SEROTONERGIC MARKERS IN PLATELETS OF PATIENTS WITH MAJOR DEPRESSION -UP-REGULATION OF 5-HT2 RECEPTORS

The uptake of [H-3]5-HT and the density (B(max)) as well as affinity ( Kd) of 5-HT uptake sites labelled with [H-3]paroxetine and of 5-HT2 re ceptors labelled by [H-3]LSD were determined in platelets from 25 medi cation-free patients with major depression and 20 normal controls. The density (B(max)) of 5-HT2 receptors was found to be significantly inc reased (by 52%) in platelets from depressed patients, particularly fem ales. No changes were found in the affinity (Kd) of 5-HT2 receptors an d in 5-HT uptake or [H-3]paroxetine binding parameters. Density of 5-H T2 receptors positively correlated with that of [H-3]paroxetine sites in control but not in depressed subjects. No correlation was found bet ween the HAMD scores and B(max) of [H-3]LSD binding. The results sugge st that upregulation of platelet 5-HT2 receptors is a useful biologica l marker in major depression, particularly in females.