武夷岩茶酸性茶多糖对2型糖尿病大鼠胆汁酸的调节作用机制

The regulatory mechanism of acidic tea polysaccharides from Wuyi rock tea on bile acids in type 2 diabetic rats

[目的]研究从武夷岩茶黄片中提取的一种酸性茶多糖对高血糖大鼠胆汁酸的影响。[方法]通过体外试验评价茶多糖对胆酸盐的结合能力;通过液质联用仪测定大鼠盲肠内容物中胆汁酸组成,并检测大鼠肝脏、胰腺的胆汁酸受体法尼醇X受体FXR、G蛋白偶联胆汁酸受体TGR5 mRNA的相对表达量;Western Blot法检测结肠组织胰高血糖素样肽-1的表达水平。[结果]茶多糖对结合型和游离型的胆酸盐均有一定的结合能力,并且对结合型胆酸盐具有更好的结合能力,当茶多糖质量浓度为2.00 mg/mL时,其对胆酸钠的结合率仅为同浓度下甘氨胆酸钠和牛磺胆酸钠结合率的57.59%,62.62%。茶多糖的干预对大鼠盲肠内容物中胆汁酸水平的影响主要表现为初级胆汁酸鹅去氧胆酸水平的增加,以及次级胆汁酸脱氧胆酸、石胆酸水平的降低。此外,其对大鼠肝脏、胰腺胆汁酸受体FXR、TGR5的mRNA表达具有上调作用;对胰高血糖素样肽-1表达水平无显著性影响。[结论]茶多糖干预可改变大鼠初级胆汁酸/次级胆汁酸的比率,而疏水性更高的次级胆汁酸在肠肝循环中吸收性更差。

[Objective]This study aimed to investigate the effects of an acidic tea polysaccharide extracted from Wuyi Rock tea"yellow slice"on bile acids in hyperglycaemic rats.[Methods]In vitro experiments simulating artificial gastric and intestinal fluids were conducted to evaluate the binding capacity of tea polysaccharides to bile salts.The composition of bile acids in the cecal contents was analyzed using Liquid Chromotography with Mass Spectrometry(LC-MS);The relative mRNA expression of bile acid receptors FXR and TGR5 in rat liver and pancreas of rats were measured,along with Western blot analysis of colonic tissues.[Results]The in vitro experiments demonstrated that tea polysaccharides possess a significant binding capacity for both bound and free bile salts,with stronger affinity for bound bile salts.At 2.00 mg/mL,the binding rate of the tea polysaccharides to sodium cholate were found to be 57.59%and 62.62%for sodium glycylcholate and sodium taurocholate,respectively.In the cecal contents of rats,intervention with tea polysaccharides primarily increased the level of secondary bile acids,including deoxycholic acid and lithocholic acid.Additionlly,the treatment upregulated the mRNA expression of bile acid receptor FXR and TGR5 in the liver and pancreas,with no significant change observed in the expression of GLP-1.[Conclusion]The intervention with acidic tea polysaccharides from Wuyi rock tea led to an increased ratio of primary bile acids to secondary bile acids.This suggests that the more hydrophobic secondary bile acids are less effectively absorbed in the enterohepatic circulation.