Antidepressant drugs given repeatedly increase binding to alpha 1-adrenoceptors in the rat cortex

The effect of antidepressant drugs, administered repeatedly, on binding to alpha 1-adrenoceptors in the rat cerebral cortex was studied using [3H]prazosin as a ligand. Imipramine, amitriptyline, citalopram and mianserin increased the binding (Bmax) assessed at 8:00 h. At 20:00 h such an effect was produced by imipramine, citalopram and mianserin. [3H]Prazosin binding in control rats was higher at 20:00 h than at 8:00 h. An increase in the density of alpha 1-adrenoceptors may be associated with the therapeutic activity of antidepressant drugs.