Stereoselective blockade of central [3H]5-hydroxytryptamine binding to multiple sites (5-HT1A, 5-HT1B and 5-HT1C) by mianserin and propranolol

Abstract

The interaction of the enantiomers of mianserin and propranolol with the binding of [³H]5-hydroxytryptamine ([³H]5-HT) to the 5-HT_1A, 5-HT_1B and 5-HT_1C sites, and with the binding of [³H]ketanserin to the 5-HT₂ site, has been evaluated in rat brain membranes. A stereoselective interaction at the 5-HT_1A, 5-HT_1B and 5-HT_1C sites was demonstrated for both compounds, with (-)-mianserin being a more potent displacer than (-)–mianserin and (-)-propranolol being more potent than (+)-propranolol. Only mianserin interacted in a stereoselective manner with the 5-HT₂ site, (+)-mianserin being the more potent isomer. The stereoselective association of mianserin and propranolol with the 5-HT_1A, 5-HT_1B and 5-HT_1C sites may prove useful in the characterization of these sites.