We studied the effect of antidepressant drugs (imipramine, amitriptyline, citalopram, mianserin: 10 mg/kg p.o. each; rolipram: 5 mg/kg p.o.) and ECS administered acutely and repeatedly (antidepressant drugs: twice daily for 21 days; ECS: once daily for 10 days) on the increase in food intake induced by clonidine (20 nmole) injected into the paraventricular nucleus of the hypothalamus in satiated rats. The response to clonidine was potentiated after repeated, but not acute, treatment with imipramine, while it was not modified following both acute and prolonged administration of amitriptyline. On the other hand, citalopram, mianserin and rolipram reduced the clonidine response after their acute and repeated administration; at the same time only 2 of these drugs (citalopram and rolipram) administered repeatedly produced such an effect in a drug-free period (i.e. 72 hr and 7 days after their last dose). A reduction of the clonidine-induced increase in food intake was observed following single and repeated application of ECS. Our results do not support the hypothesis that the subsensitivity of central alpha 2-adrenoceptors is a common feature of the prolonged antidepressant treatment.