Two strains of roof rats as effective models for assessing new-objectreaction

[摘要] Wild animals generally avoid even small and harmless novel objects and/or familiarobjects moved to a novel position, which is termed “new-object reaction”. Althoughnew-object reaction appears to be a biologically important characteristic for animals,little progress has been made in understanding the neural mechanisms underlying new-objectreaction. One reason might be the lack of effective experimental animals. Two strains ofroof rats (Sj and Og strains) were established from wild roof rats caught in Shinjuku,Tokyo and one of the Ogasawara Islands, respectively, by a Japanese pest control company.Based on the rat caregivers’ informal observations, we conducted behavioral and anatomicaltests to assess the validity of Sj and Og strains for the analyses of new-object reaction.In Experiment 1, the Sj strain showed reduced food consumption compared with the Og strainwhen food was provided in a novel way, suggesting that the Sj strain had a strongeravoidance of novel objects compared with the Og strain. Experiment 2 demonstrated that thebasolateral complex of the amygdala and bed nucleus of the stria terminalis inexperimental Sj rats had a larger percentage area compared with that of experimental Ograts, indicating these nuclei might be involved in the difference observed in avoidance ofnovel objects between the strains. Taken together, the present study suggests that Sj andOg strains are effective experimental animals for assessing new-object reaction.

[学科分类] 兽医学

[关键词] basolateral complex of the amygdala;bed nucleus of the stria terminalis;main olfactory bulb;neophobia;olfactory receptor