Effect of methiothepin on imipramine- or mianserin- induced subsensitivity of serotonergic receptors.

Effect of methiothepin on imipramine- or mianserin- induced subsensitivity of serotonergic receptors was examined in rat brain. Treatment with either imipramine plus methiothepin or mianserin plus methiothepin for 4 days resulted in a significant decrease in [3H]5-hydroxytryptamine ([3H]5-HT) binding in synaptic membranes. The binding was not significantly decreased after treatment for this period of time with either methiothepin, imipramine or mianserin alone. It is suggested that the elevated intrasynaptic 5-HT levels could contribute to potentiation effect of methiothepin on imipramine- or mianserin-induced down regulation of serotonergic receptors.