Further studies on platelet serotonin transporter binding in depression.
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.
Nemeroff
C B
CB
Department of Psychiatry and Behavioral Sciences, Emory University School of Medicine, Atlanta, GA 30322-4990.
Knight
D L
DL
Franks
J
J
Craighead
W E
WE
Krishnan
K R
KR
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
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