Types of Neurotransmitters Secreted by Enteric Neurons In an attempt to understand
better the multiple functions of the gastrointestinal enteric nervous system, research workers the world
over have identified a dozen or more different neurotransmitter substances that are released by the
nerve endings of different types of enteric neurons. Two of them with which we are already familiar
are (1) acetylcholine and (2) norepinephrine. Others are (3) adenosine triphosphate, (4) serotonin, (5)
dopamine, (6) cholecystokinin, (7) substance P, (8) vasoactive intestinal polypeptide, (9) somatostatin, (10) leu-enkephalin, (11) met-enkephalin, and (12) bombesin. The specific functions of many of these
are not known well enough to justify discussion here, other than to point out the following.
Acetylcholine most often excites gastrointestinal activity.
