Long-term antidepressant treatment decreases spiroperidol-labeled serotonin receptor binding.

Antidepressants compete at several neurotransmitter receptor binding site, but drug affinities do not correlate with clinical efficacy. Long-term, but not short-term, antidepressant treatment decreases the numbers of both serotonin and beta-adrenergic receptors. The decrease in the number of receptor sites is most marked for [3H]spiroperidol-labeled serotonin receptors and is characteristic for antidepressants of several classes.