title: Object recognition testing: rodent species, strains, housing conditions, and estrous cycle.
abstract: The object recognition task (ORT) allows assessing learning and memory processes in rodents. In this study, two areas in which knowledge about the ORT could be extended were addressed; i.e. generality to species and strains, and intervening variables including housing and estrous cycle. Regarding generality to species and strains, the ORT performance of golden hamsters was assessed. The hamsters showed sufficient exploration times, object recognition performance, and a retention-interval dependent decline similar to rats and mice. Subsequently, we tested three mouse strains which have not been described before in the ORT; i.e. OF1, NMRI, and SJL mice. OF1 and NMRI strains performed equally well, whereas the SJL strain showed low exploration times and no memory retention. Therefore, the SJL strain is unsuited for ORT experiments using a 1h retention interval and a fixed (3 min) trial duration. Furthermore, the sensitivity to a pharmacological memory deficit model (scopolamine) was tested in three rat strains. Each strain showed a dose dependent relationship, but the least effective dose of scopolamine differed among the three strains, the effect being greater in the order of Wistar, Long-Evans, Hooded Lister rats. Finally, to investigate potential intervening variables in the ORT, the effects of housing conditions and estrous cycle were investigated with rats. Single housing resulted in absolute higher performance than social housing. Furthermore, females in pro-estrus/estrus showed better performance compared to females in met-estrus/di-estrus. Taken together, object recognition appears to be a common ability of rodent species, but different strains have different memory capacities and sensitivities to scopolamine, individual housing leads to higher performance, and performance of females is dependent on the estrous cycle phase. Thus, rodent species, strain, housing, and estrous cycle should be taken into consideration in ORT studies.
authors.affiliation: Department of Psychiatry and Neuropsychology, School for Mental Health and Neuroscience-MHeNS, European Graduate School of Neuroscience-EURON, Maastricht University, Maastricht, The Netherlands.
authors.forename: Nick P
authors.initials: NP
authors.lastname: van Goethem
authors.forename: Kris
authors.initials: K
authors.lastname: Rutten
authors.forename: Franz Josef
authors.initials: FJ
authors.lastname: van der Staay
authors.forename: Linda A W
authors.initials: LA
authors.lastname: Jans
authors.forename: Sven
authors.initials: S
authors.lastname: Akkerman
authors.forename: Harry W M
authors.initials: HW
authors.lastname: Steinbusch
authors.forename: Arjan
authors.initials: A
authors.lastname: Blokland
authors.forename: José
authors.initials: J
authors.lastname: van't Klooster
authors.forename: Jos
authors.initials: J
authors.lastname: Prickaerts
mesh_terms: D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects / Q000502:physiology; D035841:Behavioral Research / Q000379:methods*; D018680:Cholinergic Antagonists / Q000494:pharmacology; D006224:Cricetinae; D004193:Discrimination Learning / Q000187:drug effects / Q000502:physiology*; D030762:Estrous Cycle / Q000502:physiology*; D005106:Exploratory Behavior / Q000502:physiology*; D005260:Female; D006799:Housing, Animal; D008297:Male; D008647:Mesocricetus; D051379:Mice; D008815:Mice, Inbred Strains; D051381:Rats; D011919:Rats, Inbred Strains; D021641:Recognition, Psychology / Q000187:drug effects / Q000502:physiology*; D012107:Research Design; D012601:Scopolamine / Q000494:pharmacology; D012737:Sex Factors; D013045:Species Specificity
chemical_list: D018680:Cholinergic Antagonists; D012601:Scopolamine