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 for 3H-ketanserin binding, 5HT-induced intracellular Ca2+ increase, 5HT-induced shape change and 3H-paroxetine binding in human platelets were measured and the correlations of each parameter were examined. Results were as follows. Both the antidepressants and the antipsychotics had inhibitory effects on 3H-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 in 3H-paroxetine binding and those in the other three parameters. These results suggest that 3H-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.