5HT2 receptor-mediated function in depressed patients: investigation by measuring 5HT-induced shape change of blood platelets.

The 5HT-induced shape change (5HT-SC) of blood platelets, which had been suggested to reflect the 5HT2 receptor-mediated function of the central nervous system (CNS), was examined in patients with depression before or after antidepressant therapy. The degree of 5HT-SC did not differ between patients before treatment (n = 17) and healthy controls (n = 26). In patients after treatment (n = 12), in whom depression had been improved but drug therapy was continued, 5HT-SC in a concentration of 10(-5) M 5HT was observed more potently than that in healthy controls or untreated patients (p less than 0.05 and p less than 0.05, respectively). In 4 patients in whom 5HT-SC was measured before and after mianserin treatment, 5HT-SC increased after the treatment. These results suggest that the 5HT2 receptor-mediated function in the CNS may not be damaged in patients with depression, and that the 5HT2 receptor-mediated function in the CNS may be enhanced by antidepressants.