Antidepressant treatment and rodent aggressive behaviour

This review examines two ‘ethologically relevant’ rodent models, the resident–intruder and social hierarchy paradigms, that are sensitive to chronic antidepressant treatment (including repeated electroconvulsive shock). These models of rodent social and agonistic behaviour demonstrate that acute and chronic treatment with antidepressant drugs (regardless of their acute pharmacological activity) induce diametrically opposite changes in rodent aggressive behaviour. The common ability of chronic antidepressant treatment to increase rodent aggression (which in turn results in increased hierarchical status in closed social groups) most likely reflects the increased assertiveness and associated externalization of emotions (indicative of increased extrapunitive aggression) expressed during recovery from depressive illness. Finally, findings that relate observed behavioural changes to underlying neurochemical changes are briefly reviewed in terms of adaptive mechanisms in the rodent central nervous system induced by antidepressants, and also with respect to suicide ideation and panicogenic responses observed in some patients at the onset of treatment with selective serotonin reuptake inhibitors for affective disorders.