Modulation of rat brain alpha 2- and beta-adrenergic receptor sensitivity following long-term treatment with antidepressants.

After 7 days of treatment with a variety of antidepressant drugs (desipramine, imipramine, clomipramine, nortriptyline, nialamide), both an increase in alpha 2-receptor density and a decrease in beta-receptor density were observed in the cerebral cortex but not limbic forebrain. However, mianserin caused a marked increase in alpha 2-receptors without any change in beta-receptors. Nisoxetine did not produce any change in these two adrenergic receptors. It is suggested that intrasynaptic norepinephrine is important but that, in addition, other factors may be involved in the increase in alpha 2-receptors induced by antidepressant drugs.