Platelet imipramine binding and serotonin uptake in obsessive-compulsive patients

Platelet imipramine binding was measured in 16 drug-free nondepressed patients (aged 20-61 years, mean +/- SD 35 +/- 8) suffering from obsessive-compulsive disorder (OCD) and in 16 sex-, race- and age-matched healthy controls. Imipramine binding capacity and affinity were not different in the 2 groups. Platelet serotonin (5-HT) uptake capacity, Vmax, was also measured in 15 of these patients and their matched controls. Vmax was significantly higher in the patients (309 +/- 149 pmol/10(9) cells/min) than in the controls (181 +/- 110). An increase in platelet 5-HT uptake supports the involvement of 5-HT in OCD and may suggest that a hyperactive serotonergic system is present in this disorder.