Platelet serotonin-2 receptors in obsessive-compulsive disorder

To examine the role of serotonin-2 (5-HT2) receptors in obsessive-compulsive disorder (OCD), we studied 5-HT2 receptors in platelets obtained from patients with OCD (n = 20) during a drug free baseline period, as well as in normal control subjects (n = 25). The maximum number of binding sites (Bmax) and the apparent dissociation constant (Kd) of 5-HT2 receptors were determined by receptor binding techniques using 125I-lysergic acid diethylamide (LSD) as radioligand. We observed that the mean Bmax of 125I-LSD binding in platelets of patients with OCD was not significantly different when compared with normal control subjects. There was also no significant difference in Kd values between patients with OCD and normal control subjects. To examine whether the baseline 5-HT2 receptors are related to the severity of illness, we determined the relationships of the baseline Bmax and Kd with baseline scores of the Hamilton Depression Rating Scale (HDRS), the Yale-Brown Obsessive-Compulsive Scale (Y-BOCS), and the National Institute of Mental Health (NIMH) Obsessive-Compulsive scale (GOCS). We found no significant correlation between baseline Bmax and Kd with the baseline HDRS, Y-BOCS, or NIMH-GOCS scores. Our results do not indicate abnormal 5-HT2 receptors in platelets of patients with OCD.