title: One-trial object recognition memory in the domestic rabbit (Oryctolagus cuniculus) is disrupted by NMDA receptor antagonists.
abstract: The spontaneous response to novelty is the basis of one-trial object recognition tests for the study of object recognition memory (ORM) in rodents. We describe an object recognition task for the rabbit, based on its natural tendency to scent-mark ("chin") novel objects. The object recognition task comprised a 15min sample phase in which the rabbit was placed into an open field arena containing two similar objects, then removed for a 5-360min delay, and then returned to the same arena that contained one object similar to the original ones ("Familiar") and one that differed from the original ones ("Novel"), for a 15min test phase. Chin-marks directed at each of the objects were registered. Some animals received injections (sc) of saline, ketamine (1mg/kg), or MK-801 (37μg/kg), 5 or 20min before the sample phase. We found that chinning decreased across the sample phase, and that this response showed stimulus specificity, a defining characteristic of habituation: in the test phase, chinning directed at the Novel, but not Familiar, object was increased. Chinning directed preferentially at the novel object, which we interpret as novelty-induced sensitization and the behavioral correlate of ORM, was promoted by tactile/visual and spatial novelty. ORM deficits were induced by pre-treatment with MK-801 and, to a lesser extent, ketamine. Novel object discrimination was not observed after delays longer than 5min. These results suggest that short-term habituation and sensitization, not long-term memory, underlie novel object discrimination in this test paradigm.
authors: Centro de Investigación en Reproducción Animal (CIRA), Universidad Autónoma de Tlaxcala-CINVESTAV, Tlaxcala, Mexico. rexvitro@hotmail.com
authors: Kurt Leroy
authors: KL
authors: Hoffman
authors: Enrique
authors: E
authors: Basurto
mesh_terms: D000818:Animals; D004195:Disease Models, Animal; D016291:Dizocilpine Maleate / Q000633:toxicity; D004305:Dose-Response Relationship, Drug; D018691:Excitatory Amino Acid Antagonists / Q000633:toxicity*; D005106:Exploratory Behavior / Q000187:drug effects; D005260:Female; D007649:Ketamine / Q000633:toxicity; D008297:Male; D008569:Memory Disorders / Q000139:chemically induced* / Q000503:physiopathology*; D011817:Rabbits; D021641:Recognition, Psychology / Q000187:drug effects*; D012727:Sex Characteristics; D018709:Statistics, Nonparametric; D013997:Time Factors
chemical_list: D018691:Excitatory Amino Acid Antagonists; D007649:Ketamine; D016291:Dizocilpine Maleate