Bupropion effects on aggressiveness and anxiety in OF1 male mice.

RATIONALE

Bupropion is an antidepressant drug that is being used to help in giving up smoking. Its behavioral effects have been evaluated in different animal models, although limited information is available regarding its effects on aggressiveness, anxiety and exploratory behavior.

OBJECTIVES

Evaluate acute effects of bupropion on locomotor activity, isolation-induced aggression, hole-board and elevated plus-maze tests in OF1 male mice.

METHODS

In the first experiment, effects of bupropion (2.5, 5, 10, 20 and 40 mg/kg) on locomotion were evaluated. In the second experiment, isolation-induced aggression was assessed in isolated male mice previously classified as short attack latency (SL) and long attack latency (LL). Mice were treated with bupropion or vehicle and confronted with standard opponents for 10 min. In experiments 3 and 4, mice were treated with bupropion or vehicle and 30 min later examined in the plus-maze or in the hole-board apparatus.

RESULTS

In the actimeter, bupropion induced a dose-dependent increase in locomotion. During agonistic encounters, bupropion (10 mg/kg and 40 mg/kg) increased time devoted to attack in LL mice. In the plus-maze, no significant differences were found between bupropion-treated and vehicle-treated mice in the percentage of entries or time spent in open arms. In the hole-board, the highest dose of bupropion (40 mg/kg) significantly decreased number of head-dips and increased latency to the first head-dip.

CONCLUSIONS

During agonistic encounters the two sub-groups of mice (SL and LL) may display differential sensitivity in drug-induced changes on aggressiveness, since bupropion increased attack only in mice with "long attack latency" in the pre-screening test. In the plus-maze, this drug does not seem to have specific actions on anxiety and in the hole-board a high dose had similar effects to those induced by anxiogenic drugs.