EFFECTS OF ANTIDEPRESSANTS AND ANTIPSYCHOTICS ON THE 5HT(2) RECEPTOR-MEDIATED SIGNAL-TRANSDUCING SYSTEM IN HUMAN PLATELETS

The IC50 values of the antidepressants amoxapine, mianserin, desiprami ne, clomipramine and imipramine, and the antipsychotics spiroperidol, chlorpromazine, levomepromazine and haloperidol for H-3-ketanserin bin ding, 5HT-induced intracellular Ca2+ increase, 5HT-induced shape chang e and H-3-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 effec ts on H-3-ketanserin binding, 5HT-induced intracellular Ca2+ increase and 5HT-induced shape change and there were significant positive corre lations between the IC50 values of these three parameters. On the othe r hand, there were no significant correlations between the IC50 values in H-3-paroxetine binding and those in the other three parameters. Th ese results suggest that H-3-ketanserin binding, 5HT-induced intracell ular Ca2+ increase and 5HT-induced shape change are useful and reliabl e tools for the assessment of the effects of the antidepressants and t he antipsychotics on the 5HT(2) receptor-mediated signal transducing s ystem in human platelets.