Resumo

Comorbidity between anxiety and depression is a remarkable issue in human behavioral disorders. Accordingly, a possible relationship between the behaviors seen in the elevated plus-maze and the forced swim test, animal models of anxiety and depression, respectively, is of great relevance. Sixty-five male rats were submitted to a plus-maze session and to a 2-day forced swim protocol. According to their time in the open arms, they were divided into three groups: Low Open (37.8 ± 5.3 s), Medium Open (96.3 ± 2.4 s) and High Open (146.7 ± 4.3 s). Analysis of variance and post hoc analysis indicated that the Low Open group showed decreases (p < 0.05, Duncan) in floating duration from forced swim Session 1 (26.0 ± 5.4 s) to Session 2 (13.3 ± 4.7 s). None of the other groups showed a similar decrease (in fact, they showed nonsignificant increases). In addition, some other plus-maze measures were coherent with time in the open arms and are suggested to also be reliable anxiety indexes: percentage of entries into the open arms, entries into and time spent in the open arm extremities, distance run in the open arms and time spent in the closed arms. Some other measures were only able to distinguish the Low Open from both the other groups. Mediation of the effect by reactivity to aversive stimulation or alterations induced by open arm exposure are possible explanations for the results.