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 (B_max) and the apparent dissociation constant (K_d) of 5-HT₂ receptors were determined by receptor binding techniques using ¹²⁵I-lysergic acid diethylamide (LSD) as radioligand. We observed that the mean B_max 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 K_d 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 B_max and K_d with baseline scores of the Hamilton Depression Rating Scale (HDRS), the Yale-Brown Obsessive-Copullsive Scale (Y-BOCS), and the National Institute of Mental Health (NIMH) Obsessive-Compulsive scale (GOCS). We found no significant correlation betwwen baseline B_max and K_d 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.