Effect of cholic acid on colonic motility in mice

The role of bile acids on the gastrointestinal motility are contradictory, especially the role of mast cells mediators in this effect. Thus, cholic acid (CA) was examined for its in vitro action on the motility of the mice colon using different doses of CA (0.3, 30, 50, 100, 200, 300 and 500 µM). The contractile activity of the colon segment was recorded as changes in intraluminal pressure under isovolumetric conditions. The mean amplitude of the peristaltic motor complexes and the frequency (interval) of phasic contractions were determined. In other experiments, to study the CA mode of action, tissues were preincubated with 5-HT3 antagonist (Granisetron hydrochloride), 5-HT4 antagonist (GR113808), H1 antagonist (Pyrilamine maleate salt) and protease activated receptor (PAR1) antagonist (BMS-200261) prior to challenge with CA (300 µM). CA inhibitory effect on contractile activity might be via its antagonistic action on the 5-HT3, 5-HT4, H1 receptors and PAR1 with variable levels. In conclusion, CA perfusion, at certain concentration levels, induced significant physiological changes in colon motility that might propose its antagonistic action on the receptors of the mast cells neuromediators.   Key words: Cholic acid, colonic motility, receptor antagonists, peristaltic motor complexes.