[Changes in 5-HT2 receptor density induced by repeated treatment with 5-HT uptake inhibitor or 5-HT agonist].

It has been known that many antidepressant drugs which have serotonin (5-HT) antagonistic activities and 5-HT antagonists can induce the reduction of 5-HT2 receptor binding by their acute or successive administration. We investigated the effects of repeated treatment with 5-HT agonists on 5-HT2 receptors in rat cerebral cortex. We used citalopram as selective 5-HT uptake inhibitor, 5-hydroxytryptophan as 5-HT precursor, and 5-methoxy-N,N'-dimethyltryptamine as 5-HT2 agonist. The 5-HT2 receptor density was decreased by repeated treatment with these respective drugs. So it may be supposed that the reduction of 5-HT2 receptor binding is induced not only by 5-HT antagonists but also by 5-HT agonists.