NOVEL ODORS EVOKE RISK ASSESSMENT AND SUPPRESS APPETITIVE BEHAVIORS IN MICE

The effects of four novel odors on risk assessment by mice (i.e., flat back approach, stretched attention, immobility) and the suppression o f appetitive behaviors were examined in two experiments. When novel od ors were presented in a straight runway, subjects spent significantly less time in the odor compartment, relative to controls, when it conta ined sheep wool, chocolate, or citronella (but not cat fur) odors. Ris k assessment behaviors occurred at similar levels among all groups and appetitive behaviors were not suppressed by the novel odors. When odo rants were scattered over one half of the subjects' home cage floor in Experiment 2, all novel odors increased the duration of at least one risk assessment measure and/or suppressed appetitive behaviors (i.e., eating, grooming, rearing). The results clearly reveal that a reasonab ly wide range of novel odors evoke at least some level of risk assessm ent which presumably reflects increased fearfulness. The odors of shee p wool and cat fur induced a wider range of such responses than did ch ocolate or cinnamon suggesting that mammalian odors may be particularl y effective stimuli. If so, however, it is clear that predator odors a re not uniquely effective in this regard. Experiment 1 also underscore s the importance of the testing environment in assessing the behaviora l effects of novel odors in mice. (C) 1993 Wiley-Liss, Inc.