BACKGROUND/AIMS We aimed to study the effect of fluoxetine on chronic colitis and its anti-inflammatory mechanism in interleukin-10-deficient (IL-10(-/-)) mice.

METHODS IL-10(-/-) mice were administered with either the vehicle or one of the two dosages of fluoxetine (1 or 5 mg/kg) by oral gavage daily for 2 weeks. Lamina propria mononuclear cells (LPMCs) were isolated from IL-10(-/-) mice treated with or without fluoxetine, and cytokine expression was measured. Bone marrow-derived dendritic cells (BMDCs) isolated from IL-10(-/-), and wild-type mice were pretreated with fluoxetine and then stimulated with lipopolysaccharide. IL-12p40 and tumor necrosis factor (TNF)-α gene expression was determined by real-time PCR. DNA-binding activity of nuclear factor-κB (NF-κB) was evaluated by electrophoretic mobility shift assay.

RESULTS Fluoxetine significantly reduced intestinal inflammation as assessed by body weight, colon length, and histopathological grading, and it inhibited the level of TNF-α gene expression in IL-10(-/-) mice. LPMCs were isolated from IL-10(-/-) mice, and cellular expression of IL-12p40 and interferon-γ was suppressed by fluoxetine treatment. Fluoxetine significantly inhibited IL-12p40 and TNF-α gene expression and protein secretion in BMDCs from IL-10(-/-) mice. DNA-binding activity of NF-κB was suppressed by fluoxetine pretreatment.

CONCLUSIONS These results indicate that fluoxetine ameliorates intestinal inflammation in IL-10(-/-) mice and inhibits hyperresponsive LPMCs and BMDCs, which suggests that fluoxetine could be a potential therapeutic agent for inflammatory bowel disease.