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S005-3

Regulation of Serotonin Transporter by Cytokines: An Implication of
Pathophysiology of Bipolar Disorder

Yuan Hwa Chou1, Wen-Chi Hsieh1, Jiing-Feng Lirng2, Shyh-Jen Wang3

1Departments of a Psychiatry, Taipei Veterans General Hospital and National Yang Ming University, Taipei,
Taiwan 2Departments of Radiology, Taipei Veterans General Hospital and National Yang Ming University, Taipei,
Taiwan 3Departments of Nuclear Medicine, Taipei Veterans General Hospital and National Yang Ming University,
Taipei, Taiwan

Content: Reduced brain serotonin transporter (SERT) has been demonstrated in bipolar disorder
(BD). The aim of this study was to explore the potential role of different cytokines on reduced SERT
in BD. Twenty-eight BD type I patients and 28 age- and gender-matched healthy controls (HCs) were
recruited. Single photon emission computed tomography with the radiotracer 123I-ADAM was used
for SERT imaging. Regions of interest included the midbrain, thalamus, putamen and caudate. Seven
cytokines, including tumor necrosis factor-α (TNF-α), interferon-γ (IFN-γ), interleukin-1α (IL-1α),
IL-1β, IL-4, IL-6 and IL-10, were measured using an enzyme linked immune-sorbent assay. SERT
availability in the midbrain and caudate was significantly lower in BD compared to HCs. IL-1β was
significantly lower, whereas IL-10 was significantly higher in BD compared to HCs. Multiple linear
regression analyses considering group and all cytokines revealed that IL-1α, IL-1β and IL-6 could
predict SERT availability in the midbrain but not in the thalamus, putamen and caudate. However,
linear mixed effect analyses demonstrated that this predictive effect was not different between HCs
and BD. While many cytokines have been proposed to be important in the pathophysiology of BD,
our results demonstrated that a significantly predictive effect of cytokines on SERT availability may
explain the role of cytokines in mood regulation. However, this predictive effect was not different
between HCs and BD, which suggests a potential underlying mechanism in BD beyond these
cytokines.