Weanling, but not adult, rabbit colon absorbs bile acids: flux is linked to expression of putative bile acid transporters.
Weanling, but not adult, rabbit colon absorbs bile acids: flux is linked to expression of putative bile acid transporters.
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断奶兔结肠吸收胆汁酸，但成年兔结肠不吸收胆汁酸：通量与假定的胆汁酸转运蛋白的表达有关。
DOI：
10.1152/ajpgi.00163.2005
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发表时间：
2006
期刊：
影响因子：
--
通讯作者：
Rao,MrinaliniC
中科院分区：
文献类型：
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作者：
Weihrauch,Dirk;Kanchanapoo,Jainuch;Ao,Mei;Prasad,Roli;Piyachaturawat,Pawinee;Rao,MrinaliniC
肠道对胆汁酸的处理是年龄依赖性的;成年人（而不是新生儿）的回肠吸收胆汁酸，成年人（而不是断奶或新生儿）的远端结肠分泌Cl−以响应胆汁酸。胆汁酸转运涉及顶端Na+依赖性胆汁酸转运蛋白（Asbt）和脂质结合蛋白（LBP）在回肠中的特点，但鲜为人知的是结肠胆汁酸转运。我们研究了结肠胆汁酸转运和潜在的转运蛋白和受体的性质。采用半定量RT-PCR方法检测成年兔、断奶兔和新生兔结肠中Asbt及其截短型t-Asbt、LBP、多药耐药相关蛋白3、有机溶质转运蛋白α和法尼醇X受体。Asbt和LBP在断奶兔中表达最高，在成年兔和新生兔中表达显著降低。回肠，但不是结肠，表达t-Asbt。ASBT，LBP和法尼酯X受体mRNA在断奶结肠中的表达与成人回肠（一种专为高胆汁酸吸收而设计的组织）中的表达相似。为了研究其功能作用，跨上皮[3 H]牛磺胆酸盐运输在断奶和成年结肠和回肠。在短路条件下，断奶结肠和回肠以及成年回肠的胆汁酸净吸收量分别为1.23 ± 0.62、5.53 ± 1.20和11.41 ± 3.45 nmol·cm−2·h−1。然而，成年结肠分泌胆汁酸（−1.39 ± 0.47 nmol·cm−2·h−1）。我们首次证明，断奶，但不是成人，远端结肠显示净胆汁酸吸收。因此，Asbt和LBP在断奶结肠中的表达增加，这与牛磺胆酸盐吸收的平行增加相关，当回肠胆汁酸再循环未完全发育时，与胆汁酸的肝肠保护相关。
Intestinal handling of bile acids is age dependent; adult, but not newborn, ileum absorbs bile acids, and adult, but not weanling or newborn, distal colon secretes Cl−in response to bile acids. Bile acid transport involving the apical Na+-dependent bile acid transporter (Asbt) and lipid-binding protein (LBP) is well characterized in the ileum, but little is known about colonic bile acid transport. We investigated colonic bile acid transport and the nature of the underlying transporters and receptors. Colon from adult, weanling, and newborn rabbits was screened by semiquantitative RT-PCR for Asbt, its truncated variant t-Asbt, LBP, multidrug resistance-associated protein 3, organic solute transporter-α, and farnesoid X receptor. Asbt and LBP showed maximal expression in weanling and significantly less expression in adult and newborn rabbits. The ileum, but not the colon, expressed t-Asbt. Asbt, LBP, and farnesoid X receptor mRNA expression in weanling colon parallel the profile in adult ileum, a tissue designed for high bile acid absorption. To examine their functional role, transepithelial [3H]taurocholate transport was measured in weanling and adult colon and ileum. Under short-circuit conditions, weanling colon and ileum and adult ileum showed net bile acid absorption: 1.23 ± 0.62, 5.53 ± 1.20, and 11.41 ± 3.45 nmol·cm−2·h−1, respectively. However, adult colon secreted bile acids (−1.39 ± 0.47 nmol·cm−2·h−1). We demonstrate for the first time that weanling, but not adult, distal colon shows net bile acid absorption. Thus increased expression of Asbt and LBP in weanling colon, which is associated with parallel increases in taurocholate absorption, has relevance in enterohepatic conservation of bile acids when ileal bile acid recycling is not fully developed.