Platelet serotonin functions in untreated major depression

The uptake of [C-14]5-HT, [H-3]paroxetine and [H-3]LSD binding was determined in platelets from 30 untreated patients with major depression and compared with corresponding variables from 30 healthy age-, sex- and season-matched control subjects. The maximum velocity (V-max) for the 5-HT uptake was significantly decreased in patients (P = 0.014) compared to control subjects. Depressed women had significantly lower V-max than female control subjects. In men, V-max did not differ between patients and control subjects. V-max was significantly lower in male inpatients compared with male outpatients (P = 0.05). The density (B-max) of 5-HT uptake sites was found to be significantly increased in patients (P < 0.05) compared to control subjects and male patients had significantly higher B-max than male control subjects, but there was no difference between female control subjects and female patients. No significant difference was found in B-max of 5-HT2-receptors between patients and control subjects. A positive correlation was found between B-max of 5-HT2-uptake sites and the degree of anxiety and between B-max of 5-HT2 receptors and MADRS scores. B-max of 5-HT2-receptors was positively correlated with the degree of suicidality. The results in the present study indicate that there may be a gender difference in serotonergic dysfunction in depression. (C) 1999 Elsevier Ireland Ltd. All rights reserved.