Institute of Physiology, University of Hohenheim, Stuttgart, Germany.
Cell Tissue Res. 2010 Mar;339(3):493-504. doi: 10.1007/s00441-009-0907-6.
Various digestive and enteroendocrine signaling processes are constantly being adapted to the chemical composition and quantity of the chyme contained in the diverse compartments of the gastrointestinal tract. The chemosensory monitoring that underlies the adaptive capacity of the gut is thought to be performed by so called brush cells that share morphological and molecular features with gustatory sensory cells. A substantial population of brush cells is localized in the gastric mucosa. However, no chemosensory receptors have been found to be expressed in these cells so far, challenging the concept that they serve a chemosensory function. The canonical chemoreceptors for the detection of macronutrients are taste receptors belonging to the T1R family; these have been identified in several tissues in addition to the gustatory system including the small intestine. We demonstrate the expression of the T1R subtype T1R3, which is essential for the detection of both sugars and amino acids in the gustatory system, in two distinct cell populations of the gastric mucosa. One population corresponds to open-type brush cells, emphasizing the notion that they are a chemosensory cell type; T1R3 immunoreactivity in these cells is restricted to the apical cell pole, which might provide the basis for the detection of luminal macronutrient compounds. The second gastric T1R3-positive population consists of closed-type endocrine cells that produce ghrelin. This finding suggests that ghrelin-releasing cells, which lack access to the stomach lumen, might receive chemosensory input from macronutrients in the circulation via T1R3.
各种消化和肠内分泌信号过程不断适应胃肠道不同部位所含食糜的化学成分和数量。被认为是肠道适应能力基础的化学感觉监测被认为是由所谓的刷状细胞执行的，这些细胞具有与味觉感觉细胞相似的形态和分子特征。大量的刷状细胞定位于胃黏膜中。然而，到目前为止，这些细胞中还没有发现表达任何化学感受器，这对它们具有化学感觉功能的概念提出了挑战。检测宏量营养素的经典化学感受器是属于 T1R 家族的味觉感受器；除了味觉系统外，这些味觉感受器还在包括小肠在内的几种组织中被发现。我们证明了 T1R 亚型 T1R3 在胃黏膜的两个不同细胞群中的表达，T1R3 对于味觉系统中糖和氨基酸的检测是必不可少的。一个细胞群对应于开放型刷状细胞，这强调了它们是一种化学感觉细胞类型的概念；这些细胞中的 T1R3 免疫反应性仅限于顶端细胞极，这可能为检测腔内腔内的宏量营养素化合物提供了基础。第二个胃 T1R3 阳性细胞群由产生生长激素释放肽的闭合型内分泌细胞组成。这一发现表明，缺乏与胃腔相通的生长激素释放肽释放细胞可能通过 T1R3 从循环中的宏量营养素中接收化学感觉输入。
