Changes in the platelet intracellular calcium response to serotonin in patients with major depression treated with electroconvulsive therapy: state or trait marker status

Platelet serotonin type 2A receptor (5-HT2A) sensitivity changes have previ ously been documented in depression, although it is unclear if this represe nts a stable trait marker of the illness, or whether it represents an acute state marker of depression that would change with treatment. Electroconvul sive therapy (ECT) may be a useful intervention to separate out trait and s tate marker status avoiding the potential confounding effects of pharmacoth erapy on receptor function. Using spectrofluorometry, the platelet 5HT(2A), receptor sensitivity as reflected by the intracellular calcium response to serotonin stimulation, was measured every week in patients suffering from major depression and undergoing ECT. There was a significant drop in the pl atelet response to serotonin stimulation over a course of ECT, with an asso ciated progressive decrease in Hamilton Rating Scale of Depression (HAM-D) scores. This may suggest either decreased sensitivity of platelet 5HT(2A) r eceptors as a mechanism of action of ECT, or changes in second messengers s uch as the inositide phospholipid system. This suggests that the enhanced s ensitivity of platelet 5HT(2A) receptors may be a state marker of major dep ression. (C) 2000 Lippincott, Williams and Wilkins.