An animal model for measuring behavioral responses to anxiogenic and anxiolytic manipulations.

A method for measuring behavioral responses of rats to both anxiolytic and anxiogenic manipulations, the open field drink test (OFDT), is described. This method utilizes the concept that in the open field, appetitive behavior is reduced because of the ambient level of fear experienced in such an environment. For the OFDT, rats were given restricted access to water for 1 h per day for 3 days, and then their behavior was assessed in an open field that contained a water spout at its center. Use of the open field permitted a number of measures to be taken; of these, "time spent drinking" was most sensitive in detecting differences. Three experiments showed that the OFDT: a) permitted dissociation between behavioral responses to an anxiolytic (diazepam) and an anxiogenic (FG7142) drug, b) detected a dose-response relationship for an anxiolytic drug (diazepam), and c) detected behavioral responses to environmental manipulations designed to increase fear (presence of an olfactory cue from rats that had received foot shock). Advantages of this test over previously described methods are outlined, and several guidelines are provided to aid investigators in using this behavioral test.