So when one thinks of serotonin, one may think of happy and pleasurable thoughts. For the most part they would be right, in that serotonin is most commonly thought of as a neurotransmitter in the central nervous system. But, the brain is not the major site of synthesis in our body. Enterochromaffin cells in the intestinal mucosa are the predominate site of serotonin synthesis, storage and release. The serotonin that is released by these cells activates neural reflexes associated with intestinal secretion, motility and sensation in the gut.
The word serotonin was coined by Page and Papport in 1948 who extracted a compound from blood serum that had vasoconstrictive properties; they were looking at factors that cause hypertension. However, they didn’t know they were actually working on the same substance isolated by Vittorio Erspamer earlier in the 1930’s. He isolated this compound from the intestine, and he called it “enteramine”.
The role of serotonin in the gut is critical as a signalling molecule and recent evidence strongly suggests that altered serotonin signalling has a fundamental role in the pathophysiology of many common gastrointestinal disorders. Serotonin is released in the gut when there is food, causing the intestine to contract. If there is an irritant in the gut lumen, more serotonin is released to make the gut move faster in order to expel its contents.
The role of serotonin in the central nervous system as well as in the digestive tract gives us a molecular basis for the old adage “we are what we eat”.
