Serotonin in the gut plays a significant role in pain sensation and digestive processes.

“within the gut serotonin is made in two places the bulk of it is made as i've just said in the endoendocrine cells which are the small endocrine cells that are part of the gi epithelium it's a minor component of the epithelium but a major component functionally of what the gut does about 80 percent of the endocrine cells make serotonin the other source is serotonin-containing nerve cells within the enteric nervous system so it is a neurotransmitter and an endocrine substance in the gut it's very important in feeling pain in the gut it's very important in triggering”