Chemosense for Luminal Environment in the Large Intestine

Abstract

Gut lumen is continually exposed to many agents, including noxious compounds. The intestinal epithelia form a barrier between the internal and luminal (external) environments. Chemical receptors that detect the luminal environment are thought to play an important role as sensors and as modulators of epithelial cell functions. The Molecular analysis of various epithelial cell membrane receptor proteins has elucidated the sensory role of these cells in the gut chemosensing system. Nutrient sensing systems by these receptors in the small intestinal epithelia are thought to in‰uence nutrient metabolism and local physiological function. Much less is known, however, about the physiological roles of chemosensing in the large intestine. We have investigated the contractile and secretory eŠects of short-chain fatty acids (SCFAs), the primary products of commensal bacteria, and the expression of SCFA receptors in the large intestine. Theˆndings indicate that the epithelia in the large intestine also detect and respond to luminal contents, particularly bacterial metabolites, for host defense. We recently reported that luminal bitter tastants and odorants aŠect transepithelial ion transport in human and rat colon, and that putative receptors are expressed in colonic mucosa. In this review, we describe the secretory eŠects of chemical stimuli on lumen associated with the expression pattern of sensory receptors, focusing on the large intestine.

Effects ofε-viniferin, a dehydrodimer of resveratrol, on transepithelial active ion transport and ion permeability in the rat small and large intestinal mucosa

“…The intestinal epithelia are sensory tissues for luminal molecules (Kaji et al. 2011b; Breer et al. ; Furness et al.…”

Involvement of the Gut Chemosensory System in the Regulation of Colonic Anion Secretion

“…For example, bacterial fermentation of indigestible carbohydrates produces short-chain fatty acids (SCFAs), which can affect various GI functions including ion transport and motility. These SCFAs can be absorbed by the colonic mucosa as energy sources [ 3 ]. On the other hand, bile acids entering the colon can be metabolized by microbiota; thus, primary bile acids are converted to secondary bile acids [ 4 ].…”