Reversal of stress-induced deficit in aggression by monoamine oxidase inhibitors

In the present study we investigated the effect of two monoamine oxidase (MAO) inhibitors: moclobemide (selective, reversible inhibitor of MAO-type A) or selegiline (selective irreversible inhibitor of MAO-type B) on electric footshock-induced fighting behavior in normal (unstressed) and chronically stressed (14 various stressors over 16 days) rats. In rats exposed to chronic stress the number of fighting attacks was reduced by about 75%. Prolonged (once a day, for 14 days) treatment with moclobemide (50 mg/kg/day) or selegiline (2 mg/kg/day) counteracted the deficit in aggression induced by chronic stress. The findings of the present study demonstrate that the selective MAO inhibitors, moclobemide and selegiline, protect against "behavioral depression" induced by the chronic stress similarly to other classes of antidepressant drugs.