Vertical sleeve gastrectomy(VSG) is becoming more and more popular among the world. Despite its dramatic efficacy, however, the mechanism of VSG remains largely undetermined. This study aimed to test interferon(IFN)-γ secretion n of mesenteric lymph nodes in obese mice(ob/ob mice), a model of VSG, and its relationship with farnesoid X receptor(FXR) expression in the liver and small intestine, and to investigate the weight loss mechanism of VSG. The wild type(WT) mice and ob/ob mice were divided into four groups: A(WT+Sham), B(WT+VSG), C(ob/ob+Sham), and D(ob/ob+VSG). Body weight values were monitored. The IFN-γ expression in mesenteric lymph nodes of ob/ob mice pre- and post-operation was detected by flow cytometry(FCM). The FXR expression in the liver and small intestine was detected by Western blotting. The mouse AML-12 liver cells were stimulated with IFN-γ at different concentrations in vitro. The changes of FXR expression were also examined. The results showed that the body weight of ob/ob mice was significantly declined from(40.6±2.7) g to(27.5±3.8) g on the 30 th day after VSG(P<0.05). At the same time, VSG induced a higher level secretion of IFN-γ in mesenteric lymph nodes of ob/ob mice than that pre-operation(P<0.05). The FXR expression levels in the liver and small intestine after VSG were respectively 0.97±0.07 and 0.84±0.07 fold of GAPDH, which were significantly higher than pre-operative levels of 0.50±0.06 and 0.48±0.06 respectively(P<0.05). After the stimulation of AML-12 liver cells in vitro by different concentrations of IFN-γ(0, 10, 25, 50, 100, and 200 ng/m L), the relative FXR expression levels were 0.22±0.04, 0.31±0.04, 0.39±0.05, 0.38±0.05, 0.56±0.06, and 0.35±0.05, respectively, suggesting IFN-γ could distinctly promote the FXR expression in a dose-dependent manner in comparison to those cells without IFN-γ stimulation(P<0.05). It was concluded that VSG induces a weight loss in ob/ob mice by increasing IFN-γ secretion of mesenteric lymph nodes, which then increases the FXR expression of the liver and small intestine.
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