Platelet 5-HT and plasma MHPG levels in patients with bipolar I and bipolar II depressions and normal controls.
BACKGROUND
It has been suggested that platelet serotonin (5-HT) content may reflect aspects of the presynaptic reuptake of 5-HT, while plasma 3-methoxy-4-hydroxy-phenylglycol (MHPG) levels may provide an index of central noradrenergic function.


METHODS
In order to determine if there is a biological distinction in 5-HT or noradrenergic function within bipolar I and bipolar II depressions, we measured levels of platelet 5-HT and plasma MHPG in 12 patients with bipolar I depression, 12 patients with bipolar II depression, and 20 normal healthy controls. All subjects were medication free for at least 4 weeks prior to the study.


RESULTS
There was a trend towards higher platelet 5-HT in bipolar I or II depressions when compared to normal controls, whereas there was no difference in platelet 5-HT levels between bipolar I and II depressed patients. When bipolar I and II patients were pooled, there was a significant increase in platelet 5-HT levels in bipolar depressives compared to normal controls, and there was a trend towards a weak positive correlation between platelet 5-HT and 21-item HAMD scores in the patient group. In contrast, there was no difference in plasma MHPG levels between the three groups.


CONCLUSIONS
This study was limited to a small sample size, single point sampling and did not match seasons.


CONCLUSIONS
Our findings did not provide supportive evidence for a distinctive 5-HT or noradrenergic function within bipolar I and bipolar II depressions. However, the finding of increased platelet 5-HT levels in bipolar depressed patients compared to normal controls is consistent with the results of previous studies, and may suggest an increase in presynaptic 5-HT reuptake, presumably resulting from diminished synaptic 5-HT availability in this condition.
Shiah
I S
IS
Department of Psychiatry, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan, ROC. ubcshiah@direct.ca
Ko
H C
HC
Lee
J F
JF
Lu
R B
RB
D000328:Adult; D001714:Bipolar Disorder / Q000097:blood*; D001792:Blood Platelets / Q000737:chemistry*; D005260:Female; D006801:Humans; D008297:Male; D008734:Methoxyhydroxyphenylglycol / Q000097:blood*; D012701:Serotonin / Q000032:analysis*; D012720:Severity of Illness Index
D012701:Serotonin; D008734:Methoxyhydroxyphenylglycol