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

ε-Viniferin is a dehydrodimer of resveratrol, a polyphenol synthesized in many plants, including grapevine. The present study investigated the effects of ε-viniferin and resveratrol on epithelial secretory and barrier functions in isolated rat small and large intestinal mucosa. Mucosa-submucosa tissue preparations of various segments of the rat large and small intestines were mounted on Ussing chambers, and short-circuit current (Isc) and tissue conductance (Gt) were continuously measured. The mucosal addition of ε-viniferin (>10(-5) mol/L) and resveratrol (>10(-4) mol/L) to the cecal mucosa, which was the most sensitive region, induced an increase in Isc and a rapid phase decrease (P-1) followed by rapid (P-2) and broad (P-3) peak increases in Gt in concentration-dependent manners. Mucosal ε-viniferin (10(-4) mol/L), but not resveratrol (10(-4) mol/L), increased the permeability of FITC-conjugated dextran (4 kDa). The mucosal ε-viniferin-evoked changes in Isc (Cl(-) secretion), but not in Gt, were attenuated by a selective cyclooxygenase (COX)-1 inhibitor and a selective EP4 prostaglandin receptor. The mucosal ε-viniferin-evoked increase in Isc was partially attenuated, and P-2, but not P-1 or P-3, change in Gt was abolished by a transient receptor potential cation channel, subfamily A, member 1 (TRPA1) inhibitor. Moreover, the mucosal ε-viniferin concentration-dependently attenuated the mucosal propionate (1 mmol/L)-evoked increases in Isc and Gt Immunohistochemical studies revealed COX-1-immunoreactive epithelial cells in the cecal crypt. The present study showed that mucosal ε-viniferin modulated transepithelial ion transport and permeability, possibly by activating sensory epithelial cells expressing COX-1 and TRPA1. Moreover, mucosal ε-viniferin decreased mucosal sensitivity to other luminal molecules such as short-chain fatty acids. In conclusion, these results suggest that ε-viniferin modifies intestinal mucosal transport and barrier functions.

Involvement of the gut chemosensory system in the regulation of colonic anion secretion

The primary function of the gastrointestinal (GI) tract is the extraction of nutrients from the diet. Therefore, the GI tract must possess an efficient surveillance system that continuously monitors the luminal content for beneficial or harmful compounds. Recent studies have shown that specialized cells in the intestinal lining can sense changes in this content. These changes directly influence fundamental GI processes such as secretion, motility, and local blood flow via hormonal and/or neuronal pathways. Until recently, most studies examining the control of ion transport in the colon have focused on neural and hormonal regulation. However, study of the regulation of gut function by the gut chemosensory system has become increasingly important, as failure of this system causes dysfunctions in host homeostasis, as well as functional GI disorders. Furthermore, regulation of ion transport in the colon is critical for host defense and for electrolytes balance. This review discusses the role of the gut chemosensory system in epithelial transport, with a particular emphasis on the colon.

Impact of cyadox on human colonic microflora in chemostat models

The aim of this study was to evaluate the microbiological safety of cyadox, a new member of quinoxaline-1,4-dioxides (QdNOs), on human intestinal flora. Four chemostats containing human fecal flora were exposed to 0, 16, 32, and 128 μg/mL of cyadox, respectively. Bacterial populations, resistance rates of two predominant bacteria and short-chain fatty acids (SCFA) were monitored daily prior to and during drug MOA Laboratory of Risk Assessment for Quality and Safety of Livestock and Poultry Products exposure. Colonization resistance (CR) of each community was determined by three successive daily challenges of Salmonella typhimurium. Efflux pump gene (oqxAB) in the Escherichia coli and Enterococcus strains were analyzed by PCR amplification and DNA sequencing. No change in SCFA was observed after exposure to different concentrations of cyadox. Lower concentration of cyadox (16 μg/mL) had no adverse effect on human microflora. However, higher concentrations of cyadox (32 and 128 μg/mL) could change bacterial population and increase the proportion of resistant E. coli and Enterococcus. More than 26% (12/46) of cyadox resistant E. coli strains contained oqxAB gene, while all the resistant Enterococcus were negative to oqxAB gene. Relationship between the occurrence of oqxAB gene and cyadox exposure is inconclusive. Our data indicated that 16 μg/mL might be the no observed effect concentration (NOEC) of cyadox. Derived microbiological acceptable daily intake (mADI) would be 1552.03 μg/kg d. The data obtained in present study indicated that cyadox was a safe member of QdNOs family of antimicrobial agents.

Evidence for an ontogenetic change from pre-programmed to meal-responsive cck production in Atlantic herring, Clupea harengus L

The effects of up to three days of food deprivation on the cholecystokinin (CCK)-producing cells in the Atlantic herring gut were assessed by quantifying the number of cells detected by in situ hybridization at three ontogenetic stages. In feeding larvae that still possessed yolk-sacs (2 and 8days after hatch, DAH), intestinal cck expression appeared to be maintained regardless of external nutritional conditions. In 30 DAH-old herring larvae with well-established exogenous feeding only, very few CCK-producing cells could be identified, indicating that cck production in the gut had shut down after three days of starvation. This suggests that cck transcription is pre-programmed by a local timer in the midgut during the yolk-sac stage, regardless of the nutritional status and presence of nutrients in the gut lumen; however, it becomes strongly influenced by the external nutritional conditions after the yolk has been completely absorbed. Our results suggest that CCK-producing cells in the gut develop "meal-responsiveness" later in post-hatch development.

Food choice as a key management strategy for functional gastrointestinal symptoms

Recognition of food components that induce functional gut symptoms in patient's functional bowel disorders (FBD) has been challenging. Food directly or indirectly provides considerable afferent input into the enteric nervous system. There is an altered relationship between the afferent input and perception/efferent response in FBD. Defining the nature of food-related stimuli may provide a means of minimizing such an input and gut symptoms. Using this premise, reducing the intake of FODMAPs (fermentable oligo-, di-, and mono-saccharides and polyols)--poorly absorbed short-chain carbohydrates that, by virtue of their small molecular size and rapid fermentability, will distend the intestinal lumen with liquid and gas--improves symptoms in the majority of patients. Well-developed methodologies to deliver the diet via dietician-led education are available. Another abundant source of afferent input is natural and added food chemicals (such as salicylates, amines, and glutamates). Studies are needed to assess the efficacy of the low food chemical dietary approach. A recent placebo-controlled trial of FODMAP-poor gluten provided the first valid evidence that non-celiac gluten intolerance might actually exist, but its prevalence and underlying mechanisms require elucidation. Food choice via the low FODMAP and potentially other dietary strategies is now a realistic and efficacious therapeutic approach for functional gut symptoms.