Antidepressants selectively antagonize the hyperactivity induced in rats by long-term isolation.

Rats isolated at 16--18 days of age showed after 10--12 months a complex behavioural syndrome in which locomotor activity was markedly increased when compared to that of group-housed controls. The hyperactivity of the socially deprived animals was selectively blocked by clinically effective antidepressants but not by other classes of psychotropic drugs. The present animal model may be of value for the detection of new antidepressants and contribute to elucidate the aetiology of depression.