and networks related to temporal conditioning. Rabbit pups are nursed once-a-day so they represent a natural model of circadian food anticipatory activity. Food antici- patory behavior in pups may be associated with neural circuits that temporally anticipate feeding, while the nursing event may produce consummatory effects. Therefore, we used New Zealand white rabbit pups entrained to circadian feeding to investigate the hypothesis that structures related to reward expectation and conditioned emotional responses would show a metabolic rhythm anticipatory of the nursing event, different from that shown by structures related to reward delivery. Quantitative cytochrome oxidase histochemistry was used to measure regional brain metabolic activity at eight different times during the day. We found that neural metabolism peaked before nursing, during food anticipatory behavior, in nuclei of the extended amygdala (basolateral, medial and central nuclei, bed nucleus of the stria ter- minalis), lateral septum and accumbens core. After pups were fed, however, maximal metabolic activity was expressed in the accumbens shell, caudate, putamen and cortical amygdala. Neural and behavioral activation persisted when animals were fasted by two cycles, at the time of expected nursing. These findings suggest that metabolic activation of amygdala-septal-accumbens circuits involved in temporal conditioning may contribute to food anticipatory activity. © 2016 Elsevier B.V. All rights reserved. Abbreviations: CO, cytochrome oxidase; FAA, food anticipatory activity; OD, optical density; PD, postnatal day; ROD, relative optical density; ZT, zeitgeber time. ∗ Corresponding author. E-mail addresses: dolivormz@gmail.com (D. Olivo), mcaba@uv.mx (M. Caba), gonzalezlima@utexas.edu (F. Gonzalez-Lima), juarodriguez@uv.mx (J.F. Rodríguez-Landa), alecorona@uv.mx, cmaa0@yahoo.com (A.A. Corona-Morales). http://dx.doi.org/10.1016/j.bbr.2016.09.015 0166-4328/© 2016 Elsevier B.V. All rights reserved.