The effect of lithium on the thrombin-induced 5-hydroxytryptamine release of human platelets in controls and subjects with affective disorders: A preliminary report

The purpose of this study was to compare thrombin-induced [³H]-5-hydroxytryptamine (serotonin, 5HT) release from platelets in normal controls and subjects with diagnosed affective disorders who were treated with lithium carbonate. In vitro lithium (10 mM) did not affect the thrombin-induced [³H]-5HT release in either controls or patients. However, the EC₅₀ of thrombin for activation of [³H]-5HT release from platelets was lower in two manic patients than in two depressed patients. This preliminary finding suggests that further comparative study of the coupling between membrane receptors involving phosphoinositide metabolism and second messenger systems and intracellular events from platelets of manic and depressive subjects may be useful for diagnostic or mechanistic purposes in the study of the affective disorders.