T1777 Decreased Ghrelin Response Mediates Upper Gastrointestinal Motility Disorder in Experimental GERD Rats

Abstract

comprehensively characterize the presence and relative abundance of most known prokaryotes in a massively parallel assay. This unprecedented means of prokaryotic profiling provides the ability to elucidate microbial composition and the potential sources of inter-bowel and intra-bowel community heterogeneity as it relates to IBS. Aim: To assess the utility of the Phylochip to characterize and compare the large intestinal microbial communities between rats with an IBS-like phenotype (“IBS rats”) and healthy control rats. Methods: Neonatal rats underwent colonic exposure to dilute acetic acid or saline in an established paradigm. As adults, rats exposed to acetic acid demonstrate persistent colonic hypersensitivity and altered bowel movement. At 8-12 weeks, rats were euthanized and DNA was extracted and amplified separately from luminal and mucosal samples from the proximal, middle and distal colons. Results: PhyloChip analysis revealed that bacteria of the phyla Bacteroidetes, Firmicutes and Proteobacteria were the dominant organisms in both groups of rats. However, there were significant differences in the relative abundances of taxa at increasing levels of phylogenetic resolution. Preliminary data analysis has uncovered abrupt variations and disturbances in microbiota composition unique to IBS rats including altered species richness, changes in diversity and decreased abundance of certain taxa within specific regions of the large bowel. Principal component analysis (PCA) based on the UniFrac distance metric demonstrates that IBS microbiota is significantly different from the microbiota of controls. UniFrac analysis also demonstrates an orderly transition of bacterial communities from the proximal to the distal cecum in control rats, a pattern that was significantly disrupted in IBS rats. Conclusions.These initial findings suggest significant alterations in the colonic microbial community in an IBS model, findings that are supported by our concomitant comprehensive metabolomic analysis of these gut segments. These systems-based approaches, along with the availability of a suitable animal model, hold the promise of providing novel insight into the role of enteric microflora in IBS.