Influence of pirenzepine on colonic serotonin changes induced by short chain fatty acid.

In this work we have demonstrated the influence of a short chain fatty acid (acetate) on the number of enterochromaffin (EC) cells containing serotonin (5HT), at two different pH (pH 6.9 absorptive stimuli, and pH 2.9 secretory stimuli), infused into the colon during one hour. The number of EC cells decrease significatively, specially in the cecum with a solution of low pH (2.9). The action of piprenzepine in preventing this reduction demonstrated that was partly mediated by a cholinergic receptor mechanism. On the other hand, a decrease on the release of 5HT to the lumen was a observed under the influence of pirenzepine. We conclude that the short chain fatty acid acetate, at a low pH induces the release of serotonin through a cholinergic mechanisms indicated by the inhibition observed with antimuscarinic drug.