The effects of antidepressants on aggressiveness induced by social deprivation in mice

The effects of four different antidepressants-imipramine, clomipramine, amitriptyline and maprotiline-on aggressiveness induced by prolonged social deprivation (isolation) in mice were studied. Acute administration of even high doses of imipramine and clomipramine did not inhibit belligerent behaviour in isolated mice. However, chronic treatment (21 days) with 10 mg/kg IP of these drugs resulted in a progressive increase in the latency period before the onset of attacks and in total suppression of fighting in about 30-40% of treated pairs. Furthermore, both drugs partially prevented the development of aggressiveness when administered to mice from the beginning of the isolation period. Amitriptyline and maprotiline differed from the foregoing drugs in that they already; inhibited aggressiveness after single, although high, doses. Maprotiline in particular was more efficacious than any of the other compounds in preventing or suppressing aggressiveness after chronic treatment at doses inactive upon acute administration. Chronic effects of antidepressants on this type of aggressiveness are tentatively explained by their ability to reduce the sensitivity of adrenergic receptors.