title: Lewis and Fischer 344 rats as a model for genetic differences in spatial learning and memory: Cocaine effects.
abstract: Lewis (LEW) and Fischer 344 (F344) rats are considered a model of genetic vulnerability to drug addiction. We previously showed important differences in spatial learning and memory between them, but in contrast with previous experiments demonstrating cocaine-induced enhanced learning in Morris water maze (MWM) highly demanding tasks, the eight-arm radial maze (RAM) performance was not modified either in LEW or F344 rats after chronic cocaine treatment. In the present work, chronically cocaine-treated LEW and F344 adult rats have been evaluated in learning and memory performance using the Y-maze, two RAM protocols that differ in difficulty, and a reversal protocol that tests cognitive flexibility. After one of the RAM protocols, we quantified dendritic spine density in hippocampal CA1 neurons and compared it to animals treated with cocaine but not submitted to RAM. LEW cocaine treated rats showed a better performance in the Y maze than their saline counterparts, an effect that was not evident in the F344 strain. F344 rats significantly took more time to learn the RAM task and made a greater number of errors than LEW animals in both protocols tested, whereas cocaine treatment induced deleterious effects in learning and memory in the highly difficult protocol. Moreover, hippocampal spine density was cocaine-modulated in LEW animals whereas no effects were found in F344 rats. We propose that differences in addictive-like behavior between LEW and F344 rats could be related to differences in hippocampal learning and memory processes that could be on the basis of individual vulnerability to cocaine addiction.
authors.affiliation: Departamento de Ciencias Farmacéuticas y de la Salud, Facultad de Farmacia, Universidad CEU-San Pablo, Spain.
authors.forename: Alberto
authors.initials: A
authors.lastname: Fole
authors.affiliation: Departamento de Psicología Básica I, Facultad de Psicología, Universidad Nacional de Educación a Distancia (UNED), Spain.
authors.forename: Miguel
authors.initials: M
authors.lastname: Miguéns
authors.affiliation: Departamento de Ciencias Farmacéuticas y de la Salud, Facultad de Farmacia, Universidad CEU-San Pablo, Spain.
authors.forename: Lidia
authors.initials: L
authors.lastname: Morales
authors.affiliation: Departamento de Ciencias Farmacéuticas y de la Salud, Facultad de Farmacia, Universidad CEU-San Pablo, Spain.
authors.forename: Carmen
authors.initials: C
authors.lastname: González-Martín
authors.affiliation: Departamento de Psicobiología, Facultad de Psicología, Universidad Nacional de Educación a Distancia (UNED), Spain.
authors.forename: Emilio
authors.initials: E
authors.lastname: Ambrosio
authors.affiliation: Departamento de Ciencias Farmacéuticas y de la Salud, Facultad de Farmacia, Universidad CEU-San Pablo, Spain. Electronic address: nolmo@ceu.es.
authors.forename: Nuria
authors.initials: N
authors.lastname: Del Olmo
mesh_terms: D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects*; D056547:CA1 Region, Hippocampal / Q000187:drug effects*; D002452:Cell Count; D003042:Cocaine / Q000494:pharmacology*; D049229:Dendritic Spines / Q000187:drug effects*; D018765:Dopamine Uptake Inhibitors / Q000494:pharmacology*; D008297:Male; D018782:Maze Learning / Q000187:drug effects*; D023421:Models, Animal; D051381:Rats; D011916:Rats, Inbred F344 / Q000235:genetics / Q000502:physiology; D011917:Rats, Inbred Lew / Q000235:genetics / Q000502:physiology; D065852:Spatial Memory / Q000187:drug effects
chemical_list: D018765:Dopamine Uptake Inhibitors; D003042:Cocaine
keywords: Addiction; CA1; Hippocampus; Radial arm maze; Spatial memory; Spine density