Acute effect of dopamine agonists and some antidepressants in stress-induced deficit of fighting behavior.

The effect of dopamine (DA) agonists (apomorphine, quinpirole) and three antidepressants (selegiline, nomifensine, imipramine), given in a single dose, on the electric footshock-induced fighting behavior was investigated in the control and chronically stressed rats. It was found that 48 h after the last session of chronic stress (various stressors applied for 16 days) the number of shock-induced fighting attacks was reduced by 50-70% in comparison with the control value. The drugs (except for imipramine), given in a single dose, 48 h after the last session of chronic stress, increased the number of fighting attacks and restored it to the control or above the control value. The same drugs at doses used, changed neither the intensity of fighting in the control (unstressed) rats nor the exploratory activity in both groups of animals. It is concluded that the short-lasting dopaminergic activation facilitates the aggressiveness reduced by chronic stress and that this effect does not depend on the locomotor activity level.