title: Further studies on platelet serotonin transporter binding in depression.
abstract: OBJECTIVE
  There is an impressive literature implicating abnormalities in serotonergic neural systems in depression. Many investigators, but not all, have reported low numbers of platelet and brain serotonin (5-HT) transporter sites in drug-free depressed patients. In the present study the authors sought to determine whether the low platelet 5-HT transporter binding in depressed patients is due to previous antidepressant drug exposure. In addition, the binding of both [3H]imipramine and the more specific ligand [3H]paroxetine to the platelet 5-HT transporter was compared in drug-free depressed patients and age- and sex-matched normal comparison subjects.
  
  
  METHODS
  In the first experiment blood samples were obtained from 12 depressed patients who had never received antidepressant drugs and 12 normal comparison subjects, and platelet 5-HT transporter binding was measured by using [3H]imipramine. In the second experiment blood samples were obtained from 28 drug-free depressed patients and 28 age- and sex-matched comparison subjects, and platelet 5-HT transporter binding was assessed by using both [3H]imipramine and [3H]paroxetine.
  
  
  RESULTS
  In the first experiment the never-medicated depressed patients exhibited fewer platelet [3H]imipramine binding sites than did the comparison subjects. In the second experiment the drug-free depressed patients had fewer platelet binding sites for both [3H]imipramine and [3H]paroxetine than did the comparison subjects.
  
  
  CONCLUSIONS
  The low number of platelet [3H]imipramine binding sites does not appear to be due to prior antidepressant drug exposure. The Bmax of platelet binding sites for both [3H]imipramine and [3H]paroxetine, ligands used to measure 5-HT transporter binding, is abnormally low in depressed patients.
authors.affiliation: Department of Psychiatry and Behavioral Sciences, Emory University School of Medicine, Atlanta, GA 30322-4990.
authors.forename: C B
authors.initials: CB
authors.lastname: Nemeroff
authors.forename: D L
authors.initials: DL
authors.lastname: Knight
authors.forename: J
authors.initials: J
authors.lastname: Franks
authors.forename: W E
authors.initials: WE
authors.lastname: Craighead
authors.forename: K R
authors.initials: KR
authors.lastname: Krishnan
mesh_terms: D000928:Antidepressive Agents / Q000494:pharmacology; D001798:Blood Proteins / Q000378:metabolism*; D002352:Carrier Proteins / Q000378:metabolism*; D003866:Depressive Disorder / Q000097:blood / Q000378:metabolism* / Q000503:physiopathology; D005260:Female; D006023:Glycoproteins / Q000378:metabolism; D006801:Humans; D007099:Imipramine / Q000378:metabolism; D008024:Ligands; D008297:Male; D008875:Middle Aged; D017374:Paroxetine / Q000378:metabolism; D011869:Radioligand Assay; D011955:Receptors, Drug / Q000378:metabolism; D012701:Serotonin / Q000502:physiology; D050486:Serotonin Plasma Membrane Transport Proteins
chemical_list: D000928:Antidepressive Agents; D001798:Blood Proteins; D002352:Carrier Proteins; D006023:Glycoproteins; D008024:Ligands; D011955:Receptors, Drug; D050486:Serotonin Plasma Membrane Transport Proteins; C027775:imipramine receptor; D012701:Serotonin; D017374:Paroxetine; D007099:Imipramine