Effects of chronic treatment with antidepressants on aggressiveness induced by clonidine in mice

Abstract

It has previously been found that a number of typical and atypical antidepressants, given chronically, intensify clonidine-induced aggressiveness in mice. Further experiments now show that chronic, but not acute, administration of nisoxetine, a selective inhibitor of noradrenaline uptake, potentiates clonidine-induced aggressiveness. Citalopram and fluvoxamine, two selective inhibitors of serotonin uptake, have no such action. Of the two isomers of flupenthixol, only thetrans-form, potentiates clonidine-induced aggressiveness in chronic experiments. Thecis-form induces an inhibiting effect. Clonidine-induced aggressiveness is also intensified by chronic, but not by acute, administration of pizotifen, an antagonist of serotonin and noradrenaline. The results seem to support the previous hypothesis that potentiation of clonidine-induced aggressiveness is mediated by anα ₁-adrenergic mechanism.