STRUGGLING AND FLUMAZENIL EFFECTS IN THE SWIMMING TEST ARE RELATED TOTHE LEVEL OF ANXIETY IN MICE

The possible involvement of anxiety and learning/memory processes in e scape-directed (struggling) behavior in a two-trial swimming test was investigated in mice, as well as the differential effects that low dos es of flumazenil (a benzodiazepine receptor antagonist) could display depending on the animals' anxiety levels. Mice showing less anxiety in the plus-maze test exhibited less struggling behavior in the first sw imming trial than the more anxious animals, suggesting a relationship between anxiety and struggling behavior in the swimming test. Flumazen il (5 mg/kg) given before the first swimming trial displayed different ial effects depending upon the animals' anxiety levels. Thus, it incre ased struggling behavior in the first swimming trial in 'low-anxiety' mice whereas the opposite tendency was observed in 'high-anxiety' anim als. Struggling decreased in the second swimming trial in all the anim als, giving support to the involvement of learning/memory processes in the two-trial swimming test. That reduction in escape-directed behavi or was greater in animals treated with flumazenil before the first swi mming session, thus indicating a slight enhancement of retention.