title: From adolescent to elder rats: Motivation for palatable food and cannabinoids receptors.
abstract: To analyze motivation, food self-administration and decision-making were evaluated in adolescent, adult, and aged rats. Subjects were trained to press a lever (fixed ratio, FR1 and FR5) in an operant chamber, to obtain chocolate flavor pellets. They assessed the progressive ratio (PR), extinction, and reinstatement of the behavior. To estimate decision-making for food, rats were trained in the conditioned place preference (CPP) paradigm: (a) associating one compartment with lab chow (LCh) one day and the other compartment with rice krisspies (RK), the next day. (b) Training similar to (a) but on the day RK was the reinforcer, it was delivered with a progressive delay. In addition, CB1 and CB2 receptor expression in the nucleus accumbens (NAcc) and prefrontal cortex (PFC) was estimated by means of Western blot. Adolescent rats consumed higher amounts of RK/body weight than adult and aged rats during FR1, FR5, and PR. Extinction was more prolonged for adolescent rats than for adult and aged rats. First CPP condition, all three groups of rats preferred the RK-associated compartment. Second CPP condition, adolescent rats developed equal preference to both compartments, while adult and aged rats preferred the RK-associated compartment. Rats per group ate a similar amount of either reinforcer. Adolescent rats exhibited low expression of CB1R in the NAcc and low expression of both CB1R and CB2R in the PFC compared with adult and aged rats. Adolescent rats display higher motivation for palatable food and an indiscriminate seeking behavior suggesting involvement of both homeostatic and hedonic systems in their decision-making processes. © 2016 Wiley Periodicals, Inc. Develop Neurobiol 77: 917-927, 2017.
authors.affiliation: Grupo de Neurociencias, Laboratorio de Canabinoides, Departamento de Fisiología, Facultad de Medicina, Universidad Nacional Autónoma de México, México, México.
authors.forename: Octavio
authors.initials: O
authors.lastname: Amancio-Belmont
authors.affiliation: Grupo de Neurociencias, Laboratorio de Canabinoides, Departamento de Fisiología, Facultad de Medicina, Universidad Nacional Autónoma de México, México, México.
authors.forename: Antonio
authors.initials: A
authors.lastname: Romano-López
authors.affiliation: Grupo de Neurociencias, Laboratorio de Canabinoides, Departamento de Fisiología, Facultad de Medicina, Universidad Nacional Autónoma de México, México, México.|Laboratorio de Neurogenómica Cognitiva, Departamento de Psicofisiología, Facultad de Psicología, Universidad Nacional Autónoma de México, Apdo. Postal 70-250, 04510, México, México.
authors.forename: Alejandra Evelin
authors.initials: AE
authors.lastname: Ruiz-Contreras
authors.affiliation: Grupo de Neurociencias, Laboratorio de Canabinoides, Departamento de Fisiología, Facultad de Medicina, Universidad Nacional Autónoma de México, México, México.
authors.forename: Mónica
authors.initials: M
authors.lastname: Méndez-Díaz
authors.affiliation: Grupo de Neurociencias, Laboratorio de Canabinoides, Departamento de Fisiología, Facultad de Medicina, Universidad Nacional Autónoma de México, México, México.
authors.forename: Oscar
authors.initials: O
authors.lastname: Prospéro-García
mesh_terms: D000375:Aging / Q000378:metabolism* / Q000523:psychology; D000818:Animals; D015153:Blotting, Western; D003213:Conditioning, Psychological / Q000502:physiology; D003657:Decision Making / Q000502:physiology; D005108:Extinction, Psychological / Q000502:physiology; D005247:Feeding Behavior / Q000502:physiology* / Q000523:psychology; D006624:Hippocampus / Q000254:growth & development / Q000378:metabolism; D008297:Male; D009042:Motivation / Q000502:physiology*; D009043:Motor Activity / Q000502:physiology; D009714:Nucleus Accumbens / Q000254:growth & development / Q000378:metabolism; D017397:Prefrontal Cortex / Q000254:growth & development / Q000378:metabolism; D017208:Rats, Wistar; D043884:Receptor, Cannabinoid, CB1 / Q000378:metabolism*; D043885:Receptor, Cannabinoid, CB2 / Q000378:metabolism*; D021641:Recognition, Psychology / Q000502:physiology; D013037:Spatial Behavior / Q000502:physiology
chemical_list: C543264:Cnr1 protein, rat; C469526:Cnr2 protein, rat; D043884:Receptor, Cannabinoid, CB1; D043885:Receptor, Cannabinoid, CB2
keywords: CB1R; CB2R; adolescents; motivation; prefrontal cortex