Changes in platelet markers of obsessive-compulsive patients during a double-blind trial of fluvoxamine versus clomipramine

Abnormalities of platelet serotonin (5-HT) transporter, which are supposed to reflect similar dysfunctions in the central nervous system (CNS), have been reported in obsessive-compulsive disorder (OCD). Other platelet parameters altered in OCD are represented by phenolsulfotransferase (PST) activity, an enzyme involved in the catabolism of catecholic neurotransmitters, and peripheral benzodiazepine receptors. Since no information is available on the behavior of these putative markers during antiobsessive treatments, the aim of the present study was to measure and compare H-3-imipramine (H-3-IMI) binding, which labels the 5-HT transporter, PST activity, and H-3-PK 11195 binding, which labels peripheral benzodiazepine receptors, in a group of 18 patients with obsessive-compulsive disorder (OCD) before and after a treatment with fluvoxamine versus clomipramine. The results showed that at baseline the patients had a decreased number of H-3-IMI binding sites, which correlated negatively with the Y-BOCS total score, an increased PST activity and no difference in H-3-PK 11195 binding, as compared with healthy volunteers. After eight weeks of treatment with either clomipramine or fluvoxamine, which was effective in all patients, the number of H-3-IMI binding sites increased significantly toward normal values, white the PST showed no change. These findings suggest that the reduction in H-3-IMI binding sites in OCD may be related to the severity of the illness and possibly to a positive response to serotonin reuptake inhibitors, and might be considered as a state-dependent marker, whereas the PST activity would seem to be a trait of the illness.