SEROTONIN-INDUCED PLATELET INTRACELLULAR CALCIUM MOBILIZATION IN DEPRESSED-PATIENTS

Serotonin(S-HT)-stimulated intracellular calcium(Ca) mobilization was measured in the platelets of depressed patients to assess 5-HT2 recept or function. The 5-HT-induced Ca response was significantly higher in unmedicated patients with bipolar depression and melancholic major dep ression than in those with nonmelancholic major depression and normal controls. The enhanced Ca response to 5-HT failed to correlate with se verity of depressive symptoms. In patients with bipolar disorder and m elancholic major depression, there was no significant difference in 5- HT-stimulated Ca response between the unmedicated group and those in r emission. These results suggest that 5-HT2 receptor function is increa sed in some types of depression, and raise the possibility that the en hanced Ca response to 5-HT may be trait dependent rather than state de pendent.