CHANGES IN PLATELET MARKERS OF OBSESSIVE-COMPULSIVE PATIENTS DURING ADOUBLE-BLIND TRIAL OF FLUVOXAMINE VERSUS CLOMIPRAMINE

Abnormalities of platelet serotonin (5-HT) transporter, which are supp osed to reflect similar dysfunctions in the central nervous system (CN S), have been reported in obsessive-compulsive disorder (OCD). Other p latelet parameters altered in OCD are represented by phenolsulfotransf erase (PST) activity, an enzyme involved in the catabolism of catechol ic neurotransmitters, and peripheral benzodiazepine receptors. Since n o information is available on the behavior of these putative markers d uring antiobsessive treatments, the aim of the present study was to me asure 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 ob sessive-compulsive disorder (OCD) before and after a treatment with fl uvoxamine versus clomipramine. The results showed that at baseline the patients had a decreased number of H-3-IMI binding sites, which corre lated negatively with the Y-BOCS total score, an increased PST activit y 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-I MI binding sites increased significantly toward normal values, white t he 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 ill ness and possibly to a positive response to serotonin reuptake inhibit ors, and might be considered as a state-dependent marker, whereas the PST activity would seem to be a trait of the illness.