Effects of chlordiazepoxide on predator odor-induced reductions of playfulness in juvenile rats

The extent to which a non-sedative dose of chlordiazepoxide (CDP) is able to modify the behavioral responses toward a predator odor was assessed in juvenile rats. Play behavior was suppressed and defensive behaviors were enhanced in the presence of a collar previously worn by a cat, when tested 24h later in the same context as that where the exposure occurred, and when tested in a context different than that in which the exposure occurred for up to 3h after exposure. CDP had no effect on the ability of cat odor to suppress play when rats were tested in the presence of the odor or when tested 24h later in the same context where that exposure occurred. When rats were exposed to a worn cat collar in their home cage and tested in a different context CDP attenuated the ability of cat odor to reduce one measure of play (nape contacts) but not another measure (pins). Rats had an opportunity to hide during testing and CDP either decreased hiding or increased risk assessment from within the hide box in all of the testing scenarios. These data suggest that CDP can alter the defensive strategy used by juvenile rats that are confronted with a predatory threat and can also lead to an earlier return to pre-threat levels of playfulness when that threat becomes less immediate.