Evaluation in rats of the dose-response relationship among colonic mucosal growth, colonic fermentation, and dietary fiber

Abstract

The dose-response relationship among dietary fiber, colonic fermentation, fecal weight, and mucosal growth were evaluated in this study. The morphometric parameter of total mucosal volume was used to assess diet-induced differences in colonic mucosal growth. Dietary fibers with a wide range of fermentability and that have previously been shown to inhibit the development of colonic neoplasia in rats were used. Sprague-Dawley rats were fed Purina Rodent Chow, AIN-76a fiber-free diet, or an AIN-76a diet supplemented with three different dietary fibers, (cellulose, guar gum, or wheat bran) at 2, 5, 10, or 15% of the diet. Diets were fed for 28 days. Total colonic mucosal volume was determined using stereologic principles and computerized image analysis; 48-hr fecal weight was measured; and the concentration of short-chain fatty acids (SCFA) in colonic contents was determined at study termination. Each type of fiber induced a dose-dependent increase in total mucosal volume of the colon and fecal weight. Mucosal volume and fecal weight were closely correlated (R2 > 0.95). Total mucosal volume was not correlated with the concentration of total SCFA or butyrate in the colon. These results indicate that diet-induced change in colonic mucosal growth, as measured by total mucosal volume, is positively correlated with fecal weight and not related to alterations in colonic fermentation. Enhanced colonic mucosal growth occurs in rats fed dietary fibers that have previously been shown to inhibit the development of genotoxin-induced colonic neoplasia in rats.

Dietary administration of resistant starch improved caecal barrier function by enhancing intestinal morphology and modulating microbiota composition in meat duck

“…The normal development of the hind gut is the foundation for maintaining barrier function and fermentability (32) . Recent research showed that RPS could increase the weight of the large intestine and the mucosa thicknesses of the caecum in pigs (33) .…”

Effects of inulin supplemented to cellulose-free or cellulose-rich diets on caecal environment and biochemical blood parameters in rats

“…All SCFA are claimed to act as trophic agents on caecal/colonic epithelium, but butyric seems to be the most and propionic the least efficient (Berggren et al, 1993). Another possible way of increased epithelium proliferation was indicated in a study by Whiteley et al (1996). These authors found that mucosal volume was correlated with digesta mass rather than with SCFA levels, concluding that physical stretching of the caecal/colonic epithelium might be a more important causal factor.…”

Expression profiling of sodium butyrate (NaB)-treated cells: identification of regulation of genes related to cytokine signaling and cancer metastasis by NaB

“…NaB is produced in the colon of mammals as a result of anaerobic bacterial fermentation of dietary fiber, undigested starch and proteins (Cummings, 1981;Bugaut and Bentejac, 1993;McIntyre et al, 1993;Mcintosh et al, 1996;Whiteley et al, 1996). NaB serves as an energy source of colonic epithelium.…”