Platelet cytosolic calcium responses to serotonin in depressed patients and controls: Relationship to symptomatology and medication

Background: Serotonin produces an exaggerated rise in platelet cytosolic calcium (Delta[Ca++](i)) in patients with mood disorders. Studies on patients with bipolar disorder consistently demonstrate calcium abnormalities. By comparison, data on patients with major depression are more variable. Methods: To determine causes of variability, we utilized Fura-2 loaded platelets to compare changes in platelet intracellular calcium levels (Delta[Ca++](i)) following serotonin stimulation in 24 patients with major depression and in 20 controls. We also sought relationships between the Delta[Ca++](i) responses and scores on clinical depression and anxiety scales. Results: We found positive correlations between Delta[Ca++](i) responses and the clinical scales across all subjects. Furthermore, depressed patients with high anxiety had significantly increased Delta[Ca++](i) responses compared to depressed patients with low anxiety. In addition, patients receiving selective-serotonin reuptake inhibitors (SSRIs) demonstrated reduced Delta[Ca++](i) responses compared to patients not on SSRIs. Conclusions: Since elevations in [Ca++](i) mediate platelet aggregation and secretion cascades, the enhanced responsivity observed in depressed and in particular anxious, depressed patients may contribute to their increased risk for vascular disease. (C) 1998 Society of Biological Psychiatry.