摘要目的:探讨长期节食状态下大鼠体内胆汁酸的变化及其机制。方法:20只健康雄性Wistar大鼠分为对照组和节食组，每组10只。对照组大鼠正常量饮食，节食组大鼠给予正常饮食量的50%饲养，12周后麻醉，采集各组大鼠血清、胆汁、肝脏和回肠组织样本，分离腹部脂肪称重，并计算腹部脂肪/体重比。计算胆汁流速。采用试剂盒和高效液相色谱串联质谱法测定各样本中总胆汁酸（TBA）及β-鼠胆酸（β-MCA）、牛磺β-鼠胆酸（Tβ-MCA）、胆酸（CA）、牛磺胆酸（TCA）、甘氨胆酸（GCA）、鹅去氧胆酸（CDCA）、甘氨鹅去氧胆酸（GCDCA）、去氧胆酸（DCA）、牛磺去氧胆酸（TDCA）、甘氨去氧胆酸（GDCA）、石胆酸（LCA）、甘氨石胆酸（GLCA）、牛磺猪去氧胆酸（THDCA）、牛磺熊去氧胆酸（TUDCA）、甘氨熊去氧胆酸（GUDCA）的浓度，采用实时荧光定量聚合酶链反应测定肝脏和回肠组织法尼醇X受体（Fxr）“肠-肝轴”通路上胆汁酸相关核受体、代谢酶和转运体小异二聚体伴侣（ Shp） 、成纤维细胞生长因子15（ Fgf15） 、胆固醇7α-羟化酶（ Cyp7a1）、甾醇12α-羟化酶（ Cyp8b1） 、胆酸盐输出泵（ Bsep） 、多药耐药相关蛋白2（ Mrp2） 、Na +依赖性胆酸盐转运体（ Asbt）等的mRNA表达量。组间比较采用 t检验。 结果:与对照组相比，节食组大鼠体重与腹部脂肪/体重比均显著降低（ P<0.01）；血清TBA水平以及胆汁流速和胆汁酸经胆汁排泄量显著升高（ P<0.05）；肝组织中β-MCA、CA、GCA、CDCA、GCDCA、DCA、GDCA、LCA、GLCA、TUDCA和GUDCA的浓度显著升高（ P<0.05），而TCA、TDCA和THDCA的浓度显著降低（ P<0.05）；回肠组织中Tβ-MCA、TCA、DCA和TDCA浓度均显著降低（ P<0.05）；肝脏中次级胆汁酸和非结合型胆汁酸浓度明显增高（ P<0.05），回肠中结合型胆汁酸浓度显著降低（ P<0.05）。与对照组比较，节食组大鼠回肠和肝脏部位 Fgf15基因表达量均显著降低，回肠 Asbt基因表达量显著上调，肝脏中 Shp和 Cyp7a1的mRNA表达水平均显著上调，而 Cyp8b1的mRNA表达量显著降低（均 P<0.05）。 结论:节食大鼠饮食结构的改变促使体内胆汁酸呈现明显的特征性变化，究其机制可能与Fxr“肠-肝轴”的适应性调控有关。

abstractsObjective:To explore the changes in bile acids of rats on a long-term dieting and the mechanisms involved.Methods:The 20 healthy male Wistar rats were divided into normal control group and dieting group, with 10 rats in each group. The rats in the control group were fed with 50% of the normal diet, anesthesia after 12 weeks, serum, bile, liver and ileal tissue samples were collected, abdominal fat was separated and weighed, and the ratio of abdominal fat to body weight was calculated. Bile flow rate was calculated. The concentration of total bile acids (TBA) and β-muricholic acid (β-MCA), taurine-β-muricholic acid (Tβ-MCA), cholic acid (CA), taurine-cholic acid(TCA), glycine-cholic acid (GCA), chenodeoxycholic acid (CDCA), glycine-chenodeoxycholic acid (GCDCA), deoxycholic acid (DCA), taurine-deoxycholic acid(TDCA), glycine-deoxycholic acid (GDCA), lithocholic acid (LCA), glycine-lithocholic acid (GLCA), taurine-hyodesoxycholic acid (THDCA), taurine-ursodeoxycholic acid (TUDCA), and glycine-ursodeoxycholic acid (GUDCA) were determined using high performance liquid chromatography tandem mass spectrometry. Real-time quantitative polymerase chain reaction was used to determine the mRNA expression of bile acid-associated nuclear receptors, metabolic enzymes and transporters along the "gut-liver axis" pathway of the liver and ileal tissue farnesol X receptor (Fxr): small heterodimer partner ( Shp), fibroblast growth factor 15 ( Fgf15), cholesterol 7α-hydroxylase ( Cyp7a1), sterol 12α-hydroxylase ( Cyp8b1), bile salt export pump ( Bsep), multidrug resistance protein 2 ( Mrp2), apical sodium-dependent bile acid transporter ( Asbt). The t tests were used for between-group comparisons. Results:Compared with the control group, the weight of rats in the dieting group had a significant decrease in body weight, abdominal fat and body weight ratio ( P<0.01). Serum TBA level, bile flow rate and bile acid excretion were significantly increased (all P<0.05); the concentrations of β-MCA, CA, GCA, CDCA, GCDCA, DCA, GDCA, LCA, GLCA, TUDCA and GUDCA were significantly increased (all P<0.05), while the concentrations of TCA, TDCA and THDCA were significantly decreased (all P<0.05). The concentrations of Tβ-MCA, TCA, DCA and TDCA in ileal tissue were significantly reduced (all P<0.05). The concentration of secondary bile acids and unconjugated bile acids in the liver was significantly increased (all P<0.05), and the concentration of conjugated bile acids in the ileum was significantly reduced (all P<0.05). After dieting, the expression of Fgf15 gene in the ileum and liver of rats was significantly reduced, the expression of ileal Asbt gene was significantly upregulated, the mRNA expression levels of Shp and Cyp7a1 in the liver were significantly upregulated, and the mRNA expression of Cyp8b1 was significantly reduced (all P<0.05). Conclusion:The change of dietary structure of dieting rats promoted obvious characteristic changes in bile acids in vivo, and the mechanism may be related to the adaptive regulation of Fxr "gut-liver axis".