Serotonin receptors in platelets of bipolar and schizoaffective patients: effect of lithium treatment.
BACKGROUND
Abnormalities of serotonin (5HT) function have been implicated in mood disorders, and lithium treatment may produce its beneficial effects by modifying serotonergic mechanisms. It has also been observed that 5HT2A receptors are upregulated both in the postmortem brain and platelets of patients with depression and suicidal behavior. However, the role of 5HT2A receptors in bipolar disorders and in the mechanism of action of lithium is unclear.


OBJECTIVE
The major objective of this study was to examine if abnormalities of 5HT2A receptors are associated with bipolar or schizoaffective disorders and if treatment with lithium would cause changes in the 5HT2A receptors.


METHODS
5HT2A receptors were studied in the platelets obtained from drug-free normal control subjects and patients with bipolar ( n=41) or schizoaffective ( n=20) disorders during a drug-free washout period and after treatment (4.0+/-0.44 weeks) with lithium ( n=16). The Bmax and K(D) of 5HT2A receptors were quantitated by binding techniques using [125I]lysergic acid diethylamide (LSD) as a ligand.


RESULTS
We observed that the 5HT2A receptor Bmax was increased in platelets obtained from drug-free bipolar or schizoaffective patients as compared with normal control subjects. The 5HT2A receptor density was even more increased in bipolar or schizoaffective suicidal patients, and the 5HT2A receptor Bmax in the non-suicidal bipolar or schizoaffective subgroup also was significantly higher than in normal control subjects. Treatment with lithium caused a significant increase in the B(max) of platelet 5HT2A receptors in bipolar or schizoaffective patients.


CONCLUSIONS
Our studies indicate that increased 5HT2A receptors may be associated with the pathophysiology of bipolar illness and that treatment with lithium further increases the density of 5HT2A receptors. Whether this increase in 5HT2A receptors caused by lithium is associated with its therapeutic mechanism of action is unclear. It is also not clear whether the increase in 5HT2A receptors in bipolar or schizoaffective patients, or in suicidal bipolar or schizoaffective patients, is a trait or state marker.
Pandey
Ghanshyam N
GN
Psychiatric Institute, Department of Psychiatry, University of Illinois at Chicago, 1601 West Taylor Street, Chicago, IL 60612, USA. Gpandey@psych.uic.edu
Pandey
Subhash C
SC
Ren
Xinguo
X
Dwivedi
Yogesh
Y
Janicak
Philip G
PG
D000328:Adult; D000704:Analysis of Variance; D014150:Antipsychotic Agents / Q000627:therapeutic use; D001665:Binding Sites; D001714:Bipolar Disorder / Q000097:blood / Q000188:drug therapy / Q000378:metabolism*; D001792:Blood Platelets / Q000187:drug effects* / Q000378:metabolism; D004359:Drug Therapy, Combination; D005260:Female; D006801:Humans; D007456:Iodine Isotopes / Q000493:pharmacokinetics; D008094:Lithium / Q000494:pharmacology* / Q000627:therapeutic use; D008238:Lysergic Acid Diethylamide / Q000493:pharmacokinetics; D008297:Male; D011618:Psychotic Disorders / Q000097:blood / Q000188:drug therapy / Q000378:metabolism*; D044402:Receptor, Serotonin, 5-HT2A / Q000378:metabolism*; D058826:Serotonin 5-HT2 Receptor Agonists; D058830:Serotonin 5-HT2 Receptor Antagonists; D013406:Suicide, Attempted; D014018:Tissue Distribution
D014150:Antipsychotic Agents; D007456:Iodine Isotopes; D044402:Receptor, Serotonin, 5-HT2A; D058826:Serotonin 5-HT2 Receptor Agonists; D058830:Serotonin 5-HT2 Receptor Antagonists; D008238:Lysergic Acid Diethylamide; D008094:Lithium