Serotonin but not norepinephrine-induced calcium mobilization of platelets is enhanced in affective disorders

Abstract

Intracellular calcium concentrations ([Ca⁺⁺]_i) in blood platelets from 11 depressed patients and 11 healthy controls were investigated. The resting [Ca⁺⁺]_i of platelets from depressed patients was 69.4±2.9 nM while that from controls was 74.6±4.0 nM. Serotonin (5-HT), at a concentration of 10 µM, increased [Ca⁺⁺]_i by 129.2±3.9 nM in platelets from depressed patients, which was significantly greater than that found in platelets from control subjects (105.2±6.0 nM). Norepinephrine (NE) 100 µM increased [Ca⁺⁺]_i by 46.1±7.1 nM in platelets from depressed patients, and by 38.6±6.1 nM in platelets from controls, respectively. These results indicate that 5-HT₂ receptor function in platelets of depressed patients is enhanced, and support the hypothesis of hypersensitivity of 5-HT₂ receptors in affective disorders.