Serotonin-induced platelet intracellular calcium mobilization in various psychiatric disorders: is it specific to bipolar disorder?

Background: Serotonin (5-HT)-stimulated platelet intracellular calcium (Ca) mobilization has been reported to be enhanced in unmedicated depressive pa tients compared to those of normal healthy subjects, which suggests increas ed 5-HT2A receptor function in these patients. It has not been ascertained whether this enhanced response is specific to some type of affective disord ers among various mental disorders. Methods: We examined 5-HT-induced plate let intracellular Ca response in 152 unmedicated outpatients with various p sychiatric disorders including bipolar disorder (BD), major depressive diso rder with melancholia (DM), major depressive disorder without melancholia ( DN), schizophrenia (SCH), panic disorder (PD), obsessive-compulsive disorde r (OCD), social phobia (SP) and bulimia nervosa (BN), and 30 normal control s. Results: We observed no significant differences in basal intracellular C a concentration among all patient subgroups and normal controls. While the 5-HT-induced Ca response was significantly and specifically higher in patie nts with ED than in normal controls, no significant differences were found in the Ca response to 5-HT between patients with DM, DN, SCH, PD, OCD, SP a nd BN, and normal controls. Limitations: The sample sizes of each group are still small. Therefore, they have to be enlarged in the continuation of th e study so as to increase the power of the statistical tests. Conclusion: T hese results indicate the possibility that enhanced signal transduction, me diated by the 5-HT2A receptor, may be specific to bipolar disorder. (C) 200 1 Elsevier Science B;V. All rights reserved.