Binding profile of trazodone and dapiprazole to some brain receptors

Trazodone and dapiprazole displace ligands binding to rat brain alpha-1 adrenoceptors. The displacement of 3H-ligands to alpha-2, serotonin1 (5-HT1), dopamine, beta and opiate receptors is either absent or takes place at relatively higher concentrations. Trazodone, unlike dapiprazole, also inhibits binding to serotonin2 (5-HT2) receptors. Some pharmacological effects show a satisfactory correlation with these data. The psychopharmacological effects of trazodone and dapiprazole are similar, whereas the binding inhibition to 5-HT2 receptors is different, which would indicate that the psychopharmacological effects do not primarily depend on these receptors. The displacement of the binding to alpha-1 adrenoceptors by dapiprazole has a time course similar to that of its brain concentrations as well as to that of sedative and alpha-blocking effects. Dapiprazole and trazodone have antinociceptive effects and inhibit the binding to opiate receptors, although at relatively high concentrations.