Effects of antidepressants and antipsychotics on the 5HT2 receptor-mediated signal transducing system in human platelets

The IC₅₀ values of the antidepressants amoxapine, mianserin, desipramine, clomipramine and imipramine, and the antipsychotics spiroperidol, chlorpromazine, levomepromazine and haloperidol for³H-ketanserin binding, 5HT-induced intracellular Ca²⁺ increase, 5HT-induced shape change and³H-paroxetine binding in human plateletes were measured and the correlations of each parameter were examined. Results were as follows. Both the antidepressants and the antipsychotics had inhibitory effects on³H-ketanserin binding, 5HT-induced intracellular Ca²⁺ increase and 5HT-induced shape change and there were significant positive correlations between the IC₅₀ values of these three parameters. On the other hand, there were no significant correlations between the IC₅₀ values in³H-paroxetine binding and those in the other three parameters. These results suggest that³H-ketanserin binding, 5HT-induced intracellular Ca²⁺ increase and 5HT-induced shape change are useful and reliable tools for the assessment of the effects of the antidepressants and the antipsychotics on the 5HT₂ receptor-mediated signal transducing system in human platelets.