{'fraction_non_alphanumeric': 0.023427331887201735, 'fraction_numerical': 0.00737527114967462, 'mean_word_length': 5.723032069970846, 'pattern_counts': {'":': 0, '<': 1, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
The Effects of Short Chain Fatty Acid Mixtures on Colonic Motility

The effects of nutrients on a variety of colonic function has been well studied. Recent evidence has suggested that sensing of many different intraluminal nutrients (glucose, amino acids) is accomplished through plasma membrane receptors within the intestinal epithelium. These membrane receptors are often linked to hormone release from enteroendocrine cells. While many digested nutrients are present at higher intraluminal concentrations within the small intestine before they are absorbed, short chain fatty acids (SCFAs) in particular are generated by bacterial metabolism of nutrients within the colon. Based on previous studies, the most prominent individual SCFAs (butyrate, acetate, and propionate) have differential effects on cellular signaling and motility within the colon. However, the overall effects of mixtures of these SCFAs, which are more similar to intraluminal conditions, have not been elucidated. In this study, we measured colonic motility of both the proximal and distal colon in response to SCFA mixtures. Motility in the proximal colon of guinea pigs was measured as full‐propagating, shortpropagating, or non‐propagating contractions through video capture and subsequent generation of spatiotemporal maps. Motility in guinea pig distal colon was measured by velocity of fecal pellet propulsion. An 30mM SCFA mixture with a molar ratio of 3:2:1 (acetate: butyrate: propionate) increased velocity of fecal pellet propulsion. This increase in distal colonic motility was inhibited by GR113808, an antagonist of 5‐HT4 receptors, suggesting that mediation of motility effects was through serotonin. Statistical comparisons of pellet velocity were made by one‐way repeated measures ANOVA. In the proximal colon, the same SCFA mixture reduced the presence of short‐propagating contractions (<50% of the tissue length) while not affecting full‐propagating contractions. These results suggest that SCFA mixtures have differential effects on propulsive motility in the proximal and distal colon of guinea pigs. Future work will elucidate the presence of the FFAR2 and FFAR3 receptors in relation to enteroendocrine cells containing serotonin and other endocrine mediators of colonic function (peptide YY, neurotensin).