Our previous study indicated increased levels of taurine-conjugated bile acids (BA) in the intestine content of mice submitted to caloric restriction (CR). In the current project, we found increased levels of free taurine and taurine conjugates, including glutathione (GSH)-taurine, in CR compared to ad libitum fed animals in the mucosa along the intestine but not in the liver. The levels of free GSH were decreased in the intestine of CR compared to ad libitum fed mice. However, the levels of oxidized GSH were not affected and were complemented by the lack of changes in the antioxidative parameters. Glutathione-S transferases (GST) enzymatic activity was increased as was the expression of GST genes along the gastrointestinal tract of CR mice. In the CR intestine, addition of GSH to taurine solution enhanced taurine uptake. Accordingly, the expression of taurine transporter (TauT) was increased in the ileum of CR animals and the levels of free and BA-conjugated taurine were lower in the feces of CR compared to ad libitum fed mice. Fittingly, BA- and GSH-conjugated taurine levels were increased in the plasma of CR mice, however, free taurine remained unaffected. We conclude that CR-triggered production and release of taurine-conjugated BA in the intestine results in increased levels of free taurine what stimulates GST to conjugate and enhance uptake of taurine from the intestine.

我们之前的研究表明，接受热量限制 (CR) 的小鼠肠道内容物中牛磺酸结合的胆汁酸 (BA) 水平增加。在当前的项目中，我们发现 CR 中游离牛磺酸和牛磺酸结合物（包括谷胱甘肽 (GSH)-牛磺酸）的水平增加，与在肠道粘膜中随意喂养的动物相比，在肝脏中没有。免费GSH的水平CR肠道均有下降相比，自由采食喂老鼠。然而，氧化谷胱甘肽的水平没有受到影响，并且由于抗氧化参数没有变化而得到补充。谷胱甘肽-S 转移酶 (GST) 酶活性增加，GST 基因沿 CR 小鼠胃肠道的表达也增加。在 CR 肠中，将 GSH 添加到牛磺酸溶液中可增强牛磺酸吸收。因此，与随意采食相比，CR 动物回肠中牛磺酸转运蛋白 (TauT) 的表达增加，并且 CR 粪便中游离和 BA 结合牛磺酸的水平较低喂老鼠。恰如其分地，CR 小鼠血浆中 BA 和 GSH 结合的牛磺酸水平增加，然而，游离牛磺酸不受影响。我们得出结论，CR 触发的牛磺酸结合 BA 在肠道中的产生和释放导致游离牛磺酸水平增加，从而刺激 GST 结合并增强肠道对牛磺酸的摄取。